Stormwater Flood Modelling Specifications

Transcription

1 Strmwater Fld Mdelling Specificatins Nvember 2011

2 Auckland Cuncil Strmwater Fld Mdelling Specificatins Dcument Versin Cntrl Dcument Versin N. Dcument Versin Date Dcument Status Details Versin 1.0 July 2011 Draft fr Internal Review Versin 2.0 September 2011 Versin 3.0 Octber Nvember 2011 First Auckland Cuncil Versin t be used fr catchment planning mdelling cntracts Secnd Auckland Cuncil Versin t be used fr catchment planning mdelling cntracts Change t initial tpgraphical survey requirements fr mdel build Nvember 2011 Page i

3 Table f Cntents Page N. 1. INTRODUCTION BACKGROUND STORMWATER MODELLING OBJECTIVES AND PURPOSES STORMWATER MODELLING ACTIVITIES AND SCOPE SYSTEMS AND PLANNING STORMWATER FLOOD MODELLING PROCESS Rapid Fld Hazard Assessment Determinatin f the Mdel Extents Review and Quality Assessment f Existing Data Finalise Mdel Extents and Mdel Schematisatin Mdel Extents and Data Quality Assessment Reprt Survey t Obtain Additinal Data Mdel Build and Test Mdel Validatin / Calibratin System Perfrmance Assessment Optins Assessment PROGRAMMING AND MILESTONES RECOMMENDED SOFTWARE OWNERSHIP NAMING CONVENTION DEFINITION OF MODEL EXTENTS INFORMATION AVAILABLE PREVIOUS MODEL REVIEW RAPID FLOOD HAZARD ASSESSMENT MODELLING MODEL EXTENTS Hydrlgical Mdel Extents Hydraulic Mdel Extents REVIEW AND QUALITY ASSESSMENT OF EXISTING DATA DATA REQUIREMENTS FOR MODEL BUILD Manhle Data Pipe Data...21 Nvember 2011 Page ii

4 4.1.3 Basins and Other Strage Areas Pumps and Other Ancillary Structures Tpgraphical Data Operatinal Data Hydrmetric Data Infrmatin Prvided by the Client DATA QUALITY ASSESSMENT Asset Data Assessment Hydrmetric Data Assessment DATA COLLECTION AND SURVEY REQUIREMENTS Asset Data Survey Requirements Tpgraphical Data Survey Requirements MODEL BUILD AND TEST MODEL BUILD DATA SOURCE TAGGING HYDROLOGICAL MODEL Rainfall-Runff Mdelling Methdlgy Hydrlgical Mdelling Parameters D HYDRAULIC MODEL D Hydraulic Mdelling Methdlgy D Hydraulic Mdel Schematizatin Sakage Representatin in 1D mdel Energy Lsses in 1D mdel D HYDRAULIC MODEL D Hydraulic Mdelling Methdlgy D Hydraulic Mdel Schematisatin Sakage Representatin in 2D mdel Energy Lsses in 2D mdel D/2D COUPLED HYDRAULIC MODEL D/2D Cupled Mdel Setup Cupling f 1D/2D Mdels INITIAL MODEL TESTING Running The Mdel Layut Representatin Instability Tests Sensibility Test Mass Balance Checks...64 Nvember 2011 Page iii

5 6. MODEL VALIDATION / CALIBRATION MODEL VALIDATION / CALIBRATION REQUIREMENTS MODEL VALIDATION / CALIBRATION PROCEDURE Sensitivity Analysis Mdel Validatin / Calibratin t Mnitring Data Mdel Validatin t Histrical Fld Incidents MODEL VALIDATION TO MIKE21 MODEL RESULTS MODEL RESULTS COMPARISON TO PREVIOUS MODEL SYSTEM PERFORMANCE ASSESSMENT SYSTEM PERFORMANCE SCENARIOS Design Strm Mdel Scenaris Land Use Develpment Mdel Scenaris Tailwater Level Mdel Scenaris Simulatin Matrix Simulatin Perid and Results Saving Time WATER BALANCE OF THE CATCHMENT CAPACITY OF THE EXISTING PRIMARY PIPE SYSTEM CAPACITY OF THE EXISTING CULVETS AND BRIDGES FLOODPLAIN MAPPING D and 2D Fldplain Mapping Buildings at Risk f Flding FLOOD HAZARD MAPPING Fld Hazard Classificatin Methdlgy D and 2D Fld Hazard Mapping FLOOD DAMAGE ASSESSMENT OPTIONS ASSESSMENT OBJECTIVES OPTIONS MODELLING AND ASSESSMENT Optins Identificatin and Mdel Runs Optins Assessment Recmmended Optins DELIVERABLES AND QUALITY SYSTEMS REPORTING SCHEDULE...87 Nvember 2011 Page iv

6 9.2 QUALITY SYSTEMS Mdel Lg-Bk Metadata Quality Assurance and Quality Checks MODEL EXTENTS AND DATA ASSESSMENT REPORT MODEL BUILD AND SYSTEM PERFORMANCE REPORT MODEL OPTIONS ASSESSMENT REPORT REFERENCES APPENDICES Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Naming Cnventin Mdel Lg-Bk Mdel Build Metadata Mdel Review Template Mdel Extents and Data Assessment Reprt Requirements Mdel Build and System Perfrmance Reprt Requirements Mdel Optins Assessment Reprt Requirements Nvember 2011 Page v

7 GLOSSARY 1-D One dimensinal means nly ne spatial dimensin is cnsidered i.e. the hrizntal directin f flw. 2-D Tw dimensinal means tw spatial dimensins are cnsidered i.e. the hrizntal and lateral directins f flw. AC Annual Exceedence Prbability (AEP) Average Recurrence Interval (ARI) Catchment Climate Change CRS Curve Number (CN) Design Strm Design Flws Drainage System Existing Develpment (ED) Energy Grade Line (EGL) Energy Lss Fldplain Fld Sensitive Area Freebard Auckland Cuncil. The prbability that a given rainfall event r flw rate will be exceeded in a single year. Average perid f time between rainfall events r flw rates which exceed a certain magnitude. An area f land draining by frce f gravity int a stream r watercurse at a given lcatin. Climate change resulting frm glbal warming due t greenhuse gas emissins. MOUSE mdelling feature t assign link crss-sectins. Defines the shape f the rainfall-runff relatinship and varies frm 0 (n runff) t 100 (cmplete rainfall). The rainfall event calculated frm histrical recrd that can be expected fr a specific AEP r ARI. The flws estimated frm varius design strms, selected as a basis fr the design f wrks in watercurses and catchments. The netwrk f pipes, streams, pen watercurses and secndary verland flw paths which carry flw within a catchment. The current land use develpment within the catchment. The ttal energy f flw at a given lcatin, it is the sum f the elevatin head, the pressure head, and the velcity head. Energy r head lss ccurs due t frictinal resistance, cntractin and expansin at entrance and exit, change in flw directin, change in elevatin and change in crsssectin. The plan extent f flding in a given AEP r ARI strm. The plan extent f flding fr 500mm (freebard) abve the 100-year ARI fld levels. Design margin t allw fr factrs mitted in the verall design (e.g. uncertainties in fld level estimatin, wave actin, lcalised water level variatins). Nvember 2011 Page vi

8 GIS Gegraphical Infrmatin System. Hydraulic Grade Line (HGL) Hydrgraph Hydrlgical Sil Grup Initial Abstractin (Ia) LiDAR Link Manning s n Maximum Prbable Develpment (MPD) Nde Overland Flw Primary Drainage System Runff Secndary Drainage System Subcatchment Time f Cncentratin Tpgraphy A line cinciding with the level f flwing water in an pen channel. In a clsed cnduit flwing under pressure, the HGL is the level t which water wuld rise in a vertical tube at any pint alng the pipe. It is equal t the energy grade line (EGL) elevatin minus the velcity head. A graph illustrating the variatin f flw with time. Sil classificatin (A, B, C, r D) accrding t infiltratin rate, where A is very high infiltratin and D is very pr infiltratin. Rainfall lsses ccurring befre runff begins, includes water retained in surface depressins, intercepted by vegetatin, evapratin, and infiltratin. Light Detectin and Ranging (Aerial Laser Survey). Link represents strmwater drainage pipes, culverts, bridges, stream channel reaches r verland flw paths. Manning s rughness cefficient t accunt fr energy lsses due t frictinal resistance t flw. The ultimate future land use develpment which will prceed up t the maximum permitted under the current District Plan. Nde represents the drainage system attributes such as manhles, inlets, utlets, junctin between pen channels, pnds. Strmwater runff travelling dwnhill ver the surface f the grund alng the path f least resistance twards streams and watercurses r the sea. The pipes, stream netwrks and pen watercurses that carry the main, frequent strmwater within a catchment. The fractin f rainfall which runs ff the land surface t the drainage system. The verland flw path that carry the excess strmwater when the capacity f the primary drainage system is exceeded. A smaller sub-area f the catchment draining t a watercurse. Time fr a water particle t travel frm the hydraulically mst distant pint f a catchment t the utlet. MOUSE mdelling feature t define natural channels which allws fr variable crss-sectins, Manning s rughness and slpe fr a channel between ndes. TP108 Auckland Reginal Cuncil Technical Publicatin 108. Unit Hydrgraph Hydrgraph prduced by a unit depth f rainfall excess falling unifrmly in time and space ver a unit area catchment. Nvember 2011 Page vii

9 1. INTRODUCTION 1.1 Backgrund The s are t be used fr all strmwater mdelling assciated with the catchment management planning prcess. Any deviatin frm the methds cntained in this specificatin must be agreed in writing with the Team Leader Strmwater Hydraulic Mdelling. This technical specificatin fr strmwater fld mdelling utlines Auckland Cuncil's (AC) requirements fr the planning and management f strmwater drainage mdelling. These specificatins define hw all strmwater mdelling prcesses shuld be carried ut and reprted n, including such aspects as data cllectin, mdel build, validatin, system perfrmance, ptins and reprting. The specificatin cntains directin, advice, and additinal infrmatin. Additinal infrmatin and advice are indented and have a different fnt clur. Any advisry ntes within the specificatin are als italicised. The additinal infrmatin helps t explain the directin given while the advice cntains ther infrmatin which the mdeller may find helpful. The current versin f the specificatin cntains sectins which are sftware specific. Sme f the terms used are prprietary t the sftware. The mdeller while being unable t cmply fully with the specificatin shuld cmply with the intent f the specificatin. If any dubt exists as t the intent f the specificatins clarificatin shuld be sught frm Auckland Cuncil. 1.2 STORMWATER MODELLING OBJECTIVES AND PURPOSES The primary bjectives f the strmwater catchment mdelling are: - T assess the current perfrmance f the strmwater drainage system in the catchment and identify where levels f service requirements are nt, r will nt be met T develp fld plain and fld sensitive area maps and t identify significant fld hazard areas including prperties with habitable flrs at risk f flding. T prvide a tl that will enable cmparative evaluatin f initiatives t mitigate flding T prvide a guide fr the management f strmwater issues in the catchment. T prvide a basis fr determinatin f actins t meet the AC strategic bjectives and level f service requirements. Nvember 2011 Page 8

10 T prvide a basis fr determining ptins t slve flding issues identified in the catchment, including an assessment f all feasible ptins and a descriptin f the recmmended wrks required. T prvide a supprting dcumentatin fr the netwrk cnsent applicatins. The purpse f the strmwater fld mdelling specificatins prvided in this dcument is t prvide a basis fr develping a detailed mdel which is suitable fr catchment-wide detailed analysis, planning and design. 1.3 STORMWATER MODELLING ACTIVITIES AND SCOPE The strmwater catchment mdelling prcess invlves investigatin f the strmwater quantity issues in the catchment as utlined belw: An assessment f the effect f develpment n the strmwater drainage system and the catchment hydrlgy. The current level f urban develpment and maximum prbable develpment scenaris will be cnsidered. Develpment f rainfall-runff mdels fr land use develpment scenaris with current and future design rainfall events nminated by AC. Develpment f mdels fr the strmwater drainage system; primary, piped, netwrk and secndary flw paths, fr the netwrk extent nminated by AC. Determinatin f the sensitivity f design fld flws and design water-levels against varying mdel parameters fr the specified scenaris nminated by AC. Validatin f predicted flws and water-levels by cmparative referencing with gauged and reprted infrmatin, where available. An assessment f the capacity f the existing mdelled drainage netwrk system t cnvey runff frm current and future design rainfall events nminated by AC and fr specified land use develpment scenaris An assessment f the level f service prvided cmpared t the desired level f service, and the identificatin f netwrk sectins that d nt prvide the necessary level f service fr the specified scenaris nminated by AC. Analysis and tabulatin f design flws and water levels fr land use develpment scenaris with current and future design rainfall events nminated by AC. Determinatin f the extent f flding and habitable flrs at risk f flding fr rainfall event and develpment scenaris specified by AC. Develpment f fld plain and fld sensitive area maps fr rainfall events and develpment scenaris specified by AC. Nvember 2011 Page 9

11 Where included in the scpe f wrks, an assessment f varius feasible ptins and the identificatin f a preferred system imprvement wrks that will alleviate flding issues identified within the catchment. 2. SYSTEMS AND PLANNING 2.1 STORMWATER FLOOD MODELLING PROCESS In this specificatin hydrlgical/hydraulic mdelling has been brken int elements fllwing the general prcedure fr mdel build, mdel validatin, system perfrmance, and mdel applicatin and as illustrated in Figure Rapid Fld Hazard Assessment Where included in the scpe f services a Rapid Fld Hazard Assessment is t be undertaken t infrm investigatins in the fllwing sectins Determinatin f the Mdel Extents Using available data and infrmatin the hydrlgical extents (including sub catchments) and the hydraulic extents t be mdelled shuld be determined and pltted. A draft hydraulic mdel schematic is t be prepared prpsing mdelling methdlgies fr the varius areas f the catchment Review and Quality Assessment f Existing Data Existing Asset and Hydrmetric data that will be used t build and run the hydrlgical and hydraulic mdels is t be reviewed and assessed fr its adequacy and accuracy against the requirements f the prject. A draft assessment f data quality is t be prepared Finalise Mdel Extents and Mdel Schematisatin A meeting is t be held with the client t agree n the mdel extents and n an apprpriate hydraulic mdel methdlgy schematic. A review f available data quality shuld be used t agree n where data gaps are critical and survey t btain missing data is required Mdel Extents and Data Quality Assessment Reprt Fllwing this meeting a Mdel Extents and Data Assessment Reprt is t be prepared and shuld include: Descriptin f the agreed Mdel Extent and Mdel Schematic. The results f a detailed assessment f the adequacy and reliability f available data in the cntext f the agreed hydraulic mdel schematic. Nvember 2011 Page 10

12 Identificatin f, and specificatin fr, additinal data needing t be btained t enable the hydrlgical and hydraulic mdels t be built t the agreed schematic and t Auckland Cuncil specificatin. Identificatin f lcatins where gd quality data is nt available but where it has been agreed that estimatin will nt impact significantly n the utputs f the mdel. Recmmended methdlgy fr cllectin f additinal data Survey t Obtain Additinal Data The survey t btain additinal data may be included in the scpe f the mdelling cntract r may be undertaken under a separate cntract. The Specificatin fr survey data t be btained is set ut in a separate dcument Mdel Build and Test The mdel shall be built using the assembled asset data and the agreed apprach t data estimatin where gd quality data is nt available. Relevant mdel build metadata shall be prepared. The mdel will be subject t a number f cnsistency checks t ensure infrmatin is crrect and interpreted crrectly. Finally, the mdel will be tested fr stability and ther accuracy requirements Mdel Validatin / Calibratin Because f limited available mnitring gauge data within Auckland Cuncil catchments a detailed calibratin f hydrlgical and hydraulic mdel may nt be pssible. In general standard hydrlgical and hydraulic parameter values based n Auckland Cuncil mdelling specificatins will be used and if measured gauging data is available the hydraulic mdel will be validated by cmparing the mdel results with the measured gauging data withut changing the hydrlgical and hydraulic mdel parameter values. If mdel validatin des nt achieve the required validatin acceptance criteria, mdel parameters may be changed t match measured data if a higher level f cnfidence exists in the measured data and large strm events ( 10 year ARI) are available. Mdel calibratin will nly be carried ut after discussin/agreement with Auckland Cuncil. Mdel will als be validated against available histrical fld incidents infrmatin System Perfrmance Assessment The validated mdel will be used as a base fr develping the land use develpment scenari mdels with current and future design rainfall events suitable fr system perfrmance assessment. Nvember 2011 Page 11

13 A Mdel Build and System Perfrmance Reprt shall be prepared, submitted and finalised which will include details f mdel build, mdel validatin and system perfrmance assessment. The system perfrmance assessment includes prductin f fldplains, fld sensitive areas, prperties at risk f flding, fld hazards, and fld damage Optins Assessment System imprvements will be necessary where the system perfrmance des nt reach nminated AC strmwater service standards. All feasible remedial wrks ptins will be systematically defined and assessed. Selected ptins will be assessed and sized in the mdel. An Optins Assessment Reprt shall be prepared, submitted and finalised. 2.2 PROGRAMMING AND MILESTONES The fllwing are significant milestnes; Prject Inceptin Mdel Extents and Data Assessment Reprt (draft, meeting and final) Mdel Build and System Perfrmance Reprt (draft, meeting and final) Optins Assessment Reprt (draft, meeting and final) Prject cmpletin. Thrughut the mdelling prcess hld pints are included t ensure the prject will deliver the required utcmes, see Figure 1. Nvember 2011 Page 12

14 Rapid Fld Hazard Assessment Data Availability and Quality Assessment Prduce Mdel Extents and Data Assessment Reprt Define Mdel Extents Mdel Extents & Reprt Review Survey MODEL BUILD Mdel Validatin Criteria Met Mdel Build & Test Yes N Meeting with AC Prduce Mdel Build Reprting and 1% AEP Fldplain Mdel Calibratin SYSTEM PERFORMANCE Mdel & Reprt Review Mdel update Apprved Mdel Build and System Perfrmance Reprt System Perfrmance Setup, Runs & Assessment (fldplain & fld hazard mapping) Fld Damage Assessment Prduce Mdel Build and System Perfrmance Reprt Mdel & Reprt Review Survey Buildings in Fldplains Any Predicted Issues N Yes Define Optins & Evaluate Prduce Mdel Optins Assessment Reprt OPTIONS CONCEPT DESIGN N Further Wrk Required Apprved Mdel Optins Assessment Reprt Mdel & Reprt Review = Hld Pints Nvember 2011 Page 13

15 Figure 1 Strmwater Catchment Fld Mdelling Prcesses 2.3 RECOMMENDED SOFTWARE The recmmended mdelling sftwares fr strmwater catchment management planning purpses are given belw: One-dimensinal Mdelling Sftware MIKE URBAN MIKE11 INFO WORKS 1D Tw-dimensinal Mdelling Sftware MIKE21 INFO WORKS ICM 1D-2D Cupled Mdelling Sftware MIKE FLOOD INFO WORKS ICM 2.4 OWNERSHIP All mdels develped and all assciated mdel build data is the asset and intellectual prperty f Auckland Cuncil. The mdel and any assciated data must be delivered in such a manner that allws the further develpment f the mdel. 2.5 NAMING CONVENTION The file and flder naming cnventin adpted is very imprtant. The flder and file naming cnventin, defined in Appendix A, is t be strictly fllwed thrughut the Prject. Nvember 2011 Page 14

16 3. DEFINITION OF MODEL EXTENTS Befre cmmencement f mdel building, a general understanding f the structure and layut f the strmwater drainage system shuld be acquired. At the early stages f the strmwater catchment mdelling study, hydrlgical extents (sub-catchments) and hydraulic extents (netwrk system) must be clearly defined, which will prvide the basis fr assessing the availability and quality f mdel build data and the need fr additinal data cllectin/survey requirements. 3.1 INFORMATION AVAILABLE All infrmatin held by AC and available fr the Prject shuld be cmprehensively listed in the Prject Brief. Infrmatin available may include; Technical Reprts Previus Catchment Management Studies Previus mdels (with dcumentatin) Strmwater asset plans, service utility plans GIS Cadastral land bundaries District Plan land use zning Strmwater management areas Strmwater catchment bundaries Impervius surface cverage Tpgraphical data (LiDAR grid and cnturs) Overland flw paths Peak verland flw rate tl (TP108 graphical methd) Strmwater catchments fr treatment devices Fldplain and fld hazard maps 2D mdel water level raster grid Depressin areas Strmwater issues register Building ftprints Rad classificatins Prperty infrmatin register GPS survey pints Sil types Nvember 2011 Page 15

17 Aerial phts Netwrk/asset data Manhles Pipes Ancillaries Open channels (flw paths, crss-sectins) Pipe cnditin Pnds/wetlands design reprts including as-built plans CCTV Fld incident reprts - Actinline recrds f flding and ersin cmplaints. Apprved Outfall Maps shwing the strmwater cnstraints. Strmwater capital wrks prject files and PIS (Prject Infrmatin System) infrmatin. Infrmatin will be prvided, upn request. Electrnic infrmatin will be prvided n suitable digital media. 3.2 PREVIOUS MODEL REVIEW At the cmmencement f the Prject, either by a Cnsultant, a sub-cntractr t a Cnsultant, r as cmmissined directly by AC, any previus mdel build and/r calibratin wrk already carried ut in the catchment shall be reviewed. The extent t which this previus mdelling can be used t meet the bjectives f the current study shuld be explred. 3.3 RAPID FLOOD HAZARD ASSESSMENT MODELLING The purpse f a Rapid Fld Hazard Assessment (RFHA) is t determine the areas which wuld be inundated if n pipe netwrk is available. This allws the mdeller t cncentrate the 1D and 2D mdelling detail in the areas f cncern. If the scpe f wrks includes a RHFA a digital elevatin mdel (DEM) will need t be develped frm the LIDAR data f the entire catchment area and then MIKE21 2D rain n grid apprach be used t prduce the 100 year ARI RFHA results. RFHA has been fund t be a valuable tl t prvide an indicatin f where mdelling effrts shuld be cncentrated and where mre detail may be required. The RFHA prvides a cnservative estimate f flding as it assumes that the pipes, culverts and catchpits are blcked. It defines the level f wrst risk f prperty flding issues within the catchment. It is recmmended t meet with the client fllwing the RFHA t discuss mdel schematisatin. It is als beneficial t meet with the peratinal staff t ensure that all areas f cncern are addressed. Nvember 2011 Page 16

18 The fllwing methdlgy shuld be used during develpment f the RFHA mdel: Develp a digital elevatin mdel (DEM) f the entire catchment area frm the LiDAR data as bathymetry fr 2D RFHA mdelling. Use a grid size f 2m x 2m (t be supplied by Auckland Cuncil). Identify significant bstructins t verland flw paths and ensure crrect representatin in the MIKE21 bathymetry. This can significantly affect the results and shuld be carefully cnsidered at the cmmencement f the prject. Use MIKE21 2D rain n grid lading apprach fr RFHA mdelling. Use future 100-year ARI design strm prfile (refer t Sectin 7.1.1) fr rain n grid lading apprach. Select Precipitatin n dry land in the Surce and Sink parameters dialg. Multi-cell verlay can be used t reduce run times. The curse t fine grid rati shuld nt exceed 3. Select eddy viscsity frmulatin as flux based cnstant and specify a cnstant value = 0.02 dx 2 /dt [m 2 /s]. Select a cnstant Manning s rughness cefficient f 0.05 fr resistance. Select a value f 0.02 fr drying and 0.03 fr flding. Select a value f 0.5m RL fr dwnstream tailwater level bundary fr sea. Time step fr Rain n Grid lading apprach is typically arund 0.2 sec. The rapid fld assessment assumes the pipe netwrk is fully blcked. Select initial water level t be used fr RFHA mdelling as filled in all depressins f the mdel bathymetry. DEM mdificatins need t be undertaken fr bridges which are unlikely t blck. Buildings can be set t true land in the bathymetry. This is dependent n the extent f building bstructins within the catchment extent and is particularly relevant in highly develped area. Hazards shuld be determined in accrdance with Hazard Classificatin given in Sectin fr presentatin and determinatin f preliminary significant fld hazards. Identificatin f buildings within the preliminary significant fld hazard areas fr flr level and tpgraphical survey. Crss-sectins survey needs t be carried Nvember 2011 Page 17

19 ut fr the lw pint f the terrain, adjacent t the buildings where the predicted 100-year ARI MPD fld level + 100mm is abve the building flr level. 3.4 MODEL EXTENTS Hydrlgical Mdel Extents Catchment Bundary: Strmwater catchment bundaries are stred in the AC crprate database. The preliminary catchment bundary prvided by AC shall be checked, and mdified as required. Any errrs r discrepancies in the preliminary catchment bundary prvided by AC shall be identified and dcumented. In sme cases a site visit shuld be carried ut in rder t verify the catchment bundary nsite. The catchment bundary shall be develped in GIS. Sub-Catchment Delineatin: Sub-catchment bundaries shall be delineated, by taking int accunt; Prject bjectives (i.e. specific level f mdelling e.g. strategic planning, cnsent, catchment management planning and design); tpgraphy i.e. land elevatin, cnturs; strmwater drainage pipe netwrk (public & private); verland flw paths; sil types; District Plan land use zning (current and future); prjected grwth areas (based n current District Plan); strmwater management areas; knwn strmwater-related issues; flw bstructins (eg. embankments, knwn pipe cnstrictins); In general sub-catchment shuld be delineated based n tpgraphy i.e. land elevatin, cnturs r DEM. Hwever sme sub-catchments may need t be adjusted cnsidering strmwater drainage pipe netwrk (public & private) r in case f where sub-catchment bundary crsses building ftprints. Once finalised the catchment bundary is t be develped in GIS. Nvember 2011 Page 18

20 The mst upstream sub-catchments (arund the catchment bundary) shall be between 2.0 and 3.0 ha in size, hwever, t include any knwn areas f flding smaller sub-catchments can be used. All ther internal sub-catchments shall be between 0.5 and 3.0 ha. Sub-catchments shuld be assigned t the drainage netwrk nde t which the majrity f runff in the physical envirnment will flw. In general sub-catchment runff hydrgraph shuld be assigned at r near mid-pint f the drainage path within the sub-catchment. Calculatin f the sub-catchment areas and ther sub-catchment attributes (length, slpe, impervius area) shall be made frm GIS Hydraulic Mdel Extents Determinatin f the hydraulic mdel extents shuld take int accunt: Prject bjectives; sub-catchment delineatin; verland flw paths; knwn strmwater-related issues; prjected grwth areas (based n current District Plan); The results f a Rapid Fld Hazard Assessment (where included in the scpe f wrks.) The hydraulic mdel extent shuld be cnsistent with the mdelled sub-catchment bundaries and shuld include all public pipes with a diameter equal t, r greater than, 300 mm. Open channel ndes shall nt be mre than 50m apart. The netwrk shuld extend far enugh dwnstream t take accunt f any hydraulic cnditin that may affect the perfrmance f the system (e.g. utlets restricted by stream r sea-levels). Where there is interactin with a stream then it may be apprpriate t incrprate the stream in the mdel at an apprpriate level f cmplexity, which shuld be clearly defined. Any ut-f-catchment inflws shall be identified. Site visits shuld be carried ut where uncertainties as t catchment bundary lcatin r netwrk cnnectivity are unable t be reslved frm desktp study. Details f hydrlgical and hydraulic mdel extents including their basis, review f any previus mdel available and details f rapid fld hazard assessment mdelling shall be utlined in the Mdel Extents and Data Assessment Reprt (refer t Sectin 9.3). Nvember 2011 Page 19

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22 4. REVIEW AND QUALITY ASSESSMENT OF EXISTING DATA The data set required t develp hydrlgical and hydraulic mdels is generally a cmpsite f existing data, frm varius surces, and additinal data that needs t be cllected in a prject specific survey. This sectin details the requirements fr the: (i) (ii) (iii) Acquisitin, review, frame-wrking and scrubbing f existing data. Assessment f the quality and adequacy, f existing data; and Prvisin f a detailed schedule fr additinal data needed t be cllected fr the develpment f hydrlgical and hydraulic mdels that will cmply with this specificatin. 4.1 DATA REQUIREMENTS FOR MODEL BUILD The mdel build prcess shall be primarily based n AC s Gegraphical Infrmatin Systems (GIS) database. In general, mst manhle and pipe data and their cnnectivity will be available frm AC s recrds Manhle Data Manhle (nde) data needed t build a hydraulic mdel includes: Manhle ID must be unique. Shall be the GIS pint ASSET ID. Crdinates (Easting, Nrthing) Manhle diameter Manhle invert level Manhle grund level (lid level) Benching (if present) Spill level (if present) Pipe Data Pipe/culvert data needed t build a hydraulic mdel includes: Pipe/Culvert ID (ASSET ID). Upstream manhle/inlet ID (ASSET ID) Dwnstream manhle/utlet ID (ASSET ID) Pipe/Culvert diameter (r ther sizing dimensin) Upstream invert level Dwnstream invert level Material Basins and Other Strage Areas Basin data needed t build a hydraulic mdel includes: Nvember 2011 Page 21

23 Basin ID must be unique Crdinates (Easting, Nrthing) Invert level Representative Level Area (surface) relatinship Representative Level Area (crss-sectinal) relatinship Outlet invert level, size and shape Grund level Overflw level and dimensin Pumps and Other Ancillary Structures Pumps and ther ancillary structures that may have a significant effect n the flw cnditins shall be included in the mdel. AC will supply all available ancillary data Tpgraphical Data Typically, tpgraphical data will cnsist f cnturs and spt levels based n LiDAR (Light Detectin and Ranging) r ther survey techniques. A tpgraphical surface may exist in GIS in the frm f a GRID (square grid with representative level fr each cell) r a TIN (Triangulated Irregular Netwrk) r spt level survey. Auckland Cuncil will supply all available electrnic tpgraphical data. Tpgraphical data are required fr sub-catchments delineatin including estimating sub-catchment attributes and incrprate tpgraphical features int the mdel, namely, verland flw paths, pen channels and fldplains, and strage detentin/ retentin/ wetland areas. Tpgraphical data may als be used t supplement missing manhle grund-level data Operatinal Data A meeting is t be arranged the relevant Auckland Cuncil Strmwater Operatins t ensure that all relevant peratinal infrmatin held by peratins staff is incrprated int the mdel build including: Netwrk infrmatin that is at variance with that shwn n GIS and recrded in the Asset Register. Operatinal issues that have a significant impact n strmwater drainage system perfrmance. Any fld incidents, ther than thse caused by temprary blckages, that have been bserved by, r reprted t, peratinal staff. Operatins staff can als prvide valuable nsite validatin. Reprted fld incidents shuld be analysed t determine the lcatin and frequency f reprted flding in the catchment. These will be used fr mdel validatin. Infrmatin n blckage incidents shuld be btained fr the perid f any flw survey r where they are assciated with flding. Nvember 2011 Page 22

24 All infrmatin prvided by peratinal staff that is used in the mdel, including crrectins t the drainage system data, shuld be dcumented in the mdel reprt. Crrectins made t drainage system data shuld be separately reprted t cuncil Hydrmetric Data Rainfall, flw and water level data are the primary surce f infrmatin fr validatin f a strmwater drainage mdel. This data may be available frm a lngterm flw gauge in the catchment. If this is unavailable then shrt term flw gauging may be cnsidered. Every flw survey shuld include bth rain and flw gauges. Fr very small mdels, the cst f any ver-design f wrks may nt justify the cst f a flw survey. Fr large systems r where the cst implicatins n remedial wrk are significant then bserved flw data frm a flw survey may be necessary Rainfall Data Several fully peratinal permanent rainfall gauges within Auckland Regin have been installed. These gauges prvide five-minute and hurly rainfall depths. Rainfall time series data frm these rain-gauges can be requested frm Auckland Cuncil. The permanent rain-gauges may be supplemented by shrt-term rain-gauge installatin Flw and Water Level Data Lng term flw gauging using permanent flw gauges is the ideal surce f data fr use in strmwater mdelling investigatins. Auckland Cuncil has installed several permanent strmwater flw gauges in varius watercurses in the city. Water-level data are cllected every 5 minutes which are cnverted t flw via established rating curves. Flw and water level time series data frm these lng-term flw gauges can be requested frm Auckland Cuncil. The permanent flw gauges may be supplemented by shrt-term flw gauge installatin Tidal Data Strmwater runff frm each catchment finally discharges int the sea and the hydraulic cnditin f the drainage netwrk system is affected by the dwnstream tidal bundary cnditins. Tidal time series level data are required fr validatin f a strmwater drainage netwrk mdel and can be requested frm Auckland Cuncil Infrmatin Prvided by the Client Infrmatin held by Auckland Cuncil and pertinent t the investigatin and mdel develpment will be listed and made available. Infrmatin prvided may include any f the fllwing where available and deemed t be relevant: Technical Reprts Nvember 2011 Page 23

25 Previus Catchment Management Studies Previus mdels (with dcumentatin and metadata) Strmwater asset plans, service utility plans Strmwater Asset Register Manhles Pipes Ancillaries Asset cnditin Data Pnds/wetlands design reprts including as-built plans Stream Register Open channels (flw paths, crss-sectins) GIS Cadastral land bundaries District Plan land use zning Strmwater management areas Strmwater catchment bundaries Impervius surface cverage Tpgraphical data (LiDAR grid and cnturs) Overland flw paths Peak verland flw rate tl (TP108 graphical methd) Strmwater catchments fr treatment devices Fldplain and fld hazard maps 2D mdel water level raster grid Depressin areas Strmwater issues register Building ftprints Rad classificatins Prperty infrmatin register GPS survey pints Sil types Aerial phts Fld incident reprts Actin line recrds f flding and ersin cmplaints. Apprved Outfall Maps shwing the strmwater cnstraints. Strmwater capital wrks prject files and PIS (Prject Infrmatin System) infrmatin. Where previus mdelling and/r calibratin wrk has been carried ut in the catchment, and where specifically nted in the scpe f wrks fr a prject, an investigatin is t be carried ut int the extent t which this previus wrk can be used t meet the bjectives f the current study. Infrmatin will be prvided upn request. Electrnic infrmatin will be prvided n suitable digital media. Nvember 2011 Page 24

26 4.2 DATA QUALITY ASSESSMENT Asset Data Assessment A cmplete cnsistency check is t be carried ut n asset data prvided and the results clearly dcumented. Cnsistency checks shall include, but nt be limited t; Identificatin f missing attribute data; Lng-sectins f all branches shuld be pltted and reviewed, and all incnsistencies identified; pipes / channels with negative gradients; lcatins where pipe diameters decrease in the dwnstream directin; lcatins where pipe invert step up in the dwnstream directin; lcatins where manhle inverts are significantly lwer than utging pipe inverts; all elevated pipe sectins (grund-levels lwer than pipe-sffit); Missing r incnsistent netwrk cnnectivity (except fr pen channel sectins); Reverse rientatin pipes (thse fr which the TO and FROM nde ID s are in reverse rder in the crprate database) Manhles fr which the grund (lid) level is significantly different t LiDAR (where available) r frm ther available infrmatin surces. Missing imprtant culverts; Missing, incnsistent, r ambiguus data relating t ther imprtant ancillaries. Spreadsheet queries can be used t identify data anmalies. Hwever, data anmalies themselves can cause ther anmalies t be falsely identified. As such, rather than perfrming extensive spreadsheet queries, it is ften quicker t perfrm a basic query, jin the results int GIS and then perfrm a manual inspectin f the data Hydrmetric Data Assessment Befre any hydrmetric data can be used fr mdel validatin the data must be carefully assessed and dcumented. The fllwing assessments shall be carried ut: Review the flw gauging cntractr s Installatin and Final Reprt (where available), identify and reprt any issues that may be cnsidered t adversely affect the mdel validatin prcess r standard. Verify whether there is sufficient representative data fr mdel validatin. Checks shall include, but may nt be limited t; Verify the data quality (pr quality r missing rainfall r runff data); Nvember 2011 Page 25

27 Analyse the data fr cnsistency between rainfall and runff vlumes fr a sufficient number f events; Cmpare cnsistency between adjacent gauges r grups f gauges n the same branch t identify pssible incnsistencies in rainfall and runff vlume. Cnsider whether an bservatin is supprted by data frm mre than ne event and by evidence frm mre than ne gauge site (eg. an upstream r dwnstream gauge n the same branch). Explanatins shuld be prvided fr all data cnsidered unrepresentative. Verify the extent, adequacy and suitability f available data t enable mdel validatin as described in Sectin 6 f this dcument. Recmmend perids r events fr mdel validatin. Where available, a minimum f three events fr validatin, but preferably as many as practical, shuld be used. Estimate average recurrence intervals fr these events. Advise whether there is sufficient data t achieve adequate validatin, and if nt present quantitative evidence, and state any implicatins fr mdel utputs, accuracy, prject csts and timeframes. 4.3 DATA COLLECTION AND SURVEY REQUIREMENTS Asset Data Survey Requirements Fr each data anmaly, a suitable reslutin needs t be established. This may be a detailed standard survey, r slving minr issues during site visits e.g. pipe diameter r cnnectivity issues, r making assumptins t reduce the survey requirements Fr example, the fllwing assumptins r estimatins may be prpsed fr cnsideratin: Fr pipe anmalies such as dwnstream reductin in diameter, the pipe diameter may be assumed t be cnsistent with recrded sizes in the surrunding netwrk. Manhles fr which the lid levels are nt knwn may have their lid levels calculated frm LiDAR grund level. Manhles fr which the invert levels are nt knwn may have their invert levels calculated frm grund level and a depth value where this is knwn. Manhles fr which the invert levels are nt knwn may have their invert levels interplated frm surrunding ndes, if the invert level is knwn fr ne f the tw immediately upstream, and ne f the tw immediately dwnstream ndes. Manhles fr which the invert levels are nt knwn may have their invert levels taken frm pipe invert values in the AC crprate database. Pipe utlet invert levels may be estimated frm upstream pipe slpe r frm tpgraphical data such as LiDAR where the cverage is sufficient. Hwever, Nvember 2011 Page 26

28 invert levels f all missing pipe inlets, inlets/utlets f pnd/wetland utlet pipes and culvert inlets/utlets must be surveyed. There may be ther assumptins which may reduce the survey requirements. Any assumptins made must nt adversely affect the mdel perfrmance. All netwrk elements need t have detailed ntes assciated with them t identify data surces, and all assumptins made need t be clearly dcumented. The survey data must be checked befre it is used in the mdel and must be updated in Auckland Cuncil crprate asset register Tpgraphical Data Survey Requirements Where tpgraphical data based n LiDAR survey r ther survey techniques are cnsidered nt sufficiently accurate t describe the crss-sectin, including natural and engineered pen channels, then surveyed crss-sectin data will be required. In general LiDAR tpgraphic data based n Arial Laser Survey technique des nt cntain grund pints belw water as laser can nt penetrate thrugh water. Therefre crss-sectin survey f the lw flw channel will be required fr perennial streams. Buildings identified within the preliminary significant fld hazard areas frm rapid fld hazard assessment mdelling shuld be listed fr flr level survey (habitable and nn-habitable flrs). Crss-sectins survey needs t be carried ut fr the lw pint f the terrain, adjacent t the buildings where the predicted 100-year ARI MPD fld level + 100mm is abve the building flr level. Surveyed crss-sectins shall be used fr 1D pen channel flw mdel and updating the bathymetry fr 2D free-surface flw mdel where needed. Maps shwing the lcatins f buildings and the crss-sectins which need t be surveyed shuld be prepared. Details f mdel build data availability and assessments, data cllectin and survey requirements including maps shall be utlined in the Mdel Extents and Data Assessment Reprt (refer t Sectin 9.3). Nvember 2011 Page 27

29 5. MODEL BUILD AND TEST This sectin details the mdel building prcesses based n the data prvided, cllected and the agreed apprach t data estimatin where gd quality data are nt available. The mdel will be tested fr stability and ther accuracy requirements. 5.1 MODEL BUILD DATA SOURCE TAGGING The surce f all imprtant mdel build data shall be tagged in MIKE URBAN data recrd cmments blck during mdel develpment prcess. Data surces and all assumptins shuld be clearly dcumented as mdelled data recrd cmments. The mdel build data tagging infrmatin shall becme the metadata which will be prepared in a spreadsheet and accmpany the mdel upn delivery. Detailed prcedures fr preparing metadata are discussed in Sectin The mdel build data shall include at least the fllwing attributes; Sub-catchments pervius/impervius area, parameter values; Ndes invert levels, grund levels, diameter, strage table, energy lss; Links diameter, width/height, crss-sectin, rughness material, upstream and dwnstream invert levels; Structures invert levels, width, crss-sectin, passive flw regulatins; Pssible surces culd include cuncil GIS, survey, derived frm ther data, e.g. LiDAR cnturs r raster grid, derived frm interplatin, extraplatin, assumptin, parameter values assigned frm literature, ARC TP108 guidelines, AC mdelling specificatins. 5.2 HYDROLOGICAL MODEL Rainfall-Runff Mdelling Methdlgy Hydrlgical mdelling will be based n the guidelines fr strmwater rainfall-runff mdelling utlined in the ARC s Technical Publicatin N. 108 (ARC, 1999). The TP108 apprach has been frmulated fr deriving design flw (peaks and vlumes) as a result f design strms. It can be applied t urban and rural areas and is apprpriate fr investigating the effects f land use change, fr example urbanisatin. The basic assumptin in the design strm apprach is the rainfall f a given ARI results in runff f the same ARI Nvember 2011 Page 28

30 The prcedure and restrictins identified within TP108 shall be fllwed; All significant strage (in channel r within fldplain) shall be included in the hydraulic mdel and nt lumped int the TP108 rainfall-runff mdel. Each sub-catchment shall be split int an impervius and a pervius prtin. Each prtin shall be mdelled separately but cnsidered as the same subcatchment, i.e. bth prtins shall flw t the same nde and their areas shall sum t the ttal sub-catchment area. Each sub-catchment shall be laded directly t the primary drainage netwrk. There shall be n free ends i.e. all upstream ndes must have a catchment laded t them Hydrlgical Mdelling Parameters The TP108 methdlgy uses tw rainfall lss parameters i.e. SCS Curve Number (CN) and Initial Abstractin (Ia) t describe rainfall lsses and runff timing parameter i.e. lag time r time f cncentratin t describe runff ruting prcess which prvides attenuatin and lag within the catchment. TP108 parameters (Curve Number, initial abstractin, lag-time, time f cncentratin and 24 hur design rainfall depth) shall be estimated in accrdance t the TP108 prescribed apprach. All lcal infrmatin, knwledge and experience must be used in cnjunctin with land use and sil type maps fr estimating Curve Number fr pervius area. Available impervius surface layer shall be used t estimate the impervius areas fr each sub-catchment fr the existing develpment (ED) scenaris. The impervius areas fr each sub-catchment fr the maximum prbable develpment (MPD) scenaris shuld be estimated based n current District Plan maximum allwable permitted impervius areas fr varius land uses. In general fr Recreatin land use, a 10% allwable maximum permitted impervius areas shuld be used and fr Rad land use, a 90% allwable maximum permitted impervius areas shuld be used fr estimating MPD impervius areas. If the estimated MPD impervius area fr any sub-catchment is less than the ED impervius area, then the ED impervius area shuld be used as the MPD impervius area fr that sub-catchment. Nvember 2011 Page 29

31 5.3 1D HYDRAULIC MODEL D Hydraulic Mdelling Methdlgy The hydraulic cmputatin f ne-dimensinal mdel is based n numerical slutin f basic 1D free surface gradually varied unsteady flw equatins (knwn as Saint Venant Equatins). The derivatin f Saint Venant equatins (equatins f cnservatin f mass and mmentum) are based upn the fllwing assumptins: The flw is apprximately ne-dimensinal i.e. the velcity is averaged ver the crss sectin and the transverse water level acrss the sectin is hrizntal. The wave lengths are large cmpared t the water depth i.e. the streamline curvature is small and thus vertical acceleratins can be neglected, hence the pressure field is assumed hydrstatic. The effects f bundary frictin and turbulence can be accunted fr thrugh resistance laws analgus t thse used fr steady unifrm flw. The average channel bed slpe is small s that the csine f the angle it makes with the hrizntal may be taken as unity. The water is incmpressible and hmgeneus, i.e. negligible variatin in density. Flw in a strmwater drainage pipe is assumed t be 1D in which the velcity is cnstant vertically and hrizntally at each sectin but varies with distance alng the pipe. Althugh flw in natural watercurses is never truly 1D, fr many cases this simplificatin prduces acceptable results. Hwever, fr cases where flw can clearly nt be described by ne dimensin (e.g. spreading flws n wide fldplains where there are large lateral variatins in the velcity field), a 2D mdel might be needed t accurately mdel the flw field. 1D hydraulic mdels usually have capability t simulate flws thrugh a large range f hydraulic structures e.g. bridges, culverts, weirs, gates, sluices. At structures the mmentum equatin is replaced by an energy equatin t slve the flw variables. In general the energy equatin is used when an accurate estimate f the energy lsses is available and the mmentum equatin is used when an accurate estimate f the frces is available. The mass-mmentum cuple f cnservatin laws are applicable t bth discntinuus (e.g. at hydraulic jumps) and cntinuus flw situatins whereas the mass-energy cuple is nt, nly applicable t cntinuus flw situatin. Nvember 2011 Page 30

32 D Hydraulic Mdel Schematizatin A typical urban strmwater drainage system cnsists f tw main hydraulic cmpnents; the primary drainage system, cmprising f the frmal strmwater drainage system made up f the pipe and pen channel netwrk, and the secndary drainage system, cmprising f the verland flw paths. These tw systems are linked by a number f weirs/rifices, as described belw. The hydraulic mdel shall realistically represent the drainage system and accunt fr ptential surcharging due t an inadequate netwrk size. This includes the fllwing key aspects; Strage: Inline and abve grund strage must be realistically represented; Cnveyance: The cnveyance f the primary and secndary system must be realistically represented, including apprpriate energy lsses (fr example channel resistance, lcal lsses at manhles and at culvert/pipe inlets and utlets); Hydraulic Cntrls: All hydraulic cntrls must be identified and realistically represented, including apprpriate lcal energy lsses (fr example inlet cntrl at the basin utlet, r weir cntrl fr a rad vertp). The asset data prvided r cllected within the agreed mdel extent shall be used t build the primary and secndary drainage system, including all pipes, manhles, pen channels, verland flw paths and fldplains, strage detentin/retentin/ wetland areas and ther ancillary structures Schematizatin f Primary Drainage System Pipe Netwrk: The pipe netwrk shall be cnstructed frm the asset data prvided alng with any ther data surces such as survey. Any estimated infrmatin in the mdel will be agreed with Auckland Cuncil. The mdel shall be based n the assumptin that all pipes, channels, culvert inlets and utlets are capable f achieving their respective discharge capacities and are unaffected by partial r ttal blckage. Additinal strage vlume t accunt fr the strage vlumes in any unmdelled reticulatin shuld be cnsidered nly where the unmdelled strage is significant, eg where the tpgraphy is flat. The methd and use f unmdelled strage must be discussed and agreed with Auckland Cuncil prir t being included in the mdel. Open Channels: Open channels may be mdelled in tw ways: CRS link A CRS link is the simplest apprach. It assumes that the link sectin is prismatic (cnstant sectin shape and slpe in the flw directin). The advantage Nvember 2011 Page 31

33 f a CRS link is that it is simple; the disadvantage is that it may nt be representative. A CRS link shall be used when the sectin is apprximately prismatic. In general CRS link shall be used fr certain verland flw paths with standard default crss-sectins where flw is less than 2.0 m 3 /s. Natural link A natural link uses the MIKEURBAN tpgraphy feature, which is a mre cmplex but mre representative apprach and which allws fr nnprismatic sectin shapes (i.e. sectin shape r slpe changing in the dwnstream directin). Natural links shall be used fr crss-sectins that change shape in the directin f flw. In general natural links shall be used fr all pen water curses and certain ver land flw paths where flw is greater than 2.0 m 3 /s. The gemetry f pen channel sectins shall be defined in the MIKE URBAN crsssectin editr as pen X-Z-R-M type, where X is the hrizntal axis (representing width) and Z is the vertical axis (representing depth r level), R is the relative resistance factr (Manning s n value can als be assigned) and M is the marker. This crss-sectin type allws t specify pen channel systems t have variable Manning s n rughness values acrss a crss-sectin which is necessary fr cmpund pen channel sectins. The markers are used in MIKE11 and MIKE URBAN fr splitting the cmpund channel crss-sectin int parallel channels. Channel cnveyance fr a cmpund channel is estimated based n parallel channel analysis which sums up the cnveyance f the parallel channels t estimate the ttal cnveyance f the cmpund channel sectin. These parallel channels are defined as thse parts f the cmpund channel sectin where the rughness value remains cnstant. Manning s n rughness values shuld be assigned distributed acrss the pen channel crss-sectin raw data in 1D mdel (MIKE URBAN and MIKE11). A glbal Manning's n rughness value f 1.0 shall be used. In MIKE11 Ttal Area, Hydraulic Radius shall be used as radius type and in case f defining Manning s n rughness values in crsssectin raw data will verrule any rughness values defined in HD parameter file. The pen channel sectins may be derived frm: Standard default crss-sectin shapes fr certain verland flw paths Crss-sectins generated frm LiDAR cnturs/grid data Surveyed crss-sectins LiDAR tpgraphic data based n Aerial Laser Survey technique des nt cntain grund pints belw water as laser can nt penetrate thrugh water. Crss-sectins derived frm LiDAR data fr perennial stream shuld include the lw flw channel based n survey r site visits. Nvember 2011 Page 32

34 Crss-sectins shall be defined alng the pen channel links at 30 50m intervals depending n changes in channel width, area, plan frm and rughness. Extent f crss-sectins shuld be at least 1m abve the predicted maximum 100yr ARI fld levels. N crss-sectin shuld include glass walls. Manhle and Channel Junctin Ndes: All manhles which lie within the netwrk extent shuld be mdelled. The manhle netwrk shall be cnstructed frm the asset data prvided, btained r estimated. Where manhle diameter infrmatin is nt available, shall be based n AC Infrastructure Design Standard Manual. In general all manhle ndes shuld be mdelled as spilling ndes unless a weir r rifice is used t cnnect t the verland flw paths then the nde shuld be sealed. Mdel results shuld be checked whether any nde is spilling, if a manhle spills a weir r rifice shuld be used t cnnect manhle t the verland flw paths and manhle nde shuld be sealed. The invert level f the channel junctin nde shuld be same as the invert f the crss-sectin assigned at the nde and the grund level shuld be abve the extent f the crss-sectin assigned at the nde. In case f channel junctin ndes spilling, the grund levels f the ndes shuld be elevated. In case f pipes discharging int pen channels r basins, pipe utlets shuld nt be directly linked t pen channel r basin ndes. All pipe utlets shuld be linked t pen channels r basins using unrestricted wide weirs Schematizatin f Secndary Drainage System Overland Flw Paths: In a strmwater system the strage and cnveyance f the secndary system is imprtant. The specificatin f the secndary flw path is a significant part f the mdel build. A representative secndary drainage system (verland flw system) shall be included in the hydraulic mdel. Overland flws shall be mdelled in a realistic manner but als in a manner cmmensurate with the accuracy f available data. The alignment f the verland flw path shall be cnceptual but realistic. Auckland Cuncil crprate GIS verland flw path shape file shall be used t schematise the verland flw path in the mdel. Where verland flw path infrmatin is nt available rapid fld assessment infrmatin will be used if available. The verland flw path wuld nt necessarily fllw every sinuus path, but in this case the path length and strage must be representative. Surface pnding can be mdelled as a link with sectins r as a basin, s lng as the crrect level-strage relatinship is reprduced. Secndary verland flw paths shall be mdelled with an verland flw link as weir r rifice which cnnects manhles t verland flw path ndes. All manhles cnnected Nvember 2011 Page 33

35 t verland flw paths shuld be sealed in rder t remve the default abve grund strage. In general, standard default crss-sectins shuld be used as a CRS link fr verland flw paths thrugh reserves r prperties r rads. Hwever, in cases f verland flw paths with flw greater than 2.0 m 3 /s crss-sectins extracted frm LiDAR cnturs/ grid data r surveyed crss-sectin if available shuld be used as a natural link with the tpgraphy feature. The invert levels f the crss-sectins extracted frm LiDAR shuld be used as invert levels f the verland flw path ndes, lcated at the same lcatins f the extracted crss-sectins Schematizatin f Strage Basins All significant strage areas which lie within the netwrk extent shuld be mdelled. This includes fld detentin, fld retentin and water quality basins, whether r nt they have been specifically cnstructed as such. Water level-surface area table assigned t a basin nde shuld be at least 1m abve the maximum expected water level at the basin. The minimum level in the strage table must be same as the invert level f the basin nde. GIS shape file fr strmwater catchments fr treatment devices and raster data fr depressin areas shuld be used t identify existing strmwater strage devices and natural depressin areas that need t be included in the mdel as basin ndes. Basin ndes used t mdel strmwater treatment pnds/wetlands shall be mdelled separately and cnnected with weirs/rifices fr inflw, utflw and verflw frm the basin. Since a nde must be cnnected t a link fr numerical slutin, a dummy link with 0.01m diameter shuld be used t cnnect the basin nde t any nearby nde. When mdelling a strage basin, due cnsideratin shuld be given t ensuring the fllwing aspects are reprduced in the mdel, where imprtant; Strage (as a functin f water-level and shuld be full at the lwest utlet level); Cnveyance (as a functin f water-level); Lcal lsses (fr example at the basin cntrlled utlet structures); Cntrls (fr example inlet/utlet cntrl fr utlet pipe, r weir cntrl fr a basin verflw, r rifice cntrl fr a pnd utlet verflw manhle). All available frmal strage basin data and pnds/wetlands design reprts including as-built plans will be supplied, if available Schematizatin f Hydraulic Structures In additin t the pipe netwrk and manhles f a strmwater drainage netwrk there may be a number f structures including culverts, bridges, utlet rifices, Nvember 2011 Page 34

36 verflw weirs and pumps. Their representatin in the sftware is generally an apprximatin t the cmplex 3D flws that can ccur thrugh a structure. As in mst cases calibratin data is nt available, mdelling f hydraulic structures shuld always be crss-checked with manual calculatins r ther sftware. Culverts: Varius types f culverts can be mdelled, including circular, rectangular r an arbitrary crss-sectin where apprpriate. Culverts shuld be mdelled based n prper survey data with apprpriate energy lsses (see Sectin 5.3.4). Bridges: Bridges shuld be mdelled with enclsed crss-sectins based n prper survey data with apprpriate energy lsses (see Sectin 5.3.4). Orifices: Varius types f rifice plates can be mdelled, including circular, rectangular r an arbitrary crss-sectin where apprpriate. In general rifices shall be used t mdel manhles verflwing t the verland flw paths. Orifices cnnecting manhles t verland flw paths shall be mdelled as circular rifice based n number and size f the cesspits cnnected t the manhle. The diameter f the rifice shall be selected assuming 25 l/ per cesspit (unless greater capacity can be used Maxpit r specifically designed) is transferred int the primary netwrk. This will limit the flw returning back t the primary netwrk. Orifice crest level shall be equal t the manhle lid level. In case f sub-catchment lading manhles, weirs shall be used t mdel manhles verflwing t the verland flw paths. Weirs cnnecting subcatchment lading manhles t the verland flw paths shall be mdelled as a brad crested weir type with a weir angle f 90, weir width f 10m (unrestricted flw), and weir crest level equal t the manhle lid level. In rder t restrict the flw returning back t the primary netwrk, the invert levels f the verland flw path ndes shuld be lwer (at-least 0.2m lwer) than the lid levels f the cnnected sub-catchment lading manhles. The mdel predicted return flws int the primary netwrk shall always be checked and where necessary mdel needs t be updated. In general, weirs/rifices shall be riented s that psitive flw signifies flw entering the primary drainage system and negative flw signifies flw leaving the primary drainage netwrk system. Weirs: Varius types f weir can be mdelled, including brad and sharp-crested weirs, in-flw r side weirs, and special weirs with a knwn Q-H relatinship and including real time cntrl, fr example autmated cntrl systems. Weirs shall be mdelled as CRS weir type with crss-sectins extracted frm LiDAR fr channel verflwing t strage basins r pen channels, culvert/bridge spilling ver the rad, and pnd/strage basin verflw/spillway. Nvember 2011 Page 35

37 Perfrmance f CRS weirs in the mdel shuld always be crss-checked with manual calculatins r ther sftware e.g. MIKE11 at lcatins where flr flding is predicted. If differs significantly CRS weir shuld be replaced by a passive flw regulatin functin based n stage-discharge (H-Q) rating table fr CRS weir derived frm MIKE11 mdelling sftware. Strmwater Pumps: Varius types f pump arrangements can be mdelled, including screw and differential head pumps and rising mains Sakage Representatin in 1D mdel Sakhles utilise the available natural grund sakage as a strmwater dispsal system. The saked water perclates thrugh the fractured basalt and becmes grundwater. There are public and private sakhles within a sakage area; the public sakhles accept the runff frm public areas like rads and sprts fields, the private sakhles accept the runff frm private residential and cmmercial/industrial lts. There are tw aspects which may be imprtant fr a sakhle; Sakage capacity each sakhle will have a maximum flw rate capacity fr transferring strmwater t the grundwater system. The maximum flw rate is usually related t the maximum driving head (when the sakhle is full). Strage each sakhle prvides strage within the bres and the chamber. This strage may be imprtant fr small events but is prbably nt imprtant fr large events. Abve grund strage will be imprtant shuld the sakhle strage chamber becme full. When mdelling sakhles and the sakage capacity, the mdeller generally needs t determine the maximum sakage capacity frm surces such as: Design reprts Maintenance reprts In-situ testing thrugh drilling brehles and using measured water inflw t understand sakage ptential Grundwater mdelling such as the Glbal Aquifer Study (PDP, 2005) Auckland City Cuncil Strmwater Sakage Design Manual (ACC, 1991) It shall be assumed that sakhle capacity is unaffected by elevated grundwater levels. Sakhles can becme blcked and need t be maintained. It is pssible that many public and private sak-hles are n lnger perfrming t their rated r design capacity leading t pr perfrmance and thereby increasing the likelihd f pnding. Nvember 2011 Page 36

38 Mdelling Public Sakhles Public sakhles are generally larger than private sakhles and shall be mdelled in a physically realistic manner. The lcatins f public sakhles can be directly imprted int the mdel frm the GIS data. The apprach taken shuld cnsider the fllwing aspects; Strage The actual strage vlume available may cnsist f several small diameter sakhle bres lying beneath a large sakhle chamber. It is imprtant t ensure that the mdel accurately replicates the available strage in the physical sakhles. Sakhle strage shuld relate t the physical dimensins f the public sakhle. Sakage Capacity The sakhle capacity can be btained frm sakage tests r by assuming a cnstant sakage rate relating t the relevant sakage zne, i.e. sakage per square area f basalt frntage. The sakage rate can be calculated by estimating the area f basalt frntage fr each water-level. Public sakhles shall be mdelled as a basin sized with a user-defined water levelplan area relatinship based n the available dimensins f public sakhles. Where n sakhle dimensins exist, but a sakhle is present accrding t GIS data, a standard sakhle dimensins shall be used based n Auckland City Cuncil Strmwater Sakage Design Manual (ACC, 1991). Water level-discharge (H-Q) relatinships shall be develped based n maximum sakage rates and the dimensins f the sakhles. The basin shall be cnnected t an utlet nde by a small dummy link. Sakhle capacity shall be represented by a passive flw regulatin n the dummy link with the user-defined water level-sakage rate (H-Q) relatinship t mdel infiltratin thrugh public sakhles int the aquifer. When mre than ne sakhle is lcated in clse prximity t anther, a single sakhle representatin may be used in the mdel, with the available vlume and flw rate increased accrdingly. The sakage capacity in these situatins is additive; interference is nt taken int accunt. Mdelling Private Sakhles In sakage areas almst every residence will have a small private sakhle. Since there are s many private sakhles and they are small, then all private sakhles within a public sakhle catchment can be lumped, as fllws; Catchment Area all private sakhle areas in a public sakhle catchment can be lumped. It is assumed that rf area nly cntributes t private sakage. Rf areas t be calculated n a sub-area basis i.e. lump several prperties tgether within ne catchment area when there are public sakhles. Strage The strage is prbably small and typical lumped private sakhle strage can be adpted. Nvember 2011 Page 37

39 Sakage Capacity Assume that the sakage capacity equals the 10-year ARI flw frm the private sakhle catchment. This flw shall be derived using the TP108 rainfall-runff mdelling apprach. Generally, mdelling private sakage is difficult as private sakhles are nt gauged and ften nt maintained. Therefre assumptins regarding sakage capacity and strage can be ptimistic. An estimate f the 10-year ARI flw (Q10) fr private sakage capacity can be btained frm an area-weighted average f the fllwing 10-year ARI specific flw (q10) frm rf area i.e. 10-year ARI flw (m 3 /s) divided by rf catchment area (ha) (based n Curve Number f 98 fr rf area); Fr CN=98 use q10 = m 3 /s/ha The private sakage capacity, Q10, is estimated as area-weighted specific flw, q10, multiplied by the private sakhle rf catchment area (ha). Private sakhles shall be mdelled as a basin sized with a user-defined water levelplan area relatinship based n typical lumped private sakhle strage. The basin shall be cnnected t an utlet nde by a small dummy link. Sakhle capacity shall be represented by a passive flw regulatin n the dummy link with the user-defined water level-cnstant sakage capacity relatinship (H-Q10) t mdel infiltratin thrugh private sakhles int the aquifer. The pragmatic assumptin that each sakhle can take the 10-year ARI flw (and n mre) is based n; Any flding as the result f a prly cnstructed r prly maintained sakhle is the respnsibility f the individual prperty wner. Serius regular flding prblems that are the result f inadequate sakage (either private r public) wuld (shuld) have already been identified and reslved. New sakhles will be designed s that they take the Q10 (10-year ARI peak flw). Flding prblems due t inadequate private sakage capacity cannt be answered accurately n such a glbal catchment scale because private sakhles (their receiving flws, their dimensins and their sakage rates) are t variable Energy Lsses in 1D mdel Energy lsses during mvement f water are primarily f tw types thse assciated with surface frictin f the flw bundary and thse assciated with rapid changes in velcity (magnitude and directin) such as when water is frced t cntract, expand r flw rund a bend. These sudden changes in velcity (either in magnitude and/r directin) generate large scale turbulence that dissipates as heat. Nvember 2011 Page 38

40 Energy Lsses due t Surface Frictin The majr energy lss in pen channels r pipe is the frictin r bundary shear lss. Open channels and pipes included in the mdel shuld be assigned with Manning s rughness cefficient n values based n the site visit, lining material, CCTV recrd inspectins, aerial phts, r ther infrmatin prvided by AC. Manning s rughness cefficient values fr pen channels are given in the fllwing tables based n Rughness Advisr (DEFRA, 2003) develped by DEFRA/Envirnment Agency, Nrthern Ireland Rivers Agency, Scttish Gvernment, HR Wallingfrd, JBA Cnsulting. Rughness Advisr is a large database f Manning s rughness cefficient values based n an extensive literature review f ver 700 references cvering existing methds and data fr estimating rughness. The values extracted frm the literature are given as an upper and lwer value als. The mid, upper and lwer values cver the range f rughness values expected fr pen channel drainage system. Tables 5.1 t 5.3 prvide Manning s n rughness values fr varius surface materials, vegetatin and irregularities (DEFRA, 2004). The mid rughness values are referred as unit rughness and need t be used t assign rughness values fr channel crsssectins. The Rughness Advisr database prvides expert knwledge and infrmatin n the rughness f an pen channel reach. Fr a channel reach, three rughness znes have been identified in the Rughness Advisr: bed, bank and fldplain (Figure 2). Each rughness zne is cmpsed f up t three cmpnents: surface material, vegetatin and irregularities. The rughness database prvides unit rughness values fr the three cmpnents. Unit rughness values need t be assigned t each f these cmpnents and then cmbined tgether using rt sum f the squares t btain the verall unit rughness fr the whle zne as fllws (DEFRA, 2003): n zne ( + + ) n sur n veg n = (1) irr where n sur, n veg and n irr are the lcal unit rughness values due t surface material, vegetatin and irregularity respectively. This methd was chsen fr cmbining lcal unit rughness values n the basis that it gives mre pririty t the mst dminant rughness cmpnent and gives gd matching with measured values. Nvember 2011 Page 39

41 Figure 2 A typical pen channel crss sectin with varius rughness znes The Rughness Advisr database is ne f the cmpnents f the cnveyance and Afflux estimatin system (CES/AES) sftware develped by Envirnment Agency, Nrthern Ireland Rivers Agency, Scttish Gvernment, HR Wallingfrd, JBA Cnsulting. CES/AES is a free sftware, can be dwnladed frm The unit rughness values given in Rughness Advisr are based n surface frictin nly i.e. bundary generated turbulence nly is accunted fr, and des nt incrprate effects f crss-sectin and plan-frm shape, lateral shearing r secndary currents, the latter f which is cnsidered in the cnveyance calculatin. The new cnveyance calculatin apprach in CES/AES sftware is based n the depth-integrated Reynlds Averaged Navier-Stkes (RANS) equatins fr flw in the streamwise directin. Varius energy lss mechanisms in cmpund channel flw are treated individually: Energy lsses due t bundary frictin caused by the resistance due t surface rughness. Turbulence lsses due t shearing between the lateral layers in regins with lateral variatins in flw velcity e.g. adjacent t a flw bundary layer; and at the fldplain main channel interface, where the water is flwing faster in the main channel than n the fldplains. Turbulence lsses due t transverse / secndary currents in regins with steep velcity gradients resulting frm planfrm (meandering/sinusity) induced rtatin. It is recmmended t use CES/AES sftware t generate verall cmbined unit rughness values fr the three rughness znes i.e. bed, bank and fldplain ver a channel reach. In general, Manning s n value identified in pen channel flw thrugh calibratin using measured data in 1D mdel n lnger represents energy lss due t bundary Nvember 2011 Page 40

42 frictin nly but bulk representatin f ther energy lss mechanisms ver a channel reach nt explicitly mdelled. As in mst cases calibratin data is nt available, a crrectin factr f the Manning s n values generated frm the Rughness Advisr database shuld be used t accunt fr additinal energy lss mechanisms (e.g. turbulence lsses due lateral shearing r transverse currents) nt explicitly mdelled in 1D mdelling sftware. It is recmmended t increase Manning s n rughness values fr channel bed and bank ver a reach by 30% in case f straight channel, 45% fr meandering channel with appreciable degree f meandering (sinusity f 1.2 t 1.5) and 60% with sever degree f meandering (sinusity greater than 1.5). Manning s n rughness values fr fldplain shuld be increased by 30%. The fllwing methdlgy shuld be cnsidered during assigning Manning s rughness values fr pen channel crss-sectins: Cnsider certain length f channel reach upstream and dwnstream f the crsssectin fr which Manning s rughness values t be assigned. Select Manning s unit rughness values fr the reach frm Tables 5.1 t 5.3 r Rughness Advisr fr the three cmpnents i.e. surface material, vegetatin and irregularities fr each crss-sectin zne e.g. left fldplain, left bank, main channel bed, right bank, right fldplain (see Figure 2). Cmbine Manning s unit rughness values fr the three cmpnents tgether by using rt sum f the squares frmulatin (Equatin 1) t btain the verall unit rughness value fr each zne separately. Increase the Manning s verall unit rughness value fr each zne by a crrectin factr t accunt fr additinal energy lss mechanisms as fllws: - Increase channel bed and bank rughness by 30% fr straight channel - Increase channel bed and bank rughness by 45% fr meandering channel with appreciable degree f meandering (sinusity f 1.2 t 1.5) - Increase channel bed and bank rughness by 60% fr meandering channel with sever degree f meandering (sinusity greater than 1.5) - Increase fldplain rughness by 30% Finally assign variable Manning s n rughness values distributed acrss the pen channel crss-sectin raw data in 1D hydraulic mdel with a glbal Manning's n rughness value f 1.0. Open channel crss-sectin cnveyance estimatin in the mdel shuld always be crss-checked with CES/AES sftware at lcatins where flr flding is predicted. In general a reach-scale Manning s n rughness values are assigned in 1D mdel whereas in 2D mdel lcal-scale rughness values are assigned. Nvember 2011 Page 41

43 Table 5.1 Manning s n Rughness Values fr Channel Bed, Bank & Fldplain Material/Substrate (DEFRA, 2004) Channel, Bank, Fldplain Surface Material / Substrate Unit Rughness Manning s n Rughness Values Lwer Rughness Upper Rughness Bedrck Cbbles mm Carse gravel 20-64mm Gravel 7-20mm Fine gravel 2-7mm Sand Silt Clay Peat Earth Cncrete Brass Steel Smth steel Crrugated steel Cast irn Wrught irn Crrugated metal Wd Clay lining Brick Rubble masnry Ashpalt Sheet piling Gabin Stne Rip-rap Wd piling Hazel hurdles Matting Fibrerlls Spiling Bare plughed sil Nvember 2011 Page 42

44 Table 5.2 Manning s n Rughness values fr Channel, Bank & Fldplain Vegetatin (DEFRA, 2004) Channel, Bank, Fldplain Vegetatin Manning s n Rughness Values Unit Rughness Lwer Rughness Upper Rughness Free-flating plants Filamentus algae Msses Trailing bank-side plants Emergent reeds Flating-leaved rted plants Emergent brad-leaved rted plants Submerged brad-leaved plants Submerged fine-leaved plants (shallw) Submerged fine-leaved plants (medium) Submerged fine-leaved plants (deep) Height-varying grass Tall grass 1-1.8m Medium grass m Turf Clean hedges (Separatin distance - 50m) Dirty hedges (Separatin distance - 50m) Crn (parallel t flw) Cttn (parallel t flw) Srghum (parallel t flw) Sybeans (parallel t flw) Sunflwers (parallel t flw) Wheat (parallel t flw) Crn (perpendicular t flw) Cttn (perpendicular t flw) Srghum (perpendicular t flw) Sybeans (perpendicular t flw) Sunflwers (perpendicular t flw) Wheat (perpendicular t flw) Wheat stems Small supple trees saplings e.g willw Scattered brush and heavy weeds Light brush and trees (winter) Light brush and trees (summer) Medium brush and trees (winter) Medium brush and trees (summer) Dense willws (summer) Cleared land - tree stumps Cleared land - tree stumps & heavy spruts Mderate t dense brush (depth belw branches) Heavy stand f trees with sme dwned (depth belw branches) Heavy stand f trees with sme dwned (depth abve branches) Cniferus trees (sparse cverage) Cniferus trees (medium density cverage) Cniferus trees (high density cverage) Nvember 2011 Page 43

45 Table 5.3 Manning s n Rughness Values fr Channel, Bank & Fldplain Irregularities (DEFRA, 2004) Channel, Bank, Fldplain Irregularity Unit Rughness Manning s n Rughness Values Lwer Rughness Upper Rughness Urban trash 20% Urban trash < 50% Urban trash > 50% Bulders 0-20% Bulders 21-50% Bulders > 50% Gryne < 20% water abve Pls Riffles Tree rts Ridges n plughed field Undulatins (fldplain) Minr irregularities (fldplain) Mderate irregularities (fldplain) Severe irregularities (fldplain) Minr bstructins (fldplain) Appreciable bstructins (fldplain) In additin t the abve Manning s rughness cefficient values fr pen channels, the fllwing Manning s n rughness values shuld be used fr clsed cnduits and verland flw paths. Table 5.4 Manning s n Rughness Values fr Clsed Cnduits and Overland Flw Path (Chw, 1959) Classificatin Manning s n Values Clsed Cnduit Metal (cated, uncated, galvanised) Clsed Cnduit Plastic Clsed Cnduit Crrugated Metal Clsed Cnduit Cncrete (finished) Clsed Cnduit Cncrete (unfinished) Overland Flw Paths alng Radways Overland Flw Paths thrugh Prperties / Parcels (fences/huses/sheds) Energy Lsses due t Turbulence In additin t the frictin lss alng a channel r pipe, there is usually a lcal lss f energy assciated with any sudden changes in velcity (magnitude and directin) e.g. at transitins, junctins, bends, entrances, exits, and bstructins. Lcal turbulence lsses are typically the dminant energy lss mechanism thrugh hydraulic structures f shrt length and high velcities. These lsses ccur ver a relatively shrt distances and are usually represented by a sudden drp in the energy grade line. Nvember 2011 Page 44

46 The lcal energy lsses are dependent n a number f factrs including the degree f submergence, the degree f cntractin/expansin, the change in angle f flw directin, the change in elevatin and the degree f manhle invert benching. The lcal energy lss is typically expressed as a functin f dynamic head (V 2 /2g) as given by K (V 2 /2g) where K is the lcal energy lss cefficient. The fllwing shuld be used fr specifying lcal energy lsses: Energy Lsses at Manhles Dummy Manhles: Use N Crss-sectin Changes i.e. n energy lss cmputatin Straddled Manhles: Use N Crss-sectin Changes i.e. n energy lss cmputatin Unbenched Manhles: Use Mean Energy Apprach with K m = 0.5 and maximum lss limit based n velcity head Half-benched Manhles: Use Mean Energy Apprach with K m = 0.3 and maximum lss limit based n velcity head Full-benched Manhles: Use Mean Energy Apprach with K m = 0.1 and maximum lss limit based n velcity head Where K m is the utlet shape cefficient in MIKE URBAN and relates nly t lcal energy lss at utlet pipe frm the manhle i.e. entrance lss at pipe inlet cnnected t the manhle. In MIKE URBAN lcal energy lsses due t change in flw directin and change in elevatin are mdelled separately based n pipe alignment and the magnitude f the difference in elevatin and added-up with energy lss due t cntractin (entrance lss) fr each utlet pipe frm the manhle. In MIKE URBAN lcal energy lss at inlet pipe t the manhle (pipe exit lss) is mdelled as (V i 2 /2g V m 2 /2g), the difference f the velcity heads in the inlet pipe i and the manhle nde m. In a case f a free inlet f a sub-critical flw, i.e. when the water level in the manhle is lwer than the critical depth level in the inlet pipe, the water level in the pipe inlet t the manhle is assumed t be equal t the critical depth. In general, since mst strmwater manhles in Auckland are benched t half height, then mst manhle lsses shuld use the Mean Energy Apprach with K m = 0.3 and maximum lss limit based n velcity head. MIKE URBAN mdelling sftware has inherent difficulties in accurately mdelling energy lsses at manhles when the utlet pipe frm the manhle is inlet cntrlled, which results in high velcity in the pipe. Fr all pipes with cmputed velcity greater than 6.0 m/s shuld be mdelled with a passive flw regulatin functin based n stage-discharge (H-Q) rating table derived frm weir/rifice frmulatin as described in HEC22 manual. Nvember 2011 Page 45

47 Hwever, the assigned flw regulatin functin is drwned ut when the pipe becmes utlet cntrlled and MIKE URBAN energy lss calculatins (entrance, pipe frictin & exit lss) thrugh the pipe take ver and prduce the crrect utlet cntrlled upstream water level at the manhle. Lcal energy lsses at manhles shuld always be crss-checked with manual calculatins r ther sftware. Energy Lsses at Structure Inlets & Outlets Culvert/Pipe/Bridge Inlets (frm pen channel): Lk at n an individual basis, use Classic Methd (max lss limit velcity head) with Ttal HLC = 0.5 (entrance lss) Culvert/Pipe/Bridge Outlets (t pen channel): Lk at n an individual basis, use Classic Methd (max lss limit velcity head) with Ttal HLC = 1.0 (exit lss) MIKE URBAN mdelling sftware has inherent difficulties in accurately mdelling energy lsses at hydraulic structures when the structure is inlet cntrlled. A passive flw regulatin functin based n inlet cntrlled stage-discharge (H-Q) rating table shuld be used at the culvert and pipe inlets. The inlet cntrlled stage-discharge rating table shuld be derived frm Culvert Manual r free culvert analysis sftware HY-8 develped by US Federal Highway Administratin. In case f bridge the inlet cntrlled stage-discharge rating table shuld be derived frm HY-8 sftware with equivalent rectangular sectin f the bridge crss-sectin r MIKE11 sftware irregular culvert rating tl. Hwever, the assigned flw regulatin functin is drwned ut when the culvert/pipe /bridge becmes utlet cntrlled and MIKE URBAN energy lss calculatins (entrance, pipe frictin & exit lss) thrugh the structure take ver and prduce the crrect utlet cntrlled upstream water level at the structure inlets. Outlets (dwnstream bundary): N energy lss specificatin is required. Fr free utfall critical depth is cmputed at the utlet with cmplete energy lss f dynamic head (V 2 /2g) f the utlet pipe/channel. This energy lss is added-up t the upstream hydraulic grade line. Perfrmance f hydraulic structures shuld always be crss-checked with manual calculatins r ther sftware e.g. HEC-RAS, MIKE11, CES/AES. Energy Lsses at Strage Basins/Pnds Strage Basins/Pnds: Use N Crss-sectin Changes i.e. n energy lss as in general strage basins/pnds are cnnected by cntrlled utlet verflw manhles, rifice plates r utlet pipes. Use circular rifice fr cntrlled rifice plate. Use rectangular rifice fr utlet verflw manhle with a width equal t the perimeter f the verflw manhle, Nvember 2011 Page 46

48 area equal t the pening f verflw manhle, and rifice crest level equal t the verflw manhle lid level. Use rectangular weir fr vertical slt and CRS weir type with crss-sectins extracted frm LiDAR fr pnd/strage basin verflw/spillway. Perfrmance f CRS weirs in the mdel shuld always be crss-checked with manual calculatins r ther sftware e.g. MIKE11. If differs significantly CRS weir shuld be replaced by a passive flw regulatin functin based n stagedischarge (H-Q) rating table fr CRS weir derived frm MIKE11 mdelling sftware. Outlet pipe frm the verflw manhle shuld be mdelled with a passive flw regulatin functin based n stage-discharge (H-Q) rating table derived frm weir/rifice frmulatin as described in HEC22 manual. Energy Lsses at Open Channel Junctins Open Channel Ndes: Use N Crss-sectin Changes i.e. n energy lss Bend lsses in pen channel shall be included within the Manning s rughness values ver a channel reach by a crrectin factr as discussed abve D HYDRAULIC MODEL D Hydraulic Mdelling Methdlgy The hydraulic cmputatin f tw-dimensinal mdel is based n numerical slutin f 2D shallw water equatins (als knwn as Saint Venant). These equatins are btained by means f averaging the full 3-D Reynld s averaged Navier-Stkes equatins fr turbulent flw ver the flw depth. The derivatin f 2-D depthaveraged Saint Venant equatins (integrated equatins f cnservatin f mass and mmentum ver the flw depth) are based upn the fllwing assumptins: The wave lengths are large cmpared t the water depth i.e. the streamline curvature is small and thus vertical acceleratins can be neglected, hence the pressure field is assumed hydrstatic. The effects f bundary frictin can be accunted fr thrugh resistance laws analgus t thse used fr steady unifrm flw. The bttm slpe is assumed small s that the csine f the angle it makes with the hrizntal may be taken as unity. The water is incmpressible and hmgeneus, i.e. negligible variatin in density. Overbank flw in wide fldplains and verland flw frm manhle verflw are examples f tw-dimensinal flw where large variatins in velcity field and changes Nvember 2011 Page 47

49 in flw directin ccur and can be efficiently represented using a 2-D hydraulic mdel D Hydraulic Mdel Schematisatin 2-D Mdelling in MIKE21 The parameter setup in MIKE21 Flw Mdel is separated int tw: basic parameters and hydrdynamic parameters. The parameters used in the fld hazard mdelling are described belw. Mdel Simulatin: The simulatin chsen can be Hydrdynamic nly, i.e. the HD mdule alne Hydrdynamic and Advectin-Dispersin, i.e. the HD and AD mdules Hydrdynamic and Mud Transprt, i.e. the HD, AD and MT mdules Hydrdynamic and ECO Lab, i.e. the HD, AD and ECO Lab mdules HD will nly need t be selected fr fld mdelling / fldplain mapping. Bathymetry: A digital elevatin mdel (DEM) f the entire catchment area frm the LiDAR data shall be develped as bathymetry fr 2D mdelling. When preparing the grid fr the 2D mdelling, the fllwing steps shuld be cnsidered: Check that tpgraphy f the linear features such as rads and railways have nt been lst r degraded during the interplatin prcess. Manual editing may be required t fix the prblem areas. A site visit is generally recmmended t investigate whether kerb lines and driveways are accurately represented, especially in areas where verland flw may ccur. In urban areas, it needs t be cnsidered whether buildings need t be represented in the grid in case these culd have significant effect n the verland flw paths. The buildings can be represented by increasing the rughness r where it is knwn that the buildings are built with cncrete fr example, the buildings can be blcked ut. This wuld need t be defined during the mdel schematisatin prcess. It needs t be determined whether the rad prfile needs t be burned int the bathymetry r nt. In flat areas the mdel culd shw the verland flw discharging int prperties whereas in reality the kerbs wuld align the flw dwn the rad. Overland flw shuld always be interrgated against site visit r street view t see whether the verland flw path is crrect. Nvember 2011 Page 48

50 Physical site inspectin f drainage structures shuld be undertaken and phtgraphic evidence f all imprtant features shuld be cllected and checked t ensure gd alignment with 2D mdel grid. Grid size f 2m x 2m shuld be used fr 2D MIKE21 rectangular mesh which will be supplied by Auckland Cuncil. In case f flexible mesh mdel, mesh size shall be f 4 m 2. A larger grid size can be used fr rural flat fldplain area as agreed with Auckland Cuncil. Where there is an pen channel mdelled in MIKE11, the DEM wuld need blcking ut cells under pen channels where the mdels wuld be cupled t avid duble cunting f the vlume. As a rule f thumb, all channels wider than 2 grid cells shuld be blcked ut. In case f mdelling pen channel in 2D mdel, the grid size shuld be small enugh that the smallest channel crss-sectin is defined by at least 5 grid cells in the area f interest. The Crilis frcing shuld be deactivated fr MIKE FLOOD simulatins as the effects are negligible fr relatively small mdelling extent fund in MIKE FLOOD studies. Use f this parameter slws dwn the simulatin. Bundary The bundaries shuld be lcated s as t minimize the impact f bundary effects such as artificial backwater frm utflw (dwnstream) and jetting f flws at inflw (upstream) bundary. Fr the inland mdel dmains, this can be simplified by raising the cells at the edge f the dmain t the true land level. This is als called clsing the bundary. It is imprtant that the extent f the grid is large enugh t accmmdate maximum fld extent, i.e. the fld waters shuld nt tuch the bundary. Initial water Level Initial water surface elevatin (i.e. initial cnditin) shuld be set t realistic water level at the beginning f the simulatin and matched with the 2D bundary cnditins. Mst cmmnly, the bathymetry grid setting the initial water level t be same as the grund surface elevatin. If the mdelling area has an pen bundary, initial cnditins shuld be set t match bundary cnditins used. In case f mdelling strmwater treatment pnds/wetlands in 2D mdel the nrmal perating level (usually utlet rifice invert) shuld be used as the initial water level i.e. pnd bathymetry needs t be filled in up t nrmal perating level r set initial cnditin using ht start t get crrect level in terrain. Surce and Sink Catchment runff may need t be inserted as surce pints nt the 2D mdel grids where n asset data is available and als in catchments where upstream verland flw needs t be represented. During the simulatin a 2D grid cell cntaining a Nvember 2011 Page 49

51 surce pint receives a discharge equal t the runff f the assciated hydrgraph f the hydrlgical sub-catchment. Flding and Drying depth Anther imprtant parameter in 2D mdel setup is flding and drying. This feature f the 2D engine gverns the status f a cell as active. The cell will nt becme active in the simulatin until the water level in it exceeds the flding value. Similarly, when the water level in a cell drps belw the drying value, the cell will cease t be active. The flding and drying values shuld be kept small t avid prblem with psitive mass balance, i.e. water generated by the engine trying t prevent water depth in cells drpping belw zer. The apprpriate values fr surface flding are 0.03 fr flding and 0.02 fr drying Sakage Representatin in 2D mdel In general sakage shall be mdelled as sink pints int the 2D mdel. Maximum sakage rate f private and public sakhles needs t be determined as discussed in Sectin The maximum sakage rate shall be used as negative flw and shall be assigned as sink pints int the 2D mdel grids. The lcatins f public sakhles can be directly imprted int the mdel frm the GIS data. All private sakhles within a public sakhle catchment shall be lumped and mdelled tgether with public sakhle Energy Lsses in 2D mdel Energy Lsses due t Surface Frictin Manning s n rughness values listed in Sectin shuld be used fr 2D mdelling f pen channels, fldplains and verland flw path areas. Manning s rughness cefficient is used in 2D mdel t represent shear stress exerted at the base f a vertical clumn f water whereas in 1D mdel it represents the shear stress exerted by the entire bed and banks bunding the flw. Additinally, the 1D representatin des nt take explicit accunt f the effects f turbulence in remving energy frm the flw s this effect is als included in the frictin factr thrugh calibratin whereas in 2D mdel turbulence are in general explicitly included thrugh terms in additin t the frictin term. Manning s n rughness values shuld be assigned spatially distributed t reflect different resistance t surface flw based n site visits, surface material, vegetatin density, land use, aerial phts, r ther infrmatin prvided by AC. Fllwing Manning s n rughness values shuld be used in relatin t mdelling building ftprints: Nvember 2011 Page 50

52 Urban Residential Buildings Rural Residential Buildings (fr building ftprints) (remainder f parcel) (fr building ftprints) (remainder f parcel) Industrial/Cmmercial r Large Buildings n site Energy Lsses due t Turbulence Turbulence lsses are usually mdelled in 2D mdel thrugh a viscsity term. In 2D mdelling the size f the 2D grid cells can be such that they may nt adequately simulate sub-grid scale turbulence, which is usually evident fr flw arund near channel bundary/bend, arund buildings, int and ut f structures. Sub-grid scale turbulence is accunted fr by viscsity r sub-grid scale turbulence term. The eddy viscsity prvides an apprximate representatin f the energy lsses due t turbulent effects at sub-grid scale that can nt be mdelled directly. The influence f the eddy viscsity term is highly dependent n the relative dminance f bundary frictin. Fr shallw verland flw cnditins it is unlikely that eddy viscsity will have a majr effect n mdel predictins as bundary frictin will dminate in mst cases. Hwever, where the velcity is rapidly changing in magnitude and directin e.g. flw in and arund structures r flw arund channel bend, the value f eddy viscsity can have a significant effect. The ability f a 2D mdel t reprduce the energy lsses due t turbulence depends n the reslutin f the mesh and the influence f any 3D effects (velcity variatin in the vertical), the finer the mesh the better the predicted hrizntal streamlines and the subsequent resulting turbulence lsses. 2D mdels may prduce different amunts f turbulence lsses depending n the reslutin f the mesh. In general 2D mdels with fine mesh prduce accurate descriptin f flw behaviur and water surface arund a channel bend and at the main channel fldplain interface where water is flwing faster in the main channel than n the fldplains. Hwever additinal energy lsses may be required in terms f higher rughness values t accunt fr pr streamlines caused by mesh carseness and 3D effects. If the flw width f a hydraulic structure (bx culvert, bridge) is larger than the 2D cell size then it may be mdelled directly in the 2D mdel. Where flw patterns are cmplex and apprach velcities are high, mdelling large bx culverts and bridges leads t mre accurate flw behaviur and water surface arund the structures. Circular culverts can nt be mdelled in 2D mdel. If the structure flw is upstream (inlet) cntrlled, it shuld be mdelled in 1D mdel. Structures mdelled in 2D may need additinal energy lsses in terms f increased rughness values t represent fine-scale turbulence lsses and 3D effects (e.g. arund bridge piers, frmatin f vena-cntracta inside a structure). Nvember 2011 Page 51

53 Perfrmance f hydraulic structures whether mdelled in 1D r 2D shuld always be crss-checked with manual calculatins r ther sftware e.g. HEC-RAS, MIKE11, CES/AES. Similarly energy lsses due t flw arund a channel bend and the crrespnding superelevatin effects can be crss-checked with the apprximate frmula t estimate the water level difference (superelevatin) at the channel bend given by BU 2 /gr (where U is the mean velcity, R is the radius f curvature and B is the channel width) (HEC22 Manual). The mst recmmended eddy viscsity frmulatin fr MIKE FLOOD is flux based cnstant. Other chices available in the mdel setup are shwn t be mre prne t numerical instability in surface flding applicatins. Flux based viscsity apprach is applicable where the depth is changing slwly spatially e.g. ver a large flat fldplain but channel flw mdelling velcity based viscsity apprach shuld be used. The fllwing rule f thumb frmula can be used fr the cnstant value: Cnstant eddy = 0.02 dx 2 /dt [m 2 /s] Cnstant eddy viscsity frmulatin is generally satisfactry when the grid size is much greater than the depth. When the depth f flw is high and/r frictin term is less dminant i.e. Manning s n value is lw, the viscsity term becmes influential and Smagrinsky eddy viscsity frmulatin shuld be used. Literature suggest that a cnstant eddy viscsity prvides a less accurate representatin f sub-grid turbulence cmpared t the Smagrinsky frmulatin as the Smagrinksy frmulatin is far mre dependent n grid size and the cefficient is recalculated every time step accrding t the change in velcity magnitude and directin. This result in higher cefficients being applied where there is greater turbulence D/2D COUPLED HYDRAULIC MODEL D/2D Cupled Mdel Setup A 1D/2D cupled mdel (MIKE FLOOD) integrates the ne-dimensinal mdels (MIKE URBAN, MIKE11) and the tw-dimensinal mdel (MIKE21) int a single, dynamically cupled mdelling system. Using a dynamically cupled apprach enables the best representatin f the different types f flws ccurring in urban strmwater drainage system by aviding extensive apprximatins required if a single apprach is applied. 1D/2D cupled mdels ffer the best representatin f urban strmwater drainage netwrks where water may be flwing within the pipe system, in pen channels and verland. A 1D/2D cupled mdel shuld be set up t represent varius strmwater drainage cmpnents in either 1D r 2D mdel as fllws: Strmwater pipe drainage netwrk shuld be mdelled in 1D hydrdynamic pipe flw mdel e.g. MIKE URBAN. Nvember 2011 Page 52

54 Narrw watercurses shuld be mdelled in 1D hydrdynamic river mdel e.g. MIKE11. Hwever if the watercurse is small cmpared t the fldplains and n existing flding issues arund the watercurse, it can be mdelled in 2D hydrdynamic free-surface flw mdel e.g. MIKE21. Wide watercurse curses can be mdelled in 2D mdel e.g. MIKE21 mdel (width > 5 grid cells). Hydraulic structures such as culverts, bridges, weirs, pumps and regulatrs shuld be mdelled in 1D hydrdynamic river mdel e.g. MIKE11. Large bx culverts and bridges (width greater than grid size) can be mdelled in 2D mdel e.g. MIKE21. Fldplains and secndary verland flw paths shuld be mdelled in 2D hydrdynamic free-surface flw mdel e.g. MIKE21. Natural surface pnding and depressin areas shuld be mdelled in 2D hydrdynamic free-surface flw mdel e.g. MIKE21. Cnstructed strmwater treatment pnds/wetlands and fld detentin pnds/wetlands (including spillways) which are well represented in LiDAR grid shuld be mdelled in 2D hydrdynamic surface flw mdel e.g. MIKE21. In case f new cnstructed pnds/wetlands where LiDAR raster data culd be inaccurate, it shuld be mdelled in 1D mdel e.g. MIKE11. Details f 1D and 2D mdel schematisatin and mdel building prcesses are discussed abve in Sectin 5.1 t 5.3. There are sme differences in setting up the 1D/2D cupled mdel cmpared t 1D and 2D mdels being built t run independently. In additin t that prvided in Sectin 5.1 t 5.3, the fllwing aspects shuld be cnsidered during setting up the 1D/2D cupled mdel in MIKE FLOOD: Sub-Catchments Cnnectin & Inletting Capacity Fr sub-catchments that cntribute directly t a pipe netwrk, shuld be set up in 1D pipe flw mdel (MIKE URBAN). In general sub-catchment runff hydrgraphs (impervius & pervius) shuld be assigned t the bttm f the manhle nde. The water will generally nt spill frm the manhle until the pipe netwrk is full. Fr sub-catchments that cntribute directly t a watercurse, shuld be set up in 1D river mdel (MIKE11). It may be necessary t setup sme sub-catchments runff hydrgraph as surce pints int the 2D mdel (MIKE21) grid. This may be necessary in sub-catchments where there is n pipe netwrk and where knwn verland flw ccurs. MIKE URBAN r MIKE11 mdel can be used t generate runff hydrgraphs t assign as surce pints int the 2D mdel (MIKE21) grids. When MIKE URBAN is cupled in MIKE FLOOD, the amunt f water let int the cupled manhle is limited by Qmax. The mdeller needs t assess what Qmax will be. It is recmmended t assess the number f cesspits in the catchment feeding t the catchment cnnectin pint and assume 25 l/s per cesspit (unless greater capacity can be used Maxpit r specifically designed) is transferred int the primary netwrk. This will restrict the flw returning back t the primary netwrk. Nvember 2011 Page 53

55 Hwever, a higher Qmax value (i.e. unrestricted) is required fr water discharging ut f the manhle. Fr this reasn all sub-catchment lading manhles shall be set up with a dummy weir f 10m width (fr unrestricted flw) which shall be cupled with 2D mdel (MIKE21) grids (sub-catchment lading manhles shall nt be cupled with 2D mdel and shall be sealed). The weir discharge will always be independent f the water level in the 2D mdel and this type f cupling is uni-directinal, i.e. flws int the 2D mdel nly and nt back. This allws mdelling n returning flw back t the primary netwrk. Manhle Type Only nrmal cver type shuld be used fr manhles when using 1D/2D cupled mdels, except fr the pressurised parts f the pipe netwrk r where there is knwledge f sealed manhle ndes. In these cases the manhles shuld be sealed and nt t be cupled. Grund Level Difference One f the imprtant aspects f cupling a 1D and 2D mdel is the agreement f grund levels between 2D mdel grid and the manhle lid levels in 1D mdel. There is a tl in MIKE URBAN that generates a level differences map. If there are large difference between 2D mdel grid and the manhle lid levels in 1D mdel, survey shuld be carried ut t cnfirm the manhle lid level. Manhle lid levels in 1D mdel shuld nt be changed t 2D mdel grid levels autmatically using sme parameters in dhiapp.ini file. It is recmmended t use M21_AS_GROUNDLEVEL=0 in dhiapp.ini file. In sme cases e.g. when MIKE URBAN pipe/culvert inlets/utlets are cupled t 2D mdel, 2D grid levels may need t be changed manually with the surveyed invert levels f the pipe/culvert inlets/utlets. Dhiapp.ini File Update There are several ther parameters in dhiapp.ini file that need t be cnsidered when MIKE URBAN mdel is used in MIKE FLOOD, cupled with MIKE21. They are cvered under the MOUSE MIKE 21 PARAMETERS heading in dhiapp.ini file. It is cmmn t leave the default values in place. Beside MOUSE MIKE21 parameters sectin, there are several parameters in dhiapp.ini file that als need t be assessed and changed if necessary: It is recmmended t increase the RESERVOIRHEIGHT (100m) and FLOODLIMIT (100m) parameters in dhiapp.ini file t prevent artificial strage being frmed abve the manhle and basin ndes. In 1D/2D cupled mdel simulatins, time step set in MIKE21 will be applied t all cupled engines thus verriding the settings in the individual mdels. It is imprtant t test the MIKE URBAN mdel stability applying the MIKE 21 time step, which is ften smaller than 1 sec. Even minr instabilities can be amplified when mdels are cupled. T enable MIKE URBAN using time step smaller than 1 Nvember 2011 Page 54

56 sec, a parameter FIXED_DECIMAL_TIMESTEP needs t be enabled and set in dhiapp.ini file. Crss Sectin Markers When a MIKE11 mdel is cupled with 2D mdel in MIKE FLOOD, in mst cases it is better t leave the fldplains in MIKE21. T achieve this, the markers 1 and 3 need t be psitined t define the main channel nly. Marker 1 defines the left bank, where the water will spill frm the main channel int the left fldplain and marker 3 designates the right bank, where the water will spill frm the 1D MIKE11 mdel t the 2D MIKE21 fldplain. Marker 2 fr reference is the stream centre line and needs t bviusly t be lcated between markers 1 and 3. Maximum dx Value Anther factr t keep in mind is the maximum dx value, i.e. the maximum distance between tw adjacent water level cmputatin pints. As h-pints are fundamental in linking, the dx value shuld relate t the grid spacing. Preferably, the reslutin shuld be the same in the MIKE21 and the MIKE11 mdels, and nt mre than 3 grid cells in flat areas. Nte that h cmputatinal pints are inserted by the cmputatinal engine at each crss sectin lcatin and the maximum dx value will be enfrced between crss-sectins. Bundary Cnditin While there are n special requirements fr lateral links, it is necessary t specify a dummy water level bundary (in MIKE11 bundary file) fr each standard r structure link pint. The lcatin f the bundary cnditin is used as a parameter in setting up the link. The value assigned is nt imprtant as it will be verridden during the simulatin by the calculated value. HD Parameter File The creek flding is represented in the maps by enabling the Maps ptin in MIKE 11 HD parameter file. This enables the integratin f MIKE21 and MIKE11 results int a single 2-dimensinal result file (.dfs2). The MIKE11 user manual gives step-by-step instructins in hw t use this feature. Sakage Representatin in 1D/2D Cupled Mdel Sakage shall be represented in the 1D mdel and linked t the 2D mdel. Where sakage exists, there is generally private as well as public sakage. Mdelling f public and private sakages including are discussed in Sectin Figure 3 belw shws schematically the representatin f sakage in 1D/2D cupled mdel. The advantages f mdelling sakage in a cupled 1D/2D mdel are: Once sakage capacity is exceeded the water will verflw n t the 2D surface and find its way t the clsest public sakhle (ensure cells are cupled where cesspits wuld be) r will flw verland Nvember 2011 Page 55

57 Inletting capacity can be mdelled by linking the 2D cells t the sakhle. This will determine then hw much water wuld be able t get int the sakhle. Lcatin f the sakhle and the cesspits are crucial in the 2D mdel t allw the verland flw t enter the sakhle if capacity is available. The results can easily be interrgated t validate the verland flw path and determine whether the cncept is crrect. Figure 3 Schematic shwing sakage representatin in 1D/2D cupled mdel Cupling f 1D/2D Mdels This sectin will give an verview f the link types available in MIKE FLOOD, as well as hw the cupling f 1D/2D mdels needs t be apprached in develping detailed Fld Hazard Mapping mdels. In-depth technical details fr the linking ptins can be fund in the MIKE FLOOD manual URBAN Links URBAN links enable exchange f flw between urban netwrk and the surface by cnnecting ne r mre cells in MIKE 21 t a manhle, a basin, a weir r a pump in MIKE URBAN. Flw int the pipe netwrk frm verland flw can be specified as weir flw equatin, rifice flw equatin r by an expnential functin. A maximum allwed flw can be specified. Nvember 2011 Page 56

58 Figure 4 MIKE URBAN t MIKE21 cupling schematic Discharge ut f the pipe netwrk t verland flw is cnsidered t be weir flw equatin, unless it is pumped. This is cmpatible with flw ut f a manhle, prvided the depths dn t get t great. Once the receiving grund is flded, the submerged weir equatin is applied. Accrding t the Guidelines fr Strmwater Mdelling (DHI, 2010) the fllwing rule applies: Orifice flw applies fr depth > 0.4 x manhle diameter, and weir flw fr depth < 0.25 x manhle diameter. An utlet in MIKE URBAN cupled 2D mdel will result in an utflw thrugh the utlet (psitive r negative) which will crrespndingly apply as a pint inflw (psitive r negative) distributed t the 2D cells in the cupling area. A pump r a weir in MIKE URBAN can be cupled t MIKE21 grids if the T-nde is nt defined. The pump/weir discharge will always be independent f the water level in the 2D mdel and this type f cupling is uni-directinal, i.e. the flw nly flws int the MIKE21 mdel and nt back. This can be fixed if needed by replacing a weir with a small pipe and an utlet and cuple the utlet instead. All sub-catchment lading manhles shall be set up with a dummy weir f 10m width (fr unrestricted flw) which shall be cupled with 2D mdel (MIKE21) grids (subcatchment lading manhles shall nt be cupled with 2D mdel and shall be sealed). This allws mdelling n returning flw back t the primary netwrk. It is pssible t cuple a nde t multiple cells in the MIKE21 rectangular grid r alternatively an area in the flexible mesh. In general, using multiple cells as ppsed t cupling t nly ne pint will enhance stability. The expnential smthing factr is available fr inlet and utlet cuplings. A value between is recmmended. The value can be reduced further (which increases the smthing) if the link causes instability prblems. If a particularly small value f the smthing factr is used, the mdeller shuld be satisfied that the results are reasnable River Urban Links The river urban link has been designed fr mdelling the dynamic interactin f the river netwrk and the cllectin system. River-Urban links cnnect MIKE URBAN and MIKE11 mdels in MIKE FLOOD. Small streams and ditches mdelled in MIKE 11 can Nvember 2011 Page 57

59 be ruted int a strmwater pipe system simply by linking the dwnstream water level bundary t the MIKE URBAN inlet nde. Outflw frm a MIKE URBAN mdel int a river can be pumped, ver a weir, r fully linked t MIKE 11 via chainage. The link is placed at the nearest crss-sectin. While pump and weir link allw nly transfer f water frm MIKE URBAN t MIKE 11, the fully linked Outlet r WL Bundary links allw reverse flw as well which makes it suitable fr mdelling backwater effects. Figure 5 1D pipe MIKE URBAN t MIKE11 cupling schematic DHI recmmend that fr all River-Urban links make sure that the bed level at the linking crss sectin is lwer than the invert level f the linked nde MIKE11 MIKE 21 links Links between MIKE 11 and MIKE 21 are the mst cmprehensive grup f links, enabling the dynamic exchange f flw between channels, streams and rivers (1D) and surface (2D). The lateral and standard links define the mvement f water bth alng the river and at the cnnectin pint between end f MIKE 11 mdel and 2D grid cells n the surface. The structure links allw fr detailed mdelling f a structure within 2D dmain which spans mre than tw grid cells (structures cnnecting adjacent cells can be mdelled directly in MIKE 21). Nvember 2011 Page 58

60 Figure 6 MIKE11 t MIKE21 cupling schematic Standard Links The standard links cnnect ne r mre MIKE 21 cells t the end f a MIKE 11 branch. This type f link is useful fr cnnecting a detailed MIKE 21 grid/mesh int a brader MIKE 11 netwrk, r t cnnect an internal structure (with an extent f mre than a grid cell) r feature inside a MIKE 21 grid/mesh. The end f branches in MIKE 11 that cnnect t MIKE 21 must have a water level bundary specified. This is a dummy bundary specificatin fr initializatin purpses nly and will nt affect the calculated values during the simulatin. Mre details n hw t cnfigure standard links can be fund in MIKE FLOOD User Manual. Lateral Links A lateral link allws a string f MIKE 21 cells t be laterally linked t a given reach f an pen channel in MIKE11, either a sectin f a branch r an entire branch. This type f link is particularly useful fr simulating verflw frm an pen channel nt a fldplain. Flw thrugh the lateral link is calculated using a structure equatin. Five alternative types f structures are available, including weirs, tabulated discharges and a standard head-lss equatin. The structure level infrmatin can be taken frm MIKE 21, MIKE11 r can be supplied in an external file. Nvember 2011 Page 59

61 Figure 7 Standard link types and hw they wrk (DHI, 2010) Mmentum is nt transferred between 1D and 2D cnnectins when using lateral links. The mmentum exchange between fast mving channel and slwer fldplain flw ccurs acrss a shear layer which is manifest as a series f vrtices resulting in substantial lss f energy due t turbulence. As discussed in Sectin a crrectin factr f the Manning s n values shuld be used fr 1D channel reach t accunt fr additinal energy lss mechanisms due t 1D channel and 2D fldplain interactins. The fllwing prcedures are recmmended: Chse the CELLTOCELL methd ver the bslete SIMPLE methd. It is mre flexible, mre accurate and is the default chice. Use a dx value in MIKE11 that is similar t the grid side length. Lateral link weir invert level shuld always be higher than the cell it is cnnecting t. Very lng sequences f linked cells will (depending n the size f the cells and the meandering f the branch) tend t be lnger than the crrespnding MIKE11 branch. Check this using the mflateral.txt file and where the match between lengths becmes unacceptable, break linked branches int smaller sectins. Stepby-step guide hw t use this feature can be fund in MIKE FLOOD manual, under the Lateral link height analysis heading. The use f the depth tlerance makes the water quite viscus belw the specified value. This slws the rapidity with which flw is transferred frm MIKE11 t MIKE21 and vice versa, aviding see-sawing. Experiment with the sensitivity f yur mdel in initial stages f the build and try t make the depth tlerance as Nvember 2011 Page 60

62 lw as pssible. This can be significant where the depth f water flwing ver the lateral link weir is relatively shallw cmpared t the depth tlerance value. If numerical instabilities are evident in mdel runs when flws reverse at these links, cnsider raising this tlerance. If flw passes between channel and fldplain ver a relatively wide bank cvered in vegetatin, pay sme attentin t the apprpriate flw resistance (i.e. Manning s n) t apply t the link. Make sure the rughness used in the lateral link is nt t high. If the value is t high then the water levels in MIKE 11 will tend t be super elevated which, except in situatins where extreme amunts f vegetatin are present, is nnsensical. If the stp bank is the earthen r similar, allwing its invert t be taken frm the MIKE 11 r MIKE 21 shuld be fine. Hwever, in case f well defined structure like side weirs cnstructed in cncrete, mre precise levels shuld be made available t the mdel by using an external ASCII file. Structure Links The structure link is used t simulate structures within the MIKE21 mdel. Fr the linkage a MIKE11 branch with upstream crss-sectin, structure, and dwnstream crss-sectin is linked t MIKE21 with tw links, ne fr each end f the structure. The link takes the flw terms frm the structure in MIKE11 and applies them directly int the mmentum equatins f MIKE11. The MIKE FLOOD manual prvides further details n the ptins available and hw t set the link up. 5.6 INITIAL MODEL TESTING Once the hydrlgical and hydraulic mdel has been substantially built, it must be subject t initial testing Running The Mdel Numerical stability and accuracy f the mdel depends n the time step selected which in turn dictates the run time f mdel simulatins. A dimensinless parameter knwn as Curant Number is cmmnly used as measure f numerical stability and defines the time step. Curant Number describes the relatinship between the speed f physical disturbances in the system and the speed at which disturbances travel in the numerical mdel. Explicit numerical scheme requires the maximum Curant Number is less than 1. Fr an implicit scheme (MIKE11, MIKE URBAN and MIKE21) this requirement is smewhat relaxed. Hwever, the Curant Number in MIKE FLOOD mdelling shuld be kept less than 1 as bth wetting and drying and links are explicit. It is recmmended t run the hydrlgical mdel (TP108 rainfall-runff methd) with a time step f 1 minute. Nvember 2011 Page 61

63 In MIKE FLOOD simulatins, time step set in MIKE21 will be applied t all cupled engines thus verriding the settings in the individual mdels. All mdel cmpnents need t be separately prir t being cupled. First MIKE21 shuld be tested t run n its wn. It is imprtant t test the MIKE URBAN mdel stability applying the MIKE 21 time step, which is ften smaller than 1s. Even minr instabilities can be amplified when mdels are cupled. T enable MIKE URBAN using time step smaller than 1s, a parameter FIXED_DECIMAL_TIMESTEP needs t be enabled and set in dhiapp.ini file. As fr ther mdelling cmpnents, it is imprtant t ensure the MIKE 11 mdel runs smthly with n instabilities at the time step used in MIKE 21. Initially, the results shuld be saved every time step t make sure there are n hidden prblems. It is recmmended t select the Add Output tab f MIKE11 HD Parameter file (hd11) and select the Lateral Inflws t enable inspectin f the flw thrugh lateral links Layut Representatin The pipe cnnectivity shall be crss-checked against the riginal data. Imprting a ge-psitined backgrund map (bitmap image r DXF drawing) int the mdelled netwrk can assist in validating crrect cnnectivity Instability Tests Initial testing shall be undertaken in rder t gain cnfidence that the mdel is perfrming crrectly withut mass errrs and numerical instabilities. Once cnfidence has been established, pre-defined rutine checks can be used later t ensure that the mdel remains stable. T test the stability f the mdel, the mdel must be run with events f differing magnitude. The fllwing events are suggested: N flw; 1 in 2-year ARI design strm; 1 in 100-year ARI design strm; Instabilities encuntered in either MIKE11, MIKE21 and MIKE URBAN are ften magnified in the cupled MIKE FLOOD mdel. It is therefre advisable t ensure that the individual mdels are stable prir t attempting t stabilise the MIKE FLOOD mdel. Instabilities may ccur in transitin areas, where a significant change in velcity r flw depth ccurs. This is ften arund structures and changes in bed gradient. The MIKE21 and MIKE11 mdel shuld be investigated in these areas. It is imprtant t try and balance the necessary mdel adjustments with the mdels ability t accurately represent the study area. Nvember 2011 Page 62

64 Factrs causing MIKE11 instabilities culd include (DHI, 2010): Changes in Flw regime (supercritical t subcritical) Structures High flw velcities Steep sectins (these can be mitigated by placing a weir at the tp f the steep sectin t facilitate the critical flw pint) Rapid water level rises T reduce the instabilities in MIKE11 the fllwing can be changed (DHI, 2010): Reducing time steps Increasing the DELTA parameter in the HD Parameter file. The smaller the time step the larger this value can be. Values f up t 0.9 are reasnable; hwever DELTA shuld stay belw 0.95.The DELTA cefficient dampens high frequency scillatins frm a MIKE11 simulatin and, fr small time step, use f higher values is unlikely t have a significant effect upn the accuracy f mdel predictins. See the MIKE11 Scientific Dcumentatin fr a mre detailed descriptin. Smthing ut steep sectins if pssible r using a mdeling weir Initial cnditins that clsely match the bundary cnditins Factrs causing instabilities in MIKE21 may include (DHI, 2010): Magnitude f surce pint discharges (if used): High inflws int a cell can cause the water level in the cell t rise significantly during a single time step. Lack f grid smthness sudden depressins r ridges may cause neighburing cells t alternate between dry and wet. Als, water may artificially accumulate in the depressins. The bathymetry shuld be checked and smthed where instabilities ccur. Areas with high velcities (changes in flw regime frm subcritical t supercritical) Flding and drying: if the switch between flding and drying cells is t rapidly it may cause instabilities The fllwing can be dne t ensure stability in MIKE21 (DHI, 2010): Reduce the time step Bundaries are sensitive t numerical instabilities, s additinal smthing f the bathymetry alng all pen bundaries may be required. Smthing f cells with surce r sink pints r near the linked cells. Increasing bth flding and drying depths may reduce instabilities, but has t be weighed up against the level f detail required fr the utputs. Nvember 2011 Page 63

65 In rder t stabilise the MIKE URBAN if instabilities ccur the fllwing can be dne: Decreasing the calculatin time step Increasing the pipe lengths by either simplifying the netwrk r by changing the minimum length in the DHIApp.ini file Increasing the distance between cmputatinal pints in the pipe netwrk Checking the bundary cnditins Checking areas where the flw transitin ccurs. The factrs that cause instabilities within the MIKE FLOOD mdel may be: Linkages levels: If the linkage levels between the MIKE11 r MIKE URBAN and the MIKE21 are cmpletely different it may cause instabilities Surce pints clse t linkages r t land values may cause instabilities Sensibility Test Sensibility test will be carried ut prir t carrying ut any mdel validatin t ensure that the mdel results are sensible i.e. within reasnably expected values. As part f the sensibility test f the hydraulic mdel, a cmparisn f peak flws and runff vlumes at critical lcatins with thse estimated by the TP108 graphical methd shall be undertaken fr 100-year ARI strm event. Fr Nrth Shre City area, a GIS shape file fr TP108 graphical methd peak flw tl is available that can be used fr cmparisn purpse. Lcal energy lsses at manhles, hydraulic structures, transitins r bends shuld always be crss-checked with manual calculatins r ther sftware. Pipes/culverts in the mdel with peak velcity greater than 6.0 m/s shuld be identified and carefully checked whether mdelled head lsses at pipe/culvert inlets are underestimated. If necessary the mdel needs t be updated cnsidering expected head lsses cmputed manually based n literature Mass Balance Checks Mass balance checks shall be carried ut t ensure that the ttal water mass unaccunted fr (cntinuity balance) is small cmpared t the ttal inflw vlume t the mdel. Usually a cntinuity errr less than abut 5% is acceptable. The mass balance is the difference between the vlumes f water entering the mdel and the utflws f the mdel as well as the vlume f water stred. In the case f a 3-way cupled MIKE FLOOD mdelling vlumes in MIKE11, MIKE URBAN and MIKE21 mdel shuld be checked (DHI, 2010): Vlume = (M11 Start M11 End) + (M11 In M11 Out) + (M21 Start M21 End) + (M21 In M21 Out) + (MU Start MU End) + (MU In + MU Out) = 0 Nvember 2011 Page 64

66 M11 Start, M11 End: The start and end vlumes in MIKE 11. In rder t utput these values it is necessary t include Ttal Vlume in the additinal results (specified in the HD11 file). The start and end vlumes can then be extracted frm MIKE VIEW, Plt->TS f System Data. M11 In: The inflws int MIKE 11, these will be via either a res11 file in terms f catchments, and/r in the BND11 file as pint inflws. M11 ut: Extract the discharge at the dwnstream bundaries, and calculate the vlume (right click n the discharge plt -> Accumulated Values) M21 Start, M21 End: Start and end vlume in MIKE 21. Open the results file, g int Tls->Statistics. T calculate the vlume, multiply the Number f Pints * Grid Size ^2 *Mean Value. M21 In: Calculate the vlume f the inflws, surce pints and flux bundaries. M21 Out: At any utflw bundaries use the M21 tlbx t extract discharge acrss a bundary. Accumulated vlume is given in the utput frm this. MU Start, MU End, MU In and MU Out: These values can be fund in Summary file prduced by MIKE URBAN run, tgether with the MIKE URBAN mass balance. It is imprtant when calculating these vlumes that the time perid cvers the entire simulatin r at least the same perid. Fr example the MIKE 21 utput results may nt start at the beginning f the simulatin. Details f hydrlgical and hydraulic mdel building prcesses including initial mdel testing results shall be utlined in Mdel Build and System Perfrmance Reprt (refer t Sectin 9.4). Nvember 2011 Page 65

67 6. MODEL VALIDATION / CALIBRATION 6.1 MODEL VALIDATION / CALIBRATION REQUIREMENTS Because f limited available mnitring gauge data within Auckland Cuncil catchments a detailed calibratin f hydrlgical and hydraulic mdel may nt be pssible. In general standard hydrlgical and hydraulic parameter values based n Auckland Cuncil mdelling specificatins will be used and if measured gauging data is available the hydraulic mdel will be validated by cmparing the mdel results with the measured gauging data withut changing the hydrlgical and hydraulic mdel parameter values. If mdel validatin des nt achieve the required validatin acceptance criteria, mdel parameters may be changed t match measured data if a higher level f cnfidence exists in the measured data and large strm events ( 10 year ARI) are available. Mdel calibratin will nly be carried ut after discussin/agreement with Auckland Cuncil. Where shrt-term r lng-term flw/level survey infrmatin is unavailable mdel validatin is t be carried ut using histrical fld incidents/reprts. 6.2 MODEL VALIDATION / CALIBRATION PROCEDURE In mst applicatins a mdel is established with the assumptin that the errrs and uncertainty assciated with the mdel can be minimised and the mdel can be used as a wrking and useful design/planning tl. The final bjective is t make the mdel fit fr purpse given acceptable uncertainty and reliability. There is n definitive sequence f wrking thrugh the stages f mdel validatin/ calibratin. The fllwing sequence is cmmnly used; Sensitivity analysis fr varying hydrlgical and hydraulic mdel parameters; Mdel validatin / calibratin against available flw/level mnitring data fr at least three strm events; Mdel validatin against reprted histrical fld incidents infrmatin Sensitivity Analysis Sensitivity analysis entails varying mdel parameters t identify what type f impact the changes have n the mdel utcmes. Sensitivity analysis shuld be carried ut systematically t rank the mdel parameters that have a significant effect n mdel utput. These parameters require special attentin t reduce uncertainty either thrugh accurate characterisatin r thrugh calibratin/validatin. Sensitivity analysis shuld be carried ut fr the fllwing hydrlgical and hydraulic mdel parameters: Nvember 2011 Page 66

68 Hydrlgical mdel parameter SCS Curve Number, Initial Abstractin Hydrlgical mdel input % f directly cnnected impervius area, time f cncentratin Hydraulic mdel parameter Manning s rughness cefficient n fr natural streams and verland flw paths thrugh prperties/parcels. Sensitivity analysis shuld als be carried ut t assess uncertainty in mdel results. Strmwater mdels are in general imperfect representatins f real systems and thus are subject t uncertainty in the predicted fld risk within the catchment. A freebard f 500mm is usually used t accunt fr the uncertainty in the predicted fld level. It is gd practice t check whether the uncertainty in predicted fld level is within the recmmended 500mm freebard. In general there are three majr surces f uncertainty in fld risk estimates: Uncertainty related t fld flw estimatin Uncertainty related t fld level estimatin and Uncertainty related t survey data. The hydrlgical rainfall-runff mdel is based n the prescriptive ARC TP108 methd and the hydrlgical mdel parameters SCS Curve Number CN, initial abstractin Ia, and time f cncentratin are selected/cmputed in accrdance t the prescriptive table r empirical equatin. As such uncertainty analysis f the hydrlgical mdel parameters is limited. The TP108 rainfall-runff mdel can be expected t be within ± 25% at a cnfidence level f 90 percent fr 2 t 100-year ARI strm events (ARC, 1999). Beside errrs assciated with survey data, Manning s rughness values are the mst significant cntributin t uncertainty in fld level estimatin. Sensitivity analysis f the fllwing parameters is recmmended: Undertake mdel runs using upper and lwer Manning s rughness values given by CES/AES Rughness Advisr database. As discussed in Sectin a crrectin factr f the upper and lwer Manning s rughness values shuld be used fr 1D channel reach t accunt fr additinal energy lss mechanisms. The mdel run results shuld be presented as tabular as well as fld differences maps. The results f sensitivity analysis shuld be presented in the Mdel Build and System Perfrmance Reprt. Nvember 2011 Page 67

69 6.2.2 Mdel Validatin / Calibratin t Mnitring Data The mdel shall be validated t at least three strm events based n available flw/level mnitring data. Mdel validatin shuld be carried ut fr all available gauges. The mdel validatin / calibratin acceptance criteria are given belw. Validatin / Calibratin Acceptance Criteria Statistics quantifying the fit between simulated flw and water level and the measured flw and water level fr each individual event shuld fall within the fllwing maximum tlerances i. Vlumetric errr. The difference in flw vlume shuld lie in the range +20% t -10%. (Mdel Gauge) ii. iii. iv. Peak flw errr. The difference in peak flw rate at each significant peak shuld lie in the range + 20% t - 10%. (Mdel Gauge) Timing errr. The difference in timing f the peaks shuld lie be in the range +1 hur t 1 hur (Mdel Gauge). Cefficient f crrelatin, r 2. The flw crrelatin shuld lie be in the range 0.60 t 1.0. v. Peak depth errr. The difference in unsurcharged peak depth shuld be within ±15% (Mdel Gauge). The fllwing methdlgy shuld be cnsidered during mdel validatin / calibratin prcess using TP108 rainfall-runff methd: The histrical rainfall events selected fr mdel validatin shuld be greater than 5-year ARI event and nt be mre than 24-hur duratin. The selected strm events shuld be cntinuus. There is sme recvery f infiltratin rates during intervals f n rain. If the perid des nt exceed an hur, it can be ignred and is expected t have negligible effects. The TP108 methd is nt suitable fr small strm events (< 2-year ARI), which is fund t be related t the variability in antecedent misture cnditin. CNs calibrated fr a small strm event may nt be useful fr extreme strm events. CNs given in TP108 methd is based n average antecedent misture cnditin and is suitable fr design applicatins. Antecedent misture cnditin is less sensitive fr 24-hur duratin Chicag type design strm. Initially TP108 prescribed mdel parameters CN & Ia shuld be used t cmpare the mdelled runff vlume with the measured runff vlume. Base flw shuld be deducted frm the measured flw time series data t estimate measured runff vlume. If mdel des nt fulfil the validatin acceptance criteria fr runff vlume, mdel calibratin can be carried ut after discussin/agreement with Auckland Cuncil. Nvember 2011 Page 68

70 Next step is t match the peak flw and shape f the hydrgraph by running the hydrlgical and hydraulic mdels. Initially TP108 empirical lag equatin shuld be used t estimate the time f cncentratin. If mdel des nt fulfil the validatin acceptance criteria fr peak flw/timing, mdel calibratin can be carried ut after discussin/agreement with Auckland Cuncil. Time f cncentratin estimatin is smewhat uncertain and can have significant effects n peak flws. Time f cncentratin may be estimated thrugh calibratin. The fllwing methdlgy shuld be cnsidered during hydraulic mdel validatin/ calibratin prcess: Water level r tidal time series mnitring data shuld be used as dwnstream bundary cnditins. If flw mnitring data shws significant base flw within the drainage system, cnstant upstream inflw bundary shuld be used as base flw based n flw mnitring data. The mdel shuld run with cnstant inflw (base flw) and cnstant dwnstream water level/tidal bundary (bth frm mnitring data) fr certain duratin befre the start f the calibratin/validatin event s that any instabilities assciated with the initial cnditin diminish ut f the entire drainage system. Initially Manning s n rughness values listed in Sectin shuld be used fr mdelling pen channels, fldplains and verland flw path areas. If mdel des nt fulfil the validatin acceptance criteria fr peak depth/timing, mdel calibratin can be carried ut after discussin/agreement with Auckland Cuncil. Manning s n value shuld be changed glbally acrss the catchment nt just the lcal area arund the gauges. Smaller strm events may be used first t validate/calibrate in-bank channel rughness values. Finally ut f bank channel/ fldplain rughness values shuld be cnfirmed using larger strm events. The results f mdel validatin shall be presented as a quantitative estimate f hw well the mdel reprduces the real-wrld. The statistics shuld be summarised fr each representative event and fr all gauges. Explanatins shuld be prvided where mdel validatin statistics lies utside the ranges stated abve. A summary f mdel validatin results and cmparisn plts shuld be presented in the Mdel Build and System Perfrmance Reprt Mdel Validatin t Histrical Fld Incidents The mdel shall be validated against reprted histrical fld incidents infrmatin. Histrical flding cmplaints may be available frm Auckland Cuncil database. Three histric rainfall events shuld be simulated using crrespnding bundary cnditins and the results shuld be cmpared t reprted flding incidents (if incidents are available). The fld incidents infrmatin shuld be crrelated with the mdel and a summary f mdel validatin results shuld be presented in the Mdel Nvember 2011 Page 69

71 Build and System Perfrmance Reprt. Explanatins shuld be prvided in case the mdel culd nt replicate the reprted fld incidents. 6.3 MODEL VALIDATION TO MIKE21 MODEL RESULTS A 2D hydraulic mdel, MIKE21, has been used fr a number f catchments within the Auckland Cuncil t develp rapid fldplain maps. The MIKE21 mdelling uses 2D grund surface generated frm LiDAR data, assumes the primary drainage system is blcked, and applies ARC TP108 strmwater inflw hydrgraphs t the upstream f each sub-catchment r rain n grid lading apprach. The 2D mdel fldplain prvides a valuable tl during the develpment f detailed 1D strmwater catchment mdel. The 2D mdel prvides a cnservative fldplain estimatin which defines the level f wrst risk f prperty flding within the Catchment. A cmparisn f the present 1D mdel fldplain with the 2D mdel fldplain shall be undertaken and the areas where 1D fldplain differs greatly cmpared t the 2D fldplain shall be identified. If needed the mdel schematisatin shuld be updated accrdingly fr accurate fld plain extent mapping. 6.4 MODEL RESULTS COMPARISON TO PREVIOUS MODEL A cmparisn f present mdelled peak flws with thse btained frm previus mdel at varius lcatins alng the drainage netwrk system shall be undertaken and the differences in peak flws between the mdelling studies shall be explained. Details f hydrlgical and hydraulic mdel validatin prcesses shall be utlined in Mdel Build and System Perfrmance Reprt (refer t Sectin 9.4). Nvember 2011 Page 70

72 7. SYSTEM PERFORMANCE ASSESSMENT System perfrmance identifies the level f perfrmance prvided by the strmwater system. The system perfrmance cnsists f the fllwing aspects; The capacity f the existing strmwater drainage system. An assessment f the level f service prvided cmpared t the desired level f service, and the identificatin f netwrk sectins that d nt prvide the necessary level f service. Fldplain, fld hazard and fld sensitive area mapping t identify significant fld hazard areas and habitable flrs at risk f flding. Design flws and water levels fr nminated design strm events and land use develpment / future rainfall scenaris. 7.1 SYSTEM PERFORMANCE SCENARIOS Design Strm Mdel Scenaris The system perfrmance assessment shall be carried ut fr the nminated 6 design strm events (2, 5, 10, 20, 50, and 100 year ARI) fr the existing and future scenaris. This equates t a ttal f 12 different simulatins, which will be used fr the perfrmance assessment f the strmwater drainage system. The existing scenari invlves using existing develpment (ED) land use and the existing rainfall depth and the existing TP108 rainfall prfile. The future scenari invlves using maximum prbable develpment (MPD) land use and the future rainfall depth and the climate change adjusted rainfall prfile. The existing 24-hur design rainfall depth shall be estimated frm the design rainfall cntur maps prvided in Appendix A f TP108 dcument (ARC, 1999). The future 24-hur design rainfall depth due t future climate change shall be estimated in accrdance t the guideline prvided by the Ministry fr the Envirnment (2008). The guideline prvides a table f percentage increase in rainfall per degree Celsius f warming fr a range f ARIs and duratins. The prjected average increase in annual mean temperature fr Auckland Regin is 2.1 C fr the perid frm 1990 t This is cnsidered fr estimating the future 24-hur design rainfall depth and develping the future nrmalised 24-hur tempral design strm prfile due t future climate change. The percentage increase in 24-hur design rainfall depth is given in Table 7.1 and the tempral pattern f the future TP108 nrmalised 24-hur rainfall intensity is given in Table 7.2. The existing and future 24-hur rainfall depth and the crrespnding Nvember 2011 Page 71

73 tempral patterns f the existing and future nrmalised rainfall intensity shall be used t develp the existing and future 24-hur tempral design rainfall prfiles. Table 7.1 Percentage Increase in 24-hur Design Rainfall Depth Average Recurrence Interval (ARI) Percentage Increase in 24-hur Design Rainfall Depth Due t Future Climate Change (2.1 C Increase in Temperature) 2-year 9.0% 5-year 11.3% 10-year 13.2% 20-year 15.1% 50-year 16.8% 100-year 16.8% Table 7.2 TP108 Nrmalised 24-hur Tempral Rainfall Intensity Prfile Time (hrs:mins) Time Interval (min) TP108 Nrmalised Rainfall Intensity (I/I 24 ) Future Climate Change Existing (2.1 C Increase in Cnditin Temperature) 0:00 6: :00 9: :00 10: :00 11: :00 11: :30 11: :40 11: :50 12: :00 12: :10 12: :20 12: :30 13: :00 14: :00 15: :00 18: :00 24: Land Use Develpment Mdel Scenaris System perfrmance shall be carried ut fr the Existing Develpment (ED) and Maximum Prbable Develpment (MPD) land use scenaris. Nvember 2011 Page 72

74 The ED scenari shall be mdelled with the existing design rainfall prfile and the MPD scenari shall be mdelled with the future design rainfall prfile. In general, land use develpment will change nly the impervius prtin f the catchment. With respect t catchment mdelling, increased develpment changes the impervius directly cnnected area and the cmbined (pervius and impervius uncnnected) area. It will als generally decrease the respnse time f the catchment. The assumptins made regarding mdelling the existing and future land use develpment scenaris must be fully reprted Tailwater Level Mdel Scenaris Fr Auckland City catchments a Mean High Water Spring (MHWS) cnstant tidal bundary cnditin shuld be used fr system perfrmance assessment. T take int accunt prbable rise in tide levels due t future climate change, a cnstant value f 0.5m needs t be added. The dwnstream tidal bundary levels t be used are: Fr Waitemata Harbur: 1.39m RL (existing scenari) and 1.89m RL (future scenari year 2100 planning hrizn) Fr Manukau Harbur: 1.94m RL (existing scenari) and 2.44m RL (future scenari year 2100 planning hrizn) Fr all ther Auckland Cuncil catchments a Mean Sea Level (MSL) cnstant tidal bundary cnditin shuld be used fr system perfrmance assessment. T take int accunt prbable rise in tide levels due t future climate change, a cnstant value f 0.5m needs t be added Simulatin Matrix Fr Auckland City catchments the simulatin matrix utlined in Table 7.3 belw shuld be used fr the system perfrmance assessment. Fr all ther Auckland Cuncil catchments the simulatin matrix utlined in Table 7.4 belw shuld be used fr the system perfrmance assessment. Table 7.3 Mdel Simulatin Matrix fr Auckland City Catchments Land Use Catchment ARI Event Design Rainfall ARI Event Tailwater Level Existing Develpment 2, 5, 10, 20, 50, 100-Year Existing 2, 5, 10, 20, 50, 100-Year Mean High Water Spring Maximum Prbable Develpment 2, 5, 10, 20, 50, 100-Year Future 2, 5, 10, 20, 50, 100-Year Mean High Water Spring +0.5m Nvember 2011 Page 73

75 Table 7.4 Mdel Simulatin Matrix fr Rest f the Auckland Cuncil Catchments Land Use Catchment ARI Event Design Rainfall ARI Event Tailwater Level Existing Develpment 2, 5, 10, 20, 50, 100-Year Existing 2, 5, 10, 20, 50, 100-Year Mean Sea Level Maximum Prbable Develpment 2, 5, 10, 20, 50, 100-Year Future 2, 5, 10, 20, 50, 100-Year Mean Sea Level +0.5m Simulatin Perid and Results Saving Time Design strms used in mdel simulatins are 24 hur duratin strms and the simulatin perid fr the hydrlgical mdel shuld be 24 hurs. Hwever, in rder t reduce simulatin time fr 2D and 1D/2D cupled hydraulic mdels, a reduced simulatin perid culd be used if agreed by Auckland Cuncil. Mdel results shuld be saved in 2 minutes time interval fr up t 1000 ha catchment area and 5 minutes time interval fr greater than 1000 ha catchment area. 7.2 WATER BALANCE OF THE CATCHMENT An assessment f water balance f the catchment shall be carried ut fr the nminated 6 design strm events under ED and MPD land use develpment scenaris as utlined abve. A summary f water balance f the catchment shall be tabulated in the reprt fr the catchment rainfall vlume and catchment runff vlume. 7.3 CAPACITY OF THE EXISTING PRIMARY PIPE SYSTEM The capacity f the existing primary pipe system shall be assessed in accrdance t the respective legacy Cuncil's Infrastructure Design Standards. The capacity f the existing primary pipe reticulatin system shuld be assessed fr tw basic flw cnditins: free full flw and backwater r dwnstream effect. Under gravity full flw cnditin, the flw is cntrlled by the frictinal resistance f the ttal circumference f the pipe and the free full flw capacity f the pipe cnduit shuld be determined using Manning s Equatin assuming flw is steady-state, the pipe is flwing full under gravity, the pipe is free frm sediment and blckage, and pipe frictin slpe equals the pipe invert slpe. Nvember 2011 Page 74

76 The pipe cnduit fr free gravity full flw cnditin shall be assessed by Q max / Q manning which is calculated as rati f maximum flw in the pipe divided by the Manning s pipe free gravity full flw capacity, e.g. if the pipe is running under pressure the rati will be abve 1.0. The pipe cnduit under backwater r dwnstream effect shall be assessed by pipe filling (D/S H max /D) which is calculated as the dwnstream maximum depth divided by the pipe diameter r height, e.g. if the pipe is under dwnstream effect the rati will be abve 1.0. The capacity f the existing pipe system shall als be assessed based n the maximum system flw thrugh the pipe cnsidering n upstream flw restrictin r attenuatin. This wuld prvide the level f flw attenuatin due t engineering within the catchment. A summary f the perfrmance f the existing pipe system fr ED and MPD scenaris shall be tabulated in the reprt fr varius flw cnditins (free full flw, backwater effect, free full flw with maximum system flw) in terms f percentages f ttal number f pipes with capacity greater than 2-year ARI, 5-year ARI, 10-year ARI, 20- year ARI, 50-year ARI and100-year ARI strm events. Mdelled peak flws and water levels alng the strmwater drainage netwrk fr varius design strm events (2-year ARI, 5-year ARI, 10-year ARI, 20-year ARI, 50- year ARI and 100-year ARI) under ED and MPD scenaris shall be tabulated in an appendix t the reprt. Thematic maps shwing the pipe capacity f the existing pipe system fr MPD scenari shall be presented in an appendix t the reprt fr varius flw cnditins (free full flw, backwater effect, free full flw with maximum system flw) in terms f varius strm events (<2-year ARI, 2 t 5-year ARI, 5 t 10-year ARI, 10 t 20-year ARI, 20 t 50-year ARI, 50 t 100-year ARI, and >100-year ARI). In additin t thematic maps f pipe capacity, a thematic map shwing the frequency f manhles verflwing fr MPD scenari shall be presented in an appendix t the reprt in terms f varius strm events (<2-year ARI, 2 t 5-year ARI, 5 t 10-year ARI, 10 t 20-year ARI, 20 t 50-year ARI, 50 t 100-year ARI, and >100-year ARI). 7.4 CAPACITY OF THE EXISTING CULVETS AND BRIDGES The capacity f the existing culverts and bridges shall be assessed in accrdance t the respective legacy Cuncil's Infrastructure Design Standards. A summary f the capacity assessment f the culverts and bridges within the catchment shall be tabulated in the reprt. In additin t the flw capacity assessment, the culverts and bridges shuld be assessed in relatin t vertpping the rads e.g. primary rads shuld nt vertp mre frequently than nce every 100 years, secndary r lcal rads shuld nt vertp mre frequently than nce every 10 years. Nvember 2011 Page 75

77 A summary f maximum water levels upstream f culverts, pipe inlets and bridges cmpared t vertpping level shall be tabulated in the reprt. 7.5 FLOODPLAIN MAPPING Fldplain areas shall be assessed in accrdance t the legacy Cuncil's Infrastructure Design Standards D and 2D Fldplain Mapping The extent f fldplains and pnding areas shuld be mapped fr the 10-year and 100-year ARI strm events fr MPD land use and the future rainfall scenari. Fr the Auckland City area the extent f fldplains and pnding areas shuld be mapped als fr the 50-year ARI strm event fr MPD land use with future rainfall scenari. All pnding areas greater than 300mm depth f flding shuld be mapped. The fld sensitive area shuld be mapped which is the extent f flding crrespnding t 100-year ARI MPD fld levels plus 500mm f freebard. The fllwing criteria shuld be fllwed in case f 1D and 2D fldplain mapping f verland flw paths: Fldplain mapping fr verland flw paths shuld be carried ut fr thse verland flw paths with flws greater than 2.0 m 3 /s. In additin, majr verland flw paths shuld be mapped with a thick red line when the verland flw exceeds 0.5 m 3 /s but is less than 2.0 m 3 /s during the 100-year ARI MPD event. Minr verland flw paths shuld be mapped with a thick green line when the verland flw exceeds 0.0 m 3 /s but is less than 0.5 m 3 /s during the 100-year ARI MPD event. A 50mm depth f flding shuld be used as the threshld fr 2D fldplain mapping i.e. the fldplain map fr each ARI strm event shuld be the areal extent f flding with a fld depth greater than 50mm. Fldplain area shuld be presented with a call-ut bx shwing the grund level plus fld levels fr the 10, 50 (if applicable) and 100yr ARI events at 50m t 100m intervals. Results frm the mdelling shuld be presented in a series f hardcpy A3 fldplain maps at Auckland Cuncil apprved scales. Nvember 2011 Page 76

78 7.5.2 Buildings at Risk f Flding Auckland Cuncil defines building flrs at risk f flding as either: Habitable includes buildings whse primary functin is a dwelling, r wrk r meeting place, including huses, cmmercial and industrial buildings, cmmunity and recreatinal buildings. Nn-habitable includes garages, haybarns and ther utbuildings. Buildings flrs ptentially affected by the fld hazard are cunted either as being belw the simulated fld level, r within 500mm f the simulated fld level. A spatial jin can be created between the flding terrain and the building plygn with the assciated flr level. The depth f flding shall be calculated n the basis f the maximum water level within the building plygn minus the flr level. The cnsultant needs t check fr any buildings that are multiple buildings r where nn-habitable buildings have been included in the calculatin. A list f significant flding areas including prbable residential/business habitable and nn-habitable flr flding and the causes f flding shuld be presented in a table in the reprt. Details f the significant flding areas including causes f flding shuld be presented in the reprt with phts. In additin, all reprted fld incidents identified thrugh issues register r questinnaire survey shall be taken int accunt with any differences with mdel utcmes explained. The fllwing list f prperties and buildings within the 100-year ARI MPD fldplain shuld be presented in an appendix t the reprt: i. List f buildings with a habitable flr flding and the frequency f habitable flr flding ii. iii. iv. List f buildings with a habitable flr within 500mm f the 100-year ARI MPD fld level (habitable flr with inadequate freebard) List f buildings with a habitable flr abve 500mm f the 100-year ARI MPD fld level (habitable flr with adequate freebard) List f prperties within the 100-year ARI MPD fld plain (nuisance flding) Nvember 2011 Page 77

79 7.6 FLOOD HAZARD MAPPING Fld Hazard Classificatin Methdlgy The NSW Fldplain Develpment Manual (2005) prvides the (depth, velcity) cmbinatin that identifies fld hazard, summarised as (depth, velcity) pairs lying utside an envelpe described by: Velcity greater than 2m/s (Vt > 2.0m/s) Depth greater than 0.3m (Dt > 0.3m) Depth * Velcity relatinship (Dt * Vt > y = -20x+6) Surface flding, as well as verland flw with unsafe depths and/r velcities were identified and defined as "significant" fld hazards (NSW, 2005). The fllwing fld hazard classificatin methdlgy has been develped based n the NSW fld hazard methdlgy which shall be used fr bth 1D and 2D mdel fld hazard mapping. The Fld Hazard Mapping identifies areas with the ptential t cause damage accrding t chsen criteria. These criteria cnsidered the fllwing aspects: Flding f private r public prperty Overland flw ccurring t such a depth and/r velcity as t pse a pssible safety hazard t vehicles and pedestrians. The utputs frm the mdel are t be used fr the fllwing applicatins: Fld Hazard Mapping Auckland City GIS layer fr internal and public infrmatin Land Infrmatin Memrandums (LIM s) It is therefre necessary t ensure that utputs sufficiently fulfil the requirements f all applicatins while maintaining cnsistency in presentatin and extractable infrmatin. The prpsed fld hazard classificatin is presented in Table 7.5 belw. The depthvelcity criteria fr each hazard classificatin are shwn in Figure 8 belw. This methd evaluates the hazard classificatin at each time step and determines the maximum/ wrst case hazard. The velcity and depth used t calculate the hazard classificatin are temprally cincidental (i.e. must be ccurring at the same time). It shuld be nted that maximum velcity and the maximum depth may nt necessarily be cincident. In 1D MIKE URBAN and MIKE11 mdels the H-pints (D-pints) and Q-pints (Vpints) are staggered, i.e. are nt lcated at the same lcatin alng the pen Nvember 2011 Page 78

80 channel branch. The depth and velcity pairs shuld be cnsistent with each ther and shall be selected as fllws: the velcity value frm a Q-pint but depth value as an average value frm the upstream and dwnstream H-pints f that Q-pint alng the pen channel r verland flw path branch. In case f 2D mdelling the depth and velcity values fr each grid cell ver the entire simulatin perid shall be extracted frm the result file and used t determine the hazard classificatin. Nvember 2011 Page 79

81 Table7.5 Fld Hazard Classificatin Categry Hazard Classificatin Descriptin Depth Velcity Criteria 1 Ptential Hazard 0.05 m < Depth < 0.1 m 2 Minr Hazard 3 Significant Hazard 0.1 m Depth < 0.3 m and Velcity < 2.0 m/s Depth 0.3 m and Depth 0.1 m & Velcity 2.0 m/s 0.4 SIGNIFICANT HAZARD 0.3 DEPTH (m) 0.2 MINOR HAZARD 0.1 POTENTIAL HAZARD VELOCITY (m/s) Figure 8 Depth Velcity Criteria fr Hazard Classificatin D and 2D Fld Hazard Mapping The fld hazard mapping shuld be based n the apprved fldplain area. The fld hazard map shuld be mapped nly fr the 100-year ARI strm event fr MPD land use with future rainfall scenari. The abve fld hazard classificatin methdlgy shall be used fr bth 1D and 2D mdel fld hazard mapping cvering the apprved fldplain area. Results frm the mdelling shuld be presented in a series f hardcpy A3 fld hazard maps at Auckland Cuncil apprved scales. In additin, the deliverables shuld include: Nvember 2011 Page 80

82 Digital cpies f the abve fld maps (in PDF frmat); All relevant mdel input files (hydrlgical and hydraulic mdels); All simulated result files; Grid files f the prcessed result files (maximum extents, depth and velcities). 7.7 FLOOD DAMAGE ASSESSMENT Fld Damage Assessment (FDA) is a methd f quantifying the value f predicted future fld damages, which can be used t supprt capital investment decisins n fld mitigatin slutins. It prvides an ecnmic analysis f cst vs. benefit f capital engineering slutins t address the risk f flding t prperty and buildings. The analysis utilises fldplain maps generated frm hydraulic mdel results t assess the degree t which prperties are inundated in the fldplains fr varius ARI strm events and derives an estimate f the damage incurred. These values can be translated int an Annual Average Damage (AAD) fr ED and MPD scenaris that represents the apprximate damage a catchment culd experience in a year. This value can be used t cmpare the csts f wrks that wuld mitigate flding against the benefits f such imprvements (the amunt f damage reduced), t prvide an ecnmic justificatin f such mitigatin wrks. The fllwing utlines the summary f the methdlgy t be used fr Fld Damage Assessment: 1) Identify buildings that lie in the 100-year ARI fld plain based n future landuse develpment and the future rainfall scenari. 2) Determine the flr levels f the identified prperties thrugh field surveys and find the flr areas f thse buildings frm GIS building ftprints. 4) Extract the predicted maximum fld level fr each building fr each Average Recurrence Interval (ARI) event frm the hydraulic mdel results. Fr a 1D mdel estimate the maximum fld level fr each building frm the fld levels f nearby mdel ndes using linear interplatin. Fr a 2D mdel select the maximum fld level frm 2D cells within the building ftprint fr each building. 5) Analysis f the available data: Cmpare the predicted fld level and flr level t determine whether r nt flding ccurs. The fld height (fld level flr level) will be used t determine fld damage. Determine the stage damage level based n the height f inundatin. Calculate the damage based n the fld height and flr area. Nvember 2011 Page 81

83 Graph the ttal damage fr each event as Damage vs. Average Recurrence Interval (ARI) (2, 5, 10, 20, 50, and 100 year). Calculate the area under the graph t btain the Annual Average Damage (AAD) fr the catchment fr ED and MPD scenaris. Calculate the net present value (based n a 50-year design perid) fr the purpses f determining the Benefit Cst Rati (BCR) f fld mitigatin prjects. The fllwing shuld be cnsidered fr Fld Damage Assessment: Identifying Buildings Buildings t be cnsidered shall be lcated within the 100-year ARI fld plain based n future land use develpment and future rainfall scenari. Fr the purpses f this FDA, nly habitable flrs are cnsidered. This means buildings such as unattached garages, uthuses, pl-huses etc, shall nt be analysed. Building Attributes There are three attributes required frm at risk buildings; flr level, flr area and land use (residential r cmmercial). If the building is classified as cmmercial, then the specific use f the cmmercial building als needs t be determined. Flr Level: Once a fldplain map has identified all the buildings which are at risk f flding fr the selected design events, flr levels are determined frm field surveys. Flr Area: The flr area f each building can be relatively easily btained based n its GIS ftprint derived frm aerial phtgraphy. This area needs t be scaled dwn based n its ftprint size t accunt fr eaves verhanging the rf (as the area f the flr is required, nt the area f the rf) using the fllwing factrs: Building Ftprint Area (m 2 ) True Area (%) Where the ftprint f a building was nt in the GIS database, the area f a simple plygn drawn ver the utline f the building s aerial phtgraph sufficed. The building ftprint is assumed t represent the area f damage. Flding is assumed nt t reach 2nd r higher level flrs. Landuse: The landuse f the flded building is determined using District Plan infrmatin. The primary purpse f FDA is t determine the degree f residential fld damage. Hwever, in sme catchments cmmercial prperties can make up a Nvember 2011 Page 82

84 large prprtin f buildings afflicted and as such, they may need t be cnsidered. Due t the large range f damage csts based n the type f cmmercial use, these need t be further defined (e.g. manufacturing, retail, ffices, educatinal, etc.). Data Analysis The first step is t cmpare the fld level with the flr level t determine the fld height f the building. This value will dictate the damage level and subsequently the amunt f damage sustained. The fld height is simply the difference between the fld level and the building flr level. Fld height = Fld Level Flr Level The ttal damage t a residential building is split between structural and cntents. Structural damage is applied n a per square metre basis and calculated by multiplying the true flr area by the damage/m 2 fr the respective fld height. Cntents damage n the ther hand is assumed t remain cnstant regardless f flr area and as such is dependent n fld height. Ttal Damage (residential) = (Structural Damage ($/m 2 ) X True Flr Area (m 2 )) + Cntents damage($)) In case f cmmercial building the ttal damage is calculated by multiplying the flr area by the damage rate per m 2 fr the respective fld height. Ttal Damage (cmmercial) = Damage Rate ($/m 2 ) X Flr Area (m 2 ) The residential and cmmercial damage rates ($) per m 2 f flr area fr different fld heights shall be supplied by Auckland Cuncil. Annual Average Damage (AAD) Once the damage t each prperty fr each mdelled strm event (2, 5, 10, 20, 50, and 100 year ARI) in a catchment has been calculated, the values are pltted as a graph f the ttal damage f each event against the Average Recurrence Interval (ARI) f the event. The area under the graph is the Annual Average Damage (AAD) f the catchment. The Annual Average Damage (AAD) shall be calculated fr ED and MPD scenaris. With the AAD it is then pssible t calculate the Net Present Value (NPV, based n a standard life f 50 years and discunting rate f 8%) f the damage t the catchment if n wrk is undertaken t alleviate flding. This can be used as a benchmark against the NPV f wrks which will prevent r minimise flding and hence reduce the damage sustained. By cmparing the rati f d nthing NPV t a particular prjects NPV, a Benefit-Cst Rati (BCR) is btained. This is in the general frm f: Benefits / Csts = ( NPV pre wrks AAD NPV pst wrks AAD ) / (NPV wrks ) Or simplified: Nvember 2011 Page 83

85 Benefits / Csts = NPV damage reductin / NPV wrks Nvember 2011 Page 84

86 8. OPTIONS ASSESSMENT 8.1 OBJECTIVES Optins mdelling and assessment shall be carried ut t alleviate flding issues within the catchment identified in the Mdel Build and System Perfrmance Reprt. Mitigatin measures required t bring the strmwater drainage netwrk up t the desired AC strmwater service levels fr nminated design strm events and land use develpment/ future rainfall scenaris shall be cnceptualised, assessed and recmmended. All prpsed feasible remedial wrks ptins will be systematically defined and assessed. In additin, apprpriate mitigatin measures shall be prpsed where enhancement is pssible. Finally a preferred system imprvement wrks shall be identified that will alleviate flding issues within the catchment. 8.2 OPTIONS MODELLING AND ASSESSMENT Optins Identificatin and Mdel Runs All the remedial wrks ptins cnsidered /recmmended in the previus studies t address the flding issues in the catchment shuld be cnsidered during identificatin f pssible fld mitigatin wrks. A number f pssible fld mitigatin wrks ptins shuld be systematically defined and cnceptualised. Mdel runs shall be carried ut fr identified fld mitigatin ptins fr nminated design strm events and land use develpment/ future rainfall scenaris. Selected remedial wrks shuld be sized in the mdel in rder t bring the strmwater drainage netwrk up t the desired AC strmwater service levels fr nminated design strm events and land use develpment/ future rainfall scenaris. Staged wrks may be prpsed. All changes made t the mdel as a result f incrprating the ptin shuld be clearly dcumented including any surce infrmatin fr the changes. All changed mdels shuld be tested fr stability and mass cnservatin Optins Assessment The csts, benefits, advantages and disadvantages f each prpsed remedial wrkable ptin shall be evaluated. A schedule f csts fr all prpsed remedial wrks identified shuld be prepared. All cst estimates shuld be based n cnstructin rates supplied by AC. Cst estimates shuld include prvisin fr design wrk, the develpment f resurce cnsent applicatins, silt cntrl measures, cntract bservatin, prject management and a 20% cntingency. Nvember 2011 Page 85

87 The financial develpment cntributin required as the result f future develpment in each catchment shuld be determined. This shuld be determined using the standard AC spreadsheet fr develpment cntributins. If the desired r statutry perfrmance standards cannt be achieved within required time scales and existing budgets, the csts/benefit debate will need t lead t slutins that are affrdable, even if the standards are nt acceptable t all Recmmended Optins A final set f preferred system imprvement wrks shall be recmmended based n; Optins evaluatin criteria, Benefit/Cst analysis, The marginal cst f achieving perfrmance standards (r setting f affrdable perfrmance standards). Fr the final set f preferred system imprvement wrks, the fllwing shall be prduced: Mitigated Fld extent maps fr the design strm events and land use develpment scenaris nminated by AC, Tabulated mitigated and unmitigated flws and capacity, Tabulated mitigated and unmitigated water-levels. Details f ptins mdelling and assessment shall be utlined in Optins Assessment Reprt (refer t Sectin 9.5). Nvember 2011 Page 86

88 9. DELIVERABLES AND QUALITY SYSTEMS 9.1 REPORTING SCHEDULE Adequate dcumentatin shuld be maintained and prvided with the mdel in rder t ensure that the maximum use can be btained frm the mdels, t give cnfidence in the mdel and results and t ensure that new users can easily understand the mdels. The fllwing reprts shall be submitted: Reprt Draft Due Date Final Mdel Extents and Data Assessment Reprt Delivered within 4 weeks f receipt f all data frm AC Delivered within 1 week f review meeting with AC Mdel Build and System Perfrmance Reprt Delivered by the agreed milestne date Delivered within 3 week f review meeting with AC Optins Assessment Reprt Delivered by the agreed milestne date Delivered within 3 weeks f review meeting with AC All the abve reprts shuld be prepared and presented electrnically in Micrsft Wrd dcument frmat. Standard dcumentatin templates in MS Wrd dcument frmat fr the abve reprts can be prvided upn request. In additin t the abve reprts, all necessary electrnic files, including mdel simulatin input and result files, system data files and databases, HTML files, metadata, mdel lg-bk, spreadsheets, PDF files, MS Wrd dcument files, GIS shape files, GIS grid files, AutCAD drawing files and ther assciated files generated shall be submitted. All surce data must be electrnically stred, clearly labelled and presented with the prject upn cmpletin. This ensures the surce data can be cmpared t any updates made in the future. The surce data and surce date f all input data must be recrded. All spatially riented data shall be presented in New Zealand Transverse Mercatr crdinate system. If data is presented in a crdinate system ther than NZTM, each dataset must be clearly referenced with a crdinate system. This applies t spatial data stred inside and utside f GIS systems. 9.2 QUALITY SYSTEMS The wrk f building a strmwater drainage mdel ften invlves large amunts f data. A quality system shuld be adpted in rder t prvide a gd framewrk fr Nvember 2011 Page 87

89 cntrlling and dcumenting the flw f data. Efficient quality systems fr mdelling prcesses will prvide systematic tracking the surce f all mdel build data and a basis fr mdel updates, validatin and justificatin fr mdel parameters used. At every phase f the mdelling Prject quality systems shall be established and fllwed t ensure cnfidence in the resulting mdel Mdel Lg-Bk A mdel lg-bk shuld be maintained with the mdel at all times. All day-t-day assumptins, majr decisins made and the basis behind them, and details f parameter adjustments shuld be dcumented in the mdel lg-bk. The mdel lgbk shall be prepared in spreadsheet, electrnically stred and accmpany the mdel upn delivery. Detailed prcedures fr preparing mdel lg-bk including a sample are utlined in Appendix B Metadata Metadata utlining the surce f all imprtant mdel build data must be maintained in rder fr AC t assess the accuracy f the mdelled asset data any time in the future. The metadata shall be prepared in spreadsheet, electrnically stred and accmpany the mdel upn delivery. Detailed prcedures fr preparing metadata including standard template fr different mdel build data attributes are utlined in Appendix C. The standard template fr metadata can be supplied upn request Quality Assurance and Quality Checks At the cmpletin f the mdel build phase, the mdel shall be internally quality assured and checked. The mdel shall be carefully reviewed and assured it as fit fr purpse befre the mdel can be cnfidently used t assess the perfrmance f the existing strmwater drainage system. A standard template fr mdel review (QA/QC) is prvided in Appendix D which shall be used t review the new mdel as well as any previus mdel available. The mdel review template is cnstantly being revised and updated t ensure mdels are adequately reviewed. 9.3 MODEL EXTENTS AND DATA ASSESSMENT REPORT A Mdel Extents and Data Assessment Reprt shall be prepared, submitted and finalised at the early stages f the Prject which will include details f rapid fld hazard assessment mdelling, details f hydrlgical and hydraulic mdel extents Nvember 2011 Page 88

90 including their basis, mdel build data availability and assessments, data cllectin and survey requirements. Table f cntents fr Mdel Extents and Data Assessment Reprt are prvided in Appendix E. The Mdel Extents and Data Assessment Reprt shall clearly identify the fllwing: Previus Mdel Review: Mdel review f any previus mdelling carried ut in the catchment using the AC standard template; Rapid Fld Hazard Assessment Mdelling: A descriptin f methdlgy used fr rapid fld hazard assessment mdelling including mdel bathymetry, any mdificatins t DEM, mdel parameter values used in the mdel, initial/bundary cnditins, mdel run time and time steps; A brief descriptin f mdel results and discussins including pst prcessing f mdel results, mass balance checks and fld hazard mapping; Mdel Extents: The mdelling study bjectives, activities and scpe; The prpsed catchment bundary and identify any errrs r discrepancies in the preliminary catchment bundary prvided by AC; The prpsed sub-catchment bundaries t an apprpriate detail; The prpsed hydraulic mdel netwrk extent t an apprpriate detail; A plan f the prpsed catchment bundary nting any differences t the preliminary catchment bundary prvided by AC; A plan f the prpsed sub-catchment including the basis f sub-catchment delineatin used; A plan f the prpsed hydraulic mdel extents including the basis f drainage netwrk alignment in the mdel and clearly defining: pipe, culvert, bridge sectins pen channel links prpsed t be mdelled surface detentin/retentin/basin areas prpsed t be mdelled and utlets. Data Availability and Quality Assessment: Nvember 2011 Page 89

91 The Reprt shall review, audit and verify all asset data (extent, quality, etc) including tpgraphical, crss-sectinal, and peratinal data prvided by AC fr building a mdel suitable fr achieving the Prject bjectives. Specifically, the Reprt shall; List f all available data including their surces manhles, pipes, culverts, pnds/ basins, flding issues, tpgraphical, peratinal, and hydrmetric data. All data deficiencies and anmalies identified including an assessment f the criticality t the prject; A summary f the shrt-term and lng-term gauging data and details f all assessments carried ut and the findings; Adequacy and suitability f the available hydrmetric data fr mdel validatin; The recmmended perids r events fr mdel validatin, and estimated return perid f these events; Data Cllectin and Survey Requirements: All assumptins made t reduce survey requirements withut affecting the mdel perfrmance; All additinal data required fr survey, including a recmmended apprach fr btaining this data cnsistent with the criticality t the prject; 9.4 MODEL BUILD AND SYSTEM PERFORMANCE REPORT This reprt shall cntain a descriptin f the wrk invlved in building, testing, and validating the mdel and assessing the perfrmance f the drainage system including an verview f the data, infrmatin, assumptins and prcesses used. Table f cntents fr Mdel Build and System Perfrmance Reprt including samples f tables and maps are prvided in Appendix F. The standard template fr the reprt can be supplied upn request. The Mdel Build and System Perfrmance Reprt shall cnsist f the fllwing sectins: Intrductin A brief descriptin f the backgrund t the mdelling study i.e. the purpse fr which the mdel was riginally built, the date it was built, and the sftware used; The general bjectives f strmwater catchment mdelling including the activities and scpe f the mdelling prject. Catchment Descriptin A descriptin f the catchment including the lcatin in the regin; Nvember 2011 Page 90

92 A descriptin f the existing strmwater drainage system, gelgy, sils, tpgraphy, existing and future land use; A brief discussin f reprted flding issues within the catchment; Mdel Build Mdelling Sftware: A descriptin f the mdelling sftware used fr hydrlgical and hydraulic mdelling f the catchment. Review f Exiting Data: A descriptin f asset, hydrmetric and tpgraphical data used fr mdel cnstructin including its surces; Summary f rainfall and flw mnitring data (if available) assessment; Hydrlgical Mdel: A descriptin f mdelling methd used fr catchment rainfall-runff prcess; A descriptin f sub-catchment delineatin, existing and future impervius areas; Basis f rainfall-runff mdel parameter estimates; Hydraulic Mdel: A descriptin f mdelling methd used fr hydraulic drainage netwrk; Details f hydraulic mdel cmpnents e.g. ndes, links, basins, weirs, rifices, cntrl structures; Details f frictinal lsses at links and head lsses at ndes; Bundary Cnditins: Summary f existing and future TP hur design rainfall depth and tempral prfiles estimates; Summary f dwnstream tidal bundary used in the mdel based n the Mdelling Tailwater Study by Maunsell; Mdel Limitatins and Assumptins: A descriptin f limitatins in the mdelling and hw they influence the applicability f the results; Nvember 2011 Page 91

93 A descriptin f assumptins made during the develpment f hydrlgical and hydraulic mdel; Initial Mdel Test: A descriptin f initial mdel test layut checks, instability tests, sensibility tests and mass balance checks; Quality Assurance and Quality Checks: The mdel has t be internally quality assured and checked and has t be stated in this sectin that it is fit fr purpse ; Mdel Validatin Mdel Gauge Validatin: A descriptin f the prcesses invlved in validating the mdel against any mnitring gauge available and the validatin achieved; Overview f rainfall events (rainfall depth, maximum intensity and event ARI) selected fr mdel validatin; Overview f mdel validatin results including explanatins where mdel validatin statistics lies utside the acceptable ranges; A descriptin f sensitivity analysis fr varius hydrlgical and hydraulic mdel parameters; MIKE 21 2D Mdel Results Validatin: A descriptin f cmparisn f the present 1D mdel fldplain with the 2D mdel fldplain; Mdel Histrical Fld Incident Validatin: A descriptin f mdel validatin prcess fr any knwn histrical fld incident infrmatin including explanatins in case the mdel culd nt replicate the reprted fld incidents; Previus Mdel Results Cmparisn: A descriptin f cmparisn f present mdelled peak flws with thse btained frm previus mdel at varius lcatins; System Perfrmance Assessment Mdel Scenaris and Simulatins: Nvember 2011 Page 92

94 A descriptin f the apprach t develping varius mdel scenaris design strm mdel scenaris, land use develpment mdel scenari, and tailwater level mdel scenaris; Summary f mdel simulatin matrix fr system perfrmance assessment; Water Balance f the Catchment: Overview f water balance within the catchment fr the nminated 6 design strm events under ED and MPD land use develpment scenaris. Capacity f the Existing Primary Pipe System: A descriptin f methdlgy fr capacity assessment f the existing primary pipe system and summary f the perfrmance f the existing strmwater pipe system; Capacity f the Existing Culverts and Bridges: A descriptin f methdlgy fr capacity assessment f the existing culverts, pipe inlets and bridges and summary f capacity and design flws; Overview f existing culverts, pipe inlets and bridges in relatin t vertpping varius classes f rads; Fldplain Mapping: A descriptin f methdlgy fr identificatin f fld risk areas and fldplain mapping. A discussin f predicted fld risk areas in relatin t the reprted flding issues identified frm issues register/questinnaire respnse. List f significant fld risk areas including the number f habitable and nnhabitable flr flding and the causes f flding; A detailed descriptin f the significant fld risk areas including causes f flding and figures shwing the flded huses; Fld Hazard Mapping: A descriptin f methdlgy fr identificatin f fld hazard areas and fld hazard mapping. A discussin f predicted significant fld hazard areas in relatin t depth and/r velcity t pse a pssible safety hazard t vehicles and pedestrians. Fld Damage Assessment: A descriptin f methdlgy fr fld damage assessment carried ut fr the catchment. Nvember 2011 Page 93

95 A brief discussin f the calculated Annual Average Damage and Net Present Value. Cnclusins and Recmmendatins Overview f cnclusins and recmmendatins determined fr the mdelling study; References A cmprehensive list f all references used in the mdelling study shall be included; 9.5 MODEL OPTIONS ASSESSMENT REPORT This reprt shall cntain a descriptin f the flding issues identified within the catchment, mitigatin ptins cnsidered, evaluatin f these ptins and final set f preferred system imprvement wrks. The reprt shuld als cntain a descriptin f the wrk invlved in frmulating and building each ptins mdel and the infrmatin used. Table f cntents fr Mdel Optins Assessment Reprt including samples f tables and maps are prvided in Appendix G. The standard template fr the reprt can be supplied upn request. The Mdel Optins Assessment Reprt shall cnsist f the fllwing sectins: Intrductin A brief verview f the backgrund, bjectives, activities and scpe f the ptins mdelling and assessment study; Flding Issues Identified A descriptin and evaluatin f the flding issues identified within the catchment frm strmwater issues database and frm system perfrmance mdelling investigatins; A brief verview f the AC s Infrastructure Design Standard in relatin t pipe netwrk, culverts, bridges, rad vertpping, habitable and nn-habitable flr flding; Previus Optins Studies An verview f all fld management ptins cnsidered in the previus studies t address the flding issues including the chrnlgy f upgrading wrks Nvember 2011 Page 94

96 prpsed fr fld mitigatin and implementatin/cmpletin f the prpsed wrks. Optins Mdelling and Assessment An verview f all ptins selected and investigated including all issues cnsidered; A descriptin f assessment f all mitigatin ptins cnsidering csts, benefits, advantages and disadvantages f each ptins; An verview f the strmwater management methds and devices cnsidered in the mitigatin ptins. A descriptin f the perfrmance level that shuld be achieved; An verview f hw the ptin has been incrprated int the mdel; An verview f Benefit/Cst analysis Recmmended Optins An verview f preferred system imprvement wrks including a full descriptin as t the reasns behind selecting each particular ptin. Cnclusins and Recmmendatins Overview f cnclusins and recmmendatins determined fr the ptins mdelling study; References A cmprehensive list f all references used in the ptins mdelling study shall be included; Nvember 2011 Page 95

97 10. REFERENCES Auckland City Cuncil (1991). Auckland City Cuncil Strmwater Sakage Design Manual. Auckland Reginal Cuncil (1999). Guidelines fr Strmwater Runff Mdelling in the Auckland Regin, Auckland Reginal Cuncil Technical Publicatin N. 108, April Auckland Reginal Cuncil (2003). "Strmwater Management Devices: Design Guidelines Manual, Auckland Reginal Cuncil Technical Publicatin N. 10, May Chw V. T. (1959). Open Channel Hydraulics. McGraw-Hill Bk C - Singapre. Danish Hydraulic Institute (2010). Guidelines fr Strmwater Mdelling using MIKE FLOOD, Tauranga City Cuncil, May DEFRA (2003). Reducing Uncertainty in River Fld Cnveyance: Rughness Review. DEFRA / Envirnment Agency Fld and Castal Defence R&D Prgramme, July DEFRA (2004). Reducing Uncertainty in River Fld Cnveyance: Cnveyance Manual. DEFRA / Envirnment Agency Fld and Castal Defence R&D Prgramme, September Ministry fr the Envirnment (2008). Climate Change Effects and Impacts Assessment, A Guidance Manual fr Lcal Gvernment in New Zealand. 2nd Editin, Ministry fr the Envirnment, Wellingtn. NSW (2005). Fldplain Develpment Manual, The Management f Fld Liable Land. New Suth Wales Gvernment, April PDP (2005). Glbal Aquifer Study, Stage 2B1, Reginal Grundwater Mdel Develpment Reprt, June USGS (1989). Guide fr selecting Manning s rughness cefficient fr natural channels and fld plains. United States Gelgical Survey Water-supply Paper Nvember 2011 Page 96

98 Appendix A. NAMING CONVENTION The file and flder naming cnventin adpted is very imprtant. N frmal naming cnventin is universal as each prject has its wn cmbinatin f features and peculiarities. It is imprtant fr the user, and als fr future users, that files and flders are named in a cnsistent manner. Strict naming cnventins shall be fllwed thrughut the Prject; The flder and file naming cnventin given belw shall be strictly fllwed thrughut the Prject. Any prpsed deviatin frm the fllwing naming cnventin shuld be discussed with Auckland Cuncil first. Flder Naming Cnventin: Mdel, GIS mapping and assciated analysis spreadsheet and dcument files shall be maintained in a clearly identified and lgically cnstructed directry (flder) tree. The fllwing structure f the flder tree shall be fllwed and where necessary additinal sub-flder culd be included: 01 Prject Management 01 Cmmercial 02 Cmmunicatin 02 GIS 01 Catchment 02 Netwrk 03 Backgrund 04 Aerial 05 Terrain 06 Crss-Sectins 07 Survey 08 Gauging 09 Pipe Capacity 10 Fld Plain 11 Optins Investigatins 03 Data Cllectin 01 Site Visits 02 Stream Walk 03 Survey 04 Gauging 04 Mdelling Wrkings 01 Data Assessment 02 Mdel Build 03 System Perfrmance 04 Optins Investigatins 05 Mdels 01 Year 1D Mdel Nvember 2011 Page 97

99 02 Year 2D Mdel 03 Year 1D-2D Cupled Mdel 04 Optins Investigatins Mdel 06 Reprting 01 Mdel Extents and Data Assessment Reprt 02 Mdel Build and System Perfrmance Assessment Reprt 03 Optins Assessment Reprt File Naming Cnventin: A prject naming cnventin shuld be established at the initial stages f the mdelling Prject and clearly dcumented with examples. Filenames shuld be as shrt as pssible but must cntain sufficient infrmatin t enable AC, the mdeller and future users t easily identify the cntent f each file and what that file represents in terms f the catchment, mdel variant, scenari, return perid, event type, versin, etc. All system, simulatin and result files shuld be kept within dedicated flders. Aspects t cnsider are; catchment name (pssibly abbreviated) catchment land use develpment (existing, future, maximum pssible) rainfall scenari (baseflw, ARI, PMF) inflw scenari (baseflw, ARI) dwnstream water-level bundary (high tide, lw tide, ARI) type f simulatin (evaluatin, remedial ptins) In additin, during mdel develpment it is gd practice t name develpment mdels with an incremental number suffix, s that previus develpment mdels are always available and can be retrieved at any time. The flder and file naming shall be frmulated prir t significant mdel-build. The flder and file naming shall be clearly dcumented and included with all mdel files prvided. Where a sequential file naming system is used in develpment f the mdel, the final set f sequentially named files shuld be cpied, and renamed accrding t the abve criteria. The mdel lg shall clearly indicate which sequentially named files have been cpied and renamed fr the final mdel set. Asset and Sub-catchment Naming Cnventin: The fllwing naming cnventins shall be used fr mdel build; Physical manhle, inlet r utlet. Use the GIS Asset ID. If Asset ID is nt available (usually fr new manhle, inlet, r utlet identified) use NEWNODE fllwed by Nvember 2011 Page 98

100 _# fllwing a cnsecutive numbering system (#). The naming f these ndes needs t be updated when GIS Asset ID becmes available. Strage ndes. Use the GIS Asset ID (usually available fr strmwater management pnds r tanks). If Asset ID is nt available use BASIN fllwed by _# fllwing a cnsecutive numbering system (#). Overland flw ndes. Use the adjacent nde (manhle, inlet r utlet) Asset ID preceded by OLF_. If Asset ID is nt available use OLFNODE fllwed by _# fllwing a cnsecutive numbering system (#). Open channel ndes. Use STRNODE fllwed by _# fllwing a cnsecutive numbering system (#). Pipe sectins. Use the GIS Asset ID. If tw pipes are amalgamated int ne, use the Asset ID f the lnger pipe. If Asset ID is nt available (usually fr new pipe r culvert identified) use NEWPIPE fllwed by _# fllwing a cnsecutive numbering system (#). The naming f these ndes needs t be updated when GIS Asset ID becmes available. Open channel links. Use STRLINK fllwed by _# fllwing a cnsecutive numbering system (#). Overland flw paths. Use the adjacent branch (pipe) Asset ID preceded by OLF_. If Asset ID is nt available use OLFLINK fllwed by _# fllwing a cnsecutive numbering system (#). Dummy links. Use Dummy fllwed by _# fllwing a cnsecutive numbering system (#). Weirs. Use the adjacent nde Asset ID. Weirs shall be rientated s that psitive flw signifies flw entering the primary drainage system and negative flw signifies flws leaving the primary drainage system. Sub-Catchments. Use the sub-catchment lading nde ID fllwed by _# fllwing a cnsecutive numbering system (#), fllwed by _Imp fr the impervius prtin and _Perv fr the pervius prtin. Crss-sectins. Use the nde ID where the crss-sectins wuld be assigned. Nvember 2011 Page 99

101 Appendix B. MODEL LOG-BOOK A mdel lg is a simulatin by simulatin accunt f changes made, and the results r effect n the mdel. The mdel lg als recrds all assumptins made, and the basis f and justificatin f these. Any changes in mdel.ini (dhiapp.ini, mike11.ini) files shall be recrded in mdel lg bk. The mdel lg ensures all changes made by the mdeller can be tracked. This is vital nt nly in understanding the prcess the mdeller went thrugh, but is an invaluable tl in the event the mdeller is n lnger available t wrk n the mdel. Files shuld be named sequentially thrughut the mdel lg-bk. N frmal naming cnventin is set; the mdeller shall define their wn cnventin and clearly detail this in the mdel lg. Simple naming methds such as 1a, 1b etc are ften effective. It is nt necessary t rename all mdel files frm simulatin t simulatin. If fr example, MOUSE prject file 2e.mpr uses files 2e.und and 2a.hgf, this wuld indicate 2e.und has been updated fr this simulatin, but the last time the hgf file was updated was at simulatin 2a. As such, nly renaming the file t be changed is very effective in tracking when different mdel prperties were last changed. Sample Mdel Lg-Bk Date & Time 29 May 3:30pm Mdel Files 1e.mpr 1a.und 1e.hgf Purpse Test mdel stability fr 100-year rainfall event Changes Started with mdel simulatin 1c.mpr, as 1d was unstable. 100-year rainfall time series added and the hydrlgical and hydraulic mdel run. Results and Cmments The mdel is stable, as expected frm previus mdel testing. Nvember 2011 Page 100

102 Appendix C. MODEL BUILD METADATA The surce f all imprtant mdel build data shall be maintained in a metadata spreadsheet. Data surces and all assumptins shuld be clearly dcumented s that subsequent users can understand and apply the mdel fr later use. Mdel build data tagging infrmatin shall be used fr the metadata spreadsheet. The mdel build data shall include at least the fllwing attributes: Sub-catchments pervius/impervius area, parameter values; Ndes invert levels, grund levels, diameter, strage table, energy lss; Links diameter, width/height, crss-sectin, rughness material, upstream and dwnstream invert levels, passive flw regulatins; Structures invert levels, width, height, diameter, crss-sectin, Q-H table; Pssible surces culd include AC GIS, survey, derived frm ther data, e.g. LiDAR cnturs r raster grid, derived frm interplatin, extraplatin, assumptin, parameter values assigned frm literature, ARC TP108 guidelines, AC mdelling specificatins, Infrastructure Design Standard Manual (IDSM). Sample Metadata fr Different Mdel Build Data Attributes: Sub-Catchment Metadata Catch ID Lcatin Area Rainfall Lss Parameter Runff Ruting Parameter Ntes _Perv GIS GIS ARC TP108 ARC TP _Imp GIS GIS ARC TP108 ARC TP108 - Nde Metadata Nde ID Nde Type Diameter Strage Table Invert Level Grund Level Energy Lss Ntes Manhle GIS - GIS GIS AC Spec Manhle AC IDSM - Estimated LiDAR AC Spec Based n u/s & d/s pipe gradient Basin - GIS GIS GIS AC Spec Inlet Default - Survey GIS AC Spec Channel Junctin Default - LiDAR Default AC Spec - Nvember 2011 Page 101

103 Link Metadata Link ID Link Type Diameter r X-Sectin U/S Invert Level D/S Invert Level Material Passive Flw Q-H Table Ntes Pipe GIS GIS GIS Pipe Estimated GIS GIS Culvert Survey Survey Survey Overland Flwpath Default LiDAR LiDAR Channel Survey Survey Survey Bridge Survey Survey Survey GIS & AC Spec GIS & AC Spec GIS & AC Spec GIS & AC Spec GIS & AC Spec GIS & AC Spec Estimated Based n u/s & d/s pipe size Based n HY8 Sftware Structure Metadata Structure ID Structure Type Invert Level Width Diameter/ Height r X-Sectin Q-H Table Ntes Weir GIS Estimated - - Based n manhle circumference Weir LiDAR LiDAR Orifice GIS - LiDAR Orifice Survey - Survey Weir GIS - - Estimated Based n cntrlled utflw Nvember 2011 Page 102

104 Appendix D. MODEL REVIEW TEMPLATE The review template is cntinually updated t ensure mdels are reviewed adequately. There may be a mre recent versin f the review frm than the ne which is included in the specificatin. The review frm represents the minimum checks which are carried ut when reviewing a strmwater mdel. General Infrmatin Mdel Versin Items Mdel file names & dates Findings Rating at right f each table belw: 0 Nt an issue 3 Majr Issue will effect mdel utput Catchment Hydrlgy Items Checked Findings & Cmments Rating Entire Catchment bundary check. Sub-Catchment ranges. area Spt check f subcatchment bundaries and their inflw nde assignment. Hydrlgical mdelling methdlgy used. Sub-Catchment pervius and impervius areas mdelling methd. Sub-Catchment impervius area % ranges in existing and future scenaris. Spt check f subcatchment time f cncentratin. SCS CN ranges in existing and future scenaris. Initial abstractin (Ia) ranges in existing and future scenaris. Netwrk Hydraulics Items Checked Findings & Cmments Rating Nvember 2011 Page 103

105 Items Checked Findings & Cmments Rating Nde naming cnventins in the mdel. Nde diameter in the mdel. Nde cver type in the mdel. Spt check f nde invert levels in the mdel cmpared t the AC GIS asset database. Spt check f nde grund levels in the mdel cmpared t the AC GIS asset database. Spt check f mdel basin strage vlume cmpared t the LiDAR cnturs. Basin mdelling methd. Manhle head lsses (utlet shapes) in the mdel. Culvert inlet & utlet head lsses (utlet shapes) in the mdel. Mdelled verland flw paths cmpared t AC GIS verland flw paths. Spt check f mdel pipe diameters cmpared t the AC GIS asset database. Pipe diameter decreasing in dwnstream directin. Any negative pipe grade in the mdel. Pipe lengths less than 10m Link frictinal lsses (Manning s n). Spt check f mdel crsssectins cmpared t the AC LiDAR cnturs. Spt check f mdel crsssectins whether it included the lw flw channel. Spt check f mdel weir crest levels cmpared t the cnnecting manhle nde grund levels. Weirs crest widths in the mdel. Spt check f mdelled peak velcities in pipes. Spt check f mdelled lng prfile. Nvember 2011 Page 104

106 Items Checked Findings & Cmments Rating Cmparisn f MOUSE hydraulic mdelled peak flws and runff vlume with the ARC TP108 graphical methd at critical lcatins. Blcking ut cells when pen channels mdelled in 1D mdel. Cmparisn f fldplain with RFHA fldplain. Bundary Cnditins Items Checked Findings & Cmments Rating Design rainstrm shape and ttal rainfall in the mdel. Dwnstream cnstant tidal bundary cmpared t the Mdelling Tailwater Study by Maunsell (2004). Mdel Perfrmance Items Checked Findings & Cmments Rating Overall mass balance (shuld be < 5%). Spt check f any instability in mdel results. Mdel Fit fr Purpse Items Checked Findings & Cmments Rating Effects f mdel errrs n predicted pipe perfrmance. Effects f mdel errrs n predicted fld levels. Recmmendatins Nvember 2011 Page 105

107 Appendix E. MODEL EXTENTS AND DATA ASSESSMENT REPORT REQUIREMENTS Table f Cntents fr Mdel Extents and Data Assessment Reprt EXECUTIVE SUMMARY 1. INTRODUCTION 1.1 BACKGROUND 1.2 STUDY OBJECTIVES 1.3 ACTIVITIES AND SCOPE 2. AVAILABLE INFORMATION 2.1 PREVIOUS STUDIES Previus Study Reprts Previus Mdel Review 2.2 DRAINAGE NETWORK DATA Asset Data Tpgraphical Data Drainage Operatinal Issues Reprted Flding Issues 2.3 HYDROMETRIC DATA Rainfall Data Flw and Water Level Data Tidal Data 2.4 ALL OTHER AVAILABLE INFORMATION 3. RAPID FLOOD HAZARD ASSESSMENT MODELLING 3.1 METHODOLOGY Mdel Bathymetry Mdel Parameters Initial Cnditins Bundary Cnditins Mdel Simulatins 3.2 RESULTS AND DISCUSSIONS Pst Prcessing f Mdel Results Mass Balance Checks Fld Hazard Mapping 4. MODEL EXTENTS 4.1 HYDROLOGICAL MODEL EXTENTS Catchment Bundary Sub-Catchment Delineatin Sub-Catchment Lading Ndes Selectin 4.2 HYDRAULIC MODEL EXTENTS Mdelled Manhles, Inlets and Outlets 42.2 Mdelled Pipes, Culverts and Channels Nvember 2011 Page 106

108 4.2.3 Mdelled Pnds, Wetlands and Other Strage Areas Mdelled Cntrl Structures 5. DATA QUALITY ASSESSMENT 5.1 ASSET DATA ASSESSMENT Missing Manhles, Inlets and Outlets Attribute Data Missing Pipes and Culverts Attribute Data Missing Pnds and Wetlands Outlets Attribute Data Missing Cntrl Structures Attribute Data Drainage Netwrk Cnnectivity Issues Dwnstream Reductin in Pipe Diameter Negative Grade Pipes Reverse Orientatin Pipes Incnsistent Manhle Invert Levels, Depths and Grund Levels 5.2 HYDROMETRIC DATA ASSESSMENT Rainfall Mnitring Data Identificatin f Suitable Events fr Mdel Validatin Rain Gauge Duble Mass Curve Analysis Flw and Water Level Mnitring Data Flw-Depth Relatinship Assessment Gauge Mass Balance Analysis Rainfall-Runff Vlume Relatinship Assessment 6. DATA COLLECTION AND SURVEY REQUIREMENTS 6.1 ASSET DATA SURVEY REQUIREMENTS Assumptins Made t Reduce Survey Requirements Manhles Depth and Lid Level Survey Culvert Inlets and Outlets Invert Level Survey Pipes and Culverts Diameter Survey CCTV Survey fr Netwrk Cnnectivity Issues Pnds and Wetlands Outlets Size and Invert Level Survey Cntrl Structures Size and Invert Level Survey 6.2 TOPOGRAPHICAL DATA SURVEY REQUIREMENTS Stream Crss-Sectin Survey Stream Lng Prfile Survey Bridge Crss-Sectin Survey 7. CONCLUSIONS AND RECOMMENDATIONS 8. REFERENCES APPENDICES A Mdel Build Data Surces B Hydrlgical and Hydraulic Mdel Extent Maps C Rainfall and Flw Mnitring Gauge Lcatin Maps D Asset Data Survey Lcatin Maps E Tpgraphical Data Survey Lcatin Maps Nvember 2011 Page 107

109 Appendix F. MODEL BUILD AND SYSTEM PERFORMANCE REPORT REQUIREMENTS Table f Cntents fr Mdel Build and System Perfrmance Reprt EXECUTIVE SUMMARY 1. INTRODUCTION 1.1 BACKGROUND 1.2 STUDY OBJECTIVES 1.3 ACTIVITIES AND SCOPE 2. CATCHMENT DESCRIPTION 2.1 LOCATION 2.2 TOPOGRAPHY 2.3 GEOLOGY AND SOILS 2.4 EXISTING AND FUTURE LAND USE 2.5 STORMWATER DRAINAGE SYSTEM 2.6 REPORTED FLOODING ISSUES 3. MODEL BUILD 3.1 MODELLING SOFTWARE 3.2 REVIEW OF EXISTING DATA Asset Data Hydrmetric Data Tpgraphical Data Operatinal Data 3.3 HYDROLOGICAL MODEL Methd Used Hydrlgical Mdel Extents Hydrlgical Mdel Parameters 3.4 HYDRAULIC MODEL Methd Used Hydraulic Mdel Extents Energy Lsses 3.5 BOUNDARY CONDITIONS Rainfall Data Tidal Data 3.6 MODEL LIMITATIONS AND ASSUMPTIONS Mdel Limitatins Hydrlgical Mdel Assumptins Hydraulic Mdel Assumptins 3.7 INITIAL MODEL TESTING 3.8 QUALITY ASSURANCE AND QUALITY CHECKS 4. MODEL VALIDATION 4.1 MODEL GAUGE VALIDATION 4.2 MIKE21 2D MODEL RESULTS VALIDATION 4.3 MODEL HISTORICAL FLOOD INCIDENT VALIDATION Nvember 2011 Page 108

110 4.4 PREVIOUS MODEL RESULTS COMPARISON 5. SYSTEM PERFORMANCE ASSESSMENT 5.1 MODEL SCENARIOS AND SIMULATIONS Design Strm Mdel Scenaris Land Use Develpment Mdel Scenaris Tailwater Level Mdel Scenaris Simulatin Matrix 5.2 WATER BALANCE OF THE CATCHMENT 5.3 CAPACITY OF THE EXISTING PRIMARY PIPE SYSTEM 5.4 CAPACITY OF THE EXISTING CULVERTS AND BRIDGES 5.5 FLOODPLAIN MAPPING 5.6 FLOOD HAZRAD MAPPING 5.7 FLOOD DAMAGE ASSESSMENT 6. CONCLUSIONS AND RECOMMENDATIONS 7. REFERENCES APPENDICES A Phtgraphs B Mdel Build Data Surces (Metadata Spreadsheet) C Hydrlgical Mdel Cmpnents D Mdel Validatin Plts E MOUSE Mdel Cmputer File Names F MOUSE Mdel Results Flw and Water Level G Thematic Maps f Pipe Capacity H Fldplain Extent Maps I List f Prperties at Risk f Flding Nvember 2011 Page 109

111 Samples f Tables and Maps in Mdel Build and System Perfrmance Reprt: SECTION 2 Map f mdelled strmwater drainage system including catchment bundary and cadastral bundaries (with rad names) in Sectin 2 as shwn belw: Nvember 2011 Page 110

112 Map f catchment surficial sil type including catchment bundary and cadastral bundaries (with rad names) in Sectin 2 as shwn belw: Map f catchment land use including catchment bundary and cadastral bundaries in Sectin 2 as shwn belw: Nvember 2011 Page 111

113 Summary f reprted flding issues in a table in Sectin 2 as shwn belw: Prperty Address Flding Issue Surce f Flding Surce f Issue 35 Cntessa Drive Habitable flr Leaky pipe flw 2002 Questinnaire 39 Glencurt Place Habitable flr Runff acrss sectin 2002 Questinnaire 3/448 Glenfield Rad Habitable flr Runff frm car park 2002 Questinnaire 5A Neal Avenue Nn-habitable flr Runff acrss sectin 2002 Questinnaire 37 Neleen Street Nn-habitable flr Runff acrss sectin 2002 Questinnaire 29 Peach Rad Nn-habitable flr Runff acrss sectin 2002 Questinnaire 354 Glenfield Rad Nuisance flding Overland flw AC PIR database 356 Glenfield Rad Nuisance flding Overland flw AC PIR database 48 Glencurt Place Nuisance flding Overland flw AC PIR database SECTION 3 Summary f asset data surces in a table in Sectin 3 as shwn belw: Asset Data Type N. Data Surces Manhles 12 Survey 85 Estimated based n upstream & dwnstream pipe slpes 478 AC GIS database Culvert / pipe inlets and utlets 33 Survey 31 Pipe utlets estimated frm LiDAR data Pipes 25 Estimated based n upstream & dwnstream pipe diameters 489 AC GIS database Nvember 2011 Page 112

114 Map f asset data surce including catchment bundary and cadastral bundaries (with rad names) in Sectin 3 as shwn belw: Summary f hydrlgical mdel cmpnents and their values in a table in Sectin 3 as shwn belw: Hydrlgical Mdel Cmpnents Values Number f sub-catchments 297 Range f sub-catchment size (in Hectares) 0.13 t 3.35 SCS curve number fr pervius area 74 SCS curve number fr impervius area 98 Initial lss fr pervius area (mm) 5 Initial lss fr impervius area (mm) 0 Existing develpment imperviusness % 41.8 Maximum prbable develpment imperviusness % 62.0 Nvember 2011 Page 113

115 Map f mdel sub-catchments including catchment bundary and cadastral bundaries in Sectin 3 as shwn belw: Summary f hydraulic mdel cmpnents and their values in a table in Sectin 3 as shwn belw: Hydraulic Mdel Cmpnents Values Ttal number f strmwater netwrk system ndes 1194 Ttal number f basin ndes 10 Ttal number f links 1143 Ttal number f strmwater netwrk system pipes 514 Ttal number f verland flw path/pen channel links 629 Ttal number f weirs 534 Ttal number f rifices 32 Ttal number f utlets 13 Nvember 2011 Page 114

116 Map f hydraulic mdel extents including catchment bundary and cadastral bundaries in Sectin 3 as shwn belw: Summary f pnd and strage basin data used in the mdel including data surce in a table in Sectin 3 as shwn belw: Pnd Name/ Lcatin Pnd Type Mdel Nde ID Bttm Level (m RL) Permanent Water Level (m RL) Kristin Wet Rthwell Wet ARC Landfill - Hugh Green Cnstellatin Drive Wet Dry Spillway Level (m RL) Data Surce Survey/ LiDAR Pnd Prject File / LiDAR As-Built LiDAR Lcal Depressin - Dry OTEHA19P LiDAR Zara Curt Plan/ LiDAR / Site Visit Nvember 2011 Page 115

117 Summary f Manning s rughness values used in the mdel in a table in Sectin 3 as shwn belw: Link Type Manning s n Value Used MOUSE Link Material Type Pipe and Culvert Nrmal Cncrete Natural Open Channel 0.08 Other Unlined Open Channel 0.05 Irn Cncrete Lined Open Channel 0.02 Ceramics Overland Flw Path Thrugh Prperty 0.10 Stne Overland Flw Path Alng Rad 0.02 Ceramics Summary f nde head lss parameters used in the mdel in a table in Sectin 3 as shwn belw: Link Type MOUSE Nde Head Lss Parameter Manhle Ndes Mean Energy Apprach With Km = 0.30 Pipe, Bridge & Culvert Inlet Ndes Mean Energy Apprach With Km = 0.30 Pipe, Bridge & Culvert Outlet Ndes Sharp Edged Outlet With Km = 0.50 Basin Ndes Sharp Edged Outlet With Km = 0.50 Open Channel & Overland Flw Path Ndes N Crss-Sectinal Changes Summary f mdelled peak flws and runff vlumes cmparisn fr sensibility analysis in a table in Sectin 3 as shwn belw: Lcatin Pipe Outlet at 34 Neal Ave Catch. Area (ha) TP108 Graphical Methd (100-yr ARI) Peak Flw (m3/s) Runff Vlume (m3) Hydraulic Mdel (100-yr ARI) Peak Flw (m3/s) Runff Vlume (m3) Differences Peak Flw , ,900 8% 1.4% Runff Vlume Kaiaptiki Stream at East , ,000 27% 0.7% Park Parade Kaipatiki Stream Outlet , ,000 26% 0.4% Nvember 2011 Page 116

118 SECTION 4 Summary f mdel sensitivity analysis results in a table in Sectin 4 as shwn belw: Impact f Manning s n value n water levels Lcatin Upper Harbur Culvert Tawa Culvert 100-Year ARI Water Level Channel n = 0.06 Channel n = 0.08 Channel n = Drive Impact f Manning s n value n peak flws Lcatin Upper Harbur Culvert Tawa Culvert 100-Year ARI Peak Flw Channel n = 0.06 Channel n = Channel n = 0.10 Drive Differences Relative t n= m 0.0m -0.04m +0.08m Differences Relative t n= % t +0.8% -1.1% t +0.8% 100-Year ARI Water Level OFP n = 0.05 OFP n = 0.10 OFP n = 0.20 t t Year ARI Peak Flw OFP n = 0.05 OFP n = 0.10 OFP n = Differences Relative t n= m 0.0m -0.01m +0.01m t t Differences Relative t n= % t 0.0% -0.3% t +0.5% Summary f mdel gauge validatin results in a table in Sectin 4 as shwn belw: Strm Events June February Octber 2006 Rainfall ARI Mnitring Gauges Vlume Difference (%) Peak Flw Difference (%) Peak Depth Difference % (m) +3.2% ARC % +5.8% 5 t 10- (+0.09m) Year ARI -5.1% NIWA % -25.2% (-0.11m) +14.2% ARC % +23.4% 2 t 5- (+0.38m) Year ARI +14.9% NIWA % +2.3% (+0.29m) 2-Year ARI ARC % +1.4% NIWA % +44.4% -1.2% (-0.02m) +50.0% (+0.50m) Ntes: + indicates mdel ver predictin and - mdel under predictin Crrelatin Cefficient (r2) 0.97 Yes 0.97 N 0.97 Yes 0.97 Yes 0.91 Yes 0.88 N Within Acceptable Criteria Nvember 2011 Page 117

119 Map f 100-year ARI Fld Depth based n 2D mdel including aerial phts in Sectin 4 as shwn belw: Summary f mdel histrical fld incident validatin results in a table in Sectin 4 as shwn belw: Fld Incident Lyns Avenue Culvert surcharging (apprximately RL 9.4m) Fld level at tp stairs f 6 Westburne Rad building (apprximately RL 3.5m) Surce District curt hearing dcument frm datawrks Predicted Fld Level RL 9.29m Crrelatin Well crrelated Site visits RL 3.41m Well crrelated Nvember 2011 Page 118

120 Summary f mdelled peak flw cmparisn results in a table in Sectin 4 as shwn belw: 100-year ARI Flws (m3/s) Lcatin 2004 CMP (MPD with Current Rainfall Scenari) Present Study (MPD with Current Rainfall Scenari) Present Study (MPD with Future Rainfall Scenari) Gladys Avenue Culvert Embassy Reserve Culvert Glenfield Cllege Culvert East Park Parade Culvert Kaipatiki Stream Outlet Nte: The 2004 CMP used 63% imperviusness fr the fully develped catchment whereas the present study used 62% imperviusness fr MPD scenari. SECTION 5 Summary f existing and future 24-hur design rainfall depths fr the nminated 6 design strm events in a table in Sectin 5 as shwn belw: Design Strm Event Existing 24-hur Design Rainfall Depth (mm) Future 24-hur Design Rainfall Depth (mm) 2-Year ARI Year ARI Year ARI Year ARI Year ARI Year ARI Nvember 2011 Page 119

121 Summary f mdel simulatin matrix fr system perfrmance assessment in a table in Sectin 5 as shwn belw: Simulatin Land Use Design Strm Event Rainfall Bundary Tide Level fr 2100 (m RL) 1 ED 2-year ARI Existing 2-year MPD 2-year ARI Future 2-year ED 5-year ARI Existing 5-year MPD 5-year ARI Future 5-year ED 10-year ARI Existing 10-year MPD 10-year ARI Future 10-year ED 20-year ARI Existing 20-year MPD 20-year ARI Future 20-year ED 50-year ARI Existing 50-year MPD 50-year ARI Future 50-year ED 100-year ARI Existing 100-year MPD 100-year ARI Future 100-year 0.5 Summary f water balance f the catchment in a table in Sectin 5 as shwn belw: Mdel Scenari Catchment Rainfall Vlume (m3) Catchment Runff Vlume (m3) Catchment Runff Vlume in % 2 year ED 190, ,520 64% 5 year ED 285, ,121 71% 10 year ED 332, ,652 74% 20 year ED 392, ,933 76% 50 year ED 463, ,268 79% 100 year ED 522, ,300 81% 2 year MPD 207, ,537 76% 5 year MPD 317, ,500 81% 10 year MPD 376, ,137 83% 20 year MPD 451, ,167 85% 50 year MPD 541, ,650 87% 100 year MPD 610, ,939 88% Nvember 2011 Page 120

122 Summary f the perfrmance f the existing strmwater pipe system in a table in Sectin 5 as shwn belw: Capacity Assessment Basis Flw Cnditin Scenari > 2yr ARI Percentage f Ttal Number f Pipes with Capacity > 5yr ARI > 10yr ARI > 20yr ARI > 50yr ARI > 100 yr ARI Maximum pipe flw cmpared t pipe full flw capacity Free full flw ED 89% 77% 71% 65% 61% 59% MPD 84% 70% 65% 61% 57% 56% Pipe dwnstream maximum depth cmpared t pipe diameter r height Backwater effect ED 62% 45% 40% 33% 28% 25% MPD 55% 38% 33% 27% 24% 22% Ttal pipe capacity cnsidering full flw & backwater effect Wrst f ED 56% 36% 30% 23% 16% 14% abve 2 cnditins MPD 47% 29% 22% 16% 12% 11% Maximum system pipe flw cmpared t pipe full flw capacity Free full flw - N ED 86% 62% 51% 42% 35% 31% upstream restrictin MPD 75% 50% 41% 34% 27% 24% Summary f capacity and design flw fr culverts, pipe inlets and bridges in a table in Sectin 5 as shwn belw: ID Culvert Lcatin 39 Gladys Avenue 52 Kaipatiki Rad Glenfield Cllege R 36 Pwrie Street Culvert Link ID Culvert Diameter (mm) Culvert Capacity Full Flw (m3/s) Inlet Cntrl (m3/s) MPD Design Flw (m3/s) 10-year ARI 100-Year ARI 10-Year Capacity Available N N N Ntes: 1. Full flw capacity assumes pipe full-barrel flw with the water surface slpe equal t the bed slpe and Manning s n values f 0.014; 2. Inlet cntrl capacity (due t culvert inlet cnfiguratin) is the flw that can enter the culvert inlet with a headwater level at the upstream culvert sffit. Nvember 2011 Page 121

123 Summary f maximum water levels upstream f culverts, pipe inlets and bridges cmpared t vertpping level in a table in Sectin 5 as shwn belw: ID Culvert Lcatin 39 Gladys Avenue 52 Kaipatiki Rad Glenfield Cllege R 36 Pwrie Street Culvert Link ID Overtp Level (m RL) 10-Year ARI Upstream Max. Water Level (m RL) ED Scenari 100-Year ARI MPD Scenari 10-Year ARI 100-Year ARI Ntes: indicates peak water level vertpping which is acceptable indicates peak water level vertpping which is unacceptable accrding t the stated cnditins. Map f significant fld hazard areas with buildings at risk f flding including aerial phts in Sectin 5 as shwn belw: Nvember 2011 Page 122

124 List f significant fld hazard areas including the number f habitable and nn-habitable flr flding and the causes f flding in a table in Sectin 5 as shwn belw. ID Fld Hazard Area Lcatin Flr Flding Habitable 100 Year ARI Strm (MPD) Nn- Habitable Habitable Flr within 500mm Habitable Flr abve 500mm Land Use 1 57 Peach Rad (1) Residential 2 Peach Rad (3) Residential 3 43 Tamahere Drive (1) Residential 4 Beaudine Avenue (2) Residential Reasn fr Flding Flding frm Stream Bank Spilling Flding frm Dwnstream Culvert Restrictin Flding frm Overland Flw & U/S Culvert Restrictin Flding frm Overland Flw & U/S Culvert Restrictin Reprted Flding Issues Yes Nne Nne Nne Appendix F Figure Reference Figure F-B2 Figure F-B2 Figure F-C2 Figure F-C2 5 Beaudine Avenue (4) Residential Flding frm Overland Flw Yes Figure F-C2 6 Cntessa Drive (7) Residential Flding frm Overland Flw Nne Figure F-C2 Ttal Nvember 2011 Page 123

125 APPENDICES Summary f the hydrlgical mdel cmpnents in a table in Appendix C as shwn belw: Table C1 Hydrlgical Mdel Cmpnents Subcatchment Name Lading Nde Area (ha) Length (km) Slpe (m/m) Pervius Area CN Imp. Area ED (%) Imp. Area MPD (%) KAI KAI KAI KAI KAI005 STR KAI Mdel validatin plts in Appendix D as shwn belw: [m3/s] Time Series Link Discharge Link Discharge _8 (OTEHA243 -> OTEHA244) External TS 1 DISCHARGE - ARC_ :00: :00:00 16:00:00 18:00:00 20:00:00 22:00:00 00:00: :00:00 04:00:00 06:00:00 08:00:00 10:00:00 12:00:00 Nvember 2011 Page 124

126 Summary f mdel simulatin file names fr varius scenaris in a table in Appendix E as shwn belw: Table E1 MOUSE Mdel File Names File Name File Type File Descriptin Kaipatiki_2009.MPR Prject File Kaipatiki_2009.UND Netwrk File Kaipatiki_2009.HGF Hydrlgical File Kaipatiki_2009.MSC Scenari Manager File Kaipatiki_ED_2yr Kaipatiki_MPD_5yr.CRF &.PRF.CRF &.PRF ED 2-Year ARI Hydrlgical & Hydraulic Mdel Result Files MPD 5-Year ARI Hydrlgical & Hydraulic Mdel Result Files Nvember 2011 Page 125

127 Summary f mdelled peak flws and water levels alng the strmwater drainage netwrk fr the nminated 6 design strm events under ED and MPD scenaris in a table in Appendix F as shwn belw: Nde IL (m RL) Table F.1 MOUSE Mdel Results Peak Water Level Nde lcatins are shwn in Appendix H Figures H-A2 H-C3 Existing Develpment Peak Water Level (m RL) Maximum Prbable Develpment 2yr 5yr 10yr 20yr 50yr 100yr 2yr 5yr 10yr 20yr 50yr 100yr OLF_ OLF_ OLF_ Verssin 4 Nvember 2011 Page 126

128 Upstream Nde Dwnstream Nde Pipe Dia (mm) Table F.2 MOUSE Mdel Results Peak Flw Nde lcatins are shwn in Appendix H Figures H-A2 H-C3 Pipe Capacity (m3/s) Existing Develpment Peak Flw (m3/s) Maximum Prbable Develpment 2yr 5yr 10yr 20yr 50yr 100yr 2yr 5yr 10yr 20yr 50yr 100yr OLF_ OLF_ N/A N/A OLF_ OLF_ N/A N/A OLF_ OLF_ N/A N/A Verssin 4 Nvember 2011 Page 127

129 Catchment and Asset Management Planning Thematic maps shwing the pipe capacity f the existing primary pipe system fr varius design strm events and flw cnditins in Appendix G as shwn belw: Fldplain extent maps (map scale 2500) in Appendix H as shwn belw: Nvember 2011 Page 128