Missouri River Flood Inundation Maps

Transcription

1 State Risk Management Team Missouri 's hazard mitigation team Missouri River Flood Inundation Maps Which is more useful, inundation maps tied to the river stage or tied to flow? Percent Count River stage 90.6% 29 Flow rate Other (please specify) 9.4% Which is more useful, inundation maps tied to the river stage or tied to flow? River stage Flow rate SurveySummary_ xlsx 1 of 19 Question 1

2 State Risk Management Team Missouri 's hazard mitigation team Which is more useful, inundation maps tied to the river stage or tied to flow? Number Date Other (please specify) Categorie s 1 Feb 4, :25 PM Maps for my area - not just a pilot area 2 Jan 28, :52 PM The connection between flow and stage is more variable than the relationship between stage and delineation. The use of rating curve adjustments minimizes the impact of stage/flow relationship variability SurveySummary_ xlsx 2 of 19 Question 1

3 Missouri River Flood Inundation Maps To help establish where the flood inundation mapping products are made available to the public, please indicate where you believe constituents in communities for which you are responsible, go for information on flooding (RSS feeds, the U.S. Geological Survey (USGS) water site, NOAA National Weather Service (NWS) websites, USACE river gages websites, TV, universities, or other)? (Select all that apply) U.S. Army Corps of Engineers NOAA National Weather Service (NWS) U.S. Geological Survey (USGS) Joint Federal Agencies (the Integrated Water Resources Science and Services or IWRSS, National Water Center) Percent Count 50.0% % % % 3 State agency for hazard mitigation State agency for floodplain management County City Levee district / owner / sponsor Multiple agencies need to show the same information Other (please specify) 21.9% % % % % % To help establish where the flood inundation mapping products are made available to the public, please indicate where you believe constituents in com 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% U.S. Army Corps of Engine ers NOAA Nationa l Weathe r Service (NWS) U.S. Geologi cal Survey (USGS) Joint Federal Agenci es (the Integrat ed Water Resour ces Science and Service s or IWRS State agency for hazard mitigati on State agency for floodpla in manag ement County City Multiple agencie Levee s need district / to show owner / the sponsor same informa tion Series1 50.0% 71.9% 34.4% 9.4% 21.9% 34.4% 40.6% 37.5% 25.0% 59.4% SurveySummary_ xlsx 3 of 19 Question 2

4 To help establish where the flood inundation mapping products are made available to the public, please indicate where you believe constituents in communities for which you are responsible, go for information on flooding (RSS feeds, the U.S. Geological Survey (USGS) water site, NOAA National Weather Service (NWS) websites, USACE river gages websites, TV, universities, or other)? (Select all that apply) Number Date Other (please specify) 1 Jan 28, :07 PM USAC river gages websites 2 Jan 28, :51 PM Silver Jackets Program website Public Media Outlets - Newspapers, Weather Channel, and 3 Jan 25, :26 PM local TV stations I checked the key sites, but all the above could offer a link to 4 Jan 25, :17 PM one or more sites. However, also suggest each agency be allowed to post the information if desired. Categorie s SurveySummary_ xlsx 4 of 19 Question 2

5 Missouri River Flood Inundation Maps How should inundation behind levees be communicated? (Select all that apply) Use a written format and place in an emergency action plan Overtops at this known elevation, stating and showing low point Display 2 or 3 inundation areas tied to timing or other assumptions (3-hour flooding area red, 6-hour orange, Only show the regulatory base flood Percent Count 15.4% % % % 2 Adopt the coming FEMA approach for mapping behind levees Other (please specify) 26.9% How should inundation behind levees be communicated? (Select all that apply) 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Use a written Overtops at this format and place in an emergency action plan known elevation, stating and showing low point Display 2 or 3 inundation areas tied to timing or other assumptions (3- hour flooding area red, 6-hour orange, 24-hour yellow) Only show the regulatory base flood Adopt the coming FEMA approach for mapping behind levees SurveySummary_ xlsx 5 of 19 Question 3

6 How should inundation behind levees be communicated? (Select all that apply) Number Date Other (please specify) Not that I would like to agree with FEMA, but mapping behind levees should be accomplished for 1 Feb 18, :50 PM they do break and would assist all forms of Emergency management and first responders when the levee does break. Not if. Overtopping at upper end of levee and showing ponding at lower end. somewhat but not 2 Feb 8, :43 PM excessively conservative approach. 3 Feb 4, :25 PM Need to look at the risk of overtopping for the design flood and the base flood events 4 Jan 28, :07 PM By levee boards Cross hatching the area with a statement explaining it is at a risk catagory associated with the levee until the point when the point the levee would be overtopped. Options 1 - There is no certainty the levee will not fail prior to overtopping. There is also a great deal of certainty in the location of the low point. Unless the levee has a designed overtopping section and appropriate superiority to ensure overtopping at that area (ETL , 8/22/1986) we should be assuming where a levee woudl overtop or how it would behave when it did. Option 2 - This is an NFIP standard and has little to nothing in relation to flood risk. If you only show 1 probability point you cannot provide a concept of the spectrum of probability, as such you cannot get people to understand their risk. This also doesnt note anything in relation to certainty 5 Jan 28, :52 PM or freeboard. Option 4 - The Missouri River flood for much much longer than 3-24 hours. If the idea is to show inundation resulting from a breach until it reaches steady state, there are to many assumptions to be reasonably (how big is the breach, does the system have unrecognized egg crating, do you notch the downstream end, is there scour at the breach, is there more than one breach, etc) Option 5 - This approach isn't fully document, and is for NFIP. Similar comments to option 2. None of the USACE certificaiton process, FEMA certified levee mapping, FEMA unaccredited mapping processes, address residual risk. Certificaiton is for the purpose of determining who shoudl be required to purchase flood risk (who is at or above a defined line of risk) it does not communicate the risk spectrum above or below that line and/or residual risk. Show areas threatened by the given river stage with a different shading. Then show inundation 6 Jan 28, :05 PM assuming a long event. Categorie s 7 Jan 25, :26 PM Separate Federally Certified Levees (FEMA and USACE) from all other types of levees and temporary flood control structures. The three categories of levees/structures would include: A. Federally Certified Levee System: --USACE or FEMA has evaluated and approved the levee system --Federally Certified Leveed Area polygon is shown on map~implies some level of protection --Levee centerline shown on map --Levee is modeled; overtopping scenario shown in depth grids B. Uncertified Levee System: --USACE or FEMA has not evaluated; or levee has failed USACE/FEMA evaluation --Federally Certified Leveed Area polygon is NOT shown on map~no flood protection is implied --Levee centerline shown on map --Levee is modeled; Flooding shown behind levee is based upon LOCAL input on the selection of a failure mechanism: (Option 1) overtopping scenario OR (Option 2) complete failure worst case scenario C. Temporary Flood Control Structure: --Sandbag lines, clay dikes, HESCO barriers etc. --Leveed area polygon is NOT shown on map ~ no flood protection is implied --Temporary structure centerline shown on map --Temporary structure is NOT modeled. 8 Jan 25, :24 PM How should inundation behind levees be communicated? (Select all that apply) Extend the base flood as if the levee does not exist and depict in a manner that identifies risk still exists for these areas even though a levee has been built SurveySummary_ xlsx 6 of 19 Question 3

7 Missouri River Flood Inundation Maps Should historic levee overtopping or failure records be used in conjunction with modeled results? (Select all that apply) Use hydraulic models to determine overtopping and extents Use historical overtopping or failure records Percent Count 56.3% % 21 Just show the protected area that could be affected 21.9% 7 Other (please specify) Should historic levee overtopping or failure records be used in conjunction with modeled results? (Select all that apply) 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Use hydraulic models to determine overtopping and extents Use historical overtopping or failure records Just show the protected area that could be affected SurveySummary_ xlsx 7 of 19 Question 4

8 Should historic levee overtopping or failure records be used in conjunction with modeled results? (Select all that apply) Number Date Other (please specify) Categories Wouldn't a modeled approach, calibrated to accomodate 1 Jan 31, :13 PM historical events, be appropriate? 2 Jan 28, :52 PM 3 Jan 25, :26 PM Unless the levee has a designed overtopping section and appropriate superiority to ensure overtopping at that area (ETL , 8/22/1986) we should be assuming where a levee woudl overtop or how it would behave when it did. Historic levee overtopping or failure records should be used to develop the hydraulic model. Failures are unique events. This group should adopt a uniform standard for displaying failure information for the public and model to a uniform event. Unique or historical failure info could be provided for "internal" purposes and shared among the project team, which would include the state agencies SurveySummary_ xlsx 8 of 19 Question 4

9 Missouri River Flood Inundation Maps How should storage effects of the floodplain be accounted for? Count Number Date Text Categories Moisture runs in trends, when in a wet cycle as prior to 2011 the reservoirs should be lowered to account for possible excess runoff. The flood 1 Feb 16, :17 PM storage capacity needs to be increased not only for upper Missouri River moisture but also to have the flexibility to decrease releases when flooding occurs below the dam system. 2 Storage effects of floodplain will not need to be accounted for in this Feb 8, :47 PM situation. 3 historic overtopping and failure reaches, which could change with levee Feb 4, :28 PM improvements 4 Where floodplain storage is available, it should be accounted for in Jan 31, :15 PM models. 5 Jan 28, :12 PM FEMA Mapping Information 6 Jan 28, :08 PM There is no amount of storage in teh floodplain that can create a sustainable peak shaving effect on the Missouri River. Gavins point provides moderate peak shaving it has a storage volume of 0.5 MAF, Fort Randal may be considered as providing true peak shaving 5.4 MAF. Missouri River floods entail a lot of water for a long time, any and all storage should be assumed to be fillable. With regard to conveaynce behind levees one a system is breached and/or overtopped, there are two reasonable appraoches. First natural valley (pretend the levee doesnt exist). Near the downstream end of the systems or just upstream of any unrecognized egg crating effect this may be an unconservative appraoch. Second, the most conservative/realistic approach woudl be to assume a breach on the upstream end, and determine steady state elevations through the system. Mapping on the riverward of the levee should remain as if there were no breach. (Note: this is an expensive proposition riddled with uncertainty and data gaps). 7 Jan 28, :57 PM High resolution LiDAR data & 2-D hydraulic modeling 8 Jan 28, :31 PM I don't know.. 9 Jan 28, :08 PM Ignore them. 10 Jan 25, :00 PM For static mapping scenarios, that are provided to the public, you 11 Jan 25, :09 PM Unsteady models, which are enabled to account for effects from floodplain storage, especially changing conditions due to a levee faillure. 12 Jan 25, :28 PM Pretty hard question to answer. Lots of assumptions need to be made. 13 Jan 25, :52 PM possibly a non-steady flow model be developed if not present for a given area SurveySummary_ xlsx 9 of 19 Question 5

10 Missouri River Flood Inundation Maps What scale should mapping products be displayed at? (Maps may be presented through a web viewer) 1 inch = 20 feet 1 inch = 40 feet 1 inch = 50 feet 1 inch = 100 feet 1 inch = 200 feet 1 inch = 500 feet 1 inch = 1,000 feet 1 inch = 1 mile 1 inch = 2 miles Percent Count 4.5% 1 0.0% 0 0.0% % 7 9.1% % % 6 9.1% 2 0.0% What scale should mapping products be displayed at? (Maps may be presented through a web viewer) 1 inch = 20 feet 1 inch = 40 feet 1 inch = 50 feet 1 inch = 100 feet 1 inch = 200 feet 1 inch = 500 feet 1 inch = 1,000 feet 1 inch = 1 mile 1 inch = 2 miles SurveySummary_ xlsx 10 of 19 Question 6

11 Missouri River Flood Inundation Maps How should inundation be broken into reaches based on gage locations? (Select all that apply) Percent Count Tie to a stream gage at the upstream end of each reach Tie to a stream gage at the middle of each reach Tie to a stream gage at the downstream end of each reach Tie to more than one gage 47.8% % % % 12 Other (please specify) How should inundation be broken into reaches based on gage locations? (Select all that apply) 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Tie to a stream gage at the upstream end of each reach Tie to a stream gage at the middle of each reach Tie to a stream gage at the downstream end of each reach Tie to more than one gage SurveySummary_ xlsx 11 of 19 Question 7

12 How should inundation be broken into reaches based on gage locations? (Select all that apply) Number Date Other (please specify) Gages should be tied to a reach that is representative of a 1 Jan 28, :08 PM simlar flow (i.e. broken up by large tributary inflows). Tied to a single stream gage to accomplish the purposes of this pilot project. Middle of the reach is ideal, but may not be possible in all situations. 2 Jan 25, :00 PM Most importantly there should be continuity between upstream and downstream map segments that "break" betwen gages. If one looks at the Leavenworth gage the dowstream extent\depth should match with the upstream extent\depth predicted by the Parkville gage. 3 Jan 25, :09 PM Use the gage in median of a defined reach 4 Jan 24, :36 PM Stream gages are few and far between - tie to the elevation of the nearest one. Categorie s SurveySummary_ xlsx 12 of 19 Question 7

13 Missouri River Flood Inundation Maps Display levees with name labels including the following categories (Select all that you feel need to be called out for potential users) Percent Count USACE program, federal and non-federal USACE program, federal only FEMA levee database Private Levees certified under the FEMA NFIP Levees protecting over 100% chance event (1-year annual exceedance probability) Levees protecting over 50% chance event (2-year annual exceedance probability) Levees protecting over 20% chance event (5-year annual exceedance probability) Levees protecting over 10% chance event (10-year annual exceedance probability) Levees protecting over 4% chance event (25-year annual exceedance probability) Levees protecting over 1% chance event (100-year annual exceedance probability) Levees protecting over 0.5% chance event (200-year annual exceedance probability) Levees protecting over 0.2% chance event (500-year annual exceedance probability) Levees protecting over 0.1% chance event (1,000-year annual exceedance probability) Other (please specify) 64.0% % % % % % % 5 8.0% % % % % % 4 8.0% SurveySummary_ xlsx 13 of 19 Question 8

14 Display levees with name labels including the following categories (Select all that you feel need to be called out for potential users) 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Levees protecting Levees over protecting Levees over protecting Levees over protecting Levees over protecting Levees over protecting Levees over protecting Levees over protecting Levees over protecting over USACE program, USACE federal program, federal FEMA levee database and non-federal only Private Levees certified 100% under chance 50% event chance (1-20% event chance (2-10% event chance (5- event 4% chance (10- event 1% chance (25- event 0.5% chance ( % event chance (200- event 0.1% (500- chance event the FEMA year NFIP annual exceedance year annual exceedance year annual exceedance year annual exceedance year annual exceedance year annual exceedance year annual exceedance year annual exceedance (1,000-year annual probability) probability) probability) probability) probability) probability) probability) probability) exceedance probability) Series1 64.0% 16.0% 28.0% 48.0% 52.0% 20.0% 20.0% 8.0% 20.0% 16.0% 32.0% 12.0% 16.0% 8.0% SurveySummary_ xlsx 14 of 19 Question 8

15 Display levees with name labels including the following categories (Select all that you feel need to be called out for potential users) Number Date Other (please specify) Categories 1 Feb 18, :53 PM All levees that within funding limitations could be diplayed in study 2 Jan 31, :15 PM More information is always better, in my view With regard to all optiosn of levee protected over XXX% chance event - how would you be sure that was provided. 3 Jan 28, :08 PM With regard to FEMA levee database, this database is being merged with the NLD in the near future. General public does not understand all the various types and % chance events tied to levee performance. Too much "detail" will over-complicate the display and confuse the public. We have to remember that we are designing these maps for the public, and not for engineers. Best to Keep It Simple. Use three categories of levees/floodwalls/temporary structures: (1) Federally Certified Levee System: --Levees that have been evaluated and meet USACE or FEMA acceptable criteria AND are rated as... 4 Jan 25, :00 PM --FEMA: certified, accredited or Provisionally Accredited. -USACE: Given an Acceptable or Minimally Acceptable performance rating (2) Uncertified Levee System -USACE or FEMA has not evaluated this levee OR -Levee has evaluated by USACE or FEMA, but has not been given an acceptable performance criteria. (3) Temporary Flood Control Structures -Locations with Emergency Action Plans that specify the location/placement of temproary flood control structures. -Sandbag lines, clay dikes, HESCO barriers Assessing the exact protection of the very small, "sweet potato ridges" 5 Jan 25, :09 PM would be a lot of work that may not be worth the effort SurveySummary_ xlsx 15 of 19 Question 8

16 Missouri River Flood Inundation Maps How will the limit of study be appropriately displayed? (Select all that apply) Lable extents of the current mapping as "Edge of study area." Just have the inundation area end with no label Percent Count 80.8% % 5 Other (please specify) How will the limit of study be appropriately displayed? (Select all that apply) Lable extents of the current mapping as "Edge of study area." Just have the inundation area end with no label SurveySummary_ xlsx 16 of 19 Question 9

17 How will the limit of study be appropriately displayed? (Select all that apply) Number Date Other (please specify) 1 Jan 28, :12 PM By counties The inundation areas should be extended to include as large of an 2 Jan 28, :08 PM area as possible. Continuous mapping (one reach matching up against annother) is ideal. Brown Line, appropriately labeled as study extent. It's important to 3 Jan 25, :00 PM communicate where the study ends. Categorie s SurveySummary_ xlsx 17 of 19 Question 9

18 Missouri River Flood Inundation Maps How will uncertainties of contributing tributary inflows be handled? (Select all that apply) Percent Count Restrict resulting inundation to flow releases from USACE reservoirs on Missouri River main stem Enable maps to show two scenarios, such as in USACE June 2011 flood maps, with main stem dam flow releases plus an assumed downstream rain event Enable maps to address various inflows at the confluence with major tributaries 12.5% % % 13 Other (please specify) How will uncertainties of contributing tributary inflows be handled? (Select all that apply) 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Restrict resulting inundation to flow releases from USACE reservoirs on Missouri River main stem Enable maps to show two scenarios, such as in USACE June 2011 flood maps, with main stem dam flow releases plus an assumed downstream rain event Enable maps to address various inflows at the confluence with major tributaries SurveySummary_ xlsx 18 of 19 Question 10

19 How will uncertainties of contributing tributary inflows be handled? (Select all that apply) Number Date Other (please specify) Categorie s Let the engineers that deal with forecasting deal with 1 Jan 28, :08 PM this. Forecasters at NWS/USACE develope flow forecasts and use rating curves which are adjusted by USACE/USGS to determine a stage. Map to stage. Determine a likely tributary inflow for each stage on 2 Jan 28, :08 PM the mainstem. I would add an additional category: Restrict the resulting inundation to flow measured by the stream gage for the specified mapping segment. It's impossible to account for the wide range of possible tributary contributions within a single static 3 Jan 25, :00 PM map. This is where dynamic mapping is required. The MO mainstem stream gages do account for the local flows that are contributing above the gage, on the mainstem Missouri. You can limit the risk that the local tribs that contribute to the mapping segment don't reduce the accuracy of the map by properly sizing the length and subsequent local contributing area within a reach. It may be appropriate to show something like three 4 Jan 24, :36 PM maps - Best Case, expected case, worst case SurveySummary_ xlsx 19 of 19 Question 10