Whole of Water Cycle Modelling Pilot Study

Whole of Water Cycle Modelling Pilot Study

Presentation Outline Background Model development Water and Sewer Stormwater Advantages of Integrated Modelling Challenges and Limitations

Project Aims To investigate the capabilities of InfoWorks ICM to simulate water movement within a property Investigate the benefits and challenges to modelling water supply, sewerage and drainage in a single model Develop a strategic model for the Monash NEC representing the whole of water cycle

Potential Benefits A spatial master planning model built from scratch with transparent inputs Better alignment of modelling assumptions Understanding of interactions between systems Opportunities to test integrated solutions

Monash National Employment Cluster Area: 38 sq. km Dwellings: 27,000 (2011) 52,000 (2051)

100 Property Pilot Model How to select the area? Introduction Overlaid all datasets stormwater, potable, sewer Reviewed systems to look for a simple pipe layout Potable system layout main driver for selection of pilot area (simple system, only a few supply points etc)

100 Property Pilot Model Selected Area

100 Property Pilot Model Potable Network

100 Property Pilot Model Sewerage Network

100 Property Pilot Model Stormwater Network

100 Property Pilot Model Model Build Process Sewer Model used as the starting point. Council stormwater drains imported. Used pit ground levels & depths to update pipe inverts. Potable water network imported Removed valves Assigned ground levels to all nodes from LIDAR Assumed pipe depth of 1m to assign invert levels Boundary points set to outfalls in ICM Ran WS model to provide pressure at boundary points Created level hydrographs using WS pressure data & applied to outfalls to provide fixed head.

100 Property Pilot Model Potable Boundary Conditions

100 Property Pilot Model Household Water Cycle Set Up Runofffrom roof Sewer Property drain Potable Demand Internal Use 3000 L Tank Tank overflow External Use Storm Water Potable Water Potable Top Up to tank

100 Property Pilot Model Model Configuration Tank Overflow to storm water (WEIR) External Use (VLDORF) Internal Usage (VLDORF) Runoff from roof 3000L Rainwater Tank Top Up to tank (VLDORF) Property drain (WEIR) Potable Water House Node Internal Water Supply (VLDORF) Sewer

100 Property Pilot Model Model Configuration

100 Property Pilot Model Flow Generation Variable Discharge Orifices Set with RTC rules set to follow the flow. 3 dummy subcatchments& pipes created for VLDORFs to follow. Flow loaded via population & WWG file RTC used to top up tank with potable when empty.

Household Diurnal Patterns Potable Demand Internal Use (Tank or potable) External Use (Tank or potable) Total Household Water Use

5,000 Property Model Household Water Cycle Set Up Runofffrom roof Sewer Property drain Potable Demand Internal Use Potable for external use 3000 L Tank Tank overflow External Use Storm Water Potable Water

5,000 Property Model Non Residential Set Up Property drain Runofffrom roof direct to Storm Water Sewer Internal Water supply Storm Water Potable Water

5,000 Property Model RTC Control Set Up IF TANK HAS WATER Runofffrom roof Property drain Internal Use Tank overflow Storm Water Sewer Potable Demand Potable for external use External Use Potable Water

5,000 Property Model RTC Control Set Up IF TANK IS EMPTY Property drain Internal Use Tank overflow Storm Water Sewer Potable Demand + Internal Use Volume Potable for external use External Use Potable Water

5000 Property Model RTC Operation Water Level in Rainwater Tank Minor rainfall to randomise tank levels 5yr 2hr event Tank fills during 5yr rainfall event Small volume in tank at the start of the event

5000 Property Model RTC Operation Internal House Supply from Rainwater Tank No flow from tank when empty

5000 Property Model RTC Operation External Use from Rainwater Tank External Use between 5pm-8pm No flow from tank when empty

5000 Property Model RTC Operation Potable Demand Potable volume increases when tank is empty (internal supply)

5,000 Property Model Model Stats 5,800 Buildings 5,301 Buildings with Water & Sewer connections 4,923 Buildings with rainwater tanks (res only) 23,197 Nodes 8,160 Pipes 15,147 Weirs 20,068 Variable Discharge Orifices 59,838 lines of RTC code

100 Property Pilot Model 1D/2D Drainage Model Building Footprints analysis Testing sensitivity to building footprints (manually digitised; automatically generated) Locked the 2D triangular mesh for easy comparison

100 Property Pilot Model 1D/2D Drainage Model Building Footprints analysis (cont.) Testing sensitivity to building footprints (manually digitised; automatically generated) Compared flood depth Tested impacts of increasing 2D surface roughness

100 Property Pilot Model 1D/2D Drainage Model Building Footprints analysis (cont.) Testing sensitivity to building footprints (manually digitised; automatically generated) Compared peak hydrographs Tested impacts of increasing 2D surface roughness

External Catchments and Inflow hydrographs Large external catchments draining into the site excluded from the model extent Inflow sources Scotchmans Ck Mile Ck West Mile Ck East Police Road 30

Waterways in 2D Scotchmans Ck, Stanley Av East Oakleigh Drain, North Rd Mile Ck, Springvale Rd 31

Waterways in 2D (cont.) Example of waterways 32

2D mesh size and Total number of Mesh Elements Model mesh size summary table: Approx. 3 to 4 hours to mesh Total number of elements: approx. 3.1 millions Smallest elements will require the model to be run at 1s timestep 33

27,000 Property Model 2051 Future Growth Model Model scaled up to approximately 49,000 properties for 2051 growth scenario. Future growth assumed to be a result of densification. No physical changes made to the model. Potable demands scaled based on growth ratio. Fraction impervious & roughness values amended in drainage surface model.

Advantages of Integrated Modelling Integrated thinking about interactions between systems Changes in one system are automatically reflected in the others Assessment of viability of alternative water sources

Challenges and Limitations Water supply system difficult to model RTC becomes cumbersome > 5000 lots Selection of model extent important Limited stormwater system data Different approach to flood modelling Different design events for systems

Questions