Development of Integrated Models for Urban Drainage Systems

1. Development of Integrated Models for Urban Drainage Systems by Ming-Ming Wang, Ph.D. student Dr. Yu-Wen Zhou, Professor Data-driven and Physically-based Models for Characterization of Processes in Hydrology, Hydraulics, Oceanography and Climate Change 6 - 28 Jan 2008 NUS, IMS

2. Acknowledge This work was supported by the National Natural Science Foundation of China (Grant No.50678009) • Institute for Mathematical Sciences (IMS) • Singapore - Delft Water Alliance (SDWA) • Tropical Marine Science Institute (TMSI) • Pacific Institute for Mathematical Sciences (PIMS)

3. Contents • Background • Integrated model framework • Modeling • Popular GIS software packages • Popular model software packages • Design of storm sewer system • Conclusion • Discussion

4. Background urban sewer system Treatment plant Receiving river

5. Background Urbanisation is a significant global trend not only calls for new sewer system, but stresses existing urban sewer system.

6. Background January 3, 2006 Sewage pipes emergency in Beijing East Third Ring Road Road collapse

7. Background - Climate Change Sudden heavy stormJuly 10, 2004 Flooding in Beijing strongest storm in a decade The storm started at 4:00 pm and continued for about 3 hours 111 mm fell on Tiananmen Square

8. Background - Climate Change Flooding paralyzes Beijing traffic Flooding in Beijing Locus Bridge of downtown Beijing the water reached a depth of over 1.5 meters Highly concerned by Chinese Premier

9. Background - Climate Change Flooding in Beijing Airport Expressway, July 31, 2006

10. Background • Large cities • Complex sewer systems • Integrated management (Pollution control, stormwater and sewage network management and flood prevention) • The need of Decision support online We need integrated complex models, using the advanced technologies (GIS, SCADA, etc.)

11. The framework of integrated model Monitoring of drainage system performances SCADA system SYSTEM INTEGRATION DATABASE Model Simulation and assessment of drainage system Presentation of drainage system and provides information GIS

12. Popular GIS software packages used in China • ESRI ArcGIS • MapInfo • MapGIS

13. ArcGIS

14. MapInfo

15. MAPGIS Underground pipeline networks management system

16. Popular model software packages used in China • US EPA • DHI • Bentley • Wallingford

17. SWMM

18. Mike Urban

19. SewerGEMS

20. Infoworks CS

21. Process of Storm to sewer network Storm Hydrological model Catchment hydraulic model Sewer

22. Modeling of Storm sewer system Rainfall Losses model Effective rainfall unit hydrograph Inflow hydrograph of the inlet Non-steady flow hydraulics numerical solutions Outflow hydrograph of sewer system

23. Design of Storm sewer system Design storms are routinely used for designing storm sewer system. A design storm is a hypothetical storm with specific duration D andreturn period T. The information of design storms is conveniently presented in the form of depth-duration-frequency (DDF) curves or intensity-duration-frequency (IDF) curves.

24. Design of Storm sewer system storm sewer system without storage facilities Need peak flow Rational method: Qp=CiA Data need: Design storm storm sewer system with storage facilities Need flow hydrograph Data need: Design storm with time distribution

25. Rainfall data in China Difference

26. Rainfall data in China • Department of urban drainage rainfall data resolution minute, hour, day • Department of hydrology rainfall data resolution hour, day, year

27. Published rainfall data Design storm With time distribution Rainfall data resolution day ? Storm pattern resolution hour, minute

28. Storm pattern Chicago storm Intensity-Duration-Frequency relationship In China, duration 5, 10, 15, 20, 30, 45, 60, 90, 120min

29. Storm pattern SCS storm pattern example a 25-year, 24-hour duration rainfall 10.01in SCS Type-III storm in Harris County using a one-hour time increment

30. storm pattern Department of hydrology in China Typical storm method Professor Van-Thanh-Van Nguyen Downscaling method Daily GCMs to sub-daily precipitation 5-min to 1 hour 1 hour to 1-day

31. Water resources problem in China Too little water Water shortage Polluted water The discharges of wastewater by industry and households have considerable detrimental effects on water quality and on public and ecosystem health. Too much water increased frequencies or magnitudes of floods.

32. Flood control & pollution control The rainwater tank as a runoff control measure is widely used. • temporary storing of stormwater, reduce flow peaks, reduce the pipe size of downstream • reduce runoff pollution • rainwater reuse

33. Flood control & rainwater reuse

34. Current storage volume calculation in China Storage volume of detention tank V = (1- α )1.5× Qmax × tc where V ——storage volume（m3）； Qmax ——design peak flow of upstream pipe（m3/s）； tc ——duration of Qmax（s）； α ——coefficient , α =Qmax/Qdownstream Storage volume of rainwater tank

35. Calculation of detention tank for flood control reduce flow peaks discharge Q Inflow hydrograph Tank volume fed downstream after the end of storm event volume fed downstream during storm event time t

36. Calculation of stormwater tank to capture the first flush reduce runoff pollution discharge Q Inflow hydrograph Tank volume the first flush time t Usually the stormwater that initially runs off an area will be more polluted than the stormwater that runs off later, after the rainfall has 'cleansed' the catchment. The stormwater containing this high initial pollutant load is called the 'first flush'.

37. Calculation of stormwater tank to capture the first flush rainfall data water quality data Monitoring water quality storage volume stormwater tank temperature, pH value, dissolved oxygen (DO), electrical conductivity, suspended solid (SS), turbidity, alkalinity, ammonia nitrogen, total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), chemical oxygen demand (CODMn), total hardness, Ca2+, Mg2+, sulfate, Fe, Mn, Cu, Zn

38. Calculation of stormwater tank to rainwater reuse Rainwater reuse discharge Q Inflow hydrograph Tank volume time t

39. Stormwater tank with multi-function (flood control, pollution control, rainwater reuse) Inflow hydrograph Tank volume V1 Inflow hydrograph Inflow hydrograph Tank volume V2 Tank volume V3 Storage volume=max{V1,V2,V3}

40. Conclusion • The aim of this work is only to provide the method for design of the storm sewer system with storage facilities in China. • The Storage volume calculation method of stormwater tank with multi-function(flood control, pollution control, rainwater reuse) is provided for China.

41. Discussion Downscaling method Daily GCMs to sub-daily precipitation 5-min to 1 hour 1 hour to 1-day urban hydrology River/watershed hydrology Small Large urban hydrology River/watershed hydrology Sub-daily to daily precipitation 5-min to 2 hour 2 hour to 1-day Rainfall(mm) Downscaling Time (hour) 5min 1 2 24

42. Stormwater tank with multi-function (flood control, pollution control, rainwater reuse) How to operate ? Inflow hydrograph Inflow hydrograph Monitoring water quality Tank volume V2 Tank volume V3 First flush diverter

43. Stormwater tank with multi-function (flood control, pollution control, rainwater reuse) Inflow hydrograph How to operate ? Tank volume V1 Outflow of outlet Water level of outlet Storms with return period 2yr, 5yr, 10yr… setting Modeling of sewer network Overflow weir to the tank IF network overflow Before this storm Empty the tank Get the storm with return period

44. Acknowledge Thank you