Ming-Ming Wang, Ph.D. student

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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
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This work was supported by the National Natural
Science Foundation of China (Grant No.50678009)
Acknowledge

• Institute for Mathematical Sciences (IMS)
• Singapore - Delft Water Alliance (SDWA)
• Tropical Marine Science Institute (TMSI)
• Pacific Institute for Mathematical Sciences (PIMS)

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Contents

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

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Background
urban sewer system
Treatment plant
Receiving river
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Background
Urbanisation is a significant global trend not
only calls for new sewer system, but stresses
existing urban sewer system.
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Background
January 3, 2006 Sewage pipes emergency in Beijing
East Third Ring Road
Road collapse
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Sudden heavy stormJuly 10, 2004
Background - Climate Change
Flooding in Beijing
strongest storm in a decade
The storm started at 400 pm and continued for
about 3 hours
111 mm fell on Tiananmen Square
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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
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Background - Climate Change
Flooding in Beijing
Airport Expressway, July 31, 2006
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Background

1. Large cities
2. Complex sewer systems
3. Integrated management (Pollution control,
   stormwater and sewage network management and
   flood prevention)
4. The need of Decision support online

We need integrated complex models, using the
advanced technologies (GIS, SCADA, etc.)
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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
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• Popular GIS software packages used in China
• ESRI ArcGIS
• MapInfo
• MapGIS

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ArcGIS
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MapInfo
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MAPGIS
Underground pipeline networks management system
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• Popular model software packages used in China
• US EPA
• DHI
• Bentley
• Wallingford

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SWMM
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Mike Urban
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SewerGEMS
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Infoworks CS
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Process of Storm to sewer network
Storm
Hydrological model
Catchment
hydraulic model
Sewer
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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
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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 and return 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.
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Design of Storm sewer system
storm sewer system without storage facilities
Need peak flow Rational method QpCiA
Data need Design storm
storm sewer system with storage facilities
Need flow hydrograph
Data need Design storm with time distribution
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Rainfall data in China
Difference
Spatial scale Temporal scale
River/watershed hydrology large year, day, hour
Urban hydrology relative small day, hour, minute
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Rainfall data in China

• Department of urban drainage
• rainfall data
• resolution
• minute, hour, day

• Department of hydrology
• rainfall data
• resolution
• hour, day, year

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Published rainfall data
Design storm With time distribution

• Rainfall data
• resolution
• day

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

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Flood control rainwater reuse
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Current storage volume calculation in China
Storage volume of detention tank
V (1- a )1.5 Qmax tc
where V storage volume(m3) Qmax design peak
flow of upstream pipe(m3/s) tc duration of
Qmax(s) a coefficient , a Qmax/Qdownstream
Storage volume of rainwater tank
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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
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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'.
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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
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Calculation of stormwater tank to rainwater
reuse
Rainwater reuse
discharge Q
Inflow hydrograph
Tank volume
time t
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Stormwater tank with multi-function (flood
control, pollution control, rainwater reuse)
Storage volumemaxV1,V2,V3
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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.

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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)
1
2
24
5min
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Stormwater tank with multi-function (flood
control, pollution control, rainwater reuse)
How to operate ?
Monitoring water quality
First flush diverter
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Stormwater tank with multi-function (flood
control, pollution control, rainwater reuse)
How to operate ?
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
Get the storm with return period
Empty the tank
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Thank you
Acknowledge