Upload
aubrey-burns
View
216
Download
0
Tags:
Embed Size (px)
Citation preview
Integrating Simulation and Design
for Stormwater Management
by
Alan A. Smith
Alan A. Smith Inc.Dundas, Ontario, Canada
A SWMM Program Classification Scheme
Representing a Drainage Network as a Tree
11 Nodes
10 Links
A node numbering convention
A time-wise marching solution
UpstreamboundaryQ = Q(t)
DownstreamboundaryH = f(Q,t)
Intermediateinflow Q(j)
A downstream marching solution
UpstreamboundaryQ = Q(t)
Intermediateinflow Q(j)
Hydrology options in MIDUSS 98
Storms RainfallLoss
Overland flowmethod
Chicago SCS CurveNumber
Triangular response
Huff quartile Runoffcoefficient
Rectangular response
Mass RainfallDistribution
Horton (movingcurve)
Linear reservoirresponse
CanadianAES
Green & Ampt SWMM RUNOFFalgorithm
Historic
Storms Infiltration Overland
Design options in MIDUSS 98
Pipes - part-full uniform flow - surcharged HGL Channels - simple trapezoidal - complex (50 points) Pond - detention, rooftop, parking lot, super-
pipe Exfiltration trench - split inflow between
outflow and exfiltration Diversion - split major and minor flows Route - modified Muskingum-Cunge method
Channel
Pipe
Pond
Trench
Diversion
Route
Benefits of On-Site Detention(for commercial developments)
(1) Should be explored before end-of-pipe BMP
(2) Runoff should be attenuated locally when possible
(3) Local control of peak flow reduces hydraulic load on centralized quality control
(4) Peak flow reduction reduces re-suspension of settled solids
(5) Reduce cost of centralized SWM facility
(6) Facilitates cost-sharing between benefiting parties.
Idealized discretization ofa commercial development
Define catchment 100% imperviousFor 450 sq.m./RD set L = 10 m @ 0.5%Generate runoff hydrographAdd to Inflow hydrographDesign pond - use Rooftop optionConfirm/edit parameters 24
litres/min/25mmRoute hydrograph
Rooftop storage
Rooftop
Rooftop storage - Q,V = f(H)
Discharge
Volume
Rooftop storage - Results
Parking lot storage (1)
Parking lot storage (2)
Rim elevation
Catch basinInvert level
Volume
Discharge
Rim capacity
Parking lot storage (3)
Rim Elevation
Flood routing
Ti+1
Ti
Xj+1Xj
Time T
Distance X
tt
xx
Cr=ct/x=2
Nucleus
Unstable
Muskingum-Cunge method
2
21
x
QD
t
Q
cx
Q
x
tcx
dhdQS
QD
f
122122
1
1
x
tc
Diffusion equation is
where D can be defined by:
subject to stability criteria
Running in Automatic mode
Created in previous manual run
Running in Automatic mode
•Test previous design for more severe storm
•Complete design in 2 or more sessions
•Add extra commands
•Modify design for more severe storm
Edit Paneland Control Panel
Applications of MIDUSS 98
Program functionality has been developed over many years of professional practice.
Has proved valuable in ‘fleshing out’ Master Drainage Plans to separate local and centralized SWM facilities
Most recent application in Belleville, Ontario to 400 ha catchment to assign cost sharing among two municipalities, 8 to 10 new developments and many existing developments.
Conclusions
Drainage design cannot easily separate simulation and design
Conclusions
Drainage design cannot easily separate simulation and design
Design process needs a highly interactive decision support system
Conclusions
Drainage design cannot easily separate simulation and design
Design process needs a highly interactive decision support system
Automatic mode allows sensitivity of design to storm magnitude to be tested incrementally.
Conclusions
Drainage design cannot easily separate simulation and design
Design process needs a highly interactive decision support system
Automatic mode allows sensitivity of design to storm magnitude to tested be incrementally.
Versatile hydrology simulation and flexible, interactive design provides a training tool for professional and student.