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Introduction to USEPA SWMM

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					  Introduction to USEPA
         SWMM
CE 572 - Analysis of Urban Water Systems
                Fall 2008



                                           1
Topics to Be Covered

  SWMM’s Capabilities
  Old SWMM v. New    SWMM
  SWMM’s Data Objects
  SWMM’s Process Models
  Additional Resources




                             2
             What Is SWMM?




SWMM is a distributed, dynamic rainfall-runoff simulation
model used for single event or long-term (continuous)
simulation of runoff quantity and quality from primarily
urban areas.                                                3
SWMM’s Process Models




                        4
 Hydrologic Modeling Features
 Spatially and    time varying rainfall
 Evaporation of standing surface water
 Snow accumulation and melting
 Interception from depression storage
 Infiltration into soil layers
 Percolation into shallow groundwater
 Interflow between groundwater & channels
 Nonlinear routing of overland flow

                                         5
     Hydraulic Modeling Features
   Handles drainage networks of any size
   Accommodates various conduit shapes as well as
    irregular natural channels
   Models pumps, regulators, storage units
   Allows external inflows from runoff, groundwater,
    RDII, sanitary, DWF, and user-supplied time series
   Uses flexible rule-based controls for pumps and
    regulators
   Models various flow regimes, such as backwater,
    surcharging, reverse flow, and surface ponding
                                                      6
 Water Quality Modeling Features

 Pollutant buildup over different land uses
 Pollutant washoff during runoff events
 Reduction in buildup from street cleaning
 Reduction in washoff from BMPs
 Inflows from user-defined sources and
  sanitary DWF
 WQ routing through the drainage network
 User-defined treatment functions

                                               7
    Typical Applications of SWMM

   Design and sizing of drainage system components
    including detention facilities
   Flood plain mapping of natural channel systems
   Control of combined and sanitary sewer overflows
   Generating non-point source pollutant loadings for
    wasteload allocation studies
   Evaluating BMPs and LIDs for sustainability goals


                                                    8
      Limitations of SWMM
 Not applicable to   large-scale, non-urban
  watersheds
 Not applicable to forested areas or
  irrigated cropland
 Cannot be used with highly aggregated
  (e.g., daily) rainfall data
 Its an analysis tool, not an automated
  design tool

                                               9
   SWMM Chronology
 1971 - SWMM I (M&E, UF, WRE)
 1975 - SWMM II (UF)
 1981 - SWMM 3 (UF & CDM)
 1983 - SWMM 3.3 (PC Version)
 1988 - SWMM 4 (UF & CDM)
 2005 – SWMM 5 (EPA & CDM)




                                 10
Old SWMM Structure




                     11
Structure of SWMM 5




                      12
SWMM 5’s Visual Objects




                          13
    Flow Routing Algorithms in
            SWMM5
   Steady Flow
        simple hydrograph translation
        applicable only to branched networks

   Kinematic Wave
        gravity force balanced by friction force
        attenuated & delayed outflow due to channel storage
        applicable only to branched networks

   Dynamic Wave
        solves full St. Venant eqns.
        accounts for channel storage, backwater effects,
         pressurized flow, and reverse flow
        applicable to any network layout
        requires smaller time step


                                                               14
           Flow Routing Algorithms in
                   SWMM5
   Steady Flow Routing
       Actually just sums instantaneous subcatchment runoff
        for all subcatchments upstream of the selected channel
   Kinematic Wave
       Uniform, unsteady flow
       No backwater, no surcharge, tree branch systems only
        unless flow splits are input
   Dynamic Wave
       Non-uniform, unsteady flow
       Backwater, surcharge, looped or parallel sewers, street
        routing of flooded sewer manholes
                                                             15
General Conceptual ModelFor
      Dynamic Wave




                              16
Link and Node Properties




                           17
        Hydraulic Boundary Condition
                  at Nodes


Grelev(NN,1)

                                       Grelev(NN,2)




               JN
                                JN+1       18
Node Flooding Options




                        19
   Surface Routing of Flood Flows



Zp(NN,1)

                                  Zp(NN,2)




           JN
                           JN+1       20
Conceptual Representation of the
  Dynamic Routing Algorithm




                                   21
Basic Flow Equation




                      22
Continuity Equation




                      23
Flow Cases Covered in Dynamic
      Routing Algorithm




                                24
Flow Cases Covered in Dynamic
      Routing Algorithm




                                25
Flow Cases Covered in Dynamic
      Routing Algorithm




                                26
Conceptual Representation of
     Storage in SWMM




                               27
Orifices and Weirs




                     28
Representation of Weirs




                          29
Representation of Pump




                         30
        EPA SWMM Web Site
http://www.epa.gov/ednnrmrl/swmm/




                                    31
  The SWMM-USERS List Server
List servers provide a means for subscribers to get quick answers to
questions and participate in discussions relating to the list server topics.
Subscription is free, and subscribers receive all the e-mail that is sent to
the list and can in turn send e-mail to the list.

The SWMM-USERS list server is a forum for users of the public-domain
USEPA SWMM program to share ideas and ask questions on issues
related to stormwater management modeling. A searchable archive of
past questions and answers is available through our SWMM Q&A
database.

To subscribe to a list, send an email to listserv@listserv.uoguelph.ca. Do
not put anything in the subject line and, in the body of the message,
include the following line (with NO other text and no brackets):

SUBSCRIBE SWMM-USERS [first name] [last name]

For example,

SUBSCRIBE SWMM-USERS JANE DOE
                                                                               32
SWMM Wrappers With GIS
     Interfaces
 XP    SWMM – XP Software
    (www.xpsoftware.com)

   Mike SWMM – DHI
    (www.dhisoftware.com)

   InfoSWMM - MWH Soft
    (www.mwhsoft.com)

   PC SWMM – CHI
    (www.computationalhydraulics.com)

                                        33
          Homework

1. Download SWMM5 from the EPA Website
      http://www.epa.gov/ednnrmrl/models/swmm/index.htm
2. Download the User’s Manual
3. Page through the Users Manual so you are
   familiar with it
4. Look at the tutorial and be prepared to run
   it in class on Thursday




                                                          34

				
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