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Introduction to USEPA Introduction to USEPA SWMMSWMM

CE 572 - Analysis of Urban Water SystemsCE 572 - Analysis of Urban Water SystemsFall 2008Fall 2008

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Topics to Be Covered

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

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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.

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SWMM’s Process ModelsSWMM’s Process Models

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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

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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

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Water Quality Modeling Features

Pollutant buildup over different land usesPollutant buildup over different land uses Pollutant washoff during runoff eventsPollutant washoff during runoff events Reduction in buildup from street cleaningReduction in buildup from street cleaning Reduction in washoff from BMPsReduction in washoff from BMPs Inflows from user-defined sources and Inflows from user-defined sources and

sanitary DWFsanitary DWF WQ routing through the drainage networkWQ routing through the drainage network User-defined treatment functionsUser-defined treatment functions

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Typical Applications of SWMMTypical Applications of SWMM

Design and sizing of drainage system components Design and sizing of drainage system components including detention facilitiesincluding detention facilities

Flood plain mapping of natural channel systemsFlood plain mapping of natural channel systems Control of combined and sanitary sewer overflowsControl of combined and sanitary sewer overflows Generating non-point source pollutant loadings for Generating non-point source pollutant loadings for

wasteload allocation studieswasteload allocation studies Evaluating BMPs and LIDs for sustainability goals Evaluating BMPs and LIDs for sustainability goals

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Limitations of SWMMLimitations of SWMM

Not applicable to large-scale, non-urban Not applicable to large-scale, non-urban watershedswatersheds

Not applicable to forested areas or Not applicable to forested areas or irrigated croplandirrigated cropland

Cannot be used with highly aggregated Cannot be used with highly aggregated (e.g., daily) rainfall data(e.g., daily) rainfall data

Its an analysis tool, not an Its an analysis tool, not an automatedautomated design tooldesign tool

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SWMM ChronologySWMM Chronology

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

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Old SWMM StructureOld SWMM Structure

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Structure of SWMM 5Structure of SWMM 5

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SWMM 5’s Visual ObjectsSWMM 5’s Visual Objects

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Flow Routing Algorithms in Flow Routing Algorithms in SWMM5SWMM5

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

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Flow Routing Algorithms in Flow Routing Algorithms in SWMM5SWMM5

Steady Flow RoutingSteady Flow Routing Actually just Actually just sumssums instantaneous subcatchment runoff instantaneous subcatchment runoff

for all subcatchments upstream of the selected channelfor all subcatchments upstream of the selected channel Kinematic WaveKinematic Wave

Uniform, unsteady flowUniform, unsteady flow No backwater, no surcharge, tree branch systems only No backwater, no surcharge, tree branch systems only

unless flow splits are inputunless flow splits are input Dynamic WaveDynamic Wave

Non-uniform, unsteady flowNon-uniform, unsteady flow Backwater, surcharge, looped or parallel sewers, street Backwater, surcharge, looped or parallel sewers, street

routing of flooded sewer manholesrouting of flooded sewer manholes

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General Conceptual ModelFor General Conceptual ModelFor Dynamic WaveDynamic Wave

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Link and Node PropertiesLink and Node Properties

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Hydraulic Boundary ConditionHydraulic Boundary Conditionat Nodesat Nodes

JN

JN+1

Conduit (N)

Grelev(NN,1)

Grelev(NN,2)

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Node Flooding OptionsNode Flooding Options

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Surface Routing of Flood FlowsSurface Routing of Flood Flows

JN

JN+1

Conduit (N)

Surface Gutter (NN)

Zp(NN,1)

Zp(NN,2)

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Conceptual Representation of the Conceptual Representation of the Dynamic Routing AlgorithmDynamic Routing Algorithm

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Basic Flow EquationBasic Flow Equation

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Continuity EquationContinuity Equation

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Flow Cases Covered in Dynamic Flow Cases Covered in Dynamic Routing AlgorithmRouting Algorithm

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Flow Cases Covered in Dynamic Flow Cases Covered in Dynamic Routing AlgorithmRouting Algorithm

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Flow Cases Covered in Dynamic Flow Cases Covered in Dynamic Routing AlgorithmRouting Algorithm

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Conceptual Representation of Conceptual Representation of Storage in SWMMStorage in SWMM

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Orifices and WeirsOrifices and Weirs

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Representation of WeirsRepresentation of Weirs

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Representation of PumpRepresentation of Pump

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EPA SWMM Web SiteEPA SWMM Web Sitehttp://www.epa.gov/ednnrmrl/swmm/

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The SWMM-USERS List ServerThe SWMM-USERS List ServerList 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

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SWMM Wrappers With GIS SWMM Wrappers With GIS InterfacesInterfaces

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)

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HomeworkHomework

1. Download SWMM5 from the EPA Websitehttp://www.epa.gov/ednnrmrl/models/swmm/index.htm

2. Download the User’s Manual3. Page through the Users Manual so you are familiar with it4. Look at the tutorial and be prepared to run it in class on Thursday