Sunday, August 30, 2015

How to use the Flow Splitter in InfoSewer for Dendritic Networks

Subject: How to use the Flow Splitter in InfoSewer for Dendritic Networks

InfoSewer, which is an extension in Arc Map, does need to have slit split defined where gravity mains merge together to determine the amount of flow in each of the downstream conduits (Figure 1).   The options for the flow splitter in each of the downstream links are:

1. Automatic Allocation

2. Fixed Flow Percentage

3. Variable Flow Percentage and

4. Inflow-Outflow Curve

At an outfall where the invert of the outfall pipe is raised compared to the inverts of the incoming and outgoing pipes a flow split of Variable Flow Percentage or Inflow/Outflow curve may work better (Figure 2). 
Figure 1. Options for Performing a Flow Split in InfoSewer

Figure 2.  The Effect of the flow split can be used to model complex situations in a dendritic model with outfalls.

Advanced Force Network Support in InfoSewer for Steady State and EPS with Emojis

🚧 The Advanced Force Network Support in a sewer system offers a sophisticated 🖥️ simulation model for multiple upstream and downstream force mains that enter and depart a singular junction chamber. This simulation is designed for Extended Period Dynamic Simulation (EPS) 🔄, considering all connected force mains, pumps, wet wells, and force main chamber junctions as one integrated force main network. This powerful feature 🌟 allows for comprehensive network analyses, particularly useful in large Sewer models that may contain more than one force main network, separated by gravity pipes and loading manholes. The various force main networks are solved iteratively, taking into account differing upstream heads and downstream tail manholes, which connect these networks to the rest of the sewer system. 🌊

🔍 Let's delve into the key elements constituting a force main network:

  • Wet Well: 🚿 This is essentially a holding tank where incoming wastewater is temporarily stored before it's pumped to a higher level or where it's temporarily retained until it can flow out to the sewer system by gravity.

  • Pump: 💦 The pump propels the wastewater from the wet well to a higher elevation. Depending on the requirements of the specific system, these pumps can vary in type and capacity. Their operation can be automatic, based on the level of wastewater in the wet well, or manually controlled.

  • Junction Chamber: 🛠️ This is a critical component where multiple force mains converge or diverge. In the junction chamber, flows from different lines are combined or separated, depending on whether they are incoming or outgoing.

  • Head Manhole or Loading Manhole: 🕳️ The head manhole, also known as a loading manhole, is where the flow from other parts of the sewer system enters the force main network. It essentially serves as the entry point for wastewater into the force main system. These structures can also be designed to handle excess flow during peak times.

  • Tail Manhole: 🚪 The tail manhole is where the flow leaves the force main network. It serves as an exit point for the wastewater, leading it out of the force main system and into other parts of the sewer network, often those operating by gravity flow.

🖥️ Elements in InfoSewer

The identification of the head and tail manhole for a force main network is astutely determined by the software itself, guided by the precise geometry of the network. A force main network springs from a wet well, incorporating pumps that establish a connection from the wet well to the force main links. The actual force main links and the force main connecting junction chambers are also integral parts of this system. Notably, the software offers the flexibility to link a force main directly to the gravity mains, bypassing the need for an intermediate wet well and pumps.

Two critical boundary conditions 📏 help define the dynamics within the force main network:

  • Water Heads at Wet Wells: 🌊 These vary as a function of the inflow from the upstream portions of the sewer network and outflow to the force main network. Essentially, as inflow rates from upstream sections change, the water head or the hydraulic grade line in the wet well adjusts accordingly.

  • Water Head at Tail Manholes: 📊 These are calculated as the maximum discharge head, a sum of the manhole invert elevation and the diameter of the force mains that terminate at that manhole.

Through these boundary conditions, the software effectively manages and simulates the behavior of the wastewater within the network, ensuring optimum functionality. As water levels fluctuate in response to inflow and outflow dynamics, the software's ability to adjust and manage these shifts helps maintain the operational integrity of the sewer system.

📚 An Example of how Newton Raphson Solves for Zero

For example, assuming there are n1 wet wells, n2 head manholes, n3 tail manholes, n4 junction chambers and l1 pumps and l2 force mains, the program must solve the network hydraulics to get n2+n4 water head values and l1+l2 flow values iteratively using the Newton-Raphson method. The solution iterates until the mass and energy of the force main network is in balance. The hydraulic equations used in the solution are essential for understanding the intricacies of the system.

InfoSewer - Minimum Travel Distance

InfoSewer - Minimum Travel Distance

Note:   The minimum travel distance in an InfoSewer or H2OMap Sewer model can be related to the mean link length in the Pipe DB Table.  Here is a table of the Mass balance check for one network versus the minimum travel distance in feet for the default values of network accuracy, minimum time length and maximum number of segments at a report time step of 1 hour.   As you can see making the Minimum Travel equal to the mode of the length histogram yields the best results even for the default model parameters.
Minimum Travel DistanceMass Balance Check:Label

Friday, August 28, 2015

How to Make a SWMM 5 Calibration File from InfoSWMM

How to Make a SWMM 5 Calibration File from InfoSWMM

Subject:  How to Make a SWMM 5 Calibration File from InfoSWMM
1st Step:  Graph a Link  in InfoSWMM using the Date /Time Format
2nd Step:  Click on the Report Button and copy the 1st two columns of data
3rd Step:  Save the  copied columns to a data file, replace the semi colon and add the name of the link  to the top of the data file as shown below
4th Step:  Connect the created calibration data file t o the SWMM 5 Calibration Data Link Flow Rate
5th Step:  Run the  Simulation and you should see two  graphs on the screen for the designated link

EPA SWMM 5 Calibration Files

The EPA SWMM 5 calibration file is only for comparing the following 12 internal variables graphically to either SWMM 4 results, monitored data or some other model results:
  1. Subcatchment Runoff
  2. Subcatchment Washoff
  3. Node Water Depth
  4. Link Flow Rate
  5. Node Water Quality
  6. Node Lateral Inflow
  7. Node Flooding
  8. Groundwater Flow
  9. Groundwater Elevation
  10. Snow Pack Depth
  11. Link Flow Depth
  12. Link Flow Velocity
The graph on your SWMM 5 screen can be saved either to the clipboard or an external file for further manipulation of the computed and observed (calibration file data) by using the commands
Edit->Copy To=>Clipboard=>Text or
Edit->Copy To=>File=>Text
Just remember that the computed variable value comes first in the text followed by the observed variable value. For example:
Link 1030 Flow
Series Elapsed Time (hours) Flow CFS
Computed 0.1667 0.0000

Thursday, August 27, 2015

How to Use the Arc Map Editor in InfoSWMM

How to Use the Arc Map Editor in InfoSWMM

Note:  How to Use the Arc Map Editor in InfoSWMM
Step 1 is to use the Edit Feature for example the Subcatchment layer to bring up the Arc Map Editor Tool.

Step 2 is to use the Reshape Feature tool or Vertex tools to bring together mis matched Subcatchment Boundaries

Step 3 is to use save the edits and then Update the DB from the Map to recalculate the area of the Subcatchments

Thursday, August 20, 2015

EPA SWMM 5.1.010 Build 5.1.010 Update with Images

Build 5.1.010 (08/05/15)
Source Engine Updates:

1.  A modified version of Green-Ampt infiltration (MODIFIED GREEN AMPT) was
    added that no longer redistributes upper zone moisture deficit during
    low rainfall events. The original authors of SWMM's Green-Ampt model
    have endorsed this modified version. It will produce more infiltration
    for storm events that begin with low rainfall intensities, such as the
    SCS design storm distributions.SNAGHTML2e5eed0

2.  A new type of weir, a ROADWAY weir, has been added. It models roadway
    overtopping using the FHWA HDS-5 method and would typically be used in
    parallel with a culvert conduit.SNAGHTML2e4b8d2

3.  Rule premises can now test whether a link has been open (or closed) for
    a specific period of time. See the Help file for more details.
4.  Unsaturated hydraulic conductivity ("K") was added to the list of
    variables that can be used in a user-supplied groundwater flow equation.
5.  A bug introduced in update 2 of release 5.1.008 that failed to include
    infiltration from LID units into the groundwater routine was fixed.

6.  A bug that failed to properly initialize the flag indicating that one or
    more LID controls was initially wet was fixed.

7.  Duplicate printing of the first line of an LID detailed report file was

8.  The Hargreaves evaporation formula was modified to use a 7-day running
    average of daily temperatures, instead of just single day values, as
    recommended by the formula's authors.

9.  Daily potential evapotranspiration (PET) was added as a system output
10. The qualrout.c module was refactored to make it more compact and easier
    to follow.

11. Storage seepage and evaporation losses are now based on the storage volume
    at the end, not the start, of the prior time step.

12. The command line used to build the engine included in the "makefile"
    for the GNU C/C++ compiler was corrected to include the OpenMP libraries.

Wednesday, August 12, 2015

SWMM5 or the Storm Water Management Model from Wikipedia - for Translation Purposes

Storm Water Management Model 

From Wikipedia, the free encyclopedia

The United States Environmental Protection Agency (EPA) Storm Water Management Model (SWMM)[1][2][3][4][5][6][7] is a dynamic rainfall–runoffsubsurface runoff simulation model used for single-event to long-term (continuous) simulationof the surface/subsurface hydrology quantity and quality from primarily urban/suburban areas. The hydrology component of SWMM operates on a collection of subcatchment areas divided into impervious and pervious areas with and without depression storage to predict runoff and pollutant loads from precipitation, evaporation and infiltrationlosses from each of the subcatchment. In addition low impact development (LID) and best management practice areas on the subcatchment can be modeled to reduce the impervious and pervious runoff. The routing or hydraulics section of SWMM transports this water and possible associated water quality constituents through a system of closed pipes, open channels, storage/treatment devices, ponds, storages, pumps, orifices, weirs, outlets, outfalls and other regulators. SWMM tracks the quantity and quality of the flow generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period composed of multiple fixed or variable time steps. The water quality constituents such as water quality constituents can be simulated from buildup on the subcatchments through washoff to a hydraulic network with optional first order decay and linked pollutant removal, best management practice and low-impact development (LID) removal and treatment can be simulated at selected storage nodes. SWMM is one of the hydrology transport models which the EPA and other agencies have applied widely throughout North America and through consultants and universities throughout the world. The latest update notes and new features can be found on the EPA website in the download section.

Program description

The EPA storm water management model (SWMM) is a dynamic rainfall-runoff-routing simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment areas that receive precipitation and generate runoff and pollutant loads. The routing portion of SWMM transports this runoff through a system of pipes, channels, storage/treatment devices, pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period divided into multiple time steps.
SWMM accounts for various hydrologic processes that produce runoff from urban areas. These include:
  1. time-varying rainfall
  2. evaporation of standing surface water
  3. snow accumulation and melting
  4. rainfall interception from depression storage
  5. infiltration of rainfall into unsaturated soil layers
  6. percolation of infiltrated water into groundwater layers
  7. interflow between groundwater and the drainage system
  8. nonlinear reservoir routing of overland flow
  9. capture and retention of rainfall/runoff with various types of low impact development (LID) practices.
SWMM also contains a flexible set of hydraulic modeling capabilities used to route runoff and external inflows through the drainage system network of pipes, channels, storage/treatment units and diversion structures. These include the ability to:
  1. handle networks of unlimited size·
  2. use a wide variety of standard closed and open conduit shapes as well as natural channels·
  3. model special elements such as storage/treatment units, flow dividers, pumps, weirs, and orifices·
  4. apply external flows and water quality inputs from surface runoff, groundwater interflow, rainfall-dependent infiltration/inflow, dry weather sanitary flow, and user-defined inflows
  5. utilize either kinematic wave or full dynamic wave flow routing methods·
  6. model various flow regimes, such as backwater, surcharging, reverse flow, and surface ponding·
  7. apply user-defined dynamic control rules to simulate the operation of pumps, orifice openings, and weir crest levels.
Spatial variability in all of these processes is achieved by dividing a study area into a collection of smaller, homogeneous subcatchment areas, each containing its own fraction of pervious and impervious sub-areas. Overland flow can be routed between sub-areas, between subcatchments, or between entry points of a drainage system.
Since its inception, SWMM has been used in thousands of sewer and stormwater studies throughout the world. Typical applications include:
  1. design and sizing of drainage system components for flood control
  2. sizing of detention facilities and their appurtenances for flood control and water quality protection·
  3. flood plain mapping of natural channel systems, by modeling the river hydraulics and associated flooding problems using prismatic channels·
  4. designing control strategies for minimizing Combined Sewer Overflow (CSO) and Sanitary Sewer Overflow (SSO)·
  5. evaluating the impact of inflow and infiltration on sanitary sewer overflows·
  6. generating non-point source pollutant loadings for waste load allocation studies·
  7. evaluating the effectiveness of BMPs and Subcatchment LID's for reducing wet weather pollutant loadings.Rainfall-runoff modeling of urban and rural watersheds
  8. hydraulic and water quality analysis of storm, sanitary, and combined sewer systems
  9. master planning of sewer collection systems and urban watersheds
  10. system evaluations associated with USEPA's regulations including NDPES permits, CMOM, and TMDL
  11. 1D and 2D (surface ponding) predictions of flood levels and flooding volume
EPA SWMM is public-domain software that may be freely copied and distributed. The SWMM 5 public domain consists of C engine code and Delphi SWMM 5 graphical user interface code. The C code and Delphi code are easily edited and can be recompiled by students and professionals for custom features or extra output features.


SWMM was first developed between 1969–1971 and has undergone four major upgrades since those years. The major upgrades were: (1) Version 2 in 1973-1975, (2) Version 3 in 1979-1981, (3) Version 4 in 1985-1988 and (4) Version 5 in 2001-2004. A list of the major changes and post 2004 changes are shown in Table 1. The current SWMM edition, Version 5/5.1.007, is a complete re-write of the previous Fortran releases in the programming language C, and it can be run under Windows XPWindows VistaWindows 7Windows 8 and also with a recomplilation under Unix. The code for SWMM5 is open source and public domain code that can be downloaded from the EPA Web Site.
Table 1. SWMM History
Release DateVersionsDevelopersFEMA ApprovalLID Controls
08/20/2015SWMM 5.1.010EPAYesYes
04/30/2015SWMM 5.1.009EPAYesYes
04/17/2015SWMM 5.1.008EPAYesYes
10/09/2014SWMM 5.1.007EPAYesYes
06/02/2014SWMM 5.1.006EPAYesYes
03/27/2014SWMM 5.1.001EPAYesYes
04/21/2011SWMM 5.0.022EPAYesYes
08/20/2010SWMM 5.0.019EPAYesYes
08/17/2005SWMM 5.0.005EPA, CDMYesNo
11/30/2004SWMM 5.0.004EPA, CDMNoNo
11/25/2004SWMM 5.0.003EPA, CDMNoNo
10/26/2004SWMM 5.0.001EPA, CDMNoNo
2001–2004SWMM5EPA, CDMNoNo
1988–2004SWMM4UF, OSU, CDMNoNo
1981–1988SWMM3UF, CDMNoNo
1969–1971SWMM1UF, CDM, M&ENoNo

EPA SWMM 5 provides an integrated graphical environment for editing watershed input data, running hydrologic, hydraulic, real time control and water quality simulations, and viewing the results in a variety of graphical formats. These include color-coded thematic drainage area maps, time series graphs and tables, profile plots, scatter plots and statistical frequency analyses.
This latest re-write of EPA SWMM was produced by the Water Supply and Water Resources Division of the U.S. Environmental Protection Agency's National Risk Management Research Laboratory with assistance from the consulting firm of CDM Inc under a Cooperative Research and Development Agreement (CRADA). SWMM 5 is used as the computational engine for many modeling packages plus components of SWMM5 are in other modeling packages. The major modeling packages that use all or some of the SWMM5 components are shown in the Vendor section. The update history of SWMM 5 from the original SWMM 5.0.001 to the current version SWMM 5.1.007 can be found at the EPA Download in the file epaswmm5_updates.txt. SWMM 5 was approved FEMA Model Approval Page in May 2005 with this note about the versions that are approved on the FEMA Approval Page SWMM 5 Version 5.0.005 (May 2005) and up for NFIP modeling. SWMM 5 is used as the computational engine for many modeling packages (see the SWMM 5 Platform Section of this article) and some components of SWMM5 are in other modeling packages (see the SWMM 5 Vendor Section of this article).

SWMM conceptual model

SWMM conceptualizes a drainage system as a series of water and material flows between several major environmental compartments. These compartments and the SWMM objects they contain include:
The Atmosphere compartment, from which precipitation falls and pollutants are deposited onto the land surface compartment. SWMM uses Rain Gage objects to represent rainfall inputs to the system. The raingage objects can use time series, external text files or NOAA rainfall data files. The Rain Gage objects can use precipitation for thousands of years. Using the SWMM-CAT Addon to SWMM5 climate change can now be simulated using modified temperature, evaporation or rainfall.
The Land Surface compartment, which is represented through one or more Subcatchment objects. It receives precipitation from the Atmospheric compartment in the form of rain or snow; it sends outflow in the form of infiltration to the Groundwater compartment and also as surface runoff and pollutant loadings to the Transport compartment. The Low Impact Development (LID) controls are part of the Subcatchments and store, infiltrate or evaporate the runoff.
The Groundwater compartment receives Infiltration (hydrology) from the Land Surface compartment and transfers a portion of this inflow to the Transport compartment. This compartment is modeled using Aquifer objects. The connection to the Transport compartment can be either a static boundary or a dynamic depth in the channels. The links in the Transport compartment now also have seepage and evaporation.
The Transport compartment contains a network of conveyance elements (channels, pipes, pumps, and regulators) and storage/treatment units that transport water to outfalls or to treatment facilities. Inflows to this compartment can come from surface runoff, groundwater interflow, sanitary dry weather flow, or from user-defined hydrographs. The components of the Transport compartment are modeled with Node and Link objects. Not all compartments need appear in a particular SWMM model. For example, one could model just the transport compartment, using pre-defined hydrographs as inputs. If you use the kinematic wave routing then the nodes do not need to contain an outfall.
Table 2. SWMM5 Compartments

Model parameters

The simulated model parameters for subcatchments are surface roughness, depression storage, slope, flow path length; for Infiltration: Horton: max/min rates and decay constant; Green-Ampt: hydraulic conductivity, initial moisture deficit and suction head; Curve Number: NRCS (SCS) Curve number; All: time for saturated soil to fully drain; for Conduits: Manning’s roughness; for Water Quality: buildup/washoff function coefficients, first order decay coefficients, removal equations. A study area can be divided into any number of individual subcatchments, each of which drains to a single point. Study areas can range in size from a small portion of a single lots up to thousands of acres. SWMM uses hourly or more frequent rainfall data as input and can be run for single events or in continuous fashion for any number of years.

Hydrology and hydraulics capabilities

SWMM 5 accounts for various hydrologic processes that produce surface and subsurface runoff from urban areas. These include:
  1. Time-varying rainfall for an unlimited number of raingages for both design and continuous hyetographs
  2. evaporation of standing surface water on watersheds and surface ponds
  3. snowfall accumulation, plowing and melting
  4. rainfall interception from depression storage in both impervious and pervious areas
  5. infiltration of rainfall into unsaturated soil layers
  6. percolation of infiltrated water into groundwater layers
  7. interflow between groundwater and pipes and ditches
  8. nonlinear reservoir routing of watershed overland flow.
Spatial variability in all of these processes is achieved by dividing a study area into a collection of smaller, homogeneous watershed or subcatchment areas, each containing its own fraction of pervious and impervious sub-areas. Overland flow can be routed between sub-areas, between subcatchments, or between entry points of a drainage system.
SWMM also contains a flexible set of hydraulic modeling capabilities used to route runoff and external inflows through the drainage system network of pipes, channels, storage/treatment units and diversion structures. These include the ability to:
  1. Simulate drainage networks of unlimited size
  2. use a wide variety of standard closed and open conduit shapes as well as natural or irregular channels
  3. model special elements such as storage/treatment units, outlets, flow dividers, pumps, weirs, and orifices
  4. apply external flows and water quality inputs from surface runoff, groundwater interflow, rainfall-dependent infiltration/inflow, dry weather sanitary flow, and user-defined inflows
  5. utilize either steady, kinematic wave or full dynamic wave flow routing methods
  6. model various flow regimes, such as backwater, surcharging, pressure, reverse flow, and surface ponding
  7. apply user-defined dynamic control rules to simulate the operation of pumps, orifice openings, and weir crest levels
Infiltration is the process of rainfall penetrating the ground surface into the unsaturated soil zone of pervious subcatchments areas. SWMM5 offers four choices for modeling infiltration:
Classical infiltration method
This method is based on empirical observations showing that infiltration decreases exponentially from an initial maximum rate to some minimum rate over the course of a long rainfall event. Input parameters required by this method include the maximum and minimum infiltration rates, a decay coefficient that describes how fast the rate decreases over time, and the time it takes a fully saturated soil to completely dry (used to compute the recovery of infiltration rate during dry periods).
Figure 2. SWMM 5's QA/QC Master Example Network. This one network includes examples 1 through 7 from the SWMM 3 and SWMM 4 Manuals
Figure 2. SWMM 5's QA/QC Master Example Network. This one network includes examples 1 through 7 from the SWMM 3 and SWMM 4 Manuals
Modified Horton Method
This is a modified version of the classical Horton Method that uses the cumulative infiltration in excess of the minimum rate as its state variable (instead of time along the Horton curve), providing a more accurate infiltration estimate when low rainfall intensities occur. It uses the same input parameters as does the traditional Horton Method.
Green–Ampt method
This method for modeling infiltration assumes that a sharp wetting front exists in the soil column, separating soil with some initial moisture content below from saturated soil above. The input parameters required are the initial moisture deficit of the soil, the soil's hydraulic conductivity, and the suction head at the wetting front. The recovery rate of moisture deficit during dry periods is empirically related to the hydraulic conductivity.
Curve number method
This approach is adopted from the NRCS (SCS) curve number method for estimating runoff. It assumes that the total infiltration capacity of a soil can be found from the soil's tabulated curve number. During a rain event this capacity is depleted as a function of cumulative rainfall and remaining capacity. The input parameters for this method are the curve number and the time it takes a fully saturated soil to completely dry (used to compute the recovery of infiltration capacity during dry periods).
SWMM also allows the infiltration recovery rate to be adjusted by a fixed amount on a monthly basis to account for seasonal variation in such factors as evaporation rates and groundwater levels. This optional monthly soil recovery pattern is specified as part of a project's evaporation data.
In addition to modeling the generation and transport of runoff flows, SWMM can also estimate the production of pollutant loads associated with this runoff. The following processes can be modeled for any number of user-defined water quality constituents:
  1. Dry-weather pollutant buildup over different land uses
  2. pollutant washoff from specific land uses during storm events
  3. direct contribution of wet and dry rainfall deposition
  4. reduction in dry-weather buildup due to street cleaning
  5. reduction in washoff load due to BMPs and LIDs
  6. entry of dry weather sanitary flows and user-specified external inflows at any point in the drainage system
  7. routing of water quality constituents through the drainage system
  8. reduction in constituent concentration through treatment in storage units or by natural processes in pipes and channels.
Rain Gages in SWMM5 supply precipitation data for one or more subcatchment areas in a study region. The rainfall data can be either a user-defined time series or come from an external file. Several different popular rainfall file formats currently in use are supported, as well as a standard user-defined format. The principal input properties of rain gages include:
  1. rainfall data type (e.g., intensity, volume, or cumulative volume)
  2. recording time interval (e.g., hourly, 15-minute, etc.)
  3. source of rainfall data (input time series or external file)
  4. name of rainfall data source
The other principal input parameters for the subcatchments include:
  1. assigned rain gage
  2. outlet node or subcatchment and routing fraction
  3. assigned land uses
  4. tributary surface area
  5. imperviousness and zero percent imperviousness
  6. slope
  7. characteristic width of overland flow
  8. Manning's n for overland flow on both pervious and impervious areas
  9. depression storage in both pervious and impervious areas
  10. percent of impervious area with no depression storage.
  11. infiltration parameters
  12. snowpack
  13. groundwater parameters
  14. LID parameters for each LID Control Used

Routing options

Steady-flow routing represents the simplest type of routing possible (actually no routing) by assuming that within each computational time step flow is uniform and steady. Thus it simply translates inflow hydrographs at the upstream end of the conduit to the downstream end, with no delay or change in shape. The normal flow equation is used to relate flow rate to flow area (or depth).
This type of routing cannot account for channel storage, backwater effects, entrance/exit losses, flow reversal or pressurized flow. It can only be used with dendritic conveyance networks, where each node has only a single outflow link (unless the node is a divider in which case two outflow links are required). This form of routing is insensitive to the time step employed and is really only appropriate for preliminary analysis using long-term continuous simulations.Kinematic wave routing solves the continuity equation along with a simplified form of the momentum equation in each conduit. The latter requires that the slope of the water surface equal the slope of the conduit.
The maximum flow that can be conveyed through a conduit is the full normal flow value. Any flow in excess of this entering the inlet node is either lost from the system or can pond atop the inlet node and be re-introduced into the conduit as capacity becomes available.
Kinematic wave routing allows flow and area to vary both spatially and temporally within a conduit. This can result in attenuated and delayed outflow hydrographs as inflow is routed through the channel. However this form of routing cannot account for backwater effects, entrance/exit losses, flow reversal, or pressurized flow, and is also restricted to dendritic network layouts. It can usually maintain numerical stability with moderately large time steps, on the order of 1 to 5 minutes. If the aforementioned effects are not expected to be significant then this alternative can be an accurate and efficient routing method, especially for long-term simulations.
Dynamic wave routing solves the complete one-dimensional Saint Venant flow equations and therefore produces the most theoretically accurate results. These equations consist of the continuity and momentum equations for conduits and a volume continuity equation at nodes.
With this form of routing it is possible to represent pressurized flow when a closed conduit becomes full, such that flows can exceed the full normal flow value. Flooding occurs when the water depth at a node exceeds the maximum available depth, and the excess flow is either lost from the system or can pond atop the node and re-enter the drainage system.
Dynamic wave routing can account for channel storage, backwater, entrance/exit losses, flow reversal, and pressurized flow. Because it couples together the solution for both water levels at nodes and flow in conduits it can be applied to any general network layout, even those containing multiple downstream diversions and loops. It is the method of choice for systems subjected to significant backwater effects due to downstream flow restrictions and with flow regulation via weirs and orifices. This generality comes at a price of having to use much smaller time steps, on the order of a minute or less (SWMM can automatically reduce the user-defined maximum time step as needed to maintain numerical stability).

Integrated hydrology/hydraulics

Figure 3. SWMM 5's LID processes include unlimited low-impact development or BMP objects per subcatchment and 5 types of layers.
Figure 3. SWMM 5's LID processes include unlimited low-impact development or BMP objects per subcatchment and 5 types of layers.
One of the great advances in SWMM 5 was the integration of urban/suburbansubsurface flow with the hydraulic computations of the drainage network. This advance is a tremendous improvement over the separate subsurface hydrologic and hydraulic computations of the previous versions of SWMM because it allows the modeler to conceptually model the same interactions that occur physically in the real open channel/shallow aquifer environment. The SWMM 5 numerical engine calculates the surface runoff, subsurface hydrology and assigns the current climate data at either the wet or dry hydrologic time step. The hydraulic calculations for the links, nodes, control rules and boundary conditions of the network are then computed at either a fixed or variable time step within the hydrologic time step by using interpolation routines and the simulated hydrologic starting and ending values. The versions of SWMM 5 greater than SWMM 5.1.007 allow the modeler to simulate climate changes by globally changing the rainfall, temperature and evaporation using monthly adjustments.
An example of this integration was the collection of the disparate SWMM 4 link types in the runoff, transport and extran blocks to one unified group of closed conduit and open channel link types in SWMM 5 and a collection of node types (Figure 2).

Low-impact development components

The low-impact development (LID) function was new to SWMM 5.0.019/20/21/22 and SWMM 5.1+ It is integrated within the subcatchment and allows further refinement of the overflows, infiltration flow and evaporation in rain barrelswales,permeable pavinggreen roofrain gardenbioretention and infiltration trench. The term Low-impact development(Canada/US) is used in Canada and the United States to describe a land planning and engineering design approach to managing stormwater runoff. In recent years many states in the US have adopted LID concepts and standards to enhance their approach to reducing the harmful potential for storm water pollution in new construction projects. LID takes many forms but can generally be thought of as an effort to minimize or prevent concentrated flows of storm water leaving a site. To do this the LID practice suggests that when impervious surfaces (concrete, etc.) are used, they are periodically interrupted by pervious areas which can allow the storm water to infiltrate (soak into the earth)
You can define a variety of sub processes in each LID in SWMM5 such as: surface, pavement, soil, storage, drainmat and drain.
Each type of LID has limitations on the type of sub process allowed by SWMM 5. It has a good report feature and you can have a LID summary report in the rpt file and an external report file in which you can see the surface depth, soil moisture, storage depth, surface inflow, evaporation, surface infiltration, soil percolation, storage infiltration, surface outflow and the LID continuity error. You can have multiple LID's per subcatchment and we have had no issues having many complicated LID sub networks and processes inside the Subcatchments of SWMM 5 or any continuity issues not solvable by a smaller wet hydrology time step. The types of SWMM 5 LID compartments are: storage, underdrain, surface, pavement and soil. a bio retention cell has storage, underdrain and surface compartments. an infiltration trench lid has storage, underdrain and surface compartments. A porous pavement LID has storage, underdrain and pavement compartments. A rain barrel has only storage and underdrain compartments and a vegatative swale LID has a single surface compartment. Each type of LID shares different underlying compartment objects in SWMM 5.
New as of July 2013, the EPA's National Stormwater Calculator is a Windows desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the United States. Estimates are based on local soil conditions, land cover, and historic rainfall records. The calculator accesses several national databases that provide soil, topography, rainfall, and evaporation information for the chosen site. The user supplies information about the site's land cover and selects the types of low impact development (LID) controls they would like to use on site. The LID Control features in SWMM 5.1.007 include the following among types of Green infrastructure:
StreetPlanter: Bio-retention Cells are depressions that contain vegetation grown in an engineered soil mixture placed above a gravel drainage bed. They provide storage, infiltration and evaporation of both direct rainfall and runoff captured from surrounding areas. Street planters consist of concrete boxes filled with an engineered soil that supports vegetative growth. Beneath the soil is a gravel bed that provides additional storage. The walls of a planter extend 3 to 12 inches above the soil bed to allow for ponding within the unit. The thickness of the soil growing medium ranges from 6 to 24 inches while gravel beds are 6 to 18 inches in depth. The planter's capture ratio is the ratio of its area to the impervious area whose runoff it captures.
Main Street Tree Planter, Miles City (281991376)
Main Street Tree Planter, Miles City (281991376)
Raingarden:Rain Gardens are a type of bio-retention cell consisting of just the engineered soil layer with no gravel bed below it.Rain Gardens are shallow depressions filled with an engineered soil mix that supports vegetative growth. They are usually used on individual home lots to capture roof runoff. Typical soil depths range from 6 to 18 inches. The capture ratio is the ratio of the rain garden's area to the impervious area that drains onto it.
Rain garden (2014)
Rain garden (2014)
GreenRoof: Green Roofs are another variation of a bio-retention cell that have a soil layer laying atop a special drainage mat material that conveys excess percolated rainfall off of the roof. Green Roofs (also known as Vegetated Roofs) are bio-retention systems placed on roof surfaces that capture and temporarily store rainwater in a soil growing medium. They consist of a layered system of roofing designed to support plant growth and retain water for plant uptake while preventing ponding on the roof surface. The thickness used for the growing medium typically ranges from 3 to 6 inches.
Intensive extensive green roofs
Intensive extensive green roofs
InfilTrench: infiltration trenches are narrow ditches filled with gravel that intercept runoff from upslope impervious areas. They provide storage volume and additional time for captured runoff to infiltrate the native soil below.
Infiltration trench (6438020585)
Infiltration trench (6438020585)
PermPave or Permeable Pavements Continuous Permeable Pavement systems are excavated areas filled with gravel and paved over with a porous concreteor asphalt mix. Continuous Permeable Pavement systems are excavated areas filled with gravel and paved over with a porous concrete or asphalt mix. Modular Block systems are similar except that permeable block pavers are used instead. Normally all rainfall will immediately pass through the pavement into the gravel storage layer below it where it can infiltrate at natural rates into the site's native soil. Pavement layers are usually 4 to 6 inches in height while the gravel storage layer is typically 6 to 18 inches high. The Capture Ratio is the percent of the treated area (street or parking lot) that is replaced with permeable pavement.
Cistern: Rain Barrels (or Cisterns) are containers that collect roof runoff during storm events and can either release or re-use the rainwater during dry periods. Rain harvesting systems collect runoff from rooftops and convey it to a cistern tank where it can be used for non-potable water uses and on-site infiltration. The harvesting system is assumed to consist of a given number of fixed-sized cisterns per 1000 square feet of rooftop area captured. The water from each cistern is withdrawn at a constant rate and is assumed to be consumed or infiltrated entirely on-site.
VegSwale: Vegetative swales are channels or depressed areas with sloping sides covered with grass and other vegetation. They slow down the conveyance of collected runoff and allow it more time to infiltrate the native soil beneath it. Infiltration basins are shallow depressions filled with grass or other natural vegetation that capture runoff from adjoining areas and allow it to infiltrate into the soil.
Wet ponds are frequently used for water quality improvement, groundwater recharge, flood protection, aesthetic improvement or any combination of these. Sometimes they act as a replacement for the natural absorption of a forest or other natural process that was lost when an area is developed. As such, these structures are designed to blend into neighborhoods and viewed as an amenity.
Dry ponds temporarily stores water after a storm, but eventually empties out at a controlled rate to a downstream water body.
Sand filters generally control runoff water quality, providing very limited flow rate control. A typical sand filter system consists of two or three chambers or basins. The first is the sedimentation chamber, which removes floatables and heavy sediments. The second is the filtration chamber, which removes additional pollutants by filtering the runoff through a sand bed. The third is the discharge chamber. Infiltration trench, is a type of best management practice (BMP) that is used to manage stormwater runoff, prevent flooding and downstream erosion, and improve water quality in an adjacent river, stream, lake or bay. It is a shallow excavated trench filled with gravel or crushed stone that is designed to infiltrate stormwater though permeable soils into the groundwater aquifer.
Vegatated filter strip is a type of buffer strip that is an area of vegetation, generally narrow and long, that slows the rate of runoff, allowing sediments, organic matter, and other pollutants that are being conveyed by the water to be removed by settling out. Filter strips reduce erosion and the accompanying stream pollution, and can be a best management practice.
Other LID like concepts around the world include sustainable drainage system (SUDS). The idea behind SUDS is to try to replicate natural systems that use cost effective solutions with low environmental impact to drain away dirty and surface water run-off through collection, storage, and cleaning before allowing it to be released slowly back into the environment, such as into water courses.
In addition the following features can also be simulated using the features of SWMM 5 (storage pondsseepageorifices,Weirs, seepage and evaporation from natural channels): constructed wetlandswet pondsdry pondsinfiltration basin,non-surface sand filtersvegetated filterstrips, vegetated filterstrip and infiltration basin. A WetPark would be a combination of wet and dry ponds and LID features. A WetPark is also considered a constructed wetland.

SWMM5 components

The SWMM 5.0.001 to 5.1.007 main components are: rain gages, watersheds, LID controls or BMP features such as Wet and Dry Ponds, nodes, links, pollutants, landuses, time patterns, curves, time series, controls, transects, aquifers, unit hydrographs, snowmelt and shapes (Table 3). Other related objects are the types of Nodes and the Link Shapes. The purpose of the objects is to simulate the major components of the hydrologic cycle, the hydraulic components of the drainage, sewer or stormwater network and the buildup/washoff functions that allow the simulation of water quality constituents. A watershed simulation starts with a precipitation time history. SWMM 5 has many types of open and closed pipes and channels: dummy, ciruclar, filled circular, rectangular closed, rectangular open, trapezoidal, triangular, parabolic, power funciton, rectangular triangle, rectangle round, modified baskethandle, horizontal ellipse, vertical ellipse, arch, eggshaped, horseshoe, gothic, catenary, semielliptical, baskethandle, semicircular, irregular, custom and force main.
The major objects or hydrology and hydraulic components in SWMM 5 are:
  1. GAGE rain gage
  2. SUBCATCH subcatchment
  3. NODE conveyance system node
  4. LINK conveyance system link
  5. POLLUT pollutant
  6. LANDUSE land use category
  7. TIMEPATTERN,dry weather flow time pattern
  8. CURVE generic table of values
  9. TSERIES generic time series of values
  10. CONTROL conveyance system control rules
  11. TRANSECT irregular channel cross-section
  12. AQUIFER groundwater aquifer
  13. UNITHYD RDII unit hydrograph
  14. SNOWMELT snowmelt parameter set
  15. SHAPE custom conduit shape
  16. LID LID treatment units
The major overall components are called in the SWMM 5 input file and C code of the simulation engine: gage, subcatch, node, link, pollut, landuse, timepattern, curve, tseries, control, transect, aquifer, unithyd, snowmelt, shape and lid. The subsets of possible nodes are: junction, outfall, storage and divider. Storage Nodes are either tabular with a depth/area table or a functional relationship between area and depth. Possible node inflows include: external_inflow, dry_weather_inflow, wet_weather_inflow, groundwater_inflow, rdii_inflow, flow_inflow, concen_inflow, and mass_inflow. The dry weather inflows can include the possible patterns: monthly_pattern, daily_pattern, hourly_pattern and weekend_pattern.
The SWMM 5 component structure allows the user to choose which major hydrology and hydraulic components are using during the simulation:
  1. Rainfall/runoff with infiltration options: horton, modified horton, green ampt and curve number
  2. RDII
  3. Water Quality
  4. Groundwater
  5. Snowmelt
  6. Flow Routing with Routing Options: Steady State, Kinematic Wave and Dynamic Wave

SWMM 3,4 to 5 converter

The SWMM 3 and SWMM 4 converter can convert up to two files from the earlier SWMM 3 and 4 versions at one time to SWMM 5. Typically you would convert a Runoff and Transport file to SWMM 5 or a Runoff and Extran File to SWMM 5. If you have a combination of a SWMM 4 Runoff, Transport and Extran network then you will have to convert it in pieces and copy and paste the two data sets together to make one SWMM 5 data set. The x,y coordinate file is only necessary if you do not have existing x, y coordinates on the D1 line of the SWMM 4 Extran input data[ set. You can use the command File=>Define Ini File to define the location of the ini file. The ini file will save your conversion project input data files and directories.
The SWMMM3 and SWMM 3.5 files are fixed format. The SWMM 4 files are free format. The converter will detect which version of SWMM is being used. The converted files can be combined using a text editor to merge the created inp files.== SWMM 5 Climate Change AddOn ==

SWMM-CAT Climate Change AddOn

The Storm Water Management Model Climate Adjustment Tool (SWMM-CAT) is a new addition to SWMM5 (December 2014). It is a simple to use software utility that allows future climate change projections to be incorporated into the Storm Water Management Model (SWMM). SWMM was recently updated to accept a set of monthly adjustment factors for each of these time series that could represent the impact of future changes in climatic conditions. SWMM-CAT provides a set of location-specific adjustments that derived from global climate change models run as part of the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project Phase 3 (CMIP3) archive (Figure 4). SWMM-CAT is a utility that adds location-specific climate change adjustments to a Storm Water Management Model (SWMM) project file. Adjustments can be applied on a monthly basis to air temperature, evaporation rates, and precipitation, as well as to the 24-hour design storm at different recurrence intervals. The source of these adjustments are global climate change models run as part of the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project Phase 3 (CMIP3) archive. Downscaled results from this archive were generated and converted into changes with respect to historical values by USEPA's CREAT project (
Table 3. SWMM5 Input File Data Section Names
Input SectionInput SectionInput SectionInput SectionInput Section
The following steps are used to select a set of adjustments to apply to SWMM5:
1) Enter the latitude and longitude coordinates of your location if available or its 5-digit zip code. SWMM-CAT will display a range of climate change outcomes for the CMIP3 results closest to your location.
2) Select whether to use climate change projections based on either a near term or far term projection period. The displayed climate change outcomes will be updated to reflect your choice.
3) Select a climate change outcome to save to SWMM. There are three choices that span the range of outcomes produced by the different global climate models used in the CMIP3 project. The Hot/Dry outcome represents a model whose average temperature change was on the high end and whose average rainfall change was on the lower end of all model projections. The Warm/Wet outcome represents a model whose average temperature change was on the lower end and whose average rainfall change was on the wetter end of the spectrum. The Median outcome is for a model whose temperature and rainfall changes were closest to the median of all models.
4) Click the Save Adjustments to SWMM link to bring up a dialog form that will allow you select an existing SWMM project file to save your adjustments to. The form will also allow you to select which type of adjustments (monthly temperature, evaporation, rainfall, or 24-hour design storm) to save. Conversion of temperature and evaporation units is automatically handled depending on the unit system (US or SI) detected in the SWMM file.
Figure 4. The EPA SWMM5 Climate Change Program
Figure 4. The EPA SWMM5 Climate Change Program

EPA stormwater calculator based on SWMM5

Other external programs that aid in the generation of data for the EPA SWMM 5 model include: SUSTAINBASINSSSOAP and the EPA’s National Stormwater Calculator (SWC) which is a desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the United States (including Puerto Rico). The estimates are based on local soil conditions, land cover, and historic rainfall records (Figure 5).
Figure 5. The EPA stormwater calculator for simulating long-term runoff with LID and climate change.
Figure 5. The EPA stormwater calculator for simulating long-term runoff with LID and climate change.

SWMM platforms

A number of software packages use the SWMM5 platform. These include:

See also


  1. ^ Metcalf and Eddy, Water Resources Engineers, and University of Florida 1971. Storm Water Management Model, US EPA, Washington, D.C. Vol. I - Final Report, 11024DOC 7/71. Vol. II - Verification and Testing, 11024DOC 8/71. Vol. III - User's Manual, 11024DOC 9/71. Vol. IV - Program Listing, 11024DOC 10/71.
  2. ^ Huber, W. C., J. P. Heaney, M. A. Medina, W. A. Peltz, H. Sheikh, and G. F. Smith. 1975. Storm Water Management Model User’s Manual, Version II. U.S. Environmental Protection Agency, Cincinnati, Ohio.
  3. ^ Huber, W. C., J. P. Heaney, S. J. Nix, R. E. Dickinson, and D. J. Polmann, 1981. Storm Water Management Model. User's Manual Ver. III, U.S. Environmental Protection Agency
  4. ^ Huber, W. C. and R. E. Dickinson, 1988, Storm Water Management Model. User's Manual Ver. IV, U.S. Environmental Protection Agency
  5. ^ Roesner, L.A., R.E. Dickinson and J.A. Aldrich (1988) Storm Water Management Model – Version 4: User’s Manual – Addendum 1 EXTRAN; Cooperative Agreement CR-811607; U.S.EPA; Athens, Georgia.
  6. ^ Rossman, Lewis A., Storm Water Management Model User’s Manual, EPA/600/R-05/040, U.S. Environmental Protection Agency, Cincinnati, OH (June 2007)
  7. ^ Rossman, Lewis A., Storm Water Management Model Quality Assurance Report, Dynamic Wave Flow Routing, EPA/600/R-06/097, September 2006

SWMM 5 Vendors

AI Rivers of Wisdom about ICM SWMM

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