How to Set Up Hot Start Files in InfoSWMM for a Fixed Boundary Outfall

Subject:  How to Set Up Hot Start Files in InfoSWMM for a Fixed Boundary Outfall

If you have a fixed boundary outfall condition in your model and want to prevent reverse flow when you run your simulation the best way is to use the Hot Start files to fill up the links and nodes at the start of the simulation.

1^st Step:  Turn off the DWF inflow so that ONLY the flow from outfall enters the network.  Use the Process Models in Run Manager to turn off and turn on the Dry Weather flow.

2nd Step:  Run the simulation first SAVING a Hot Start File using zero initial node depths and link flows.

3rd Step:  Save and Use Hot Start Files until the initial and final volume in your Network stays the same. 

4th Step:  Check the Initial and Final Stored Volume in the output text file

5th Step:  Check to see if you nodes are stable by using a Junction Group Graph

6th Step:  Now Run the Simulation with flows turned an and the network will start out with the Boundary Condition depths and stable flows

3 Types of Subcatchment Flow in SWMM 5

Subject:   3 Types of Subcatchment Flow in SWMM 5

There are three types of Subcatchment flow in SWMM 5

 1.   Impervious area with depression storage in which the runoff from the precipitation is delayed due to the depression storage.  Evaporation occurs based on the depth of water in the subarea of the Subcatchment.

2.   Impervious area without depression storage in which the runoff from precipitation is NOT delayed.  Evaporation does occur based on the depth of water in the subarea of the Subcatchment.
3.   Pervious area with depression storage in which the runoff from the precipitation is delayed due to the depression storage.  Evaporation and Infiltration occurs based on the depth of water in the subarea of theSubcatchment. 

How to Set a Flap Gate in InfoSWMM

Note:  How to Set a Flap Gate in InfoSWMM

You can set a flap gate in InfoSWMM either by using the attribute browser and changing the Flap Gate Installed to Yes or No or by using the DB Editor and changing the Flag for Flap Gate Installed to Yes by using the Block Edit tool.   The DB method is better for changing many conduits. 

SWMM 5 Arrow Direction Question

Subject:   SWMM 5 Arrow Direction Question

A question often asked is what happens to the flow in a SWMM 5 link if the downstream and upstream node names are entered in reverse.    The flow will be exactly the same as if the nodes were entered in the right order but the flow in the link will be negative.  As long as the inflow to the model is at the same node in both alternate models the node depth, the link upstream depths and upstream cross sectional areas will be the same.  For example, the flow out of Nodes 80408A and 80408 will be the same but the flow out of 80408 will be negative and the flow out of 80408A will be positive.

SWMM 5, H2OMap SWMM and InfoSWMM Time Step Guide

Subject:    SWMM 5, H2OMap SWMM and InfoSWMM Time Step Guide

If you use a variable time step in SWMM 5 or InfoSWMM/H2OMAP SWMM it is hard to gauge the proper value of the conduit lengthening.  You want to use a value that does not increase the volume of the network yet does increase the length of the shortest links so you can use a longer time step.  A good approximation to the time step that you want to use is shown in the image.  

The Time Step Guide in seconds is Link Length / [Velocity + sqrt(g*Maximum Depth)] with the assumption that the velocity at maximum depth is about the value of the wave celerity for closed links or sqrt(g*Maximum Depth).  Normally (unless pumps are involved) the average time step used during the simulation is a good gauge of the time to use for the simulation.  For example, in this model run the time step used is 13 seconds which is about the conduit lengthening time step of 20 seconds * adjustment factor of 0.75

Siphon Simulation in SWMM 5 and InfoSWMM

Subject:  Siphon Simulation in SWMM 5 and InfoSWMM

A Siphon is simulated in SWMM 5 and InfoSWMM using the basic node and link data and downstream boundary condition:

1.   Inflow can be time series, dry weather flow pattern, wet weather inflow or Subcatchment Runoff,
2.   The boundary condition can be either a free outfall, fixed or time series,
3.   The node invert, node maximum depth and node surcharge depth are defined by the user or network,
4.   The link lengths, diameters, link offset depths upstream and downstream are defined by the user of the network,
5.   The node depths, link flows, link depths and link cross sectional areas are calculated at each time based on the node continuity equation and the link momentum and continuity equation.  The link flows are a function of the friction loss, head difference across the link and the difference in the cross sectional areas of the link.
6.   In the particular model the Inflow at node MH1 fills up the MH1 depth which causes the links downstream to start flowing – the head difference across the links drives the flow up and over the siphon.

Aquifers in SWMM 5

Subject:   Aquifers in SWMM 5

Groundwater in SWMM 5 is modeled as two zones: (1) Saturated and (2) Unstaturated.  The data for the Groundwater Simulation consists of physical data in an Aquifer and elevation and flow coefficient and exponent data in the GroundwaterData.  The Aquifer data object can be applied to multiple Subcatchments but each Subcatchment has its own set of Groundwaterdata.  For example, in this model all of the Subcatchments share the same Aquifer data but each Subcatchment has different elevation and flow data – the labels on the basin are the groundwater elevations.

InfoSWMM and H2OMap SWMM Pump Summary Table

Subject:   InfoSWMM and H2OMap SWMM Pump Summary Table

The Pump Summary Table in Report Manager tells you how often the pumps turn on (Start-Up Count), the percent of the simulation time it was used (Percent Utilized) and the maximum, minimum and average flow for the pumps.

You can also see flows in the downstream links from the pumps in the force mains along with the pumps.

 

If you use the Mixed Graph Control you see the Pump flows and Link Flows on the same Graph

You can control the replay of the HGL Plot by altering the stepping time in Graph Settings

How to Use Domain Manager in InfoSWMM to Reduce the Output File Size

Subject:   How to Use Domain Manager in InfoSWMM to Reduce the Output File Size

If you want to save the output at a small report time step (2 seconds in this case) and you have a long simulation or large model then the reading of the graphicalo results may not be as speedy as you want.  You can save ONLY the DOMAIN to the output binary file however to make this smaller and faster to react.

Step 1.  Define your Reporting Time Step and Your Routing Time Step.  In this case we are routing at 1 second but saving the DOMAIN results every 2 seconds.

  

Step 2.  Clear your existing DOMAIN and Create a DOMAIN based on the area you are most interested in during the simulation.

Step 3.  Use the Advanced Tab in Run Manager and select Domain as the Output Scope – this will save only the Domain to the output binary file.

  

Step 4.  Run the simulation using Run Manager and then look at the output.  You are restricted to 8800 graph points but the number of points in the Report Table is unlimited.

Step 5. You can use the Data Plot Option (right mouse click) to see a subset of the larger than 8800 data points. 

 

InfoSWMM Report Manager and Field Statistics

Subject:  InfoSWMM Report Manager and Field Statistics

You can also use the mixed graph feature to plot the pump flow and the downstream flows on the same graph.  If you click on the Report command then you can also use aField Statistics command to see the Statistics for each Link and Pump.   The right mouse button for the Report also allows you to make a scatter plot and graph the flows in theforcemains versus the flows in the pumps.  

Dry Weather Flow in InfoSWMM and H2OMap SWMM

Dry Weather Flow in InfoSWMM and H2OMap SWMM

Dry weather flow can be added to any node in H2OMAP SWMM.  The dry weather flow is computed as the average flow * the monthly pattern * the daily pattern * hourly pattern * the weekend daily pattern to give the Dry Weather Flow at any time step (Figure 1).   Since the four types of patterns (Figure 2) are all multiplied together then for Saturday and Sunday the hourly pattern and the weekend hourly pattern will both be used.   This will have the effect of overestimating the flow if the multipliers are greater than 1 and underestimating theflow if the multipliers are less than one.  You should enter the  Pattern X for the Weekend Hourly Pattern in H2OMAP SWMM  where

X  = Weekend Hourly Pattern / Hourly Pattern

So that when the pattern X is multiplied by the Hourly Pattern the program will use the intended Weekend Pattern.

Figure 1.  How Dry Weather Flow is Computed in H2OMAP SWMM

Figure 2.  The Four Types of Time Patterns in H2OMAP SWMM, InfoSWMM and SWMM 5 

How to Make a Small Model out of a Large Model in H2OMAP Sewer and InfoSewer

Subject:  How to Make a Small Model out of a Large Model in H2OMAP Sewer

The process is easy if you use Domain and Facilities.  

Step 1.  Use the Trace Upstream Network Command in Utilities to find the upstream network from your node of interest.  The upstream network is saved to a Domain.

Step 2.  Use the Facility Manager to 1^st deactivate the whole network and then 2^nd to add the Domain to your Facility or the nodes and links that you will simulate

You now have a smaller network to examine in Detail.  You may have to make a temporary Outfall node to run the model if there are no Outfalls in the model.

SWMM 5 QA and Application Manuals on the EPA Web Site

Subject:   SWMM 5 QA and Application Manuals on the EPA Web Site

The EPA Web Site has three manuals that you can download at http://www.epa.gov/nrmrl/wswrd/wq/models/swmm/#Downloads

1.   SWMM Applications Manual
2.   SWMM 5 Quality Assurance Report
3.   SWMM 5 Users Manual

Infiltration Data in SWMM 5

Subject:  Infiltration Data in SWMM 5

If you are using Non linear Reservoir Modeling in SWMM 5 there are

1.   Five parameters for Horton Infiltration,
2.   Three parameters for Green-Ampt and
3.   Two parameters for CN infiltration, one parameter (conductivity) has been deprecated by the EPA in SWMM 5.   The Drying Time is used to regenerate the Infiltration Rate for continuous simulation.  Only two parameters are now used for CN infiltration:  The CN value itself and the drying time.

Aquifer and Groundwater Objects in SWMM 5

Subject:   Aquifer and Groundwater Objects in SWMM 5

There are two types of data objects in SWMM 5 to describe the Groundwater flow component.  There is a Groundwater data object associated with a Subcatchment that describes flow equations, the interaction between the Subcatchment infiltration and the Groundwater component and an Aquifer data object that describes the characteristics of the Aquifer that may span one or more Subcatchments.  The Groundwater data is specific to one Subcatchment but the Aquifer may

 

SWMM 5 Culvert Data from FHWA, HDS No. 5, Hydraulic Design of Highway Culverts, 1985

Subject:  SWMM 5 Culvert Data from FHWA, HDS No. 5, Hydraulic Design of Highway Culverts, 1985

If you use the culvert option in later versions of SWMM 5 then when the inlet control equation flow is less than the computed St Venant flow then the FHWA equations will be used for the current iteration in the SWMM 5 Dynamic Wave Solution.

Three Hidden Secrets to Speeding up your SWMM 5, H2OMAP SWMM or InfoSWMM Model

  

Minimum Time Step               Average Time Step        Maximum Time Step

Minimum Time Step (sec)             0.984

Average Time Step (sec)              9.071

Maximum Time Step (sec)            30.000

Percent in Steady State (%)          0.000

Average Iterations per Time Step  4.821

Use a maximum time that will lower your average iterations per time step to speed up the simulation,decrease the maximum time step to lower the number of iterations, use equivalent conduit lengthening to increase the minimum time step, the model is fastest if the minimum and maximum time steps are not too small or large compared to the average time step.  Adjust the stopping tolerance and the number of iterations if you can to speed up your model You can also decrease the number of iterations or the stopping tolerance to speed up the model or improve the continuity error of themodel.   If you are doing a continuous simulation then you can have a reduced graphical output data set to speedup the simulation

  

If you have a duo or quad core computer another option to speed up the simulations is to use 1, 2, 3 or 4 cores for the simulation 

Elevation Interpolation from a Contour in H2OMAP SWMM

Subject:  Elevation Interpolation from a Contour in H2OMAP SWMM

The node invert elevation or the node maximum depth can be interpolated if you use the Elevation Interpolation Tool inH2OMAP SWMM.

Steps	Action
1.   Make a Contour Plot of the Node Invert Elevations.
2.   The Created Contours are now a layer inH2OMAP SWMM.
3.   Recreate the Invert Elevation from the Contourby using the Value Field and Interpolate Field.
4.   You can  also estimate the Maximum Depth of the Node from the Contour and the known Node Invert Elevation.

How to see what you have in the various scenarios of InfoSWMM

Subject:  How to see what you have in the various scenarios of InfoSWMM

How to see what you have in the various scenarios – a tool I use a lot is Scenario Explorer which shows you how to see thevarious datasets associated with a data set along with the relationship between the Base and Various Child Scenarios.

 

SWMM 5 Inlet Control Culvert Equations

Subject:   SWMM 5 Inlet Control Culvert Equations

The newer option for SWMM 5 culverts uses three culvert classifications and associated equations to compute the inletcontrolled flow into a culvert using the FHWA (1985) equations.  The culvert code in the culvert.c code of SWMM 5 uses:

1.   Two Equations for Unsubmerged culvert flow,
2.   One Equation for the Transition flow, and
3.   One Equation for Submerged flow.

How Does the Green Ampt Initial Moisture Defiict Work in InfoSWMM and SWMM 5?

Subject:   How Does the Green Ampt Initial Moisture Defiict Work in InfoSWMM and SWMM 5?

This graph shows the values of the internal SWMM 5 parameters for Green Ampt Infiltration for the pervious area of a Subcatchment during a simulation.  The parameters are:

·         Soil Moisture = IMD Max – (FUMax – FU)/Upper Soil Zone Depth
·         FU or current moisture content of the upper zone of the of the soil
·         FUMax which is the saturated moisture content of the upper zone in feet and stays constant during the simulation
·         IMD Max is the user defined Initial soil moisture deficit and is a fraction

Figure 1.  How Soil Moisture changes over time.

Figure 2.  Soil Moisture and IMD are related – the Soil Moisture has a maximum of IMDMax.