Stormwater Management Model (SWMM) Information for watershed water quality, hydrology and hydraulics modelers (Note this Blog is not associated with the EPA). You will find Blog Posts and Twitter Embeds on the Subjects of SWMM5, InfoSWMM, InfoSewer, ICM SWMM Networks, SWMM4 and SWMM in general.
Wednesday, June 29, 2011
Thursday, June 23, 2011
SWMM 5 Clocktime RTC Rules for Pumps, Weirs and Orifices
Subject: SWMM 5 Clocktime RTC Rules for Pumps, Weirs and Orifices
You can use the Control or RTC rules in SWMM 5 to adjust the settings of the weirs, pumps and orifices based on the clock time each day of your simulation. Here is an example that will adjust orifice height every ½ hour for 7 orifices at one time using two sets of rules.
RULE R1a
; Half hour setting
IF SIMULATION CLOCKTIME = 0:30:00
OR SIMULATION CLOCKTIME = 1:30:00
OR SIMULATION CLOCKTIME = 2:30:00
OR SIMULATION CLOCKTIME = 3:30:00
OR SIMULATION CLOCKTIME = 4:30:00
OR SIMULATION CLOCKTIME = 5:30:00
OR SIMULATION CLOCKTIME = 6:30:00
OR SIMULATION CLOCKTIME = 7:30:00
OR SIMULATION CLOCKTIME = 8:30:00
OR SIMULATION CLOCKTIME = 9:30:00
OR SIMULATION CLOCKTIME = 10:30:00
OR SIMULATION CLOCKTIME = 11:30:00
OR SIMULATION CLOCKTIME = 12:30:00
OR SIMULATION CLOCKTIME = 13:30:00
OR SIMULATION CLOCKTIME = 14:30:00
OR SIMULATION CLOCKTIME = 15:30:00
OR SIMULATION CLOCKTIME = 16:30:00
OR SIMULATION CLOCKTIME = 17:30:00
OR SIMULATION CLOCKTIME = 18:30:00
OR SIMULATION CLOCKTIME = 19:30:00
OR SIMULATION CLOCKTIME = 20:30:00
OR SIMULATION CLOCKTIME = 21:30:00
OR SIMULATION CLOCKTIME = 22:30:00
OR SIMULATION CLOCKTIME = 23:30:00
THEN ORIFICE R1 SETTING = 0.90
AND ORIFICE R2 SETTING = 0.90
AND ORIFICE R3 SETTING = 0.90
AND ORIFICE R4 SETTING = 0.90
AND ORIFICE R5 SETTING = 0.90
AND ORIFICE R6 SETTING = 0.90
AND ORIFICE R7 SETTING = 0.90
RULE R1b
; hour setting
IF SIMULATION CLOCKTIME = 0:00:00
OR SIMULATION CLOCKTIME = 1:00:00
OR SIMULATION CLOCKTIME = 2:00:00
OR SIMULATION CLOCKTIME = 3:00:00
OR SIMULATION CLOCKTIME = 4:00:00
OR SIMULATION CLOCKTIME = 5:00:00
OR SIMULATION CLOCKTIME = 6:00:00
OR SIMULATION CLOCKTIME = 7:00:00
OR SIMULATION CLOCKTIME = 8:00:00
OR SIMULATION CLOCKTIME = 9:00:00
OR SIMULATION CLOCKTIME = 10:00:00
OR SIMULATION CLOCKTIME = 11:00:00
OR SIMULATION CLOCKTIME = 12:00:00
OR SIMULATION CLOCKTIME = 13:00:00
OR SIMULATION CLOCKTIME = 14:00:00
OR SIMULATION CLOCKTIME = 15:00:00
OR SIMULATION CLOCKTIME = 16:00:00
OR SIMULATION CLOCKTIME = 17:00:00
OR SIMULATION CLOCKTIME = 18:00:00
OR SIMULATION CLOCKTIME = 19:00:00
OR SIMULATION CLOCKTIME = 20:00:00
OR SIMULATION CLOCKTIME = 21:00:00
OR SIMULATION CLOCKTIME = 22:00:00
OR SIMULATION CLOCKTIME = 23:00:00
THEN ORIFICE R1 SETTING = 0.5
AND ORIFICE R2 SETTING = 0.5
AND ORIFICE R3 SETTING = 0.5
AND ORIFICE R4 SETTING = 0.5
AND ORIFICE R5 SETTING = 0.5
AND ORIFICE R6 SETTING = 0.5
AND ORIFICE R7 SETTING = 0.5
Monday, June 20, 2011
Hot Start Files are used to define the initial heads and flows in SWMM5
Subject: Hot Start Files are used to define the initial heads and flows in the nodes and links of the model.
The creation of the Hot Start File for your sanitary, combined or stormwater network is a three step process:
1. Save the 1^{st} Hot Start file using an empty system as the initial conditions,
2. Use the 1^{st} Hot Start file as the initial condition in the second run and Save the 2^{nd} Hot Start File
3. In the 3^{rd} Run Use the 2^{nd} Hot Start file as the initial conditions of your network.
4. It is not necessary that the Hot Start Files be exact in the initial depths or flows but only approximate so that the network in not empty.
Sunday, June 19, 2011
InfoSewer and InfoSWMM Nodes
Subject: InfoSewer and InfoSWMM Nodes
InfoSewer and InfoSWMM are link/node networks but the nodes are of different types in both models. InfoSewer has a distinction between loading manholes or junctions and chamber junctions that start or separate Force Main links. InfoSewer nodes are types 1 through 4 and InfoSWMM nodes are types 5 through 8 in this image.
InfoSWMM has more generic node types than in InfoSewer so a junction can be both a Loading and Chamber Manhole if you are more familar to the InfoSewer names.
InfoSWMM 2D Layer Properties and Mesh Results
Subject: InfoSWMM 2D Layer Properties and Mesh ID
You can use the Layer Properties for layers in the Table of Contents to see the Mesh ID and other simulation data for the 2D mesh in InfoSWMM 2D. The Mesh ID can be seen using the Labels/Label Expression command and if you use an expression you can see the results data as well on the mesh. The Mesh ID is used as the label as well in the 2D Output modeling report. The Net Inflow and Net Outflow is by Mesh ID. In this example, the flow comes out of Node 80408 to Mesh ID 131 and enters the 1D network again at Mesh ID 848.
InfoSWMM 2D Layer Properties and Mesh ID
Subject: InfoSWMM 2D Layer Properties and Mesh ID
Subject: InfoSWMM 2D Layer P
You can use the Layer Properties for layers in the Table of Contents to see the Mesh ID and other simulation data for the 2D mesh in InfoSWMM 2D.

Steady State Flow Analysis in InfoSWMM using a Ramp DWF  Method 2
Subject: Steady State Flow Analysis in InfoSWMM using an External Flow Time Series
Subject: Steady State Flow An
This can be easily created using a few steps in InfoSWMM. The flow ramp is in the Routing Interface File. The advantage is that you are able to have different ramps for the various nodes using this method.
Step 1: In Run Manager Set up the Process Models Options to use just the External Inflow and NOT the Dry Weather Flow
Step 2. Create the External Inflows File (see the help file for the format)
SWMM5 Interface File
300  reporting time step in sec
1  number of constituents as listed below:
FLOW CFS
2  number of nodes as listed below:
36
24
Node Year Mon Day Hr Min Sec FLOW
36 2002 01 01 00 00 00 0.000000
24 2002 01 01 00 00 00 0.000000
36 2002 01 01 01 00 00 1000.
24 2002 01 01 01 00 00 1000.
36 2002 01 02 01 00 00 1000.
24 2002 01 02 01 00 00 1000.
This file loads two manholes with a ramped inflow up to 1000 cfs to again drown out the wet wells and cause the pumps to have a steady flow.
Step 3. Use the Tab File command and use the created External Inflows File
Step 4. Run the simulation and see if the pump flows are constant.

Steady State Flow Analysis in InfoSWMM using a Ramp DWF  Method 1
Subject: Steady State Flow Analysis in InfoSWMM using a Ramp DWF
Subject: Steady State Flow An
This can be easily created using a few steps in InfoSWMM.
Step 1: Using Scenario Explorer make a cloned Child Scenario and a cloned DWF Set which will be later modified.
Step 2: Using DB Manager and the BlockEdit tool and increase the mean DWF by a factor of 10, 100 or 1000 to drown out all Wet Wells and cause the pumps to turn on and stay turned on during the simulation in the newly created DWF Set.
Step 3. Run the batch manager and create two output files – Normal and Steady State for comparison.
Step 4. You can now compare the two scenario's using Output Manager and the Compare Graph tool. The Ramped Model should have constant flows in both links and pumps. It was not necessary to change any of the patterns.
Step 5. The model is still in balance – the excess DWF Inflow ends up as flooded flow and is listed as Internal Outflow.

SWMM 5 Fixed Surface Water Depth Boundary Condition
Subject: SWMM 5 Fixed Surface Water Depth Boundary Condition
A large difference between SWMM 5 and SWMM 4 is how the Groundwater Aquifer interacts with the drainage network. In SWMM 4 since the hydrology was simulated in the Runoff Block, the results saved to an interface file and the hydraulics were simulated in the Extran Block it was not possible to have a time step to time step interaction between the Aquifer and the Open Channels. SWMM 5 has integrated hydrology and hydraulics so it is possible to use either a Fixed Surface Water Depth for each Subcatchment or the Receiving Nodes Node Depth Invert Elevation – the Aquifer Bottom Elevation. The groundwater thus flows either to a fixed boundary condition as in SWMM 4 or to a time varying boundary condition.
SWMM 5 Threshold Groundwater Elevation
Subject: SWMM 5 Threshold Groundwater Elevation
A large difference between SWMM 5 and SWMM 4 is how the Groundwater Aquifer interacts with the drainage network. In SWMM 4 since the hydrology was simulated in the Runoff Block, the results saved to an interface file and the hydraulics were simulated in the Extran Block it was not possible to have a time step to time step interaction between the Aquifer and the Open Channels. SWMM 5 has integrated hydrology and hydraulics so it is possible to use either a fixed Threshold Groundwater Elevation for each Subcatchment or the Receiving Nodes Invert Elevation.
Aquifers in SWMM 5
Subject: Aquifers in SWMM 5
Subject: Aquifers in SWMM 5
Groundwater in SWMM 5 is model

Saturday, June 18, 2011
3 Types of Manholes in SWMM 5 and InfoSWMM
Subject: 3 Types of Manholes in SWMM 5 and InfoSWMM
There are three types of interior manholes in SWMM 5 and InfoSWMM as regards water surface elevations above the Node Rim Elevation:
1^{st} Excess Water leaves the Node as flooded water if the water surface elevation equals the Rim Elevation (Figure 1 and Gravity Mains),
2^{nd} Excess Water is stored in the manhole as pressurized depth if the Node Surcharge Depth is used (Figure 2 and Force Mains)
3^{rd} Excess Water is stored above the Node Rim Elevation (Surface Ponding and Figure 3)
Figure 1. The default node in SWMM 5 and InfoSWMM has just the Manhole Invert Elevation, the program calculated elevation of the highest connected link and the Node Maximum Depth or Rim Elevation. If the Water Surface Elevation exceeds the Rim Elevation then any excess flow is lost as flooded flow.
Figure 2. A force main or pressure in SWMM 5 and InfoSWMM has the Manhole Invert Elevation, the program calculated elevation of the highest connected link, the Node Maximum Depth or Rim Elevation and the Node Surcharge Depth. If the Water Surface Elevation exceeds the Surcharge Elevation then any excess flow is lost as flooded flow but this allows more the links to have more pressure and hence more flow.
Figure 3. The flooded Node option in SWMM 5 and InfoSWMM has just the Manhole Invert Elevation, the program calculated elevation of the highest connected link, the Node Maximum Depth or Rim Elevation and Node Ponding. If the Water Surface Elevation exceeds the Rim Elevation then any excess flow is NOT lost but stored in the ponded area. The depth of the ponded area is a function of the ponding area and the excess inflow. If the water surface elevation goes below the Rim Elevation then the ponded volume flows back into the network.
InfoSWMM and Arc GIS Layer Properties for Force Mains and Gravity Mains
Subject: InfoSWMM and Arc GIS Layer Properties for Force Mains and Gravity Mains
An important advantage of using InfoSWMM is the ability to use all of the Arc GIS layer and programming tools. For example, you can use the layer properties in the Table of Contents to color and create symbols for the force mains and gravity mains in InfoSWMM. The Force Main variable (which is a Yes/No parameter) is selected as the field value in the Symbology Tab of Layer Properties which allows you to color and size the link based on the Force Main property of is you do a Layer Join the link property and simulation results.
Friday, June 17, 2011
InfoSWMM Note About Pump Wet Wells
Subject: Wet Well Maximum depths and Pump Start and Pump Off Depths
The Wet Well has
· An invert elevation and
· A Maximum Depth
The Pumps have
· Pump On Depth
· Pump Off Depth
· Pump Head – Discharge Curve or
· RTC Rules
The Links have a
· Invert Elevation into the Wet Well and
· Invert Elevation into the Downstream Force Main
· Crown Elevation
Sunday, June 12, 2011
Detention Pond Infiltration and Evaporation Losses
Subject: Detention Pond Infiltration and Evaporation Losses
You can also add a storage pond infiltration and surface evaporation losses to the pond. The surface evaporation is added to the infiltration (computed from the green ampt parameters); a storage volume summary listing the average and maximum volume and the percent loss from the combined infiltration and evaporation from the ponds. The pond infiltration loss during a time step is basd on the areal weighed average depth, the Green Ampt infiltration and the Area of the pond.
infiltration_detetention_pond.inp Download this file
You can also add a storage pond infiltration and surface evaporation losses to the pond. The surface evaporation is added to the infiltration (computed from the green ampt parameters); a storage volume summary listing the average and maximum volume and the percent loss from the combined infiltration and evaporation from the ponds. The pond infiltration loss during a time step is basd on the areal weighed average depth, the Green Ampt infiltration and the Area of the pond.
infiltration_detetention_pond.inp Download this file
Subject: Detention Pond Infil
You can also add a storage pond infiltration and surface evaporation losses to the pond. The surface evaporation is added to theinfiltration (computed from the green ampt parameters); a storage volume summary listing the average and maximum volume and the percent loss from the combined infiltration and evap

Detention Basin Basics in SWMM 5
Subject: Detention Basin Basics in SWMM 5
What are the basic elements of a detention pond in SWMM 5? They are common in our backyards and cities and just require a few basic elements to model. Here is a model in SWMM 5.0.022 that even has a fountain in the real pond – which we not model for now. The components of the model are:
1. An inlet to the pond with a simple time series – a subcatchment can be added to it in a more complicated model but for now we will just have a triangular time series,
2. A pipe to simulate the flow into the pond from the inlet,
3. A Storage Node to simulate the Pond that consists of a tabular area curve to estimate the depth and area relationship,
4. A Storage Node to simulate the Outlet Box of the Pond
5. Two Small Rectangular Orifices to simulate the low flow outflow from the pond at an elevation less than the weir
6. A large rectangular orifice to simulate the normal inflow to the Box
7. A rectangular weir to simulate the flow into the box when the pond water surface elevation is above the box
8. The outlet of the Box is a circular link with a Free outfall as the downstream boundary condition
9. The flow graph in the image shows the flow into the box starts from the two small orifices, next from the large orifice and finally from the top of the box or the weir.
What are the basic elements of a detention pond in SWMM 5? They are common in our backyards and cities and just require a few basic elements to model. Here is a model in SWMM 5.0.022 that even has a fountain in the real pond – which we not model for now. The components of the model are:
1. An inlet to the pond with a simple time series – a subcatchment can be added to it in a more complicated model but for now we will just have a triangular time series,
2. A pipe to simulate the flow into the pond from the inlet,
3. A Storage Node to simulate the Pond that consists of a tabular area curve to estimate the depth and area relationship,
4. A Storage Node to simulate the Outlet Box of the Pond
5. Two Small Rectangular Orifices to simulate the low flow outflow from the pond at an elevation less than the weir
6. A large rectangular orifice to simulate the normal inflow to the Box
7. A rectangular weir to simulate the flow into the box when the pond water surface elevation is above the box
8. The outlet of the Box is a circular link with a Free outfall as the downstream boundary condition
9. The flow graph in the image shows the flow into the box starts from the two small orifices, next from the large orifice and finally from the top of the box or the weir.
Friday, June 10, 2011
InfoSewer Link and Head Calculations for Steady Flow
Note: Steady State InfoSewer solution solves for the link flow and node heads
Here is an example of how the Steady State InfoSewer solution solves for the link flow and node heads or depths:
Here is one example of this sequence of events: The downstream head at the outfall causes a backwater condition in all of the links. The d/D and q/Q is based on the manhole loading flow in the 1st pass and indicates the pipe is NOT full. However, in the 2nd Pass where the manhole depths are calculated from downstream to upstream the effect of the downstream boundary condition is felt. The head shows that there is a full downstream boundary condition which is reflected in the condition of backwater and in the adjusted depth value. The links are now full and the full depth is reflected in the value of the adjusted depth and the graphical presentation.
How to interpret this result:
1. Based on the manhole loading to the network the pipes are NOT full which is indicated by the value of d/D and q/Q, however
2. Based on the head calculations which account for downstream boundary conditions the pipes are full due to the backwater effect. The backwater condition is reflected in the value of the adjusted depth – the adjusted depth shows the pipe to be full.
Figure 1. Backwater is caused by the downstream boundary condition and shows full pipes but d/D is less than 1 based on the 1^{st} Pass Link Flow Values.
Figure 2. InfoSewer solves for the flows in the links in the 1^{st} pass and the heads at the nodes in the 2^{nd} pass for the Steady State solution.
Figure 3. Pipe Summary Table Shows the Pipe Adjustments based on 2^{nd} Pass Head calculations and the d/D and q/Q values from the 1^{st} Pass Link Flow Calculations.
Figure 4: Two Pass Solution for InfoSewer (1) Flow and (2) Head
Here is an example of how the Steady State InfoSewer solution solves for the link flow and node heads or depths:
• 1^{ST} Flow is computed in each link and d and d/D is calculated based on pipe flow and manhole loading data and not the adjusted data from the 2^{nd} pass.
• 2^{nd} InfoSewer adjusts the link depth based on the manhole head and lists the adjusted depth in the browser and the Report Table after the manhole depths are calculated from downstream to upstream in the network.
• Result: The HGL graph shows the link d and d/D based on pipe flow not the adjusted depth so you are looking at the results of the 1^{st} pass in the links and the 2^{nd} Pass in the Nodes in a HGL Plot for a Steady State Simulation.
How to interpret this result:
1. Based on the manhole loading to the network the pipes are NOT full which is indicated by the value of d/D and q/Q, however
2. Based on the head calculations which account for downstream boundary conditions the pipes are full due to the backwater effect. The backwater condition is reflected in the value of the adjusted depth – the adjusted depth shows the pipe to be full.
Figure 1. Backwater is caused by the downstream boundary condition and shows full pipes but d/D is less than 1 based on the 1^{st} Pass Link Flow Values.
Figure 2. InfoSewer solves for the flows in the links in the 1^{st} pass and the heads at the nodes in the 2^{nd} pass for the Steady State solution.
Figure 3. Pipe Summary Table Shows the Pipe Adjustments based on 2^{nd} Pass Head calculations and the d/D and q/Q values from the 1^{st} Pass Link Flow Calculations.
Figure 4: Two Pass Solution for InfoSewer (1) Flow and (2) Head
Note: State InfoSewer solution solves for the link flow and node heads
Here is an example of how the Steady State InfoSewer
• 1^{ST} Flow is computed in each link and d and d/D is calculated based on pipe flow and manhole loading data and not the adjusted data from the 2^{nd} pass.
• 2^{nd} InfoSewer
• Result: The HGL graph shows the link d and d/D based on pipe flow not the adjusted depth so you are looking at the results of the 1^{st} pass in the links and the 2^{nd} Pass in the Nodes in a HGL Plot for a Steady State Simulation.
Here is one example of this sequence of events: The downstream head at the outfall causes a backwater condition in all of the links. The d/D and q/Q is based on the manhole loading flow in the 1st pass and indicates the pipe is NOT full. However, in the 2nd Pass where the manhole depths are calculated from downstream to upstream the effect of the downstream boundary condition is felt. The head shows that there is a full downstream boundary condition which is reflected in the condition of backwater and in the adjusted depth value. The links are now full and the full depth is reflected in the value of the adjusted depth and the graphical presentation.
How to interpret this result:
1. Based on the manhole loading to the network the pipes are NOT full which is indicated by the value of d/D and q/Q, however
2. Based on the head calculations which account for downstream boundary conditions the pipes are full due to the backwater effect. The backwater condition is reflected in the value of the adjusted depth – the adjusted depth shows the pipe to be full.
Figure 1. Backwater is caused by the downstream boundary condition and shows full pipes but d/D is less than 1 based on the 1^{st} Pass Link Flow Values.
Figure 2. InfoSewer solves for the flows in the links in the 1^{st} pass and the heads at the nodes in the 2^{nd} pass for the Steady State solution.
Figure 3. Pipe Summary Table Shows the Pipe Adjustments based on 2^{nd} Pass Head calculations and the d/D and q/Q values from the 1^{st} Pass Link Flow Calculation
Figure 4: Two Pass Solution for InfoSewer (1) Flow and (2) Head

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