SWMM5, InfoSWMM

Subject:   Dry Weather Flow in SWMM 5

Dry weather flow can be added to any node in SWMM 5.  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 the flow if the multipliers are less than one.  You should enter the  Pattern X for the Weekend Hourly Pattern in SWMM 5  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 SWMM 5

Figure 2.  The Four Types of Time Patterns in SWMM 5.0.022

Subject:   How to use the Report Feature of the HGL Plot in InfoSWMM

 The report feature of the HGL plot helps you understand in more detail the pump flows, forcemain flows and node heads.

 Step 1. Load the Domain in the HGL Plot using Report Manager

Step 2. Click on the Report Command to Show the HGL Data in Tabular Format

Step 3.  Format the Results Table from the HGL Plot to see the data better.

Step 4.  Now we have the heads, flows and velocities for the pumps, nodes and force main links in our Domain around the pump of interest at time steps of 2 seconds,  We can now see how the flows, heads and velocities change downstream from the pump.

Step 5.  Force Mains, Nodes and Pumps in our Table

Step 6.  The pump turns on and the flow moves downstream to the force mains – the heads in the nodes increase to balance the flow at each node.  As you can see there is a 1 to 2 GPM decrease due to attenuation as the flow from the pump moves into the force mains.

Step 7.  The pump turns off and flows downstream decrease.  You can get negative flow if the downstream head is higher than the upstream head of the link.

Step 8.  Use Advanced Labeling and the HGL Plot Stepping Interval to see all of the data in your Plot.

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.