Finding total demanded volume for a scenario in WaterCAD and WaterGEMS

  Applies To 
  Product(s): WaterGEMS, WaterCAD
  Version(s): CONNECT Edition, V8i
  Area:  Output and Reporting
  Original Author: Scott Kampa, Bentley Technical Support Group


How can a user find the total volume demanded in a system?

Steps to Accomplish

Option 1 - Totalizing Flow Meter

For a simple system with a single source, right click on the pipe next to that single source reservoir, choose Totalizing Flow meter, and note the total volume figure.

Option 2 - Using Criticality

First, you can use the Criticality tool. There is a TechNote on Criticality here. This is used to find areas that may be impacted by system outages, but does report the total volume demanded. Go to Analysis > Criticality. Select the New button in the upper left and choose the scenario you want the total volume demanded for. Next, highlight the scenario name on the left. For Scope Type, select "Entire Network" and click the Compute button.

Now, highlight Outage Segments on the left and click the Compute button. Once that is completed, highlight Criticality on the left.

Be sure to put a checkmark in the "Run Hydraulic Engine" select at the top. With that done, click Compute. The fields will fill in, inlcuding Total System Demanded.

Option 3 - Using Pressure Zone manager

Second, you can use the Flow Balance Tool in the Pressure Zone manager. Go to Analysis > Pressure Zones. Click the New button and select the scenario you want data for. Highlight the scenario name and make sure Scope Type is set to "Entire Network". Then click the Compute button. Now click the Flow Balance icon.

Choose Volume from the options. The total volume demanded for each pressure zone will be listed. The sum will be the total volume demanded

Option 4 - Using Calculation Summary

You can use the data in the Calculation Summary to find the total volume. The calculation Summary has the total flow demand at each time step. The key to this is to make sure that the flow units coincide with the output units. For instance, you would need a demand reported every minute if you use GPM, or every hour for liters/hour.

Once you have the data in the calculation summary, you can generate a report of the Calculation Summary and export the file to Excel. Or, check the total demand at the top, which shows an average of all the time steps. So, in this case if you want to see a volume, ensure that the time step increments are even. Meaning, if the calculation time step is 1.0 hours, ensure that there are no intermediate time steps, or the averaging won't provide a volume. Intermediate time steps can occur when a tank is full/empty or controls need to trigger. In the calculation options, you can choose "Constant" as the "Reporting time step" and set the value equal to the calculation time step. This will ensure that the calculation summary only reports the total demand at each even calculation time step, which also means that the total demand (average) shown at the top could be used to get a volume figure.

Note that you can click the copy button and paste into Excel. Remember that units are very important for this method. It will not work if you have flow units of GPM and an increment of hours.

See Also

Positive volume vs negative volume in Totalizing Flow Meter

Finding total volume of water in SewerCAD and SewerGEMS

  • Created by Bentley Colleague
  • When: Wed, Aug 21 2013 3:48 PM
  • Last revision by Bentley Colleague
  • When: Mon, Jul 23 2018 4:17 PM
  • Revisions: 8
  • Comments: 0