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The software will not tell you what valves to close to create a DMA, or where to install the meter. Using the Pressure Zone Manager, you can try different ways to isolate DMA's.
You would select the valve locations and the software will display the color coded DMA's, and provide statistics such as demand, minimum and maximum HGL, minimum and maximum ground elevation, minimum and maximum pressure, and the labels for the boundary elements, pipes, and nodes in the DMA. Go here for an example.
There is a support solution on the Pressure Zone Manager which includes a section on identifying DMA's.
For the flow data, there are a few different ways to enter it, depending on your needs.
a. You can take the flow that was measured at the entrance of the DMA and divide it by the number of nodes in the DMA. This is assuming you do not already have demands in the model. Open the Demand Control Center under Tools. Click the New button and choose to Initialize Demands for all Elements. Right-click the base demand column header, select Global Edit and enter the flow value result from dividing the measure flow by the number of nodes.
b. To distribute demands proportionally to their service areas, the LoadBuilder tool can be used.
1) You would need to create a single polygon shapefile covering the entire DMA with a flow attribute containing the flow measured at the DMA entrance.
2) Establish the service area polygons representing each node. The easiest way to do this is to use the Thiessen Polygon tool under the Tools menu.
3) Open LoadBuilder (Tools > LoadBuilder)
4) Click the New button and select Proportional Distribution by Area under Area Load Data
5) Select your service area (Thiessen Polygon) and select the single polygon shapefile as the Flow Boundary Layer
6) For the "Flow Field", select the attribute containing the DMA entrance measured flow.
7) LoadBuilder will then distribute that flow among all the nodes, proportional to their service area.
3. If you have field data measurements from within the DMA and want to distribute the demands more accurately, you could use Darwin Calibrator.
a. You would first need to follow the steps in #2.
b. Then go to Analysis > Darwin Calibrator
c. Enter all your field measurements.
d. Enter demand adjustment groups. Darwin Calibrator will use a genetic algorithm to attempt to adjust the demands such that the results match your observed values (pressure, flow, etc.). Some demands may be reduced while others may be increased.
If you already have built-out DMAs in your model but have a need to simplify them down to a single junction (representing the demand/inflow to that DMA), here are some options:
1) Use Skelebrator (available in WaterGEMS) on each particular DMA to simplify down to a single junction (which may take several passes) which will automatically combine the base demands.
2) Look at the flow in the entrance to the DMA, delete everything in the DMA downstream of it (using the downstream trace query if needed) and then assign that flow to a junction at the entrance location. Alternatively you could make the DMA inactive instead of deleting them, if you need to preserve the "full" version in another scenario.
Special Interest Group recording - "Creating District Metered Area for Water Auditing and Non-Revenue Water Control"