This article explains how to use the District Metered Areas tool in WaterGEMS and WaterCAD, to quickly generate District Metered Areas (DMA’s) in your model.
A video demonstration is embedded further below.
Note: This tool is available starting with version 10.02.01.06. If you have an older version, please see the below section titled "Other Methods for DMA generation".
District Metered Areas or DMA’s are areas in a water distribution network which are isolated from the whole of the system. This way the flows in and out of the DMA can be metered or quantified. DMA’s provide a more accurate way of tracking water user and loss in the system. DMA’s are created in such a way that they can be isolated from the system without adversely affecting the demands, pressures and supply for the rest of the system.
Some key points to consider while establishing a DMA;
The DMA tool in WaterGEMS and WaterCAD can help the user easily demarcate a DMA based on the user’s defined criteria. DMA creation is an iterative process and this tool allows merging adjacent DMA’s and controlling the user defined criteria for DMA creation.
Before the model is delineated into different DMA’s the following points should be considered;
A typical workflow to begin DMA delineation would be as follows;
The District Metered Areas tool can be found under Analysis > Analysis Tools > More > District Metered Areas.
The DMA tool uses an algorithm which will create DMA’s based on the boundaries specified. It is based on clustering principles where nodes within a DMA are highly connected with each other but only loosely connected with the rest of the system. Once you specify boundary or transmission, you are overriding that calculation.
At the start of a DMA run, every node is a potential DMA and all pipes are potential links between DMAs. If the DMA Status is not set to Boundary, the algorithm checks all links and finds the total number of links connected to the two end nodes of a link. The link with the minimum number of links connected to the link end nodes will be the candidate to be merged and the two DMAs are merged to one DMA. If two links have the same minimum number of links connected to link end nodes, the one that was checked first will be the candidate to be merged.
Also, changing a pipe from Active to Inactive will change the order of pipes with smaller number of links connected to pipe end nodes. Therefore, the order of links to be merged will be different and DMA results can be different.
There are three types of elements which can serve as boundaries because they can be either closed or opened. These are;
Each of the above elements has an initial setting as “Boundary Candidate” under the property “DMA Status”. The pipes however, have four different properties;
For pumps and valves there are only two states; “boundary candidate” and “boundary”;
Once the District Metered Areas tool is selected the following dialog box opens up;
There are several toolbar commands at the top. Before the DMA algorithm is used for DMA demarcation, there are a few options you must consider before modeling. In the “Assign DMA Status” command, there is an option for “Initialize DMA Boundary Status”. This option allows you to set your parameters for DMA creation. If you only want a particular element(s) to serve as boundaries you can define it so in this option; you can specify the same as an initial criterion for DMA demarcation. Basically, this option allows you to “globally edit” and assign the desired DMA status for an element. This is especially useful in cases where you know that a particular element type is supposed to be a “boundary” or a “boundary candidate”.
With this initialization you can define default “DMA status” for the above elements based on your DMA generation requirements. In the snapshot above, pumps and pump batteries are considered as “Boundary” which means that these represent fixed DMA boundaries. Hence for the above case pumps or pump stations will act as DMA boundaries. However, this depends on your interpretation of a DMA. For a very large network some intermediate / intermittent / smaller pumps may be ignored if you are considering large metered areas and small fluctuations with such pumps are within allowable tolerances. This can be true also for cases where a large number of DMA’s are generated causing you to merge a bunch of them.
As another example, if you know that all PRV’s will be DMA boundaries, then you can tell the DMA tool to always have them as DMA boundaries during the DMA analysis (separating your DMAs), by choosing “boundary” in the field next to “PRV’s” in this tool. This will globally change the DMA Status of PRVs to “boundary”. If you are not yet sure which PRVs should be DMA boundaries, you can let the tool decide (based on other criteria) by choosing “boundary candidate” next to the PRV option, which will set all PRVs’ DMA Status to “boundary candidate”.
The rest of the commands are as follows;
Once the “Compute” command is executed with either the “Target Number of Nodes” or “Target Pipe Length”, the DMA tool creates DMA’s as per user defined criteria.
The DMA tool enables us to demarcate DMA’s automatically but there are a few guidelines which can help you generate DMA’s satisfactorily;
Longer overview and demonstration on our YouTube channel:
This section deals with means and methods for DMA generation in WaterGEMS / WaterCAD versions below CONNECT Edition Update 2 (10.02.01.06).
Option 1 : Using the Pressure Zone Manager to try to isolate a DMA:
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.
Option 2 : If you have flow data that was collected at the entrance of the DMA, and upstream and downstream pressure at the PRV in the entrance of the DMA, you can follow this procedure:
Option 3 : Simplifying Existing DMA's to a single junction:
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:
Create and manage pressure zones and DMA's in WaterCAD and WaterGEMS
Special Interest Group recording - "Creating District Metered Area for Water Auditing and Non-Revenue Water Control"