The DMA algorithm is based on graph theory and the concept of "modularity". A group of pipes that are highly connected with one another will have a high modularity, while those more distant will have a low modularity. Pipes that have a high modularity are grouped into a DMA (while also considering user specified criteria such as the desired size of the DMA). Adjacent DMA's with high modularity can be merged by the user if desired.

The DMA analysis will identify boundary elements for each DMA. Two types of elements can serve as boundaries because they can be closed and/or metered. These are:

1. Pipes
2. Nodes that can be closed:
   1. Pumps
   2. Pump Batteries
   3. PRVs
   4. TCVs
   5. GPVs

Each of these elements can be assigned several different DMA status settings. Each starts with as a "Boundary Candidate" and each can be changed by the DMA tool or by the user.

Pipes can have four states:

• Boundary Candidate - these are open pipes which can become closed to create a DMA boundary by the DMA Solver.
• Boundary – these pipes are either closed to form a boundary (by setting the pipe status to closed) or are considered DMA flow meter locations.
• Transmission mains – these pipes are not included in any DMA’s by the DMA solver. Large transmission mains are usually not included in a DMA and are kept open. The user should select which pipes should be considered transmission mains based more on function than on size. This designation should be made prior to running the DMA solver.
• Assigned – once the DMA analysis has been run and the user is satisfied with some of the DMA results, parts of the system can be fixed and not included in future analysis. The pipes inside these DMAs are considered “assigned” to their particular DMA.

While one goal of DMA creation is to have each DMA be of comparable size. A second goal is to avoid closing an excessive number of valves to create a DMA. In some highly gridded systems, it may not be possible to create DMA's with a small number of closed valves. In those cases, the algorithm creates fairly large DMA's. The user may still not be satisfied with the number of valves. In those cases, the user can manually merge adjacent DMA's to form a larger DMA with fewer closed valves.

Assign Customer Meters in Boundary Edges to Connected DMAs

It is possible that there are customer meters associated with DMA boundary links. If there are customer meters associated with boundary links, the customer meters need to be assigned to boundary link connected DMAs. We use customer meter Demand Distribution (Start) field value and distance from customer meter to boundary link start node to determine how many customer meters and which customer meter to be assigned to boundary link start node DMA and stop node DMA.

The following are the steps to determine how many customer meters and which customer meter to be assigned to boundary link start node DMA and stop node DMA:

1. Find all customer meters associated with the boundary link and read Demand Distribution (Start) field value for the customer meters.
2. Add all Demand Distribution (Start) values to get total demand distribution to start node. If the fraction of total demand distribution is larger than or equal to 0.5, the number of customer meters to be assigned to start node DMA equals the smallest integer value that is larger than total demand distribution. If the fraction of total demand distribution is smaller than 0.5, the number of customer meters to be assigned to start node DMA equals the largest integer value that is smaller than or equal to total demand distribution. Assume the number of customer meters to be assigned to start node DMA is N.
3. For all customer meters associated with the boundary link, calculate the distances from customer meters to boundary link start node. Sort customer meters in ascending order in a list based on the distance to boundary link start node.
4. Assigned the first N customer meters in the list to DMA that boundary link start node is in. Assign the rest customer meters in the list to DMA that boundary link stop node is in.

In the following example, there are 9 customer meters associated with DMA boundary link. Each customer meter has Demand Distribution (Start) value 0.5. The calculated total demand distribution is 4.5. Therefore, 5 customer meters that are close to boundary link start node are assigned to start node DMA (green color) and the other 4 customer meters are assigned to stop node DMA (blue color).