Water Network Sectorization based on genetic algorithm and minimum dissipated power paths

Water Network Sectorization (WNS) consists in dividing the water system into independent districts in order to achieve sectors with independent water supply or to improve the network protection. When each district is supplied by its only water source the districts can be defined as i- DMAs (isolated District Meter Areas) because they are completely cut off, by closed gate valves, from the rest of the water network. This isolation of the i-DMAs could decrease significantly the hydraulic performance of the water system reducing its topologic (network loops) and hydraulic (diameter sections) redundancy. Traditionally the design of a WNS is carried out by empirical or simulation assisted trial-and-error approaches that are difficult to apply to large water distribution systems. In this paper an original methodology for an automatic sectorization of a water network is proposed. The methodology is based on Shortest Path techniques that allow defining a tree graph of the network; specifically in this case dissipated powers are used as weights of the pipes (or links). Once the districts are found, a swapping phase follows achieved using a genetic algorithm that allows refining the choice of nodes that belong to each district. The objective function of the genetic algorithm is based on network mean pressure. The methodology is tested, using different performance indices, on two real water supply systems: Parete (a small network in Italy) and Matamoros (a large network in Mexico).