Identification of district metered areas in looped water distribution networks using the graph theory

The introduction of District Metered Areas (DMAs) in looped water distribution networks can provide a series of advantages. The measurement of flows entering and leaving the districts allows for the easier and faster identification and location of leaks; the simplification of the evaluation of the water balance provides improvements in the water distribution network management. In networks where contamination accidents are possible to happen, the division into independent districts allows for the minimization of the potential movement of contaminants throughout the system, increasing water security. However, the design of DMAs in existing looped water distribution networks, especially in urban areas, involves a high number of decision variables and the effects of the implementation of districts have to been evaluated, in order to not affect the quality of the service to the customers. A number of technical reports, based on previous experiences, providing for guidelines and design criteria that have to be taken into account for the successful implementation of DMAs, are available in literature. The present study illustrates a new methodology, based on graph theory, for designing a given number of districts in looped water distribution networks: it allows for the generation of different solutions, that are different possible layouts of the districts, that can be compared on the basis of performance indicators. The methodology here presented takes into account some important DMAs design criteria: the maximum and minimum size recommended for a district, the connectedness of each district with the water supply source and the absence of links between the districts (independence between districts). A recursive bisection procedure has been applied for the creation of districts, while an algorithm for graph traversal has been used for verifying the properties of reachability of each district from the water source and connectivity between the nodes. The application of the proposed methodology to a case study has proved its effectiveness for DMAs design in real urban water distribution networks.

Una nuova metodologia per la progettazione di distretti in reti di distribuzione idrica a maglie chiuse viene proposta. Tale metodologia consente di dividere una reti idrica in un prefissato numero di distretti, aventi caratteristiche che rispecchiano i criteri di progettazione consigliati in letteratura: i distretti risultanti infatti, presentano dimensioni appropriate dal punto di vista della domanda idrica, sono connessi alla fonte di alimentazione e sono idraulicamente indipendenti gli uni dagli altri. La metodologia sviluppata è in grado di generare un certo numero di soluzioni alternativa, le cui prestazioni vengono valutate allo scopo di confrontarle e decidere quale adottare. Infine, l’efficacia della procedura di distrettualizzazione proposta viene dimostrata mediante la sua applicazione ad un caso di studio.