Impact of networks sectorization on water pressure transient in pipelines – Case study of Casablanca city, Morocco

The sectorization of Water Distribution Networks (WDN) is characterized by permanent and periodic valve closures to control the volumes distributed and help to manage water losses. These valve maneuvers are characterized by wave propagations of varying severity. These transient phenomena are considered as a major problem in the under-load networks operation. These maneuvers can lead to bursting and breakage of the pipes because of water hammer. In this research work, we are interested in evaluating the impact of valve operations on the occurrence of transient regimes in a Discrete Hydraulic Sector (DHS) of the water distribution network of the city of Casablanca. The required hydraulic model for a real distribution network was established using the Bentley HAMMER. Several simulations with various transient severities of valve closures were performed and simulated in the field. Three examples have been considered: a pipe with and without a connection, a mesh network and a pipe with opening fire hydrant. The simulations thus carried out show that the sudden opening and closing, in the case of the valve of large diameter and pipe with a high wave propagation velocity, the transient phenomenon results in a significant induced pressure head which could lead to (i) significant transient severities in the pipelines, (ii) probable occurrence of leaks (iii) distribution break. The findings of this research work and the proposed approach would promote for the utility managers a new process to follow of partitioning a WDN without mechanical stress on the pipe components during the operation of sectorization.