Analysis of Intermittent Water Distribution Networks Using a Dummy Emitter Device at Each Demand Node

Abstract

The pipe component of a water distribution network (WDN) is sized based on the fixed design demand considering a peak factor and design period. Simulation of the designed network by a hydraulic solver provides nodal pressure head, head loss, velocity, and flow in each pipe as the prime outputs for the design demand, and it can also be used for extended-period simulation for a particular demand pattern over the supply hours. But, in reality, the behavior of the network does not match with such a result in an intermittent water supply (IWS) system due to the fact that all house service connections behave as an uncontrolled orifice. This has made it a challenging task in understanding and in predicting the behavior of the networks by the municipal engineer once the water starts flowing through the house service connections (HSCs). Though the municipal engineer provides the same pipe size for HSCs to all residences, the flow received by each house could vary based on the available pressure head at the ferrule point of the main water supply pipeline. In reality, maintaining constant pressure at each HSC is not feasible due to frictional head loss. Hence, variation in flow at the HSC is inevitable even with a small water supply system. This paper illustrates how to simulate the behavior of an IWS system based on the number of HSCs provided to each pipeline using a hydraulic solver. Hydraulic simulation of the water distribution network that provides IWS to consumers can be implemented easily by adding a fictitious node by assigning an appropriate emitter coefficient to each demand node through a fictitious link having a check valve in it. The method for finding the appropriate value of the emitter coefficient that helps in simulating HSCs is illustrated in the present work.