Operating Water Distribution Networks during Water Shortage Conditions Using Hedging and Intermittent Water Supply Concepts

Abstract

Population increase and requirements as well as water resource limitations reveal the necessity for the optimal operation of water distribution networks (WDNs), especially during shortage events. Because WDNs directly affect lifestyles, operational plans that take into account abnormal conditions are necessary. Under such circumstances, some possible solutions, such as transferring water from other basins or using recycled waters, may be inapplicable or insufficient, as continuous operation of WDNs would not be possible anymore. This paper proposes hedging or intermittent water supply as a contrasting way against a water shortage juncture. In this method of operation and in a specific time span during the operational period, the amount of water supplied to each consumer could be different even if their demands are equal. Thus, the selection of a policy that guarantees equity in supplying consumers’ demands has to be considered. In addition, supplying demands with sufficient pressure would promote consumers’ satisfaction. Hence, this method of operation needs a planning methodology that takes into account equity, satisfaction, available water, consumption fluctuations, and other social constraints besides hydraulic parameters influencing the behavior of WDNs and the interaction between them. The quantification of the aforementioned parameters and constraints requires mathematical models that simulate the behavior of networks and optimize the mentioned goals. In this paper, the operation of two networks is examined. The honey-bee mating optimization (HBMO) algorithm is used as the optimization tool linked to EPANET 2, which is the hydraulic simulator of the networks. To compare various methods of facing water shortage, WDN performance criteria are also calculated. Results show that a 100% resiliency criterion for hedging and intermittent water supply is 25–50% more favorable than other methods. In addition, a nodal resiliency criterion of water allocated under various operational methods and irrespective of initial storage volume of the reservoir show the superiority of intermittent water supply compared with other approaches, indicating the efficient management of available water allocated in the operational period.