Equitable Water Access in Intermittent Water Supply Systems

Abstract Submission: Water supply systems (WSS), initially designed for continuous operation, are forced to be operated intermittently due to factors not limited to water scarcity, power shortages, financial constraints, ineffective operational strategies, and deteriorating water infrastructure. Such systems are defined as intermittent water supply (IWS) systems. To adapt to the water scarcity induced by the erratic water supply routines in IWS systems, the consumers of such WSS undertake flexible consumption behaviors characterized by storing the limited water available during shorter supply periods in intermediate storage facilities for subsequent usage during more extended non-supply periods. These intermediate storage facilities act as buffers and help consumers tackle water scarcity to certain levels. However, intermediate water storage introduces discrepancies in hydraulic conditions across the WSS and ultimately disturbs the equity in water access, where some consumers at hydraulically advantageous locations within the WSS have greater access to water than others. Since the existing modeling tools cannot mimic dynamic and flexible consumption dynamics typically experienced in IWS systems, their application in optimizing the WSS operations to ensure equitable water access is questionable. To address this, the present study proposes a simulation-optimization framework integrating an advanced EPANET-based hydraulic simulation model with a Genetic Algorithm (GA)-based optimization model. The hydraulic simulation model mimics the water consumption behavior typical of IWS systems by modifying the network architecture by adding artificial elements in every demand node. The GA-based optimization model revolves around the objective – maximization of equity – and provides optimal operation strategies satisfying the general hydraulic flow constraints and the practical constraints specific to the challenges faced by WSS operators in typical rural settings. The applicability of the proposed framework is demonstrated by optimizing the pumping schedules for a real-world rural WSS in Southern India, fed by an unconfined aquifer with limited recuperation ability.

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