Subsystem-based pressure dependent demand analysis in water distribution systems using effective supply

Abstract

In this study, Subsystem-Based Pressure Dependent Demand (SPDD) analysis is implemented using the concept of effective supply to eliminate the uncertainties caused by the Head-Outflow Relationship (HOR) in Pressure Dependant Demand (PDD) analysis. This study optimizes the nodal water demands to satisfy the nodal pressure requirement under the abnormal condition defined as the part of the water distribution systems that is closed due to maintenance, rehabilitation, or accidents. The total water supply is optimized and defined as the effective supply, which is the maximum water supply while maintaining the nodal pressure requirements (25 psi) to guarantee the customer's convenience. A meta-heuristic algorithm, the Harmony Search (HS) algorithm, is applied to optimize the system. To decrease the effect of the HOR uncertainties, an optimization method is proposed in this study using the EPANET model that is widely used for the hydraulic simulation. To evaluate the applicability of the suggested model, Supply Index (SI), Pressure Index (PI), Effective Supply Index (ESI), and Subsystem Importance Index (SII) are also defined and calculated from a real-sized network. This paper firstly tried to perform pressure dependent demand analysis for subsystem without the HOR equation that has been an important issue in water distribution system analysis. The developing method could be a good alternative for the design and maintenance of water distribution systems.