Water Rationing Model for Water Networks under Short-Term Water Supply Shortage
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Protecting water infrastructure systems from intentional attacks and developing strategies to make the water networks robust, resilient, and more immune to intentional attacks have been one of the top priorities in water industry since the September 11, 2001 terrorist events. The water distribution system typically consists of multiple subsystems in grid or network patterns. An intentional attack on a well-selected set of physical components can result in catastrophic disruption of water service. This paper presents a mitigation model which can reduce or minimize adverse consequences when a water network suffers from significant water shortage due to functional failures of critical facilities due to intentional physical attacks. The model developed in this study can be also applicable to water supply shortage situations due to non-intentional incidents such as major pump failures or main breaks. The proposed model optimizes a water supply plan for water customers utilizing the information regarding the priority of water customers in emergency situation, their functional sensitivity to water supply, and dynamic nature of water demand patterns. The solutions generated from the model are water rationing plans which can guarantee at least a short-term water supply to every water customer in 24-hour period. A Genetic Algorithm based program linked with a hydraulic solver (EPANET 2.0) is developed to find optimal rationing plans. A test of the developed program using an example water network in EPANET 2.0 manual indicates that the proposed model can successfully generate water rationing plans to reduce the consequences while meeting hydraulic constraints in water networks. The findings of this paper will provide a practical approach that can be used by managers of water networks in preparing emergency operations of their water networks. Copyright ASCE 2006.