Identification of contaminant sources in water distribution systems using simulation-optimization method: Case study

In this paper, the authors propose a new approach, the simulation-optimization method, to solve a nonlinear contaminant source and release-history identification problem for a complex water distribution system. This approach is based on optimization analysis, using the EPANET water distribution system model as a simulator. In this approach, EPANET is used to generate concentrations at arbitrarily selected monitoring locations by specifying release histories of potential contaminant sources that are arbitrarily located within the water distribution system. This information is used in a continuous optimal predictor-corrector algorithm to identify the sources and their release histories. Throughout the simulation sequence, the water distribution system being studied is assumed to operate under, known hydraulic operational patterns. The optimization model that is used as a corrector to estimate the release histories of the contaminant sources is designed to identify the similarity between the simulation response and measured data at monitoring locations. This information exchange is developed as a closed-loop system resulting in a convergent algorithm. Three scenarios, derived from the publicly documented Dover Township (Toms River), N.J., water-distribution system are tested using the proposed approach. Results show that the approach is effective, efficient, and robust in identifying locations and release histories of contaminant sources.