Solving the inverse problem of deliberate contaminants intrusions into water distribution systems

A methodology is developed and applied for solving the general inverse problem of a deliberate contaminant intrusion into a water distribution system: given a contaminant detection at one or more online monitoring/sensors stations - identify the injection characteristics: (1) location, (2) starting time, (3) intensity (mass time), and (4) duration. The algorithm is based on the randomized pollution matrix (RPM) concept, developed in previous works by the authors, and taking into account the monitoring stations detection sensitivity, their response delay, and possible different injection probabilities throughout the system. The model outcomes are the system nodes with the highest likelihood to be the injection locations; the approximated injection starting times; intensities; and durations. The model is demonstrated through a base run and sensitivity analysis using a simple example application. Copyright ASCE 2005.