Shankar Narasimhan S

Water Distribution Networks (WDNs) are an integral part of society. Deliberate introduction of chemical or biological agents through accessible sites of a WDN can spread through the entire system and cause widespread damage to public health. In order to protect against such deliberate attacks on a WDN, an effective and efficient online monitoring system through sensors is needed. It is clear that sensors located at different nodes respond at different times depending on which vulnerable node is attacked. In the present study, we design sensor networks for contamination detection and identification which exploit the differences in sensor response times as additional information. A hydraulic analysis of the network is first carried out for a given loading condition to determine the flow directions and flow velocities in different pipes. Directed paths between vulnerable nodes and potential sensor nodes are used to construct a bipartite graph, and the sensor network design problem is formulated as a minimum set cover problem. Algorithms based on greedy heuristics are used to solve the set cover problem and obtain the corresponding sensor network. The proposed method is applied on two WDNs, and the use of sensor response times to obtain a design with reduced number of sensors is demonstrated.

Water Distribution Networks in many rural areas supply water from storage reservoirs at the source of water to a group of villages through gravity or by pumping. Due to poor operational policies, they often fail to meet the demand of the beneficiary villages. This work proposes a rational technique for scheduling the supply in such networks to maximize the water delivered to the villages in an equitable manner. A secondary objective is to minimize the number of valve operations. The problem is formulated as a LP followed by an ILP. The parameters in the optimization problem are obtained by simulations of a well calibrated hydraulic model or experimental data if such a model is not available.

Optimal operation of water distribution networks can be posed as a scheduling problem where the objective is to meet the time varying demand while meeting constraints on supply, pressure etc. In the present work, we propose a robust optimization problem to address uncertainty in the parameters of the model used for optimization. The resulting problem is a second order cone program that can be solved efficiently. The formulation ensures a high probability of meeting the demands, adding to the practical significance. Further, we provide the results of applying this technique on a laboratory scale water distribution network.