Two-Tiered Sensor Placement for Large Water Distribution Network Models

Abstract

Water distribution network models for large municipalities have tens of thousands of interconnecting pipes and junctions with complex hydraulic controls. Many water security applications, including sensor placement optimization, require detailed simulation of potential contamination incidents. The postsimulation optimization problem can easily exceed memory on standard desktop computers. Large networks can be skeletonized to reduce computation; however, this alters network hydraulics, and therefore sensor placement. The objective of this paper is to evaluate a two-tiered sensor placement approach that combines hydraulic and water quality simulations using all-pipes, or original, network models with subsequent geographic aggregation of time and impact values to reduce memory requirements. The two-tiered approach first places sensors on aggregated regions, then refines the solution to actual nodes in the original model. The two-tiered sensor placement approach is compared to results using the original network and skeletonized networks based on solution quality, memory use, and runtime. Results show that skeletonized networks introduce error in sensor placement. Two-tiered sensor placement using geographic aggregation replicates the original model solution to within 5% in most cases.