Optimal location and sizing of stormwater basins at watershed scale

Nonpoint source pollution control requires the implementation of best management practices (BMPs) at various locations in a watershed. One important aspect of the watershed strategy is to find the optimal placement and design of BMPs so that their combined effect is most cost-effective. An innovative method is presented for optimizing the placement and configurations of BMPs at the watershed scale. Heuristic optimization techniques are coupled with a watershed model, which is the agricultural Nonpoint Source Pollution model (AnnAGNPS) in this case, and BMP simulation module to find a least cost set of solutions that meet the pollutant load reduction requirements. An impoundment module imbedded in AnnAGNPS, and modified to address the sediment accumulation and resuspension effect, is used to provide the means of evaluating the long-term performance of detention ponds. A scatter search algorithm is applied to finding the least cost solution. The optimization framework developed herein provides a tool for stormwater management practitioners to examine and analyze the treatment efficiencies of stormwater control alternatives and to determine a robust and cost-effective design of stormwater treatment systems.