Tufts Watershed Loading Function: Best Management Practice Model for Decision Support

A watershed model was developed for optimization-based best management practice (BMP) decision support related to non-point source nutrient control. The decision support system could be useful in watershed management, such as defining or complying with a Total Maximum Daily Load (TMDL). Tufts Watershed Loading Function (TWLF) was based on the Generalized Watershed Loading Functions (GWLF) [Haith and Shoemaker, 1987] and modified to allow for daily simulation of nutrient load generation, BMP behavior and optimization of watershed quality management alternatives. It was applied to the Aberjona River watershed, a small, highly urban basin located northwest of Boston, Massachusetts. BMP simulation models were created with input from local stakeholders to represent a broad range of management options including street sweeping, reduction in fertilizer application, porous pavement, grass swales, and constructed storage. The decision support interface allows users to quickly test scenarios involving BMP options in various land use areas, and could be part of negotiations and public decision making processes. In addition to scenario testing, optimizations were also performed using a genetic algorithm to search for efficient remedial solutions given limited management budgets.