Abstract
Abstract
The purpose of this study was to develop a tool for the optimal placement strategy of structural best management practices (BMPs) at the watershed scale. It consists of three interacting components: a simplified BMPs simulation model, a zero-dimensional reservoir water quality model (unsteady, time-variable Vollenweider model), and an optimization model (genetic algorithms). A posttreatment program that combines BMP simulation, channel routing, reservoir water quality models, and genetic algorithms was developed. Both total suspended solids and total phosphorus were taken into account, and three types of BMPs were considered. By changing the constraints, three scenarios were analyzed in this study. The total phosphorus concentration should satisfy oligotrophic, mesotrophic, and eutrophic conditions, while the total suspended solids concentration should be kept below 25 mg/L. This study analyzes three different time-scale scenarios: short term (March 28, 2003 to April 14, 2003), long term (2002–2003), and design storms (2-year/2-h and 5-year/4-h). Near optimal solutions found in this study were compared with former research on the Fei-Tsui Reservoir watershed. For future detailed planning and designing, decision makers or designers can adopt the BMPs placement strategies developed in this study. Several nonstructural BMPs are also suggested as sound alternatives for nonpoint source pollution control when there are topographic and land ownership problems.