A shuffled box complex-based optimization model for watershed management

This paper describes the development of an optimal management model based on the modified Box Complex method of constrained optimization for an urban watershed impaired by point and non-point sources of pollution. The modified method is called the Shuffled Box Complex method of constrained optimization. This is achieved by linking the Shuffled Box Complex-based optimization model to a macro-level water quality simulation model for an urban watershed impaired due to low dissolved oxygen. The macro-level simulation model consists of a BOD load simulation model for the three streams of the Beargrass Creek watershed in Louisville, Kentucky. A nonlinear constrained optimization framework is thus formulated to allocate biochemical oxygen demand (BOD) loads in a way that satisfies economic as well as water quality considerations in the watershed. The optimal integrated watershed management model is used to evaluate various water quality management strategies leading to the optimal water quality management strategy for the watershed. A sensitivity analysis is performed to evaluate the performance of the management model with regard to varying dissolved oxygen standards enforced for the study area. The proposed optimization framework can serve as a useful management tool for watershed decision makers to formulate and evaluate different management strategies leading to effective capital improvement projects for the watershed. The cost of capital improvement projects in large urban watersheds can exceed 1.0 billion dollars and the use of such an optimization-simulation approach can result in significant savings by providing optimal solutions.