Development of a Decision Support System for Evaluating BMP Efficiencies at Watershed Scale.

A decision support system (DSS) is needed to evaluate best management practices (BMPs) at the watershed scale for their environmental impacts as well as their associated cost-benefit analysis. Work is in progress to develop a GIS/BMP-DSS, which comprises the watershed model AnnAGNPS (capable of assessing landscape processes) coupled with the one-dimensional dendritic channel network simulation model CCHE1D. Based on the imposed watershed management scenario, the AnnAGNPS performs the simulation of rainfall-runoff and sediment erosion in each sub-watershed, and provides the loadings to the nodes of the channel network model. Once fully tested, the DSS will be capable of aiding the decision makers to design BMP implementations and evaluate their efficiency by simulating and analyzing the responses of the watershed and the channel network, including sediment transport, channel morphodynamics and water quality. The definition of management scenarios, interaction with the simulation models, and the final analysis of simulation results for aiding decision making process will be handled by a user-friendly graphical user interface (GUI) with full GIS capability, which is developed as an add-on extension to ArcMap. This architecture gives the user, in addition to the functionalities of the DSS, the full power of the ArcGIS system. An economic analysis component will also be developed, with plans to test some specific economic variables that watershed planners may find useful. The results of a case study using DSS at the Choptank watershed in Maryland will be presented.