Distributed-parameter watershed models are often utilized for evaluating the effectiveness of sediment and nutrient abatement strategies through the traditional (calibrate->validate->predict) approach. The applicability of the method is limited due to modeling approximations. In this study, a computational method is presented to determine the significance of modeling uncertainties in assessing the effectiveness of best management practice (BMPs) in two small watersheds in Northeastern Indiana with the Soil and Water Assessment Tool (SWAT). The uncertainty analysis aims at (1) identifying the hydrologic and water quality processes that control the fate and transport of sediments and nutrients within watersheds, and (2) establishing uncertainty bounds for model simulations as well as estimated effectiveness of BMPs. The SWAT model is integrated with a Monte-Carlo based methodology for addressing model uncertainties. The results suggested that fluvial processes within the channel network of the study watersheds control sediment yields at the outlets, and thus, BMPs that influence channel degradation or deposition are the more effective sediment control strategies.

"January 2007." Title from title screen (viewed on Jan. 27, 2011). Final report "EPA/600/R-08/036." Includes bibliographical references (p. 83-91). "Contract Number: 4C-R330-NAEX."