|Development of Duration-Curve Based Methods for Quantifying Variability and Change in Watershed Hydrology and Water Quality (EPA/600/R-08/065) May 2008
During the past decades, the U.S. Environmental Protection Agency (EPA), the U.S. Department of Agriculture (USDA), and other federal program administrative and regulatory agencies spent considerable amounts of time and money to manage risks to surface waters associated with agricultural activities, urbanization, and other avenues of nonpoint source pollution. A variety of best management practices (BMPs) exist for this purpose and have been installed throughout the country, yet very little is known about their overall effectiveness in reducing stressors at the watershed scale. The objective of this research is to explore and develop uniform methods for simple quantification of hydrology and water quality data, focusing on watersheds containing agricultural BMPs. A significant motivation for the research is to provide tools that can be used to identify and quantify the major factors that connect watershed hydrology and water quality (such as climate, soil type, slope, and land use). These connecting factors are important for evaluating the effectiveness of agricultural and other BMPs because they often determine stream and stressor management decisions. Research methods must take into account natural variability and uncertainty in watershed response to BMP installation and precipitation events. The research project documented in this report is a collaborative effort, funded through an Interagency Agreement between EPA’s National Risk Management Research Laboratory and USDA’s North Appalachian Experimental Watershed (NAEW) in Coshocton, OH. Project objectives were achieved through an examination of historical data collected at the NAEW, with examinations of other related databases. As a result of this research, methods were developed to quantify BMP effectiveness and to understand how natural systems respond to watershed changes over time. The research will benefit states and other stakeholders faced with assessing the performance and effectiveness of BMPs within a watershed management framework.
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