Development of Sediment and Nutrient Export Coefficients for U.S. Ecoregions |
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Authors: | Michael White Daren Harmel Haw Yen Jeff Arnold Marilyn Gambone Richard Haney |
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Affiliation: | 1. Agricultural Research Service, US Department of Agriculture, Temple, Texas;2. Blackland Research & Extension Center, Texas A&M AgriLife Research, Temple, Texas |
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Abstract: | Water quality impairment due to excessive nutrients and sediment is a major problem in the United States (U.S.). An important step in the mitigation of impairment in any given water body is determination of pollutant sources and amount. The sheer number of impaired waters and limited resources makes simplistic load estimation methods such as export coefficient (EC) methods attractive. Unfortunately ECs are typically based on small watershed monitoring data, which are very limited and/or often based on data collected from distant watersheds with drastically different conditions. In this research, we seek to improve the accuracy of these nutrient export estimation methods by developing a national database of localized EC for each ecoregion in the U.S. A stochastic sampling methodology loosely based on the Monte‐Carlo technique was used to construct a database of 45 million Soil and Water Assessment Tool (SWAT) simulations. These simulations consider a variety of climate, topography, soils, weather, land use, management, and conservation implementation conditions. SWAT model simulations were successfully validated with edge‐of‐field monitoring data. Simulated nutrient ECs compared favorably with previously published studies. These ECs may be used to rapidly estimate nutrient loading for any small catchment in the U.S. provided the location, area, and land‐use distribution are known. |
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Keywords: | sediment nutrients surface water hydrology simulation nonpoint source pollution |
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