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Assessing SWAT’s Performance in the Kaskaskia River Watershed as Influenced by the Number of Calibration Stations Used
Citation:
Chiang, L., Y. YUAN, M. H. MEHAFFEY, M. JACKSON, AND I. Chaubey. Assessing SWAT’s Performance in the Kaskaskia River Watershed as Influenced by the Number of Calibration Stations Used. Transactions of the ASABE. AMERICAN SOCIETY OF AGRICULTURAL AND BIOLOGICAL ENGINEERS, ST. JOSEPH, MI, 0(0):1-12, (2013).
Impact/Purpose:
The benefits that people gain from the natural ecosystems, termed ecosystem services, include provisioning services, regulating services, cultural services and supporting services (MA, 2004). The measurement of ecosystem services is the new strategic focus for the United States Environmental Protection Agency’s (EPA) Ecosystem Services Research Program (ESRP). The ESRP’s mission is to conduct innovative ecological research that provides the information and methods needed by decision makers to assess the benefits of ecosystem services to humans, and, in turn, to shape policy and management actions at multiple spatial and temporal scales. The ESRP’s Future Midwestern Landscapes (FML) study aims to quantify the current magnitude of ecosystem services in the Midwestern U.S., and to examine how those services would change over the next decade, given the growing demand for biofuels. The EPA established new statutory requirements in 2010 for the use of biofuels, including annual targets for individual fuels, which initially require only corn starch-based fuels (U.S. EPA, 2010). Corn is one of the most energy-intensive crops used for biofuel production requiring greater amounts of nitrogen fertilizer and pesticides such as atrazine. Although an increase in corn production can have a positive energy balance, it also has many negative impacts on environmental quality such as soil erosion and nutrient and pesticide losses to water bodies. For example, more than 70% of the nitrogen and phosphorus delivery to the Gulf are contributed from the agricultural lands in the Mississippi River Basin; and these increased nutrient fluxes are linked to seasonal hypoxia in the northern Gulf of Mexico (Alexander et al., 2008).
Description:
The Future Midwestern Landscapes (FML) project is part of the U.S. Environmental Protection Agency’s new Ecosystem Services Research Program, undertaken to examine the variety of ways in which landscapes affect human well-being. The goal of the FML project is to quantify current and future ecosystem services across the region and to examine changes expected to occur as a result of the growing demand for biofuels. In this study, the Kaskaskia River watershed, Illinois was selected to investigate the effect of different HRU definitions on Soil and Water Assessment Tool (SWAT) model performance. The SWAT model has been developed to evaluate the effectiveness of agricultural management practices on watershed water quality at various temporal and spatial scales. Our model evaluations include performance using different Hydrologic Response Unit (HRU) definitions, and multi-variable and multi-site calibration and validation for streamflow, sediment and nutrient loadings. The results showed that the finer the HRU definition, the better the model performance would be. However, no considerable differences in model performance were found for the drainage area with only few dominant land uses. The results of multi-variable and multi-site calibration and validation showed an improvement on model performance and highlighted that greater calibration efforts are needed to assess the hydrological process at various spatial scales.