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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #305196

Title: Multi-site evaluation of APEX for crop and grazing land in the Heartland region of the US

item Baffaut, Claire
item NELSON, NATHAN - Kansas State University
item VAN LIEW, MIKE - University Of Nebraska
item SENAVIRATNE, ANOMA - University Of Missouri
item BANDHARI, AMMAR - Kansas State University
item LORY, JOHN - University Of Missouri

Submitted to: Annual International SWAT Conference
Publication Type: Abstract Only
Publication Acceptance Date: 5/2/2014
Publication Date: 7/25/2014
Citation: Baffaut, C., Nelson, N., Van Liew, M., Senaviratne, A., Bandhari, A., Lory, J. 2014. Multi-site evaluation of APEX for crop and grazing land in the Heartland region of the US [abstract]. Annual International SWAT Conference. P. 73.

Interpretive Summary:

Technical Abstract: The Agricultural and Policy Environmental Extender (APEX) is powerful and useful to estimate the edge-of-field impacts of management practices. A drawback is that it needs to be calibrated for each site, which requires resources and data. The objective of this study was to compare annual model performance for flow, sediment and phosphorus transport under two parameterization schemes: an out-of-the-box (OOTB) parameterization based on readily available data and a fully calibrated parameterization based on site specific soil, weather, event flow and water quality data. The analysis was conducted for 18 watersheds at five different sites representing hydrologic conditions ranging from well to poorly drained soils and management systems covering row crop under different tillage systems and grazing systems. Model performance was based on the Nash Sutcliffe efficiency (NSE), the coefficient of determination (r2) and the regression slope between simulated and measured loads. Although the OOTB model performance for flow was acceptable (NSE = 0.5), calibration improved it (NSE = 0.6). Acceptable simulation of sediment and total phosphorus transport (NSE = 0.7 and 0.6, respectively) was obtained only after full calibration at each site. Analysis of the calibrated parameter sets is ongoing to define a regional APEX parameterization that will be further evaluated on additional sites. A regional parameterization will be beneficial to conservation and resource management agencies who consider using APEX as a management and prioritization tool and for regional analyses.