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Impact of the Agricultural Research Service watershed assessment studies on the Conservation Effects Assessment Project Cropland National Assessment

Jeffrey G. Arnold, R. Daren Harmel, Mari-Vaughn V. Johnson, Ronald Bingner, Timothy C. Strickland, Mark Walbridge, Chinnasamy Santhi, Mauro DiLuzio, Xiuying Wang
Journal of soil and water conservation 2014 v.69 no.5 pp. 137A-144A
Agricultural Research Service, Conservation Effects Assessment Project, Farm Bill, National Institute of Food and Agriculture, Natural Resources Conservation Service, Soil and Water Assessment Tool model, algorithms, calibration, conservation practices, cost effectiveness, cropland, databases, development aid, ecosystem services, environmental assessment, environmental monitoring, funding, governmental programs and projects, guidelines, model validation, national surveys, quality control, scientists, streams, uncertainty, watersheds
USDA initiated the Conservation Effects Assessment Project (CEAP) in 2002 to analyze societal and environmental benefits gained from the increased conservation program funding provided in the 2002 Farm Bill. The Natural Resources Conservation Service (NRCS), Agricultural Research Service (ARS), and National Institute of Food and Agriculture (NIFA) initiated the CEAP Watershed Assessment Studies to estimate conservation benefits at the national and regional scales and to establish a scientific understanding of the impacts of conservation practices at the watershed scale. ARS initiated and led the ARS benchmark watershed studies. The benchmark watershed studies were structured into five specific objectives that included: 1) Database Development. 2) Watershed Design. 3) Modeling of Watersheds. 4) Economic Assessment. 5) Regionalization of Models. 6) Quality Assurance. This paper focuses on the impacts of Objective 3, Modeling of Watersheds, on the CEAP national assessments and the larger science community. Impacts include: 1. The APEX and SWAT models used in the national assessment were calibrated and validated at finer resolution than was previously possible using USGS stream gage data. During calibration and validation, several model shortcomings were discovered and consequently numerous improvements were made to both models. 2. Work on model validation guidelines provided statistical goodness-of-fit recommendations for the CEAP national assessments. In addition to the direct impact on CEAP simulations, the manuscript from the study has been cited in over 1,100 studies and is having impact well beyond CEAP. 3. Work on uncertainty created tools that are now being used more routinely in applying models for conservation and environmental assessment. 4. Tools were developed to aid in development of responsive watersheds and to estimate cost-effectiveness of specific practices, suites of practices, and targeted placement. 5. Additional model development and validation was conducted to improve model response to timing of man¬agement and temporal resolution of process algorithms. ARS scientists and their collaborators continue research and watershed monitoring at several of the benchmark watersheds. The models are constantly being upgraded to meet the needs of CEAP and other conservation assessments across the globe.