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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Publications at this Location » Publication #331943
Title: Sensitivity of simulated conservation practice effectiveness to representation of field and in-stream processes in the Little River Watershed

Author
item CHO, JAEPIL - Apec Climate Center (APCC)
item HER, YOUNGGU - Florida Department Of Agriculture
item Bosch, David - Dave

Submitted to: Environmental Modeling and Assessment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2016
Publication Date: 8/24/2016
Citation: Cho, J., Her, Y., Bosch, D.D. 2016. Sensitivity of simulated conservation practice effectiveness to representation of field and in-stream processes in the Little River Watershed. Environmental Modeling and Assessment. 22(2):159-173.

Interpretive Summary: Placement and evaluation of conservation practices on agricultural land is an important component of watershed evaluation. Watershed-scale simulation models provide useful tools for this evaluation. Thorough evaluation of these models improves their reliability as well as public perception of their results. Here we assess the sensitivity of the SWAT model to it's input parameters and evaluate conservation practice effectiveness for one agricultural watershed in the South Atlantic Coastal Plain of the United States. Increasing the amount of acreage in conservation practices had the greatest load reduction for total phosphorus (TP), followed by sediment and finally total nitrogen (TN). The results indicated that conservation practices would have a limited impact on streamflow volume, but could significantly impact sediment and TP loads within this region.

Technical Abstract: Evaluating the effectiveness of conservation practices (CPs) is an important step to achieving efficient and successful water quality management. Watershed-scale simulation models can provide useful and convenient tools for this evaluation, but simulated conservation practice effectiveness should be responsive to parameter values used to represent the practices in the modeling. The objectives of this study were to (1) assess the impacts of a set of conservation practices on hydrology and water quality of a watershed and (2) evaluate the sensitivity of SWAT modeling outputs and simulated conservation practice effectiveness to parameters. The modeling study was conducted in an agricultural watershed, the subwatershed K (16.9 km^2) of the Little River Experimental watershed located in the South Atlantic Coastal Plain of the United States. Sensitivity analysis showed that hydrologic response unit (HRU) and watershed-scale simulations for water quality were most sensitive to CN and FILTERW parameters. Load reduction rates as a function of increased aerial coverage of the conservation practices were greatest for total phosphorus (TP), followed by sediment and total nitrogen (TN). The results indicated that conservation practices would have a limited impact on streamflow volume, but could have a significant impact on sediment and TP loads within this region. Watershed scale TN and TP loads were also sensitive to in-stream nutrient transformation process represented using the QUAL2E algorithm in SWAT. The study clearly demonstrated the most sensitive model parameters and the optimal conservation practices for this watershed.