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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #323989
Title: Evaluation of alternative management practices with the AnnAGNPS model in the Carapelle Watershed

Author
item ABDELWAHAB, OSSAMA - University Of Bari
item Bingner, Ronald - Ron
item MILILLO, FABIO - University Of Bari
item GENTILE, FRANCESCO - University Of Bari

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2016
Publication Date: 7/1/2016
Citation: Abdelwahab, O.M., Bingner, R.L., Milillo, F., Gentile, F. 2016. Evaluation of alternative management practices with the AnnAGNPS model in the Carapelle Watershed. Soil Science. 181(7):293-305.

Interpretive Summary: Evaluation and assessment of watershed agricultural management practices are critical in selecting the best practices possible to control erosion and improve the downstream water quality. Watershed models have been extensively used within the U.S. for this purpose, but evaluations outside of the U.S. have been limited. An evaluation of the USDA watershed model AnnAGNPS and conservation management practices for erosion control was performed within a southern Italy experimental watershed for 2007-2011. Implementation of alternative management practices implemented throughout the watershed demonstrated through the model simulations that by applying reduced tillage practices, erosion could be reduced by 12%, but treating those same areas with no tillage practices could reduce erosion by 44%. Targeting the highest erosive areas within the watershed to replant to forest conditions reduced sediment loads from 5% to 97%. Understanding how the model performs under unique conditions with agricultural practices that are not common in the U.S. can provide insight into enhancements that may be needed to improve the model. These model assessments are critical since they are often the only means to evaluate the effects of conservation practices on water quality within a watershed.

Technical Abstract: The Annualized Agricultural Non-point Source (AnnAGNPS) model can be used to analyze the effectiveness of management and conservation practices that can control the impact of erosion and subsequent sediment loads in agricultural watersheds. A Mediterranean medium-size watershed (Carapelle) in Apulia, Southern Italy, was used to evaluate the model and the effect of Best Management Practices (BMPs) for sediment load control. A monitoring station located at the Ordona Bridge is instrumented to continuously monitor stream flow and suspended sediment loads. First the AnnAGNPS model was used to predict runoff and sediment load without calibration during a five years period. On the annual scale, the model showed a good prediction capability for runoff (R2=0.8, NSE=0.7), and satisfactory results for sediment load (NSE=0.5, R2=0.5). Based on the current conditions of the watershed as a baseline scenario, the effectiveness of alternative conservation practices was also evaluated. The No-Till practice applied to the entire cropland area reduced the sediment erosion in the watershed by 44% and the sediment yield from cells to streams by 20%. Reduced tillage reduced soil erosion, sediment yield and sediment load by 12%, 7% and 4% respectively. Targeting the highest eroding cropland sub-watersheds proved to be a promising technique of sediment erosion reduction. In fact high sediment producing areas were identified and targeted by substituting different percent areas of cropland with forest, and consequently sediment loads were reduced from 5% to 97%. The effect of vegetated streams and riparian buffers as natural traps increasing the in-situ sediment deposition was also considered.