Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2006
Publication Date: 3/9/2007
Citation: Pieri, L., Bittelli, M., Wu, J.Q., Dun, S., Flanagan, D.C., Pisa, P.R., Ventura, F., Salvatorelli, F. 2007. Using the Water Erosion Prediction Project (WEPP) model to simulate field-observed runoff and erosion in the Apennines Mountain Range, Italy. Journal of Hydrology. (2007) 336:84-97. Interpretive Summary: Modern erosion models are computer programs that are used to estimate the amount of runoff and soil loss that may occur from a farmer’s fields. It is important to check how well these models work by comparing them to measurements of actual runoff and erosion in the field. The Water Erosion Prediction Project (WEPP) model is one current erosion model. In this study, data from a field experiment in northern Italy was used to test the WEPP model. We found that WEPP did a good job of simulating the water runoff and the soil loss from a steeply sloping (15%) field with a continuous corn cropping system. The model was also applied to two other cropping systems there (corn-wheat and corn-wheat-wheat-alfalfa-alfalfa), and the simulations showed that the conventional corn-wheat rotation resulted in the highest predicted surface runoff and soil loss. The alternative conservation rotation of corn-wheat-alfalfa-alfalfa had the lowest predicted soil loss. This research impacts scientists, conservationists, action agency personnel, farmers and others concerned about use of erosion prediction models for soil conservation planning. Results here provide additional confidence in predictions with the WEPP model.
Technical Abstract: The Water Erosion Prediction Project (WEPP) model was tested using data from a detailed field-scale study conducted on experimental plots in the Apennines Mountain Range, Northern Italy. Runoff, soil water and sediment data, together with weather information, were automatically collected on a continuous hourly basis. WEPP was first applied to simulate transient surface runoff, soil water and erosion. Several input parameters, including the biomass energy ratio for evapotranspiration and the surface effective hydraulic conductivity, were calibrated using field-observed runoff, soil water, erosion and plant biomass data. The calibrated model was then used to simulate the hydrologic and erosion impacts of three typical crop rotations, and therefore to evaluate their abilities in reducing surface runoff and sediment transport. Results indicated that, with the definition of a restrictive layer at the bottom of the soil profile and the calibration of two important hydraulic and crop parameters (surface effective hydraulic conductivity and the biomass-energy ratio), WEPP could adequately model the water balance for the study plot. For the study area continuous corn under the conservation practice that delays primary and secondary tillage is a sustainable cropping system that produces minimal surface runoff and soil erosion. However, this mono-cultural practice may lead to accelerated soil quality degradation. On the other hand a four-years rotation (Corn-Wheat-Alfalfa-Alfalfa), proved to strongly reduce soil erosion under these pedo-climatic settings.