Modeling and Evaluation of Alternative Agricultural Management Practices in Sand Creek Watershed

Abstract

Abstract A watershed methodology was applied with the ADAPT model to simulate monthly flow and sediment loadings from Sand Creek watershed, an agricultural watershed in south central Minnesota. Model inputs were derived from a GIS overlay of land cover, tillage practice, slope, and soil layers. The model was calibrated by comparing predicted monthly flow and sediment loadings against observed data for the watershed from 1994 to 1996. Statistical evaluation of results produced r 2 agreement of 0.85 for flow and 0.70 for sediment when compared against observed data. Using the calibrated model, alternative agricultural management practices involving adoption of conservation tillage and rotational grazing within Sand Creek watershed were evaluated. Adoption of conservation tillage throughout the watershed produced little change in overall total flow, however, total sediment loadings were reduced by 32.9%. A land use change scenario in which 32% of cropland in the watershed was converted from conventional to conservation tillage and 13% was converted from crops with conventional tillage to pasture produced a 7% decrease in flow and a 33.4% reduction in sediment loss when compared to current conditions.