Estimating Erosion, Water Quantity and Quality Changes in Response to South Dakota Grassland Conversion using System Dynamics

About the Presentation

South Dakota is a mosaic of grasslands, wetlands, and cropland. A continued shift from grassland to cropland has occurred over the past 10 years and is expected to continue for the next 50 years. The rate of future conversion may vary greatly depending on economics, policy, and demographic factors. In any case, the land conversion will influence cumulative erosion from arable soils which could potentially impact stream and river hydrology and water quality. Quantifying future changes for these three externalities is important to understand the possible consequences of grassland conversion. This presentation will show forecasted results for rill and sheet erosion, water quality and quantity for a subset of my study area within the Big Sioux River (BSR) water catchment under various grassland conversion scenarios. A System Dynamics approach will address the dynamic complexity of this system by capturing its structure and behavior and revealing key leverage points that influence change for these environmental externalities. It also provides a robust method to generate estimates for water catchments with fewer data. Annual grassland conversion has been captured using a recently developed thematic map of the contiguous United States (1947-2062; USGS 2014). Spatial land cover, soils, and climate data have been delineated by hydrologic unit codes 10 (HUCs). The subset HUC-10, Skunk Creek, model provides forecast future annual erosion, water quantity and quality under different potential future grassland conversion rates over the next 50 years. This initial model will then be locally calibrated for the remaining study area in the BSR and the other water catchments to provide sub-catchment and whole catchment estimates, giving insight for future landscape scale externalities of grassland conversion in South Dakota