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

摘要

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, 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. 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) and integrated via subscripts to parameterize HUC 10 (sub-catchments; 53 unique catchments) and HUC 6 (total catchments; aggregate of the 53 HUC 10s) water-catchments. The model forecasts future annual erosion and water quantity and quality changes under different potential future grassland conversion rates over the next 50 years, giving insight for future landscape scale externalities of grassland conversion in South Dakota.