Integrated Assessment of Bioenergy Land Use and Climate Change on Ecohydrologic Response in the Midwest USA.

High yielding perennial grasses such as Miscanthus and switchgrass, and crop residues such as corn stover are expected to play a significant role in meeting US biofuel production targets. We have improved process representation of simulating bioenergy crops in the Soil and Water Assessment Tool (SWAT) model and have used the improved model to determine potential impacts of various plausible bioenergy crop production scenarios. The bioenergy scenarios, included: production of Miscanthus × giganteus and switchgrass on highly erodible landscape positions, agricultural marginal land areas, and pastures, removal of corn stover at various rates, and combinations of these scenarios. The hydrology and water quality impacts of land use change scenarios were estimated for two watersheds in Midwest USA (1) Wildcat Creek watershed (drainage area of 2,083 km²) located in north-central Indiana and (2) St. Joseph River watershed (drainage area of 2,809 km²) located in Indiana, Ohio, and Michigan. We have also simulated the impacts of climate change and variability on environmental sustainability and have compared climate change impacts with land use change impacts. The study results indicated improved water quality with perennial grass scenarios compared to current row crop production impacts. Erosion reduction with perennial energy crop production scenarios ranged between 0.2% and 59%. Stream flow at the watershed outlet were reduced between 0.2 and 8% among various bioenergy crop production scenarios. Stover removal scenarios indicated increased erosion compared to baseline conditions due to reduced soil cover after stover harvest. Stream flow and nitrate loading were reduced with stover removal due to increased soil evaporation and reduced mineralization. A comparison of land use and climate change impacts indicates that land use changes will have considerably larger impacts on hydrology, water quality and environmental sustainability compared to climate change and variability.