Impacts of Biofuel-Induced Agricultural Land Use Changes on Watershed Hydrology and Water Quality

Abstract:

The US Energy Independence and Security Act (EISA) of 2007 has contributed to widespread changes in agricultural land uses. The impact of these land use changes on regional water resources could also be significant. Agricultural land use changes were evaluated for the Red River of the North Basin (RRNB), an international river basin shared by the US and Canada. The influence of the land use changes on spring snowmelt flooding and downstream water quality was also assessed using watershed modeling. The planting areas for corn and soybean in the basin increased by 62% and 18%, while those for spring wheat, forest, and pasture decreased by 30%, 18%, and 50%, from 2006 to 2013. Although the magnitude of spring snowmelt peak flows in the Red River did not change from pre-EISA to post-EISA, our uncertainty analysis of the normalized hydrographs revealed that the downstream streamflows had a greater variability under the post-EISA land use scenario, which may lead to greater uncertainty in predicting spring snowmelt floods in the Red River. Hydrological simulation also showed that the sediment and nutrient loads at the basin’s outlet in the US and Canada border increased under the post-EISA land use scenario, on average sediment increasing by 2.6%, TP by 14.1%, nitrate nitrogen by 5.9%, and TN by 9.1%. Potential impacts of the future biofuel crop scenarios on watershed hydrology and water quality in the RRNB were also simulated through integrated economic-hydrologic modeling.