Scenarios of bioenergy development impacts on regional groundwater withdrawals

Irrigation increases agricultural productivity, but it also stresses water resources (Huffaker and Hamilton 2007). Drought and the potential for drier conditions resulting from climate change could strain water supplies in landscapes where human populations rely on finite groundwater resources for drinking, agriculture, energy, and industry (IPCC 2007). For instance, in the North American Great Plains, rowcrops are utilized for livestock feed, food, and bioenergy production (Cassman and Liska 2007), and a large portion is irrigated with groundwater from the High Plains aquifer system (McGuire 2011). Under projected future climatic conditions, greater crop water use requirements and diminished groundwater recharge rates could make rowcrop irrigation less feasible in some areas (Rosenberg et al. 1999; Sophocleous 2005). The Rainwater Basin region of south central Nebraska, United States, is an intensively farmed and irrigated Great Plains landscape dominated by corn (Zea mays L.) and soybean (Glycine max L.) production (Bishop and Vrtiska 2008). Ten starch-based ethanol plants currently service the region, producing ethanol from corn grain (figure 1). In this study, we explore the potential of switchgrass (Panicum virgatum L.), a drought-tolerant alternative bioenergy feedstock, to impact regional annual groundwater withdrawals for irrigation under warmer and drier future conditions. Although our research context is specific to the Rainwater Basin and surrounding North American Great Plains, we believe the broader research question is internationally pertinent and hope that this study simulates similar research in other areas.