Using cumulative potential recharge for selection of GCM projections to force regional groundwater models: A Nebraska Sand Hills example

In the NSH by 2099, the Median projection indicates an increase in GRp of 3 mm/yr (+5%) relative to the 2000-2009 baseline of 52.6 mm/yr. The Wet projection has an average increase of 22 mm/yr (+42%), and the Dry projection shows an average decrease of 15 mm/yr (−29%), relative to the baseline. Effects of projection period duration and time-step averaging on selection of GR projections with this approach are discussed. The new detailed GRp projections clarify varying trends of past large-scale analyses of the Northern High Plains region and indicate the possibility for substantial future changes in the NSH hydrologic system. This approach can be extended to other arid-to-humid regions with available GCM hydroclimate projections.