Interdependence of groundwater dynamics and land-energy feedbacks under climate change

Climate change will have a significant impact on the hydrologic cycle, creating changes in freshwater resources, land cover and land-atmosphere feedbacks. Recent studies have investigated the response of groundwater to climate change but do not account for energy feedbacks across the complete hydrologic cycle. Although land-surface models have begun to include an operational groundwater-type component, they do not include physically based lateral surface and subsurface flow and allow only for vertical transport processes. Here we use a variably saturated groundwater flow model with integrated overland flow and land-surface model processes to examine the interplay between water and energy flows in a changing climate for the southern Great Plains, USA, an important agricultural region that is susceptible to drought. We compare three scenario simulations with modified atmospheric forcing in terms of temperature and precipitation with a simulation of present-day climate. We find that groundwater depth, which results from lateral water flow at the surface and subsurface, determines the relative susceptibility of regions to changes in temperature and precipitation. This groundwater control is critical to understand processes of recharge and drought in a changing climate.