On the impact of climate variability on surface water-groundwater interactions at the catchment scale.

Climate variability and change is expected to impact groundwater resources through changes in recharge and evapotranspiration rates. However, the magnitude and direction of change as a result of projected increases in temperature and changes in precipitation rates and patterns are poorly understood. In this study, we used an integrated groundwater–surface water–land surface model (ParFlow.CLM) across a semi-arid catchment located in the central west New South Wales, Australia to explore variability in water and energy fluxes under historic condition and scenarios of climate change. The Baldry hydrological observatory situated in a topographically flat terrain has the area of 2 km2 and contains two distinct land cover types of pasture and a regenerated Eucalyptus forest. High resolution groundwater level measurements in the site reveal differences in groundwater connectivity in wet versus dry periods in pasture and Eucalyptus forest for the historic condition. Using downscaled climate forcing obtained from three regional climate models for eastern Australia, variability in surface water-groundwater exchange examined under various scenarios of climate change. It is expected that a fully integrated hydrologic model like ParFlow.CLM improve predictions in land-atmospheric feedback processes under changes in hydrologic conditions.