Modelling the future of groundwater resources in central Spain

Abstract

This paper looks at the potential implications of land use and climate change for replenishment of the five aquifers which lie beneath the Upper Guadiana catchment in central Spain. The impacts of scenarios for climate and land use change on groundwater recharge are explored using a physically based hydrological model. (Research is the downward flux of water from the base of the root zone, beyond which water is no longer available for evapotranspiration and forms part of the groundwater resource.) The model is integrated for a series of climate change scenarios spanning the range of predictions from general circulation models. Aquifer replenishment through recharge from the main four cover types is examined for each scenario and the implications for groundwater resources are examined. These climate scenarios are then coupled with a scenario for change in irrigated land use in the Guadiana derived from a cellular automata model based on historical change. The implications of coupled climate and land use change are discussed. The results indicate that current climatic variability has greater impacts on groundwater recharge than a number of extreme scenarios for climatic change. Although the impact of the land use change scenario is greater than that of the climate change scenarios, it is still significantly less than current vairability and represents a relatively small change at the catchment scale. This change is too small to significantly affect groundwater resources but may impact surface flows.