This focal area seeks to assess the medium and long-term impacts of climate change on groundwater resources and establish relevant mitigation and adaptation strategies on the global, regional and local scales. Few studies have been done until recently on the potential impact of climate change on groundwater referencing its relation to surface water. The most important direct effect of climate change on groundwater is associated with recharge patterns. Spatial and temporal distribution of precipitation, air temperature, evapotranspiration, soil moisture, groundwater levels and response time of aquifers are the main natural factors controlling groundwater recharge in different climatic zones. Reaction of deep, non-renewable and fossil aquifers to climate change impacts will last centuries or millennia; reaction of shallow, karst and coastal aquifers can last in case of groundwater recharge only weeks, months or years.
Models for prediction and quantification of groundwater systems response to the impact of climate change are facing several uncertainties due to lack of a consistent soil and groundwater global dataset. To calibrate hydrological models for simulation of spatially and temporally changing groundwater recharge, discharge and storage and inclusion of a groundwater component into land surface models require improvements in terrestrial and satellite based groundwater monitoring and monitoring data assessment and management. Coastal aquifers prone to depletion and accompanying land-level lowering contributing to sea-level rise need particular attention.
The potential impacts of climate change on groundwater quantity and quality have to be analyzed and quantified in terms of their social, economic and environmental effects on and risks for population and groundwater dependent ecosystems. Several activities will be carried out under GRAPHIC project whose continuation in IHP VIII has been proposed.