Isotopic assessment of the impacts of climatic and hydrological changes on wetland-groundwater ecosystem interactions

Groundwater systems act as a buffer against climate variability when surface water systems are low. However, replenishment of the groundwater system via recharge is being impacted not just by climate change but also by variable groundwater management practices and land use changes. Visualisation of these impacts on groundwater is difficult, driving assumptions that the resource is more resilient than it is. In contrast to groundwater systems, wetlands provide strong visualisation of how water resources are impacted by both natural and anthropogenic processes. Wetlands and groundwater systems are not independent entities though since connectivity between them is essential to maintaining the quality and quantity of water in both. Understanding this connectivity is critical for the long-term protection of wetlands as well as sustainability of groundwater systems. Local authorities and decision makers can see the impacts on wetlands but to understand how these impacts flow to the groundwater system requires a quantitative assessment of hydrological fluxes and processes in wetlands. These include identifying water sources and sinks, intra-wetland flow paths, evaporation processes, and water residence time. Environmental stable and radioactive isotopes, together with conventional hydrogeological tools (remote sensing, GIS, pumping tests, geophysical tools and hydrochemistry), provide unique information on origins, interactions, and transit times that are key to better understanding hydrological processes and fluxes in these changing environments. The CRP will evaluate the impact of hydrological change, driven by land use changes and climate change, in wetland areas on the quantity of groundwater linked to the wetland systems. As wetlands provide an important buffer against the impacts of both drought and floods, understanding their functional relationship to the linked groundwater system is thus an important requirement for mitigation of the future impacts of climate change. The CRP will provide guidelines on how to use both stable and radioactive isotopes to assess groundwater resources through the lens of wetland systems in Member States.