Potential Impacts of Climate Change on Groundwater Supplies to the Donana Wetland, Spain

Climate change impacts on natural recharge and groundwater-wetland dynamics were investigated for the Almonte-Marismas aquifer, Spain, which supports the internationally important Do ana wetland. Simulations were carried out using outputs from 13 global climate models to assess the impacts of climate change. Reductions in flow from the aquifer to streams and springs flooding the wetland, induced by changes in recharge according to different climate projections, were modelled. The results project that the change in climate by the 2080s, under a medium-high greenhouse gas emissions scenario, leads to a reduction in groundwater resources. The reduction in mean recharge ranges from 14%-57%. The simulations show that there is an impact on hydraulic head in terms of the overall water table configuration with decreases in groundwater level ranging from 0-17 m. Most simulations produce lower discharge rates from the aquifer to stream basins, with significant reductions in the larger La Rocina (between -55% and -25%) and Marismas (between -68% and -43%) catchments. Water flows from these two basins are critical to maintain aquatic life in the wetland and riparian ecosystems. Modelled climate-induced reductions in total groundwater discharge to the surface are generally larger than current groundwater abstraction rates. The results highlight that effective strategies for groundwater resources management in response to future climate change are imperative.