Modelling Groundwater – Surface Water Interactions Under Climate Change Scenarios: insights from Axios Delta, Greece.

Competing multi-sectorial water demands as well as demands for ecosystem services in coastal aquifers exert significant pressures to local water resources. Climate change is already altering spatiotemporal rainfall and runoff distributions intensifying the management challenge. In this context, this work is looking at the impact of water allocation practices on the aquifer of the Axios river delta under climate change impact scenarios. The area is characterized by agricultural activities, primarily water intensive rice cultivation. Urban water supply is supported by the exploitation of the local aquifer. Reduced precipitation is expected to increase the risk of salinisation of this coastal aquifer. At the same time, a decrease in river flow was recorded during the last decades. Numerical simulations of groundwater – surface water interactions are carried out to understand process dynamics. A drought scenario is simulated to assess the impact of climate change and the corresponding drought management response plan on the shifting fresh/saltwater interface. The drought response scenario involves banning irrigation and increasing groundwater abstraction. The groundwater model shows that flood irrigation forms a hydraulic barrier to saline intrusion. This type of groundwater model predictions can inform water resources management policies and examine the effectiveness of interventions to support sustainable socioeconomic activity while protecting environmental health.

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