This study analyses the impact of the sea level rise due to climate change and overpumping on the groundwater of Mitidja Plain (Algeria). According to the forecast performed under scenarios RCP 8.5 of the maximum sea level rise of 2.0 meters along the coast of the Algiers Bay, we estimated the new coastline positions during the years 2050, 2100 and 2200 by the Digital Terrain Model (DTM). The sea water intrusion that occurred in the Mitidja coastal aquifer was then studied by flow simulations using MODFLOW and applying the Ghyben−Herzberg theory to determine the freshwater/saltwater interface position along the coast of Algiers Bay. In particular, the flow simulations were carried out, initially, during 1983, when no overpumping from the Mitidja groundwater was recorded. Then, MODFLOW was applied again to study the groundwater flow during 2010 under overpumping conditions.
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During MODFLOW simulations, the groundwater measurements carried out by the National Agency for Hydraulic Resources (NAHR) were used as boundary conditions. Resulting maps of piezometric contour heads and velocity vectors of the groundwater flow field during overexploitation were obtained. Groundwater velocity achieves the maximum value of 0.38 m/d in the area of the pumping-well station near Hamiz, where pumping caused groundwater depressions up to 12-14 m below sea level. The thesis results suggested the implementation of artificial soil barriers in some places along the coast, and management actions, i.e. pumping flowrate limitations, wastewater reuse for irrigation and managed aquifer recharge in order to restore the Mitidja groundwater.
