The impact of climate change on groundwater resources in coastal aquifers: case of the alluvial aquifer of Mitidja in Algeria

The climate change has an effect on groundwater aquifers in some parts of the world. Algeria is considered as a vulnerable country in the world regarding the availability of water resources. The water supply is the main challenge of the public institutions under these natural conditions and human activities. The goal of this work is to assess the impact of climate change on groundwater resources, especially in the coastal aquifers, case of Mitidja in northern Algeria. In this study area, rainfalls were decreased at about 20% from 1905 to 2011, with a significant irregularity in this period. The analysis of piezometric map shows a decrease of groundwater levels from 1974 to 2010 at more than 10 m in average. It shows also high salinity in the coastal sector due to seawater intrusion after the overexploitation of groundwater in the catchment fields. It shows a high value of electrical conductivity (average of 2200 mu S/cm), and high concentration of chlorides (an average of 386 mg/l). The analysis of physicochemical parameters of groundwater shows also high concentrations of nitrate for the major part of the plain, they are moderately higher than the standard value (50 mg/l). It is due to the anthropogenic activities in Mitidja plain such as the agricultural origin, primarily linked to the intensification and abusive uses of fertilizers. We can also report urban pollution in this plain, which comes from the discharge sewerage networks without treatment.