Integrated modeling of surface water and groundwater interactions in the Eastern Mitidja Plain, North Algeria: investigating the impact of human activities and climate change

ABSTRACT The interaction between surface water and groundwater is a crucial factor in understanding water resources' dynamics and in promoting sustainable groundwater development, particularly in regions affected by human activities and climate change. This work aims to investigate dynamic interactions between El Hamiz river and Eastern Mitidja alluvial aquifer (North Algeria) using a regional three-dimensional groundwater numerical model (MODFLOW 6). A typical scenario analysis approach was conducted using historical and projected climate data from CMIP5 and CMIP6 models, as well as current and projected groundwater abstraction rates. The findings demonstrate major shifts in the flow dynamics over time. In 1982, the aquifer replenished the river at a rate of 2.59 m3/s. However, in 2019 a new state was observed in which the aquifer was recharged by the river at a rate of 0.73 m3/s. This decrease in flow rate can be linked to over-pumping and decreased recharge rates, which are expected to continue in the future. Future forecasts show that groundwater misuse affects groundwater dynamics more than climate change. However, the Algerian government's projected saltwater desalination and upgraded irrigation methods could provide a substantial contribution to the sustainable growth of groundwater resources, with a potential increase of up to 14 meters.