No abstract

Surface water and groundwater are two interrelated components, where the influence of one automatically affects the quantity and quality of the other. These exchange flows are robustly influenced by some mechanisms such as permeability, lithological nature of the soil, landscape, in addition to the difference between the hydrometric height of the river and the piezometric level of groundwater. The study area of Bou Ahmed plain is vulnerable to intensive pumping mainly in the coastal fringe. The increase in water demand, due to demographic development, is accompanied by pressure on groundwater abstraction which causes significant drops of the groundwater level. The main objectives of this study are to develop Geographic Information System database and mathematical models to analyze spatial and temporal hydrogeological characteristics and hydrodynamic functioning of groundwater flow of the Bou Ahmed aquifer. The present work exhibits the characteristics of the river-groundwater exchanges in an alluvial plain. Therefore, we quantified the flows exchanged between a river and its groundwater using GIS tools along with measurements of parameters obtained by the differential gauging, which was carried out in the field, and hydrogeological boreholes data. These quantified flows, moreover, enabled us to eventually estimate the uncertainties related to the use of the GIS method. These results will also be used to support a set of groundwater simulations based on MODFLOW code in the Bou Ahmad aquifer. These models also associated with develop Geographic Information System will help to better plan, manage and control the groundwater resources of this aquifer.

Many coastal aquifers have experienced seawater intrusion (SWI) into fresh groundwater aquifers. The principal causes of SWI include over-pumping and events such as climate change (CC) and rising sea levels. In northern Morocco, the Rmel-Oulad Ogbane coastal aquifer (ROOCA) supplies high-quality groundwater for drinking water and agriculture. This favorable situation has led to increased pumping, resulting in environmental challenges such as dropping water table and SWI. Furthermore, the climate has resulted in less recharge, with an estimated annual precipitation of 602 mm and an average temperature of 18.5 °C. The goal of this study is to determine how CC, over-pumping, and sea-level rise (SLR) affect SWI. Computational groundwater and solute transport models are used to simulate the spatial and temporal evolution of hydraulic heads and groundwater solute concentrations. The calibration is based on steady and transient groundwater levels from 1962 to 2040. SWI simulations show that the NW sector of the coastal area would be polluted, with the toe reaching 5.2 km inland with a significant salinity (15–25 g/L). To protect the fresh water in the reservoir from SWI, enhanced groundwater development and management approaches for this aquifer are required, such as artificial recharge from surface water.

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