Using Major Ion and Stables Isotopes to Characterize Groundwater Recharge and Hydrochemical Processes in a Mountain-Plain Area: A Case Study in High-Atlas of Marrakech, Morocco

Piedmont landscape is especially important as groundwater recharge zones. Determination groundwater recharge origin and qualitatively, evaluate their contribution on groundwater in piedmont area of Haouz plain was based on the use of geochemical and isotopic analysis of groundwater, surface water and springs of the contact zone between the High-Atlas Chain and the Haouz plain.  The correspondence in the space evolution of the various chemical elements of evaporitic origin (SO42-, Cl-, Sr2+) in groundwater, piedmont springs, and surface water reveals the existence of recharge water from the adjacent High-Atlas Chain. The various recharge modes of the different aquifers (High Atlas and Haouz plain) determined by isotopic analysis, shows that the source of groundwater both for the alluvial aquifer of Haouz and piedmont seems to be composite between a direct infiltration on the High-Atlas tributaries and a remote recharge from the bordering High Atlas aquifers. Remarkable mountain bloc recharge was observed in the piedmont area near the axis of syncline structures, which have layers of Mesozoic and Cenozoic deposits and control groundwater mineralization both in piedmont and plain. Keywords: Groundwater recharge, Interaction groundwater-river, Mountain block recharge, Isotopic signature, Hydrochemical proces

Potential Hydrogeological, Environment and Vulnerability to Pollution of the Plio-Quaternary Aquifers of the Coastal Basin of Essaouira (Morocco)

The Essaouira synclinal area is part of the semi-arid areas of Morocco which are subject to the impacts of climate and anthropogenic pressures. It is also expected to experience an important agro-industrial development. Water requirements are important for the development of all these activities. Although the situation is not yet alarming, the fact remains that the quality of groundwater resources is constantly put to the test because of the growth sources as diffuse pollution that point. To prevent pollution of groundwater, one approach is the knowledge of especially vulnerable areas. It is for this reason that this study was initiated to produce a map of intrinsic vulnerability of aquifers in the region. The method used to make the card is the numerical rating DRASTIC method (Aller et al. 1987). In the case of this coastal area, which includes two main aquifers superimposed; the Plio-Quaternary and Turonian, the resulting vulnerability is compounded by the risk of infiltration navy. The Rainfall in the area does not exceed 300 mm year-1, the average temperature hovers around 20 ° C. The results indicate that the region is dominated by the class of high vulnerability (61%) followed by the class of very high vulnerability (20%), then the class medium vulnerability (15%) and the class of low vulnerability (4 %). Class very high vulnerability is located in the western coastal area. The center of the basin is dominated by the class of high vulnerability to the east, past the middle and low class. Almost throughout the Oued Ksob is particularly dominated by the class of high vulnerability. Keywords: basin of Essaouira; aquifer; semi-arid regions; hydro geochemistry;  stable isotopes; recharge; vulnerability, pollution, DRASTIC, management, protection of water resource

Isotopic Tool and Problematic of Recharge in Semi-Arid Area: The Case of the Coast Zone of Essaouira Basin (Morocco)

The Essaouira coastal zone is one of the Moroccan semi-arid areas with annual rainfall not exceeding 300 mm/year. This area contains several main aquifers such as: The Plio-quaternary aquifer consisting of sandstones, the Turonian aquifer composed of chalk-dolomitic rocks, the Barremian-Aptian aquifer content in calcareous clay formations, fossil limestone and sandstone and the Hauterivian aquifer housed formations of marl clay alternating with hard siliceous limestone and calcareous marl. The study had framework on the most important aquifers of the Eassouira coast zone, while having as principal objectives the dating of underground waters of the region and the sampling of main water points that supply drinkable water to the city as well as to the rural agglomerations. Different water samples were collected from drillings, sources and wells belonging to the Plio-quaternary, Turonian, Barremian-Aptian and Hauterivian aquifers of the studied region. Their electric conductivity, pH and temperature were measured in situ and water samples were collected for 18O, 2H and 3H determinations. A meteoric local line was determined and compared to the world meteoric line.The apparent radiocarbon ages of the studied aquifers were evaluated. The recharge to the main aquifers of the studied region was investigated. It has been shown by this study that the recharge rate to the deep Turonian aquifer is very low. This may cause a shortage in water supply to the Essaouira city and its surrounding region. Among the concerned aquifers, the Turonian provides more than 50 % of drinkable water to Essaouira city and rural villages and must therefore be subject to a rational and durable exploitation of the groundwater resources. Keywords: Essaouira basin, semi-arid, 18O, 2H, 3H and 14C isotopes, aquifer recharg

Using Geochemical and Isotope Investigations for Groundwater Management Strategies Under Semi-Arid Area: Case of the Wadi Ouazzi Basin (Morocco)

The characteristics of Essaouira basin water resources are a semi-arid climate, which is severely impacted by the climate (quantity and quality). Considering the importance of the Essaouira aquifer in the groundwater supply of the region, a study was conducted in order to comprehend this aquifer groundwater evolution. The Essaouira aquifer is a coastal aquifers located on the Atlantic coastline, southern (Morocco), corresponding to a sedimentary basin with an area of near 200 km2.A water sampling from twenty wells, drillings and sources belonging to the Plio-quaternary and Tu-ronian aquifers was realized (what was realized). Samples examined from the ground for electric conductivity and temperature, determined waters belonging to the Plio-quaternary and Turonian aquifers present very variable electric conductivities from 900 µs/cm to 3880 µs/cm. In spite of this variability, they form the same family and are characterized by sodium-chloride facies. There exists, however, a good correlation between the electric conductivity and chloride and sodium contents. Therefore the lower electric conductivities are situated in the North quarter immediately in the south of the Wadi Ouazzi. Keywords: Management, Wadi Ouazzi, Drought, Strategies, Semi-arid, Turonian, Plio-Quaternary