In this paper, we focus on the underground imaging and on mapping of fractures network in the Bittit Spring area that constitutes one important rising spring at the junction between the TMA and the SaГЇs Basin, with a great average annual flow of about 1600вЂ‰l/s (Figure 1(b)). The goal of this study is to characterize the transition between the reservoir of the TMA where the water is accumulated and the SaГЇs Basin where the water is used.

(b) Geological map of Bittit area with surveyed area in black rectangular. Therefore, a better understanding of hydrogeological behaviour of fracture and karst networks is fundamental for management and protection of water resources. The geometry of the aquifer, water flow paths, and the complex underground karstic organization are misknown due to lack of high resolution geophysical survey. Groundwater circulation from TMA to the SaГЇs Basin is complex due to fracturing and to karstic Quaternary travertine overlying Lias carbonates. The Liassic reservoir of TMA dips in the SaГЇs Basin under a thick Tertiary marly series, forming an important confined aquifer (Figures 1(a) and 1(b)).

This aquifer can supply water to two large cities (Fez and Meknes) and small villages. This reservoir is connected to large aquifer located the in SaГЇs plain, at north of the TMA. It makes difficult to define optimally the potential areas of drilling. Although it represents a large groundwater potential, it is still badly exploited because of the lack of data about fracture network, aquifer geometry, and recharge area. The water flows essentially along open fractures and karst cavities, with very low matrix permeability. It is one of the most important reservoirs in northern Morocco because of the climatic context and of its structure. The Tabular Middle Atlas (TMA) located at the NW border of the Middle Atlas is made up of Liassic limestone and dolomite forming a complex karstic system locally highly fractured (Figure 1(a)). The western border is well watered (from 1000 to 1500вЂ‰mm annually) because of the meteorological perturbations coming from the Atlantic Ocean. The mountain has cold winters with persistent snow above 2000вЂ‰m. The Middle Atlas is a mountain long of about 350вЂ‰km from south-western to north-eastern Morocco, located between the Rif and High Atlas. The precipitations are mainly located in mountains while water requirements are located in the plains: a good understanding of water transfer between these areas is absolutely necessary.

The climate changes (decrease of rainfalls) and the increase of water needs for human activities (farming, industry, individual needs) make critical the management of water resources. Water resources and management is one of the major environmental issues in Morocco. This result leads to propose hydrological behaviour of water from the Tabular Middle Atlas and the SaГЇs Basin at the Bittit Spring, which takes into account for both horizontal flows through stratification joints or karst and through subvertical fractures. Joint interpretation of geophysical, geological, structural, and synthetic simulation data allowed identifying a conductive horizontal shallow layer overlying two subvertical families of fractures of NE-SW and NW-SE directions. The synthetic data were calculated for the similar model expected in field data inversion and inversion result of these synthetic data used as a guide for the interpretation of the inverse data resistivity sections. The high resolution capabilities of the electrical tomography were used to define the geological draining features in the framework of water paths from the TMA to the karstic springs. Electrical resistivity tomography (ERT) survey was focused on the Bittit area that is one of the most important outlet discharges, and it is representative of the relations between the TMA and the SaГЇs Basin. The TMA is one of the most important aquifers in northern Morocco that supplies the deep aquifer of the SaГЇs Basin. Direct current Resistivity (DCR) method was carried out to characterize the hydrogeological connection between the Tabular Middle Atlas (TMA) and the SaГЇs Basin.

2022.03

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