Prospección de recursos hídricos subterráneos en el área de Zug (Tiris, Sahara Occidental)

Zusammenfassung

The area of Zug is located in the southwestern corner of the Tiris dorsal, in the Western Sahara. The area is characterized by outcrops of materials, mainly gneisses of archaic age and fractured granitic rocks, which in the southern sector are covered by aeolian sand sheets. A hydrogeological survey of the territory has been carried out, and boreholes and dug wells have been located and analyzed and this information integrated with the sparse outcrops. Based on this study, two hydrogeological domains have been established: Zug and Azzefal. From the analysis of satellite images, field work, geophysical profiles, a well inventory and chemical analysis, three priority areas for the location of future water supply wells have been identified: 1) alluvial fans, preferably located on the slopes of the dikes that cross the Tiris dorsal; 2) sabkhas (salt flats) as places of concentration of ephemeral runoff and subsurface infiltration of accumulated water; 3) highly fractured granitic areas. Some of these three cases coincide with existing wells in this area. Electrical tomography shows how, in specific locations, low resistivity values reach 50 metres, opening up the possibility of finding sufficient water to meet the aforementioned needs. The water quality is not suitable for human supply directly from the well without chemical treatment. The area is still full of opportunities for future research, but only when a more stable political situation exists.