Mapping potential areas for groundwater storage in the High Guir Basin(Morocco):Contribution of remote sensing and geographic information system

Identification of water potential areas in arid regions is a crucial element for the enhancement of their water resources and socio-economic development. In fact, water resources system-planning can be used to make various decisions and implement manage- ment of water resources policies. The purpose of this study is to identify groundwater sto- rage areas in the high Guir Basin by implementing Geographic Information System (GIS) and Remote Sensing methods. The required data for this study can be summarized into five critical factors: Topography (slope), lithology, rainfall, rock fracture and drainage. These critical factors have been converted by the GIS into thematic maps. For each cri- tical parameter, a coefficient with weight was attributed according to its importance. The map of potential groundwater storage areas is obtained by adding the products (coeffi- cient × weight) of the five parameters. The results show that 50% to 64% of the total area of the High Guir Basin is potentially rich in groundwater, where most of fracture systems are intensely developed. The obtained results are validated with specific yield of the aqui- fer in the study area. It is noted that there is a strong positive correlation between excel- lent groundwater potential zones with high flows of water points and it diminishes with low specific yield with poor potential zones.

Contribution of the 3D Geological Model to the Study of the High Basin Ziz Jurassic Aquifers Structure (Central High Atlas, Morocco)

The high Ziz’s basin, which is part of the Central High Atlas, contains Jurassic superficial and deep aquifers. The information sheets are still fragmentary and insufficient because of the basin’s large size and its complex geological structure. In order to improve the knowledge of these aquifers and the determination of the structure of aquifers, a 3D geological model was developed in this study. It was constructed from information provided by 200 mechanical soundings and 81 electrical surveys and geological maps. Compiled holes were analyzed, coded and integrated in the software Groundwater Modeling System 6.0 (GMS 6.0). For doing this, five lithostratigraphic units were considered: the Domerian, the Toarcian, the Aalenian, the Bajo-Bathonian and the Quaternary. The operation of the 3D stratigraphic model allowed making it closer to the geometry of Jurassic aquifers.

A Methodology for Filtering and Inversion of Gravity Data: An Example of Application to the Determination of the Moho Undulation in Morocco

In this paper, we perform a comprehensive explanation of the geophysical inversion of gravity data, as well as, how it can be used to determine the Moho undulation and the crustal structure. This inversion problem and the necessary assumptions to solve it will be described in this paper joint to the methodology used to invert gravity data (gravity anomalies). In addition, the application of this method to the determination of the Moho undulation will be performed computing the Moho undulation in the Moroccan area, as an example. Before the inversion, it is necessary the removing of the gravity effects for shallow and very deep structures, to obtain the deep gravity anomaly field that is associated to the deep structure and Moho undulation. These effects will be removed by a filtering process of the gravity anomaly field and by subtraction of the gravity anomalies corresponding to the very deep structure. The results presented in this paper will show that the inversion of gravity data is a powerful tool, to research the structure of the crust and the upper mantle. By means of this inversion process, the principal structural features beneath of Morocco area will be revealed.