This study evaluates the annual loss of soil in the sub-basin of Oued Haricha (Tahaddart basin, Western Rif, NW Morocco). The integration of revised (RUSLE) and modified (MUSLE) soil loss empirical equations of Wischmeier and Smith in combination with GIS permits the modelling of soil erosion at the scale of parcels. The characteristics of precipitation and runoff, the soil properties, the culture system and the current working practices of soil in the sub-basin of the Oued Haricha are collected from local data. The digital terrain model is used to generate topographic factors. The combination of different RUSLE factors shows that the annual soil is 62.72 t/ha/year and corresponds to an average level of risk. The total losses calculated by MUSLE method are valued at 221,468 t/year. The rates of loss due to linear erosion are 82,652 t/year. These soil losses represent 20.33% of the total losses, and confirm that the losses on the slopes outweigh the losses due to the river system. Sedimentation module shows that the areas of high erosion (greater than 200 t/ha/year) are concentrated in the reliefs with average and high slope and occupy 38% of the total area. The deposition areas occupy the centre of sub-basin and constitute 9.12% of the total area. These deposits were concentrated on the edges of major rivers and the outlet of the sub-basin and contributed to siltation of the April 9, 1947 dam.

A pre-accretional extensional platform of the North African Tethys during the Toarcian-Aalenian (Iguer Awragh-Afennourir syncline, western Middle Atlas, Morocco). A stratigraphic study and mapping allow defining the particular features of this area of the southwestern Middle Atlas (Morocco) during the Toarcian and the Aalenian. Numerous spectacular variations in thickness and facies are documented by the discovery of coralline build-ups dated to the Late Toarcian. They occur along the palaeostructures. Development of the structures occurred in several stages: (1) initial differentiation during the Early and Middle Toarcian; (2) homogenisation during the Late Toarcian, after the construction of the reefs. The Aalenian history is similar: differentiation (Early Aalenian)-homogenisation (Middle to Late Aalenian). Two palaeostructural trends are evident: SW-NE and transverse SSW-NNE to south-north. These caused separation of several subbasins, which alternatively deepened and shallowed, probably due to the tilting of several blocks to the southwest.

Malgré le grand nombre de puits et forages d’eau réalisés dans les différentes régions karstiques du Maroc, de nombreux inconnus subsistent encore concernant les critères d’implantation et le coût final des ouvrages. Afin d’optimiser les campagnes de forage à venir, une méthodologie de prospection multicritère a été adoptée dans la région karstique nord‑orientale du Maroc. Elle s’articule selon trois axes, à savoir : 1) détermination des linéaments hydrogéologiques à partir du traitement et interprétation des images satellitaires radar SAR ERS-1 et Landsat ETM+; 2) application de la géophysique électrique par (a) sondages électriques pour la détermination des épaisseurs des niveaux d’altération et de fracturation et par (b) trainées électriques pour la localisation précise de la zone de passage des linéaments hydrogéologiques, et finalement 3) application des techniques de Sondage par Résonance Magnétique (SRM) pour la vérification de la présence d’eau. Les différents résultats de sondages mécaniques réalisés à la suite de cette campagne de prospection montrent un taux de réussite très satisfaisant.In spite of the great number of water wells and drillings carried out in various karstic areas of Morocco, many unknown factors still remain concerning criteria for installing such works and for the final costs. To optimize future drilling campaigns, a multi-criteria method of prospecting was adopted in the karstic area of north-eastern Morocco. It is presented according to three axes: 1) the determination of hydrogeologic lineaments based on the analysis and interpretation of SAR ERS-1 and Landsat ETM+ images; 2) the application of electrical resistivity methods by (a) vertical electric soundings (VES) for the determination of the thicknesses of weathered layers and of fractures, and by (b) electric resistivity profiling for the determination of the exact location of hydrogeological lineament zones; and finally, 3) the application of Magnetic Resonance Sounding (MRS) for the verification of the presence of water. The various results of mechanical drilling carried out following this prospecting campaign show a very satisfactory rate of success

Abstract. Flood is considered to be one the worst kind of hazard. It has severe effects on human society in the form life losses, damages to property, roads, and on natural setting. The inventory of affected sites in Morocco is important for better risk management. This article describes the detailed process for creating, modeling, and designing the flood database. This design allows homogenization of data exchanges between national stakeholders and follows international standards for flood risk management. It is standardized and could be interoperable.