The occurrence of heavy rains in the Diamare Division (far north of Cameroon), makes this region a sensitive area to recurrent floods. This work provides a flood susceptibility map, which is an important tool for risk management, allowing priority areas to be defined for detailed studies. The methodology applied is Analytical Hierarchy Process (AHP) combined with spatial analysis in GIS. Six flood-conditioning factors were chosen based on their relevant contribution to the flood, and on the expert opinion. These factors have been weighted to determine each factor importance, in the flood occurrence. According to the map, 24, 71% of the study area, was identified as an area with very high susceptibility, whereas very low, low, moderate and high susceptibility zones covered 5,63%; 9,9%; 25,24% and 34,52% of the area, respectively. The quality of susceptibility mapping was validated by the perfect projection of historical floods in the very high and high susceptibility zones.
This work provides the map of mass movements hazard, which presents the most common phenomena in the N'fis watershed. The study is part of the contribution to the watershed management, which is highly vulnerable to natural hazards, and also in the context of the production of information and awareness documents. The methodology is the creation of thematic maps in GIS by combining, determining factors (slope, lithology, fracturing) in triggering land instabilities in the region, following decision rules. These maps are subsequently combined to yield a map of mass movements hazard. The latter shows four areas of susceptibility to hazard: low, medium, high and very high. The class of high susceptibility to hazard occupies 50.83% of the surface of the study area. This shows the sensitivity of the area to potential risks. These results were compared to the realities on the ground, allowing the validation of the method used.
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