Landslides are an important hazard in the Oued Larbaa catchment area. 54 slope movements
were identified in a 267 km2
test site, corresponding to 3.3% of the total area. The landslides that
have occurred in recent decades and six predisposing factors were mapped for applying Informative
value method to assess landslides susceptibility. The results show that close to 30% of the catchment
area has a high to very high susceptibility to mass movements, 25% presents medium susceptibility
and 45% a low to very low threat. The obtained results are critically compared and validated through
the construction of The success rates curves and the computation of the corresponding Area Under
Curves. The vulnerability of elements exposed to this risk was estimated by a method based on
indices that quantify the damages according to four criteria, personal injury, structural damage,
functional loss and ignorance of the hazard by population. These indices were represented
cartographically. Total vulnerability is obtained by the overlay of four maps and the summation
indices. The combination of the two techniques leads to a hierarchy of the field according the
landslides risk. Areas where the risk is highest cover 21%, 69% has medium risk and 10% are only
slightly threatened.