First International ASRO Geological Congress, El Jadida (Morocco), March 15-17, 2017 Abstract Book [ASRO-GC-2017] ISBN: 2409-4730
Contribution of GIS and geotechnics for the study of land movements, case of the Oriental Rif, Morocco TAHOURI Jad 1, TAHOURI Ibtissam 2, SADIKI Abdelhamid 1, MOHSSINE Mohammed 1, BENJELLOUN TOUIMI Khalid 2, MESRAR Haytam 1 1: Laboratory of geodynamics and natural resources (L. G. R. N). Faculty of Sciences Dhar El Mahraz; Sidi Mohamed Ben Abdellah University, Fez, Morocco. E-mail:
[email protected] 2: Bureau of Technical, Geological, Environmental and Quality Studies (BET BTK), Kenitra-Maroc / LaboRoches, Studies, Control and Tests in B.T.P, Kenitra-Morocco. 3: Laboratory of Geosystems - Environment and Sustainable Development (L.G.E.2.D). Faculty of Sciences Dhar El Mahraz; Sidi Mohamed Ben Abdellah University, Fez, Morocco.
Abstract: Landslides are an important hazard in the Oued Larbaa catchment area. 111 slope movements were identified in a 26706.81 ha test site, corresponding to 5.4% of the total area. The landslides that have occurred in recent decades and six predisposing factors were mapped for applying method to assess landslides hazard. The method is based on the principle of fuzzy logic, it consists to determining the information value that reflects the probability space, determining the temporally probability, then determining the fuzzy memberships and finally the fuzzy superposition with a gamma equal to 0,9. 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 22%, 21% has medium risk and 47 % are only slightly threatened. Through this study, it was observed that the risk areas are not necessarily that contains a large number of slides or a high degree of susceptibility but it is those who expose a large number of issues. KEYWORDS: Landslide risk, Fuzzy logic, Fuzzy memberships, susceptibility, vulnerability. Riskmap.
