Qualitative and quantitative evaluation of the ground movement risk on an urban cartographic scale Example of QUEMADO (Eastern Rif, Morocco)

Evaluation qualitative et quantitative du risque ’mouvement de terrain’ à une échelle cartographique urbaine Cas du versant QUEMADO (Rif oriental du Maroc)

Université Mohammed V, Faculté des sciences, Unité de recherche GEORISK, LGRN, 4 Avenue Ibn Battouta-Agdal, BP 1014, Rabat, Maroc

Abstract

The morphostructural examination of QUEMADO slope, contributes to distinguish the vulnerability indications that refer to the ground movements. They are supported by the combination of geological, geo morphological, hydro geological parameters. In addition, the seismic activity that is known in this area increases the vulnerability of the coastal areas. Thus, many cracks and locatable indices in the studied area constitute a witnesses of movement risk that threat directly the projects, the installations and the urban constructions of Al Hoceima city, in proximity of the studied cliff.

The present study is consecrated to achieve a comparative study of the evaluated risk “ground movement” by two methodological approaches. The qualitative approach which is most usually employed, and the quantitative approach that requires a scientific effort of adaptation and reproducibility. The risk evaluation is based on using four data components; mainly the topographical slope, the lithology, the geomorphology and the ground occupation. The results were interpreted by a discrete analysis of the unstable areas through the land reconnaissance