CARTOGRAPHIE DES ZONES A RISQUE DINONDATION PAR DEBORDEMENT DES COURS DEAU DANS LA REGION SEMI-MONTAGNEUSE DE MAN : APPROCHE PAR TELEDETECTION ET ANALYSE MULTICRITERE

The semi-mountainous region of Man has been affected by recurrent flooding, linked to overflowing waters, since the 2010s in connexion with climatic variability. Numerous material and human damages are linked to these floods. Face to this, this studys aim was to map areas at risk of overflow flooding in the region, with a view to helping manage these floods. Methods used include remote sensing, Geographic Information Systems and multi-criteria analysis. Factors taken into account are rainfall, topography, drainage density and soil types for the hazard, and land-use entities and population exposure for vulnerability. All these factors were mapped using satellite images and soil, demographic and field data. Thematic maps were weighted, standardized and integrated into the GIS on the basis of multi-criteria analysis. Obtained results are hazard, vulnerability and risk maps. These maps were validated by the identification and geolocation of flood-related land features. High-hazard, high-vulnerability and high-risk zones represent 36.56%, 42,39% and 33,94% of the region respectively. High-risk zones cover around 75%, 50% and 30% of the Danane, Man and Logouale departments respectively. Knowledge of these at-risk areas is an asset for decision-makers in choosing priority actions to be taken against flooding.