River flood modeling for integrated flood risk management: case of Tahaddart watershed (Northwestern Morocco)
In the Mediterranean region, both past and future flood patterns require planners and decision makers to take flood risk into account. Actually, flood frequencies will rise due to climate change. In this context, it is crucial to identify areas potentially at risk in order to set better management practices. The methodology used in the article can provide a tool for assessing flood risk at the watershed scale. It is based on the idea that the risk of flooding is the result of the hazard factor (physical intensity-frequency of natural phenomenon) and the vulnerability factor (land use sensitivity to flood damages). Hazard assessment is a combination of the two notions of flood recurrence and submergence. On one hand, hydraulic modeling tracks the spatio-temporal evolution of the flood and on the other hand vulnerability assessment deals with land-use and explains why direct and indirect economic damages occur when water floods a particular area. The study took place in the Tahaddart watershed (northwestern Morocco). Flood hazard is really high and vulnerability moderate. But the urban areas' extension results in a growing vulnerability and explains how 8% of the watershed is prone to flooding of which half is assessed as high risk. A flood risk map has been produced to help local authorities and planners design mitigation measures and aim at the most pressing areas. They will thus be able to act more efficiently in case of a flood.