Floodplain mapping based on GIS techniques in Oued Fez watershed

Abstract

The urban flood risk appears among the major environmental preoccupations of actors in resources management and land planning; and this issue is exacerbated by the climatic and the global change factors. Flood, considered as one of the worst weather-related natural disaster, cause severe damages to life, properties and environment. For the floodplain mapping, we adopted an approach based on modeling of flows processes. The main sources of information are maps, hydro-meteorological data, Digital Elevation Model (DEM), satellite images, field observation, etc. This research presents a straightforward approach for processing input and output of the HEC-RAS hydraulic model, to enable two and three dimensional floodplain mapping and analysis in the ArcGIS environment. The study area concerns Fez located in Saiss plain. The agglomeration of the city is actually being developed in the area of confluence of all the hydrologic network of Oued Fez watershed. This watershed, which is composed of several sub-basins, receives its water from six essential Oueds. The results of the study indicate furthermore that Geographic Information System is an effective environment for floodplain mapping and analysis. The resulting GIS maps, consisting of flood hazard, floodplain extension and risk maps. This helpful information can guide the local early warning system of flood and identify the areas facing flood risks. Key Words: Floodplain mapping, Hydraulic modeling, Oued Fez, Morocco