Contribution of GIS and Hydraulic Model for Water Related Risk Management in the Saharan Region: Case of Flooding in the Wadi Bechar Watershed

The city of Bechar in Algeria, recorded some extreme events. Among these, the flood of 2008 which marked an exceptional flood of 830 m3/s of flow, and also that of 2012 and 2014. The problem underlined is that most of the city of Bechar has a sprawl urban prolonged on the banks of the watercourse of Oueds Bechar which causes a major risk on the life of the inhabitants. The objective of our work is to estimate the risk of flooding by the mapping of the flood, the latter consists in determining the flows of the return periods of 25ans, 50ans and 100ans for this, it is necessary the adjustment of the flows by Gumbel law, using a computer support HEC-RAS, HEC-GeoRAS and ArcGis for the mapping of the event. Finally, this work allowed us to determine the zones at risk of flooding and to classify them according to the height of flood waters.