SUMMARY
Flooding is an unpredictable natural phenomenon, especially in recent years. The town of Bechar in the southwest of the Algeria, characterized by a dry climate recorded flooding in these last 10 years, including those of 2008, 2012 and 2014.Their essential causes lie with the intensity of precipitation, the specificities of the watershed and to sprawl urban city, including the extension along the Wadi Bechar represents a danger, both for the city and its population.Therefore, it is necessary to study the risk of flooding, to mitigate the magnitude and temper any damage these floods could cause. The objective of this work is in fact a study of mechanisms of management and reduction of the risk of flooding in urbanized areas.It will be to extract the water level along the Wadi Bechar and inside the city, relying on the HECRAS software, through a hydraulic modeling, during periods of different back and according to a hydrological study preliminary.This action allows to define areas at risk of flooding, to identify the water level, at the level of each point flooded, while offering facilities of the Oued Bechar, which can be put in place, for real protection of residents against any danger of flooding.