Assessement of flood hazards in eastern Mitidja Plain (Hamiz river and Reghaïa river) Algiers - Algeria

Abstract : The Eastern Mitidja Plain, highly urbanized in its Northern part, is crossed by two main rivers: the Réghaïa and Hamiz wadis. Along these wadis, anarchical buildings are developing. An exceptional flood may weaken these zones. Flood hazard détermination needs a statistic analysis of daily maximum rainfalls, which adjustments to the Gumbel law allows to determinate the maximum rainfall for different return periods. The calculation of maximum discharges linked to différent return periods allows evaluating the overflowing on cross section along the Hamiz and Réghaïa wadis. Hazard maps, obtained for each wadis, evidence zones that are potentially threatened by flooding. Such maps should be considered and used as the main tools reduce the risk.