Predetermination of flood flows by different methods: Case of the catchment area of the Biskra Oued (North-East Algeria)

Abstract

For several years now, the problem of extreme rainfall events has been acutely felt in Algeria, particularly the risk of flooding which threatens several towns, which have already faced this hazard with tragic consequences. To fight against floods, a long series of flood flow measurements is necessary, which unfortunately is not the case most of the time (Daifalah et al Technol Sci Rev Sum 34:74–84, 2017). This is the case of the Wadi Biskra catchment area. The stopping of the hydrometric stations of El kantara, and Djemoura; controlling this catchment area, over an area of 2787 km2, poses a serious data problem. To overcome this handicap, we have used the values of maximum flows, the recent series available covers a period of 28 years (1968–1995). Whereas the Djemoura station: the recent series available covers a period of 22 years (1972/1993), which fits well with the Gumbel law. From the adjustment line, the values of probable floods for different return periods of 2–1000 years were determined. To protect the population against floods caused by floods, operational and reliable forecasting tools are required. The rain-flow model uses knowledge of rainfall. It is applicable at any point in the hydrographic network. Among these hydrological models, a probabilistic model (Gradex) has been chosen to assess the risks of extreme floods, and which allows extrapolation to different return periods. To achieve our second objective, which is the possibility of reconstructing flood flows using empirical formulae based on precipitation. The two formulas used for the determination of the flood flows (Turazza formula and Sokolvosky formula) gave identical results to those measured at the gauging station.