Hydrological Modeling of Sediment Transport in the Semi-arid Region, Case of Soubella Watershed in Algeria

This paper summarizes the major hydrologic studies of the sediment transport in Algeria through a case study of Soubella watershed in Hodna basin (Algeria). Since the 70s, the Algerian Agency of Water Resources (ANRH) has installed a large number of gauging stations, which allowed carrying out many studies about sediment transport. The major contributions aimed principally to model and estimate the suspended sediment transport. Through these studies, the sediment-rating curve is the large discussed model; it is the best significant model for all the basins presented here below. Wadi Soubella watershed (183.5 km²) is characterized by an aggressive, irregular and violent rainfall. The mean annual precipitation is 288.5 mm (associated with a coefficient of variation Cv = 33% observed during 27 hydrological years 1973–2003). The results show a high specific suspended sediment yields (126 t km⁻² year⁻¹) associated with a higher interannual variability (Cv = 61%). Over the 20 years of this study, total sediment flux is mainly observed during two months: September (45.12%) and October (24.13%). Thus, the early autumn floods are responsible for most of the sediment transport. In Soubella watershed, the sediment-rating curve explains more than 75% of the variance for the whole data (pairs Q-C) at the instantaneous, monthly and seasonally scale and only 70% for the annual scale. A significant regressive relationship (logarithmic) between the sediment-rating curve coefficients (a, b) is obtained at the monthly scale for wadi Soubella and other wadis in Algeria.