干旱区生态环境知识资源中心

In arid and semi-arid areas, characterized by limited and often torrential rainfall, climatic factors play an essential role in explaining soil loss at the basin scale. Indeed, the largest share of solid materials export occurs during floods. The present study deals with the evaluation and quantification of sediment transport in the Wadi El Hammam basin, a large sub-basin of the Macta watershed characterized by strong rates of erosion. The sensitivity of rocks to erosion, the intensity of rainfall, and the human-induced alterations to the flow regime explain why the flux of suspended solids (SS) transported by the Wadi El Hammam may reach very high values. The sediment budget related to the of rainfall-runoff-sediment transport process shows good relationships, especially between the equivalent discharge (Q) and the quantity of sediment transported (C). Statistical models to reproduce SS flux are presented. After calibration and validation of models at the measured time scales, they are used to reconstruct time series of SS flux estimated from historical data of water discharge and rainfall., The relationship C-Q was modelled at the flood scale and adjusted by a power function Y = aX(b); statistical analysis of the constant a and exponent b was used to explain the behaviour of these two parameters and lead to a better understanding of the practical and theoretical aspects of the processes at work in the watershed.