干旱区生态环境知识资源中心

The relation between sediment load and water discharge in Algerian rivers is complex and difficult to assess. Some of these difficulties are related to sampling methods and the lack of data particularly those related to the suspended sediment concentration. Hydrologists often use rating sediment transport curves to define the water discharge/suspended sediment relationship and to estimate suspended sediment concentrations for use in flux calculations. Although there are many methods for developing rating curves, the most commonly used is a power function Y=aX(b) that relates suspended sediment concentration (discharge) to water discharge. This study aims to analyze the power relationship between suspended sediment discharge and water discharge, quantify the suspended sediment intakes deposited on Sidi M’hamed Ben Aouda (SMBA) reservoir and verify the validity of this relationship for different time scales. The study also focuses on analysis of largest floods contributions to suspended sediment transport and on hysteresis effect on the relationship between suspended sediment concentration C and liquid flow Q. The analysis at different time scales of the power relationship between solid discharge and liquid flow rate in Mina river basin reveals an evolution trend of the parameters a and b. It shows that these parameters and specific indicators of the basin are close to those found by many researchers who have worked on arid and semi-arid regions. Fines sediment loads calculated show that they are practically the same for different estimation approaches, carrying a maximum error of 8%. Analysis of annual floods contributions on suspended sediment load shows that much of suspended sediment load is evacuated by some floods and it is not rare to find, during an average water year, that 80 or 95% of the suspended sediment load is attributed by two or three floods and only in about 5% of annual time. The study of the fundamental relationship between the suspended sediment concentration C and liquid flow Q during floods allows observing clockwise, counter clockwise and figure-eight hysteresis loops. It also allows initiating priority anti-erosion measures to increase the useful life and preserve the hydro potential of SMBA reservoir.