Production and transport of suspended sediment in Sikkak wady (Tafna – North West Algeria)
Silting and solid transport constitute, by their importance, a major problem in Algeria (agricultural land degradation, silting up of reservoirs). Hydrotechnical design and planning studies very often come up against the problem of the lack or of the reduced availability of data on solid transport. Many researchers try to find a work around to tackle this problem by developing models specific to the watersheds studied. These are used to fill the gaps due to the lack of measurement data and to extend the existing series according to the water flow information that is often measured. The purpose of this study was to quantify solid transport and erosion rates in the Sikkak river basin, to determine periods of active erosion and to establish a model relating the transport of solids to the flow rate (Qs as a function of Ql). The Sikkak basin is located in north-western Algeria, covers an area of 218 km2, and includes the Sikkak dam with a capacity of 30 Hm3. We used instantaneous water discharge and suspended sediment loads measured at the Aïn Youcef station from September 1972 to August 1990. Results of analysis of the instantaneous values of suspended solid flow and their relations with water discharge show the existence of two periods of active erosion. The annual solid and liquid contributions vary greatly from one year to the next. The mean of the soil erosion rate is evaluated at 170 t•km‐2•yr‐1, varying between 4 and 745 t•km‐2•yr‐1. These values are very moderate compared to those reported for other basins of the Algeria and the Maghreb, but are very close to the values for some of the Tafna basins.