Abstract
Certain part of wash load which entered a reservoir is settled on the bed as sediment. Sediment occupies the storage capacity of reservoirs and reduces the amount of available surface water resource. Especially in North Africa which has the low vegetation land cover in the catchment and long retention time due to the clear precipitation difference between summer and winter, the wash load inflow and the sedimentation ratio is very high. In order to discuss managing the sedimentation, the behaviour of the wash load in the water body of a reservoir have to be grasped. In this study, sediment traps and auto recording thermometers were placed in the different depth in order to know what depth the floodwater enters. The amount of trapped sediment is equivalent to average sedimentation ratio. In addition, the bed area which might receive the sedimentation is estimated by numerical simulation. The volume of sediment estimated from the trapped sediment and the bed area is almost equivalent to the sediment volume which was estimated by the bathymetric survey.
