Theme 1-4-Prediction of deposited sediment at the entrance of Toushka project

Abstract

The south valley canal aims to create a new civilization and society where it is expected to serve water for the agriculture of about 540000 feddans. The entrance of this canal is located 10 km downstream Toushka spillway (250 km upstream Aswan High Dam-AHD). The most important component of Toushka project is the huge pump station. It consists of 21 pumps (18 are operational and 3 are stand by). They take water from AHD reservoir through a channel of about 4km length. It is of utmost importance to predict the amount and time needed for sediment to reach this channel. One-dimensional model for sediment transport and consolidation in Aswan High Dam Reservoir-AHDR (Abdel-Aziz T.M. 1991) is used for this purpose. The model is based on the principle equations of water volume conservation, water momentum conservation and a general sediment transport equation, based on an improved rating curve for Dongola station at the inlet and a modified Shield’s equation at the reservoir. Also, an improved consolidation model independent of the sedimentation time was used, where the average bed density was calculated as a mass balance of the existing consolidating sediments influenced by deposition or erosion. The model shows that the average thickness of deposited sediment at Toushka cross section (256 km upstream AHD) is 13 cm in year 2000 from the beginning of reservoir operation (in May 1964). This is very close to the actual measurements. Consequently, more runs were done for the model to predict the average thickness of deposition in 2010. It is expected to reach about 19 cm, which indicates that the rate of deposition is about 3 cm every 5 years at the location of the pump station.