Sediment transport of the Blue Nile at Khartoum

摘要

The Blue Nile supplies the Nile River with the largest proportion of water and sediment. Nevertheless, very few, often contrasting data are reported in the literature about its sediment yield. This paper deals with detailed field measurement of suspended sediment transport taken at Khartoum during three flood seasons in the late 1960s. The pattern of suspended sediment concentration, discharge and grain-size variation with flow is analysed and suspended sediment yield is calculated and compared with data from different sources. No bedload transport measurements are reported in the literature for the Blue Nile. The flow data measured in the field consent to select several dune geometry criteria and to adopt the dune bedforms migration method to calculate bedload transport. The same procedure is applied also to the bedload data measured in four reaches of the Nile River, downstream of the High Aswan Dam, with channel and sediment characteristics comparable with those of the Blue Nile at Khartoum, to ascertain which dune geometry criterion provided the most reliable results. The Bagnold (1980) and Martin (2003) equations predict similar values of bedload transport that are compared with the very few bedload data assessed by other authors using different equations and methods. Finally, a good relation between flow velocity and bedload transport rate is found.