Analysis on sediment resources downstream the Three Gorges Project

The river sand has a dual attribute of both catastrophability and resource availability, and the resource availability becomes more and more apparent now. This paper analyzes the variation of sand and gravel resources downstream the Three Gorges Project (TGP) using hydrological data. Results show that sediment entering downstream channel greatly reduced in initial operation of TGP, and the annual sediment load at Yichang hydrological station is 0.0542 billion tons since 2003 to 2012. Sediment load regains to 0.1516 billion tons at Datong which is almost 3 times that of Yichang due to riverbed erosion and supply of tributaries and lakes. Other large-scale reservoirs upstream of TGP also leads to less sediment released from TGP reservoir. Only riverbed erosion contributes to regaining of sediment concentration. 1-D mathematical modeling results show that, the annual average sediment load at Datong would regain to half of that before the impoundment of TGP by 2032.