Variation of Sediment Discharge of the Pear l River Basin from 1955 to 2005
51 年来珠江流域输沙量的变化

Draining at the southern part, the Pearl River is the third largest river in China. The Pearl River is the collective name of West River, North River and East River. Based on long series data (1955-2005) of the water and sediment discharge at the main hydrological stations and the precipitation in the drainage basin, this paper aimed to reveal the variation pattern of the sediment discharge and the causes of the Pearl River. The results are: (1) sediment discharge at Shijiao (North River), Boluo (East River), Qianjiang and Gaoyao (West River) stations show a decreasing trend, while Liuzhou (at Liujiang River, a tributary of West River) and Nanning (at Yujiang River, a tributary of West River) an increasing trend in 1955-2005; (2) the average sediment discharge into the sea from the Pearl River (the sum of the North River, East River and West River) in 1955-2005 is 7529×104 t/yr with a decreasing trend (not significant statistically). The main conclusions are: (1) the variation of precipitation contributed greatly to the yearly fluctuation of the sediment flux, but little to the decreasing trend of the sediment discharge into the sea; (2) the phased variation trend of sediment discharge into the sea is relevant to soil loss and water and soil conservation; (3) dam construction is the main cause of the decrease of the sediment discharge into the sea; and (4) a further decrease of the sediment discharge into the sea may occur in the future decades, which may cause serious environmental problems at the estuary such as slowdown of coastline progradation or even retreat. Further and in-depth study is urgently needed in view of the economic significance of the Pearl River Delta in China and the environmental issues in the estuary, including the coastal region of Hong Kong.