关键词: 年径流量, 年输沙量, 水沙关系, 长江干流河道

Abstract: A relationship among runoff and sediment load, influential factors and flowsediment is firstly established. Four types of analytical methods on annual runoffs and sediment loads are then summarized, namely, probability and statistics analysis, regressing and fitting curves, correlation analysis and accumulationcurve method. Finally, characteristics and changing tendency of annual runoffs and sediment loads of the Changjiang River main channels are analyzed, on the basis of observed data of Cuntan, Yichang, Jianli, Hankou and Datong gauging stations during 1950-2005. Results of analysis show that (1) annual runoff increased along downstream of Changjiang River main channels while annual sediment load kept constant, the change of sediment load was roughly 10times greater than runoff, and the correlation of flow and sediment transport became feeble longitudinally along downstream of the main channels; (2) during 1950-2005, annual runoffs of the main channels basically remained unchanged while annual sediment loads showed the tendency of decrease, with obvious reduction in 1990s and accelerative decrease after 2000; (3) in regard to the effect of the Gezhouba Project and the Three Gorges Project during impounding period of 135 mNWL (normal water level), the change of upstream incoming runoffs and sediment loads was the main influential factor acting on the change of downstream runoffs and sediment loads and scouring of downstream river channels, and its effect was relatively larger than effects of flow and sediment regulation of the projects.