Abstract

The Jialingjiang River basin is one of the main sediment contributing areas in the upper reaches of Changjiang River. Great changes have taken place in the runoff and sediment characteristic in recent years. Compared with that before the year of 1990, the annual average runoff during the period from 1991 to 2003 in the Jialingjiang River basin has decreased by 23 percent and the suspended sediment load decreased 105 million t, by 74%. The main factors to the variation include the rainfall decrease, sediment detention of hydraulic structures, soil and water conservation activities, river channel sand dredging and sedimentation. By means of typical investigations and analysis, the contributing rate of each factor to the sediment decrease at Beibei Station has been figured out. The result shows that the decrease in runoff has contributed to the decrease in total sediment runoff by 33%, the soil and water conservation measures have contributed to a reduction by 18%, the sediment detention of hydraulic structures by 30% and river channel sand dredging, sedimentation and other factors by 21%.

Keywords: Jialingjiang River, Runoff and sediment characteristic variation, Quantitative analysis on contribution of influence factors