Analyze of the scour restoration characteristic of the bed material load in the downstream from the hydroproject

The bed material load is the main part of the variation of erosion and deposition of the riverbed. After the construction of hydroproject, the downstream river erosion development in long-distance and long periods are subject to the scour processes to resume along the river. With large quantities of measured data as the basis, this paper analyzes the restoration characteristic of the bed material load in the downstream from the hydroproject. It shows that with the erosion development in the downstream from the hydroproject, the bed material load sediment charge increased along the river, in the other hand , there has been a marked increase in the separation particle size between wash load and bed material load, which leaded to the increase of the bed material load particle size. Due to the bed material load particle size increase, the sediment-laden capacity of flow reduces. The gap between the sediment charge of bed material load and the sediment-laden capacity of flow is less than the gap between the sediment charge of bed material load and that before the impoundment, and it decrease along the river. The restoration of the bed material load along the river is much more adequate than that of the suspended load sediment charge. This restoration characteristic determine the law of the vertical erosion development in the downstream from the hydroproject.