Abstract

The present research has been carried out within the frame work of the target program “Integrated research in the Amur River Basin” of the Far East Branch, Russian Academy of Sciences.

The paper features the results of geomorphological studies in the lower reaches of the Zeya River, which is one of the largest left tributaries of the Amur River. The studies of the erosion and fluvial processes in the Zeya valley as well as the current channel processes of the Zeya River have revealed the peculiarities of the channel formation in its lover reaches. Basing on the analysis of the bed-load we established a character of the changes in its composition in the Zeya River channel and its main supply sources i.e. fluvial processes developed within the basin.

The sediments brought in the channel in great volumes due to the fluvial processes cause the replacement of the channel meandering (290-137 km) by its subsequent braiding (137-0 km).

The regulation of the river flow and the related rearrangement of the hydrologic characteristics (first of all, it is a reduction in maximum water discharge) resulted in the additional decrease in a transportation capacity of the stream, active sediment accumulation and intense channel reformation within the lower section of the Zeya River. Due to the above factors the braiding process has grow sharper and has become more complex. There are also features of the sediment accumulation in the lower Zeya channel. A preservation of that tendency can cause the activation of the landslide processes on the right bank of the Zeya River.

Keywords: The Zeya River, channel processes, channel-forming alluvium, bed-load, water level changes, sediment accumulation, erosion, grain-size distribution of alluvium.