Abstract: As alluvial bifurcate channels, the tail channels of Ganjiang River are divided into West River and East River, of which the former evolved into west branch and north branch and the latter developed into middle branch and south branch. In recent years, human activities has fundamentally changed the hydrologic regime of the tail reaches of Ganjiang River, hence affecting the water resources utilization and water eco-environment in the downstream. In the purpose of investigating the effects of regulating projects, we examine the influences of flood level, water diversion ratio, and flow velocity distribution on the river regime in the presence of different regulating projects via physical model test. Test results verify that controlled blocking project in the north branch has apparent effect on the flood level, water diversion ratio, and flow velocity distribution in each branch, whereas dredging in the south branch and building sluices in the four branches have slight impact. Dredging in the south ranch mainly results in the shift of major streamline towards the left bank, while has little impact on sectional maximum flow velocity. The test results offer reference for the optimization of the regulation projects.

Key words: channel regulation project, river network, flow characteristics, water diversion ratio, flow velocity distribution, model experiment, tail channels of Ganjiang River