Primary Research On Impact Of Bank Lines-developing Projects On Flooding Preventing

As society and economy on the riverside regions developed faster and faster, the bank lines-developing projects were growing quickly. These projects in the riverway, would increase the water level, change the velocity of flow and transform the river regime. If the projects were not programmed or constructed reasonably, the projects would be too concentrated. Subsequently, the safety of flood control would be threatened. In the past, the flood control evaluation had been taken only in individual project, but hardly in projects groups, which would generate overlaying effect.In the paper, the generalized physical model experiment and the two-dimensional hydrodynamic mathematical model were applied in research of overlaying effect caused by [rojects group. The main achievements werer as follows:(1) The reault of generalized physical model experiments showed that the influence of projects group can't be considered as the linal summation of individual docks, but connect with space, number of the piers and docks and so on. Along with the increase of docks and decrease of space between piers, the ratio of water penetrating would diminish seriously. The water barrier effect appeared, accordingly, the sink roughness raised.(2) The hydrodynamic mathematical model showed that the bridges and docks would generate overlaying effect to the water level and veolicity. When the density of docks was big enough, the increase of water level will rise seriously. Also, the calculating results showed that in Wuhan reach, the reasonable density of docks groups would be 1.33 per km. If the density was bigger than that, the overlaying effect would appeare.(3) The influence of individual projects to flood control and river rigem was limited, but influence of series projects makes a big difference. The bankline-developing projects should be guided by the program, and also the whole reach should be evaluated. When a water involved projects was taken a flood control evaluation, influence of other projects in the same reach should also be considered.It is proposed that in the future, the projects are programmed to avoid overlaying effect. As for the unreasonable built docks, it is suggested to be transformed or dismantled, for the sake of flood control safety.