Computation Of Discharge Process At Inlet Of Flood Diversion Area

As one important part of the flood control system, the flood diversion area plays an very important function in the flood control project, and it is very important to model the flood routing in the flood diversion area. When modeling the flood diversion area, one problem that needs to be solved is to model the discharge variation process at the entrance of the flood diversion area. Now, the discharge at the entrance is usually calculated by weir formula, and when the submerged discharge appeared, the minimum flow is larger than zero, but with the water depth boost gradually, when the water depth equals to that of the river, the inflow at the entrance equals to zero during calculating the flood diversion area, so its is absurdity to calculate the discharge with weir formula. In this paper, the horizontal 2-D numerical model is applied to model the rule of discharge variation at the entrance of the flood diversion area.Particular contents in five chapters are presented as follows:Chap.l The object and aim of study in the paper is given, and it summarizes the current research situation of flood routing and Flood diversion area calculating and Flow over weir calculating. And the main methods of flood routing are recounted, As well as the numerical methods in common use to describe flow movements in hydrodynamics have been introduced detailed in the paper.Chap.2 The equation of the two-dimension current numerical model is introduced simply, and using the established numerical model to simulate the steady flow over weir and simulative Flood diversion area, Seen from the result calculated, It is credible to use the two-dimension current numerical model to simulate the steady flow over weir; At the same time, From the simulation of Flood diversion area we can get the following conclusion: with the depth increased, The entering current is changed from freedom to submerged, and the discharge by the gateway is gradually reduced with the increase of the submerged extent, When the water level in the Flood diversion area is equal to which in watercourse, the value of discharge is zero.Chap.3 It analyses the course of discharge of gateway from a few possible influencing factors, That is to find out the main influencing factors of Coefficient of discharge and flood routing, The results indicate that the main influencing factors of Coefficient of discharge are the opposite depth and the length of the weir.Chap.4 It analyses the main influencing factors of submerged coefficient from afew possible influencing factors, Such as roughness ?> relative height of weh% the location and width of gateway etc, The results indicate that the main influencing factors of Submerged coefficient are the opposite depth and the submergence extent. Then using the method of regression analysis to seek the regression equation of Coefficient of discharge and Submerged coefficient with each influencing factors.Chap. 5 It sums up the whole paper and prospect further research work.