Study And Application On Hydrologic-hydrodynamic Coupling Model In Dagujia River Catchment

In the hills, plains mixed areas, the watershed underlying surface is change drastically, the condition of runoff and concentration are complex, river flow is both affected by upstream water, the downstream backwater jacking and other main stream flow. The traditional hydrology flood forecast model can’t be well reflected the runoff features in this kind of basin. In order to solve this situation, consider combining hydrology model and hydraulics model in turn to studied on flood forecasting model in hills, plains mixed area In order to reflect river confluence the truth as much as possible; Secondly with the aid of computer and other tools to solve the saint venant equations, it can get the water level process and discharge in the cross section of the river channel. Finall, use the hydrologic-hydraulic coupling model as a channel flow ability influence factors analysis tools.The main research content and results ars as follows:(1) In view of the traditional watershed hydrological models can’t accurately describe the river flow movement, first DHF model is adopted to establish the hydrology model of study area, and then detailed study the the principle and construction method of Preissmann off-center implicit scheme, analyzes the special model parameters and the boundary conditions in the process of building a one-dimensional hydrodynamic model.Finally studied the hydrological hydrodynamic model coupling method and its computer implementation. The hydrological and hydrodynamic coupling model is set up as a tool of river flood forecast and flood protection ability of river course.(2) In order to guarantee the model for calculating the reliability, to prove the advantage of coupling model, using MIKE11HD model instead of one dimensional hydrodynamic model to simulate the flood in the cross section of the river basin export. Then built DHF flood forecasting model in waijia river basin. Results indicate that two kinds of water dynamic model calculated results error is very small, and simply use the DHF model’s results fitted not well with measured data, the error of, especially flood peak flux and flood peak appearance time is large, this model can’ t well reflect regional runoff yield and concentration characteristics and river flow evolution process.In conclusion, the coupling model had higher accuracy, reasonable construction, stable and reliable calculation, could go for the river basin flood forecasting in the future.(3)The qingyang river ofent revealed flood events when the discharge less than the safety discharge. In order to solve the problem, firstly analyze the factors of this problem; then built the hydrologic-hydrodynamic coupling model in the whole basin. Finally, design different model simulated input conditions and analysis the flow ability and influencing factors of qingyang river, including wajiahe river flow and the water level change of estuary. Research results show that when the reservoir discharge is larger than the wajiahe river flow, the reservoir discharge is the largest impact; when the reservoir discharge is less than the wajiahe river flow, the wajiahe river flow is the largest impact. The maximum discharge of menlou reservoir must controll in 1200m3/s, once the waijia river have a flood, must reduce the discharge of reservoir to ensure the safety of qingyang river.Lastly, the conclusions and problems need to be further studied are given at the end of the paper.