Research On Water Level Forecasting Model In Downstream Of Changjiang River

To analysis damages of flood in current downstream of Changjiang River, the importance of the flood control, the key problems and the difficulties of water level forecasting in the reaches, the paper studied models for channel flood routing: to base on St.Venant equations and be solved with four-point linear implicit schemes, according to terrain as well as geography position is considered, to introduce the reverse direction of analytical method to simulate flux of every branch, and then one-dimensional hydrodynamic model is constituted. The validation result shows that with this method can simulate practicable flow pattern and possess certain precision, and then it can be used to water level forecast.Forecast of the lower boundary condition in tidal reach's one-dimensional hydrodynamic model is researched. According to influencing factor of tidal reach's water level, harmonic analysis is used to forecast the lower boundary condition, which has thought over daily mean water level. The validation result shows that precision of prediction can satisfy flood forecast's demand.The application of the one-dimensional hydrodynamic model and harmonious analysis method in Changjiang River is analyzed, the results of which are then compared. The result shows that one-dimensional hydrodynamic model is preferable. At one time, the model contains real time correction, so that it is banausic. Harmonious analysis method is used to forecast key station of long-time water data, and it can ascertain definite precision of forecasted. It present a method for water regime predictions if tidal rivers in defect of cross-section.