The Study Of The Static Forecast Means Of The Water Level In Tidal Reach

Being influenced by both the inland runoff and the inrush of the sea tide, the current of the tidal reach, which flows complicatedly in-to-fro, is seasonal and variable. When we forecasting the tide level of a tidal reach, the flood upstream and the tide downstream should be considered, and at the same time, the general effect of many intricate factor including regional inflow, wind power, wind direction and air pressure should also be considered. Thus the tide level forecast of tidal reach is more complicated and difficult.In this paper, the present research of the tidal level forecast of tidal reach was analysis, the necessary and the feasibility of doing research on the tidal level forecast of tidal reach was discussed, furthermore the theory, the method and the technical specialty of the tidal level forecast was recapitulated. Based on the physical mechanism of the change of tidal level which is of the tidal reach of Chang Jiang river basin, and started at the influence factor of the tide course of the tidal reach, the auto regressive model of time series was set up to forecast the discharge of Da Tong station upstream; The astronomical tide forecast model of Wu Song station was set up by the matured means of harmonious analysis. Then based on the equivalent water level method and combined with threshold regressive model, the real-time tidal level forecast model was set up.The tidal level forecast system of San Jiangying was exploited by modern computer technology which was keeping to the goal and the principle in designing flood forecast system, to validate the applicability of the model being researched. Using the system to forecast the tidal level of San Jiangying, the precision of the results forecasted were analyzed, and the back propagation neural networks method, which is widely used in-and-aboard at present, was used to do a contrast. The forecasting results made it clear that: the threshold regressive model accord with the physical mechanism of the change of tidal level of tidal reach; the data used by the model is simple; and the results forecasted is basically satisfied the criterion of precision of the practical forecast, and the application of the back propagation neural networks model needs a further study and improvement.