Development Of The Watershed Flood Forecasting Model And Its Application To A Basin In Semi-Aridy And Semi-Humid Region

During the process of developing the hydrologic watershed model, much work has been done for humid regions and the computation methodology for humid areas was relatively mature, but the work for semi-arid and semi-humid regions were rare and poor. Either in the domestic or on abroad, the hydrologic watershed model still has problems to be solved before it mat be put inyo use in the semi-arid and semi-humid regions. Therefore, study on the model development for semi-arid and semi-humid regions is of significance both to hydrologic theory and to practical application.Starting from analysis of defects of the existing hydrologic models, focusing on the disadvantages of the models for semi-arid and semi-humid regions, the structure, parameters and functionc of the ShuangChao model were expounded by means of comparative analysis and group comparison in this dissertation. At the same time, the XinAnJiang Model, which is famous in China, was introduced and its success was expounded with the theory of systemic modelization.Based on the comprehensive analysis on XinAnJiang and ShuangChao model, and the understanding of the hydrologic characteristics in semi-arid and semi-humid regions, a new model for the semi-arid and semi-humid regions was developed according to the theory of systemic modelization, which will be abbreviated to SAH in the diassertation. Then, the structure and characteristics of the SAH model were elaborated in detail.In order to validate the SAH model, three hydrologic models (SAH Model, XinAnJiang Model and ShuangChao Model) were applicated to the upper reaches of Wenyu River, ShanXi Province. It was shown by simulation of 14 rain-runoff events that the proposed SAH model was better than the other two, because of its suitable structure and pertinent features. And it was shown by simulation results that there was no obvious systemic deviation, and that the setting of model parameters was measured up to the systemic modelization.The setting and calibration of model parameters were of significant to the hydrologic watershed model, so that the relativity and sensitivity analysis were conducted. It was shown by the analysis that a little relativity was existed but almost independent between layer and layer of the SAH model parameters. The parameter's relativity was appeared within the layer of the SAH model. The 8 parameters of SAH model,3 were lower sensitive parameters,4 were medium ones, and only 1 was high sensitive one. These parameters composition made the model more stable.Through the comparative studies of results of SAH and XinAnJiang Model applicated to Wenyu watershed, and model structure analysis and relativity and sensitivity analysis of parameters, a primary conclusion was obtained that the SAH model structuere was fit for runoff formulation law of semi-arid and semi-humid regions, the developing process was in accordance with modelization theory and mathematical approach.The time scale analysis was conducted, in which the effects of input rainfall data with different time step on the runoff forecasting were discuss. It might provide some usefull information for flood forecasting with rainfall data with different time step, especially for urban rush flood caused by heavy storm with short duration.