Research Of Hydraulic Geometry In Alluvial Channels Based On Extreme Hypotheses

The extreme hypothesis is common law used in the research of riverbed evolution of alluvial channels presently. So far, there have been many extreme hypotheses proposed and used to explain the self-adjustment of alluvial channels. Hydraulic geometry are the results of the adjustment of alluvial channels, so this paper uses extreme hypotheses to study hydraulic geometry in alluvial channels. Primary contents of this research are as follows:1. The research methods in hydraulic geometry have been analyzed comparatively. Each method is based on some inadequate theory. In this paper, the author does a comparative analysis of the source and basic relations of these research methods to find out their insufficiencies and correlation. On the basis of the above analysis, the author draws a conclusion that the extreme hypothesis method is most fitful for hydraulic geometry's research.2. A unified hydraulic geometry model by using extreme hypothesis is put up, and the facts of influencing hydraulic geometry are analyzed completely in this paper. The author points out that the cross-section shape, equation of water flow, equation of sediment transport rate, and extreme hypothesis are all affect the research of hydraulic geometry. Moreover, the results of the hydraulic geometry by using the maximum J,Q sor Q is presented.3. By using the above unified hydraulic geometry model, the hydraulic geometries of some special cases are analyzed and compared with other research results. Also, the unified hydraulic geometry model is compared with field data, the results by this paper agree well with measured data. So, the unified hydraulic geometry model can be used for the calculation of actual problems.4. The formula of basic hydraulic geometry relation is presented theoretically based on the researches of hydraulic geometry. And this relation has high precision when certificated by some existing hydraulic geometry relations.