Study on the measurement method of river bed roughness
[Objective]The roughness of river bed surface is an important research content in river dynamics.[Methods]Statis-tical analysis is used to quantify the roughness of river bed surface.Without considering the macroscopic undulation of the river-bed,the initial rough bed surface is artificially paved with non-uniform natural sand,and the flow rate is gradually increased to coarsen the bed surface.After the coarsening is completed,the accurate digital elevation of the test bed surface is obtained by la-ser scanning technology.Based on the statistical theory,the structural characteristics of the surface layer of the river bed after coarsening under different incoming water conditions are explored,and a new method for measuring the roughness of the bed sur-face is established by using the theoretical model satisfied by the statistical parameters of the bed surface elevation and the varia-tion function.[Results]The result show that the fitting relationship between Manning roughness n and median particle size is general,and the correlation coefficient is 0.649.The fitting relationship between n and standard deviation,mode and skewness is good,and the fitting relationship between n and kurtosis is relatively poor.There is a good correlation between n and the typical parameters of the three variogram spherical models.The fitting relationship between the nugget value of the average variogram of the profile and the base value and n is excellent,and the correlation coefficient is above 0.89.[Conclusion]The result show that the representative particle size method can be used to describe the roughness characteristics of the bed surface at certain times.The standard deviation of the elevation data increases strictly with the increase of the flow intensity and its mode decreases strictly with the increase of the flow structure,which makes them excellent indicators for quantifying the roughness of the bed sur-face.The monotonic trend of skewness and kurtosis makes it possible to be used as a measure of bed roughness.The gold value and the abutment value can be used as indicators of the roughness of the bed surface.In this study,the method of measuring the rough-ness of river bed surface is discussed by statistical method,which has some enlightenment for the measurement of roughness.
bed roughnessstatistical parametersmanning roughnessvariogramspherical modelhydraulic characteristics
国家科技期刊平台
NSTL
万方数据
维普
