Review and assessment of the theories of stable alluvial channel design

Abstract

Deformable alluvial channels are known to adjust their geometry and slope to achieve stable conditions for a specified influx of water and sediment. Designing the stable alluvial channel has been a captivating topic for scientists and engineers around the globe for years. The work which was commenced by Kennedy in 1895 has been continued and various approaches have been given so far, some of which are quite interrelated and others emerged with different ideas. In this comprehensive study, some of the classic and widely accepted approaches published in the literature have been thoroughly reviewed and have been verified with available river regime data. The data set has been sub divided into three categories based on the median bed material size (sand, gravel and cobble or boulder), in order to examine the applicability of various methods available for the design of stable alluvial channels. Detailed discussion related to the properties of the intercept coefficients in power function theory is not available in published literature. In this study, the coefficients are first calibrated and then applied with the respective exponents in order to derive the hydraulic geometry. Further, the derived hydraulic geometry from various approaches is summarized and discussed with comparative view point. The analysis shows that prediction from recently developed model based on the principle of maximum entropy and minimum energy dissipation is better than other approaches for the entire range of data set. The same model has been further generalized by assuming a wide trapezoidal channel cross-section through which an improvement in the prediction has been observed.