Entropy-Based Approach of Hydraulic Geometry of Navigable Canals

Abstract

In navigable canals, ship hydrodynamics compared to water flow have been the most dominant dynamic factors that influence the evolution of cross-sectional morphology, so that the existing hydraulic geometry relations used for natural alluvial rivers are not applicable to navigable canals. In this paper, a time-dependent hydraulic geometry relation was derived as a function of channel bottom width, cross-sectional average water depth above the lowest design navigable water level, and time and coefficients based on the concepts of entropy and probability. Field surveys were conducted at two segments of the Grand Canal in Jiangsu Province, China to obtain measured hydraulic and morphologic variables. Then, the coefficients in the derived relation were analyzed in combination with ship hydrodynamics, and compared with the common used value, which shows better accuracy with larger determination coefficient of .744 and .94 for the two segments, respectively. Furthermore, comparisons between the calculated and measured hydraulic geometry of fixed cross-sections of the two segments were made. The obtained relative error of 59% and 18% of all predicted results is less than 5% and between 5% and 1%, respectively, indicating that the derived relation can be applied in navigable canals.