Transverse energy loss slope in meandering channels

Abstract

Limited research has been conducted on transverse energy loss in meandering channels. Previous studies made assumptions regarding a linear vertical profile of transverse velocity and rectangular cross sections with horizontal transverse beds, neglecting the effects of nonlinear transverse velocity profiles and transverse bed slopes that contribute to topographic steering. In this study, a novel expression for the transverse energy loss slope is derived analytically. This expression incorporates a nonlinear vertical distribution for transverse velocity and considers non-rectangular cross sections, thereby improving the computation of roughness coefficients in curved channels. A topographic steering number is introduced, which indicates the presence of topographic steering when it exceeds unity. The developed equation rectifies the previous underestimation of sinuosity in natural rivers when compared to existing equations. Additionally, an expression for superelevation is derived, accounting for channel roughness and transverse bed slope, unlike previous equations. The study reveals that roughness can significantly affect the height difference between outer and inner banks. Under higher roughness conditions, the height difference can exceed predictions from existing formulas by up to 50%. This emphasizes the importance of considering roughness effects in accurately estimating superelevation. The developed equations are validated through comparisons with available field, laboratory, and numerical data.