Dimensionless Equations for Hydraulic Jump Stilling Basins Downstream of Gabion Stepped Chutes

Flows in stepped chutes built with gabions have been studied for about four decades and have found applications mainly in small dams and drainage systems. This paper presents a literature review of experimental studies on the subject, especially those that published data and methodologies for designing stepped chutes in gabions. A dimensionless methodology for predicting the main design variables is proposed, and equations were proposed for this purpose. These equations, based on physical principles and statistically supported, involve characteristics of stilling basins of hydraulic jump downstream of stepped chutes formed by gabions and the main quantities related to the design of these hydraulic structures. More than 160 data points were used, each of them involving several parameters of the adopted physical models, making the proposed methodology valid for five different slopes of the downstream face of the stepped chutes. The new equations allow for calculating the length and elevation of the stilling basin bottom. They also allow the determination of the supercritical depth at the basin inlet and the estimation of the height of the continuous end sill of the stilling basin. The proposed equations present strong correlations and adherence to the experimental data in the literature and reveal the missing data about the subject considering the existing literature. In addition, an application example illustrates the use of the developed methodology and compares the present results with those obtained from a methodology available in the literature.