Energy Dissipation down a Stepped Spillway with Nonuniform Step Heights

Although most stepped spillway-design guidelines were developed for uniform step heights, a nonuniform stepped design might be a practical alternative in some cases. A physical study was conducted in a moderate slope-stepped chute (1V:2H) and five stepped configurations were tested for 0.7 < d(c)/h < 1.9. Detailed air-water flow measurements were performed for each configuration and the results were compared in terms of flow patterns, energy dissipation, and flow resistance. The basic findings showed minor differences between all configurations and indicated that the rate of energy dissipation was about the same for uniform and nonuniform stepped configurations. But the observations suggested that the nonuniform stepped configurations might induce some flow instabilities for smaller flow rates. DOI: 10.1061/(ASCE)HY.1943-7900.0000455. (C) 2011 American Society of Civil Engineers.