Converging Stepped Spillways: Simplified Momentum Analysis Approach

Abstract

Roller compacted concrete (RCC) stepped spillways are growing in popularity for providing overtopping protection for aging watershed dams with inadequate auxiliary spillway capacity and for the construction of new dams. Site conditions, such as limited right-of-way, topography, and geological formations, often dictate that these spillways converge. Convergence increases the flow depth near the training walls and alters the stilling basin design requirements as compared with traditional straight spillways. A simplified control volume momentum analysis is presented for predicting the minimum vertical training wall height necessary to prevent wall overtopping in converging stepped spillways. An expression is developed to predict vertical training wall height as a function of centerline flow depth, centerline velocity, chute slope, and convergence angle. A three-dimensional