Hydraulic Design of Stepped Cascades, Channels, Weirs, and Spillways

Book excerpt: Stepped channels and spillways have been used for more than 2,500 years but recently new construction materials have renewed interest in stepped chutes. The steps significantly increase the rate of energy dissipation taking place on the spillway face and reduce the size of the required downstream energy dissipation basin. Stepped cascades are also used in water treatment plants to enhance the air-water transfer of atmospheric gases and of volatile organic components. This book presents new material on the hydraulic characteristics of stepped chute flows. Two different flow regimes can occur: nappe flow regime for small discharges and flat channel slopes; and skimming flow regime - the hydraulics of each flow regime are described. The book also covers the effects of flow aeration and air bubble entrainment as well as the process of air-water gas transfer taking place above the stepped chute. Practical examples of hydraulic design and a critical review of the risks of accidents and failures with stepped channels makes this book an essential reference tool for professional engineers, postgraduates and researchers in the field.