Flow Resistance and Design Guidelines for Embankment Stepped Chutes

Recently the design flows of many dams have been re-evaluated, resulting in spills often larger than the original ones. In many cases, occurrence of revised flows would result in dam overtopping because of insufficient storage and spillway capacity of reservoirs. Embankment dams whilst common are more likely to fail than other dam types when overtopped in an uncontrolled manner because of breaching or complete erosion of the downstream face of the embankment. Despite the catastrophic effects of dam failure, dam overtopping constitutes still most identified collapses. Stepped chutes with moderate slopes represent a convenient embankment overtopping protection because of its large energy dissipation potential and its compatibility with recent construction methods (RCC, rip-rap gabions). New experimental flow resistance results are presented herein to help designers to predict accurately energy dissipation on moderate slope stepped chutes. Some recent advances in design guidelines are also discussed.