Large-scale headcut erosion testing

The development and movement of gully headcuts can cause major damage in earth emergency spillways. A 1.8-m-wide and 29-m-long flume with 2.4-m-high sidewalls was constructed to perform research on headcut advance. Headcut advance tests were conducted holding discharge, overfall height, and backwater level constant while varying soil properties. Two soil types were examined, and the soil properties were altered by compacting the material in the flume at varying moisture and density conditions. The observed headcut advance rates varied by a factor of more than 100 depending on the placement conditions. By placing a sand layer under the upstream half of the fill, the influence of a sand layer on headcut advance was also examined. Headcut advance and failure mechanics were observed and described.