HEADCUT EROSION RESEARCH

A headcut is a vertical or near vertical drop or discontinuity on the bed of a stream channel, rill, or at the upward head of a gully. Headcut migration affects the landscape, threatens bridge crossings, and endangers the integrity of earthen spillways and embankments during flooding conditions. Understanding headcut migration and the parameters that drive this phenomenon is a complex geologic and engineering challenge. A research program has been conducted to examine headcut erosion processes in compacted cohesive soils. A headcut test facility was constructed, and a systematic examination of the dominant parameters that influence headcut erosion was performed. The influence of soil properties, hydraulic forces, overfall geometry, and multiple material layers in the profile were examined. The influence of weathering and fractured materials was also investigated. The stream power range of the tests was from 2 to 12.6 kW/m. Migration rates from 0 to 18.6 m/h have been observed. Predictive relationships for headcut advance rate and vertical scour downstream of the headcut have also been investigated. This research enhances and helps quantify our understanding of the headcut erosion process.