Skip to main content
ARS Home » Research » Publications at this Location » Publication #77363
Title: HEADCUT MIGRATION RESEARCH

Author
item Hanson, Gregory
item Robinson, Kerry

Submitted to: Watershed News
Publication Type: Popular Publication
Publication Acceptance Date: 4/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Headcut migration impacts the landscape, contributing significantly to soil erosion, sediment delivery, and land dissection. A headcut is a vertical or near-vertical drop or discontinuity in a channel bed normally caused by flow concentration. Water flowing over a headcut causes this landform to move upstream. Headcut migration in gullies and streams often results in structural damage to road crossings. Gully movement is also a common form of damage experienced in earth spillways, embankments, and levees. Understanding headcut migration and the parameters that drive this phenomenon is a complex engineering challenge. Research is being conducted by the USDA Agricultural Research Service to examine the headcut processes in a controlled laboratory environment. Large-scale flume tests have been conducted to determine the influence of the attacking hydraulic forces and the resisting soil forces on headcut migration. This research program has addressed 1) the benefits of compaction, 2) the influence of an erodible layer in the soil profile, 3) the influence of discharge, overfall height, and tailwater, and 4) the relationship of measured soil properties to the migration rate and erosion process. This research augments our understanding of headcut erosion processes and improves our ability to predict headcut migration rates.

Technical Abstract: Headcut migration impacts the landscape, contributing significantly to soil erosion, sediment delivery, and land dissection. Headcut migration in gullies and streams often results in structural damage to road crossings. Gully movement is also a common form of damage experienced in earth spillways, embankments, and levees. Understanding headcut migration and the eparameters that drive this phenomenon is a complex engineering challenge. Research is being conducted by the USDA Agricultural Research Service to examine the headcut processes in a controlled laboratory environment. The study is being conducted in a 1.8-m wide by 29.3-m long flume with 2.4-m high sidewalls. This research program has addressed 1) the benefits of compaction, 2) the influence of an erodible layer in the soil profile, 3) the influence of discharge, overfall height, and tailwater, and 4) the relationship of measured soil properties to the migration rate and erosion process. Tests indicate that proper attention to compaction can reduce migration rates by 100 fold or more. Tests also demonstrated that the presence of a sand layer can increase the migration rates 10 fold or greater. For the range of conditions examined in the flume, changes in the discharge and overfall height have not had a dramatic influence on headcut advance rates whereas tailwater level downstream of the overfall was observed to influence the advance rate more than seven fold for the tested soil conditions. Measured soil properties such as compaction water content, density, stress-strain characteristics, and erodibility were significantly correlated to the headcut migration rate. For example, the advance rate was found to decrease as the average density and soil strength increased.