Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2000
Publication Date: N/A
Technical Abstract: The formation and upstream migration of headcuts in rills, row-crop furrows, and ephemeral gullies is an important factor in soil losses and sediment yield from agricultural lands. Recent experimental research has added new insights on erosion due to migrating headcuts. It has been observed that once steady state is reached, headcut migration rate, scour-hole geometry, and sediment yield remain constant. Within individual experiments, the morphology of the headcut did not vary significantly during its migration once steady-state conditions were achieved. The headcut self-corrected variable boundary conditions to maintain a self-similar morphology dependent upon the characteristics of the plunging jet. Morphologic similarity was also observed as flow discharge increased. Near the brinkpoint, headcut shape was wholly dependent on the erosive recirculation within the scour hole and virtual collapse of all bed profiles was observed. The present analysis takes advantage of the observed self-similarity properties to develop an integral solution to the sediment continuity equation for a migrating headcut. This property is also used to formulate simple mathematical models of headcut migration rate and scour geometry. Computed results yield acceptable comparisons with measured values.