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ARS Home » Research » Publications at this Location » Publication #98747
Title: PROCESSES OF HEADCUT GROWTH AND MIGRATION IN RILLS AND GULLIES

Author
item Robinson, Kerry
item Bennett, Sean
item CASALI, JAVIER - PUBLIC UNIV. NAVARRA
item Hanson, Gregory

Submitted to: International Journal of Sediment Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The formation and movement of large and small gullies causes large soil losses and introduces enormous amounts of sediment into our nation's waterways. Gullies can also cause bank stability problems, threaten earth dams, and undermine roads and bridges. Experimental research examined the rates of small gully movement and the scour hole geometry. The headcut movement is related to numerous parameters such as the bed slope and the initial headcut height. Factors influencing the movement of large gullies in compacted cohesive soils are also described. Test results suggest that there are many similarities in the growth and movement of gullies of all sizes. This information is helpful in developing methods to minimize gully erosion. This study should be of interest to a wide range of disciplines interested in rill and gully erosion.

Technical Abstract: The formation and upstream migration of headcuts significantly increases soil losses and sediment yield from agricultural lands, threatens the structural integrity of earthen dams, and can undermine roads and bridges. Recent research using large and small flume tests has provided new insights on these erosion processes. Under controlled experimental conditions, steady-state soil erosion due to migrating headcuts has been simulated for rills and along crop furrows. During migration, headcut shape, size, rate of movement, and sediment yield remained constant. Downstream of the headcut, a soil bed was constructed where slope was dependent upon the sediment yield from the headcut and the flow transport capacity. Soil erosion processes were also examined in a large outdoor facility simulating gully headcuts. Using a compacted cohesive soil, headcut migration rate was observed to decrease as the average density and average unconfined compressive strength increased. While the flow rate and overfall height were not observed to have a major impact on advance rates, a sand layer at the base of an overfall did have a dramatic influence on advance rates. The erosion processes and flow structure within the large gully headcuts were strikingly similar to those in rills and crop furrows. The commonality of form and process in these soil erosion phenomena suggests that erosion prediction technology and mitigation measures may be developed and widely applied.