Morphodynamics of Headcut Development and Soil Erosion in Upland Concentrated Flows

Abstract

In agricultural regions, gully erosion is now recognized as a dominant source of soil loss, and the development and upstream migration of headcuts is critical to the initiation, incision, and dissection of these upland areas. This study examined the effect of soil texture on headcut development and migration using four common soils from the southeastern United States, tested on bed surface slopes ranging from 1 to 5% and overland fl ow rates ranging from 45 to 71 L min −1 . In response to this fl ow, actively migrating headcuts developed with migration rates ranging from 0.00001 to 0.0025 m s −1 , maximum scour depths ranging from 0.042 to 0.148 m, and sediment discharge rates ranging from 0.00017 to 0.0356 kg s −1 depending on the soil and boundary conditions imposed. Nearly all experimental runs resulted in steady-state soil erosion, wherein the headcut developed attained a constant rate of migration, shape, and sediment discharge as a function of time. These experimental observations were successfully compared with predictive equations for mass conservation, jet entry angle, maximum scour depth, and migration rate developed for actively migrating headcuts in upland concentrated fl ows. These results further demonstrate that systematic headcut development can occur in a range of soils, slopes, and fl ow rates, and that modifi ed jet impingement theory can be used to predict the erosional characteristics of these headcuts, thus providing the necessary analytical framework for improving soil erosion prediction technology.

Fine sediment sources in Conservation Effects Assessment Project watersheds

“…These determinations assume that the depth of erosion was achieved instantaneously or over a short period of time. In low intensity runoff events, rills and shallow gullies would likely erode gradually to shallow depths and produce sediment with an upland signature, while in high-intensity runoff events, thicker layers would likely be eroded especially if erosion occurs as headcuts or knickpoints in the gullies (Bennett et al 2000;Wells et al 2009Wells et al , 2013, resulting in more channel-like signatures. Studies of the eight watersheds indicate that gully processes were not important on most of the watersheds and thus fine sediment contributions from gullies for the measured storms were likely insignificant.…”

Assessment of Factors Affecting Ephemeral Gully Development in Badland Topography: A Case Study at Garbheta Badland (Pashchim Medinipur,

“…Gullies are formed by the amputation of soil from narrow channels through the accretion of surface runoff, tends to fabricate more sediment loss than other forms of soil erosion such as overland flow [6][7][8][9]. Today, it is renowned as a major land degradation issue, causing both impacts on-site, through direct soil loss and off-site, through sediment deposition in downstream environments.…”

Mechanism of Gully-Head Retreat - A Study at Ganganir Danga, Paschim Medinipur, West Bengal

“…Gully erosion produces large volumes of sediment that are transported downstream with detrimental effects on water quality, reservoir capacity and floodplains (Bryan, 1990;Poesen et al, 2003;Wells et al, 2009Wells et al, , 2010. In any channel network, approximately half of the total length of channels lies with un-branched fingertip tributaries (i.e.…”