Application of a simple headcut advance model for gullies

Abstract

Gully erosion begins in streambanks and uplands as a consequence of adjustments in driving forces on the landscape imposed by changes in land use or climate. The deleterious effects of gullies worldwide have led to many site-specific studies of gully form and function. In the continental United States, gully erosion in agricultural land has destroyed valuable farmland yet, prediction of gully processes remains problematic on a national scale. This research has proposed a simple method to predict gully headcut advance. When combined with SWAT hydrologic flow routines, the model predicted gully headcut advance with reasonable accuracy on a daily time step for time periods exceeding two decades. The model was tested in two distinct land resource areas of the United States with differing climate, soils, cover and drainage. The inputs for the headcut model have been kept simple as the model will be applied over large areas. Model inputs consist of headcut height, headcut resistance (based on soil erodibility and a rootcover factor), and daily flow. The model is compared with an annual time step model used in assessment of headcut advance and appears to offer a better way to assess gully headcut advance.

An experimental study on the effects of grass root density on gully headcut erosion in the gully region of China's Loess Plateau

“…Therefore, the plunge pool advanced due to the change in the entrance angle and position of the jet flow (Stein et al, ). Compared with the absence of roots in the bare land plots, the presence of a root system influenced the headcut retreat and was conducive to the formation of a hanging soil‐root matrix at the gully head (Allen et al, ; Rengers & Tucker, ). Moreover, the GRD suddenly increased by a considerable distance once the hanging soil‐root matrix collapsed.…”

“…On the one hand, land surface coverage has proven to be a strongly related factor that influences the gully erosion rate and topographical threshold conditions for gully head development (Hayas et al, ; Li et al, ; Mukai, ). On the other hand, the effect of vegetation on reducing gully erosion is mainly due to the increase in soil resistance, which potentially depends on root characteristics (Allen, Arnold, Auguste, & Dunbar, ; Knapen, Poesen, Govers, Gyssels, & Nachtergaele, ; Torri et al, ; Vannoppen, Vanmaercke, De Baets, & Poesen, ). Different plant species have different root tensile strengths (De Baets et al, ), and plant species with fibrous roots provide greater additional cohesion in soil (Zegeye et al, ).…”

“…Pollen‐Bankhead and Simon () and Simon, Pollen‐Bankhead, and Thomas () indicated that soil tensile strengths in banks and headcuts increase with increasing root density, root size, and species. A root‐related parameter has also been used in some gully erosion models (Allen et al, ; Temple & Hanson, ). In summary, previous studies have revealed that the effect of vegetation on the control of gully headcut erosion depends on the vegetation coverage and root characteristics, which can greatly improve the soil cohesion and tensile strength of the soil‐root matrix (Gyssels, Poesen, Bochet, & Li, ; Knapen et al, ; Vannoppen et al, ).…”

Gully erosion processes, disciplinary fragmentation, and technological innovation

“…These models employ conservation equations, fluvial (advective) processes, mass-wasting (diffusive or discrete) processes, and various criteria for the initiation of a channel that could migrate upstream with time (De Ploey, 1989;Willgoose et al, 1991a, Willgoose et al, 1991bHoward, 1994Howard, , 1999Bull and Kirkby, 1997;Sidorchuk and Sidorchuk, 1998;Kirkby and Bull, 2000;Sidorchuk, 2005). Recent landscape evolution models now include a gully headcut advance mechanism that considers the combined effects of plunge-pool scour and mass failure 48 S. J. BENNETT AND R. R. WELLS (Alonso et al, 2002;Istanbulluoglu et al, 2005;Flores-Cervantes et al, 2006;Rengers andTucker, 2014, 2015;Allen et al, 2018), which have been supported by specially-designed experiments . As noted by Vanmaercke et al (2016), rates of gully headcut advance are very sensitive to rainfall intensity.…”

Impacts of different vegetation restoration options on gully head soil resistance and soil erosion in loess tablelands

“…Gully headcut erosion induced by concentrated flow that is generated from the loesstableland is the main source of soil erosion in the loess tableland and gully region of the Loess Plateau, and thus the improvement in soil resistance of gully heads to concentrated flow is essential for controlling gully headcut erosion. Previous studies have indicated that vegetation restoration at gully heads is conducive to improving soil anti-erodibility and controlling gully head migration (Guo et al, 2018;Allen et al, 2017). However, few studies have been conducted to evaluate the effects of vegetation restoration at gully heads on soil resistance to concentrated flow erosion.…”