Experimental study of hydraulic characteristics on headcut erosion and erosional response in the tableland and gully regions of China

Abstract

AbstractSevere long‐term gully headcut erosion, which further decreases the area of Yuan, is a serious yet poorly understood issue for local ecological environments and social development. Nevertheless, although the hydraulic characteristics of headcut erosion in the loess tableland and gully region of the Loess Plateau remain unclear, they constitute critical inputs in headcut erosion prediction models. The goal of this study is to evaluate the hydraulic properties of concentrated flow and the headcut erosion process and to identify the influence of flow energy consumption on headcut erosion in the loess tableland and gully region. A series of in situ simulated rainfall and runoff scouring experiments were carried out to achieve this goal under flow discharges of 100, 200, 300 and 400 L min−1 with a rainfall intensity of 0.8 mm min−1. The total sediment yield was 1660–3850 kg and increased linearly with increasing flow discharge. The contribution rate of soil loss volume at gully head increased with experiment time and was 2.7 times greater than at the upstream area. The concentrated flow was turbulent and supercritical during the erosion process. The headcut retreat distance, flow velocity, Reynolds number, shear stress, stream power, velocities at the brink and bottom, and flow energy consumption at 100–400 L min−1 were 5.5–25.5 cm, 0.63–1.48 m s−1, 1244–8593, 0.65–4.45 Pa, 0.61–4.22 W m−2, 0.78–2.47 m s−1, 5.23–5.88 m s−1, and 3.52–12.63 J s−1, respectively, all of which increased with increasing flow discharge. A positive power function was found between the sediment yield and flow energy consumption, which can be helpful in establishing soil erosion model based on erosion processes. These findings ultimately improve our understanding of headcut erosion in the tableland and gully regions of the Loess Plateau.