Response of the headcut erosion process to flow energy variation in the
loess gully region of China
Abstract
Headcut erosion is usually associated with the consumption and
transformation of flow energy that occurs when runoff is used to
transport sediment. Therefore, flow energy variations in the headcut
erosion process are critical in the loess gully region of the Loess
Plateau. The aim of this study was to clarify the effects of the flow
discharge and slope gradient on flow energy and the response of the
headcut erosion process in the gully region of the Loess Plateau. This
study examined the headcut erosion process using slope gradients ranging
from 1° to 7° in the upstream catchment area and downstream gully bed
and inflow discharges ranging from 3.6 to 7.2 m3·h-1. The results showed
that the slope gradient has a significant impact on the potential energy
in the upstream catchment area; thus, changes in the slope gradients
produced changes in the sediment yield. Moreover, the flow discharge
significantly influenced not only the potential energy but also the
kinetic energy in the upstream catchment area and downstream gully bed.
The kinetic energy at the downstream gully bed was
0.03~0.16 J·s-1 lower than that in the upstream
catchment area due to the flow drop at the gully head. Greater energy
consumption occurred at the gully head than in the upstream catchment
area and downstream gully bed, and the gully head contribution to the
flow energy consumption was 44.30~64.29%, which
increased with increasing flow discharge and decreasing slope gradient.
The influence of the slope gradient on the sediment yield was more
significant than that of the flow discharge, and a nonlinear regression
equation was developed to estimate sediment the yield. The flow energy
consumption was significantly correlated with the sediment yield. These
findings could improve our understanding of the flow energy
characteristics and headcut evolution process during headcut erosion.