Gully erosion and sediment transport in a small subtropical catchment, South China

Discharge and sediment concentration were monitored at two dams, as well as gully erosion at four locations during 1988–1989 in the Shenchong experimental basin (0.73 km2) located in subtropical Deqing County, Guangdong Province. The temporal pattern of sediment concentration at the basin outlet is closely related to gully discharge and due to the proximity of the gully sediment source to the gauging station, the hysteresis pattern at the lower dam is dominantly clockwise. Discharge thresholds exist in the sediment concentration-discharge relationships at both the upper and the lower dams. At the upper dam, they are related to the presence of local wetlands which act as a buffer to sediment transport in the channel. At the lower dam, they result from variable sources of sediment as well as early flow cessation in gullies. Computation of sediment yield from gullies confirms that they accounted for over 85% of the sediment load that passed through the lower dam.