GULLY EROSION AND SEDIMENT TRANSPORT IN A SMALL SUBTROPICAL CATCHMENT, SOUTH CHINA

Discharge and sediment concentration were monitored at two dams, as we ll as gully erosion at four locations during 1988-1989 in the Shenchon g experimental basin (0.73 km(2)) located in subtropical Deqing County , Guangdong Province. The temporal pattern of sediment concentration a t the basin outlet is closely related to gully discharge and due to th e proximity of the gully sediment source to the gauging station, the h ysteresis 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 rela ted to the presence of local wetlands which act as a buffer to sedimen t transport in the channel. At the lower dam, they result from variabl e sources of sediment as well as early flow cessation in gullies. Comp utation of sediment yield from gullies confirms that they accounted fo r over 85% of the sediment load that passed through the lower dam.