Temporal Variations of Flow-sediment Relationships in a Highly Erodible Catchment of the Loess Plateau, China

The flow-sediment relationship is important to understand the soil erosion and land degradation processes in severe eroded areas. This study researches on variations of streamflow, sediment load, and flow-sediment relationship on multi-temporal scales (annual, flood season and, monthly scales) in a highly erodible catchment of Chinese Loess Plateau. The results demonstrated that the streamflow, sediment load, sediment concentration, runoff coefficient, and sediment coefficient all experienced evident reductions, and the decrease in the middle and downstream stations was more significant compared with the upstream stations. The land use changes and implementation of soil and water conservation measures played major role for the streamflow and sediment load reductions with respect to precipitation change, and the runoff coefficient and sediment coefficient linearly decreased with the percentage of conservation measure area. The runoff-sediment yield relationship on annual, flood season, and monthly scales could be generally characterized by the linear function, and the slopes during the post-change period was lower than those during the pre-change period of sediment load. The sediment concentration-streamflow discharge relationship represented consistent form over the entire study period, and the logarithmic function was appropriate to describe the relationships on the three timescales. The decrease of sediment concentration contributed greatest (607%) to sediment reduction compared with runoff productivity of rainfall (302%) and precipitation (91%). Copyright (c) 2015 John Wiley & Sons, Ltd.