Shifts of Streamflow-Sediment Relationships Across Multi-Temporal Scales in the Yellow River

Abstract

Understanding the streamflow-sediment relationship of large rivers is essential for sustainable basin management. The multi-temporal scale streamflow-sediment load coupling regimes, particularly under extreme flood events, remain inadequately understood. This study investigated streamflow-sediment relationships and hysteresis patterns across annual, monthly, and flood-event scales in the Yellow River during 1950s–2022, and the correlations between coefficients of streamflow-sediment relationship were determined. We found that annual streamflow and sediment load generally exhibited a linear relationship, while on the monthly and flood-event scales, the power-law sediment rating curves well captured the relationships between discharge (Q) and sediment concentration (SC) (SC = aQb). The streamflow-sediment relationships on different scales all became weakened over time. Notably, there was stable linear relationships between b and ln(a) in sediment rating curves on both monthly and flood-event scales, with a consistent slope (around −0.14) over different periods. Further, pronounced hysteresis patterns emerged on both monthly and flood-event scales, with loops shifted from simple clockwise forms to complex figure-eight geometries, indicating the shift of sediment supply limitations to enhanced resuspension and altered sediment delivery dynamics. Construction and impoundment of large reservoirs closely coincided with shifts in streamflow-sediment relationships and hysteresis patterns, with ecological restoration measures further modulating streamflow–sediment dynamics across scales. The findings reveal pronounced nonlinearity in the streamflow–sediment relationship, underscoring the need to account for scale-sensitive and dynamic sediment transport processes when managing large river systems characterized by high sediment loads and long-term regulation.