Sediment transport rate variability over time: Individual and synergistic effects of precipitation and flow

Study region: the midstream of Yellow River (MYR). Study focus: The changing dynamics between water and sediment in evolving environments present significant challenges for water resources management. However, previous research regarded the drivers of basin sediment yields as fixed or separate, overlooking their potential co-evolution. We develops an integrated framework for assessing how the individual and synergistic effects of precipitation and flow influence sediment transport rates (STR) over time. The framework can determine trend turning points in variables, characterize water-sediment response relationships, and analyze their relative contribution rates. An empirical study was carried out using long-term daily measurement data (1953–2022) of precipitation and flow and monthly STR records from seven basins in the MYR. New insights: Results indicate that the framework can be used to reveal the varying relative contributions of individual or co-evolution trends of precipitation and flow to STR variation. For MYR, the two-dimensional relationships (precipitation-flow, precipitation-STR, and flow-STR) and three-dimensional relationship (precipitation-flow-STR) showed decreasing strengths after 2000. During the study period, the contribution of precipitation trend changes to STR trends has a relative small change (0 %-24 %). The contribution of flow trend changes increased from 0.1 % to 11 % pre-1979–0.2 %-23 % during 1980–1999, and 26 %-134 % after 2000. The co-evolution of precipitation and flow trends contributed relatively little to STR pre-1979 (0.2 %-12 %), but that significantly changed during 1980–1999 (0.2 %-24 %) and after 2000 (30 %-153 %). • Proposed a framework for analyzing precipitation and flow's impact on STR variation. • The impacts of precipitation and flow changes on STR are not static but vary over time. • Revealed flow trends' growing influence on STR, stressing its importance.