Four-decades of sediment transport variations in the Yellow River on the Loess Plateau using Landsat imagery.

The Yellow River is globally recognized for its significant sediment load, primarily attributed to its passage through the Loess Plateau. Notably, effective soil erosion control measures have led to a substantial decrease in sediment transport since the 1950s. However, a lack of comprehensive and detailed data impedes understanding of long-term spatiotemporal changes in suspended sediment concentration (SSC). To address this gap, this study utilizes in-situ daily data from 12 hydrological stations (SSC range: 0.41–1.08 × 106 mg/L) to develop a high-precision SSC model for Landsat series sensors (R2 > 0.86, root mean square error (RMSE) < 1105.74 mg/L, and mean absolute percent difference (MAPD) < 39.67%). Significant spatial variabilities in SSC are observed within the Yellow River and its main tributaries. Temporally, 97.39% of the investigated river sections (N = 480) exhibited a decreasing trend from 1986 to 2022, of which 50% are statistically significant (p < 0.05). Generally, the SSC was higher in summer and fall (2998.16 mg/L) with higher water discharge compared to winter and spring (1126.25 mg/L), although the seasonal variability weakened during the 1980s–2020s. Analysis of suspended sediment flux identified the Huangfu, Kuye, and Fen Rivers as major sediment sources for the Yellow River, while suspended sediment deposition/erosion varies across different sections. Driver analyses revealed that human sediment control projects are the primary contributors to the decrease in SSC, whereas natural factors predominantly influence intra-annual SSC variability across different years. This study is important for understanding the spatiotemporal variations in SSC within the Yellow River and its tributaries, monitoring sediment transport dynamics in global rivers and providing scientific references for watershed ecology and water resource management. • A Landsat-based algorithm was developed for estimating SSC in the turbid Yellow River. • The spatiotemporal variations of SSC over four decades were presented for the first time. • SSC exhibited spatial heterogeneity and a declining trend since the 1980s. • The decline in SSC is primarily attributed to conservation policies on the Loess Plateau. • The transport flux of SSC revealed sediment deposition or erosion in various river sections. [ABSTRACT FROM AUTHOR]