Spatiotemporal Variations of Sediment Discharge and In‐Reach Sediment Budget in the Yellow River From the Headwater to the Delta

Strong anthropogenic activities and climate change have caused distinct hydrology and sediment dynamics in river systems worldwide. Yet, the integrated picture of sediment discharge changes and quantitative attribution of these changes from a basin-wide perspective were limitedly understood. In this study, we quantified the variations of sediment discharge and in-reach sediment budget in the Yellow River basin (YRB) during 1956–2019 and examined the underlying reasons. Both streamflow and sediment load in the YRB have substantially decreased during 1956–2000 except the headwater, and the reduction rate increased along the mainstem. However, the streamflow has significantly increased (p < 0.05) since 2000 due to increased precipitation, and the sediment load at most stations tended to stabilize. The contribution of soil conservation measures (SCMs, including check-dams, terraces, grass plantation, and afforestation) and reservoirs to sediment load reduction was more than 50% in the headwater and middle reaches and over 90% in the upper and lower reaches. The sediment yield coefficient decreased linearly with reservoir capacity and exponentially with the proportional area of SCMs (p < 0.01). With continuous dam construction, the channel erosion in the headwater decreased to nearly zero, and the sediment deposition in the upper and middle reaches increased linearly with storage capacity of reservoirs. In contrast, the sediment deposition in the lower reaches displayed a linear correlation with the concentration of sediment derived from the middle reaches (p < 0.05). This study provides quantitative results for sediment dynamics of entire river system, which facilitates development of sustainable watershed management strategies.