Synthesis analysis of sediment load changes in the Yellow River Basin

Assessing the spatiotemporal variations and driving factors of sediment load (SL) in the Yellow River Basin (YRB) is fundamental for scientific governance and targeted management. This study quantifies the spatiotemporal dynamics of SL and sediment budgets across different sections of the YRB, utilizing observations from 110 gauging stations from the 1950s to 2021. A hybrid framework integrating machine learning with the LOADEST model was employed to reconstruct natural SL and distinguish the impacts of climate change and human activities. Annual SL declined consistently and significantly along the main stream and most tributaries, except in the source regions. The most pronounced reduction occurred in the middle and lower reaches of the YRB, where SL decreased by approximately 86%–92% during 2000–2021 relative to the 1950s–1968. The Lanzhou–Toudaoguai section underwent sediment deposition, whereas the Toudaoguai–Tongguan section exhibited a source-to-sink dynamic that facilitated downstream sediment flushing. The Water–Sediment Regulation Scheme, implemented by Sanmenxia and Xiaolangdi reservoirs, has significantly enhanced downstream flushing, resulting in substantial increases in sediment transport from Huayuankou to Lijin since 2002. Human activities, including reservoir construction and soil and water conservation measures, contributed approximately 77%–83% to SL reduction in the YRB during 2002–2021. Sustainable ecological restoration and sediment regulation strategies are essential for improving water use efficiency, maintaining or restoring ecosystem balance, and advancing the overall sustainable development of the YRB. These findings could offer valuable insights for the long-term ecological restoration and sediment management.