Variations in water and sediment of the Yellow River: Historical perspectives, current Status, and future outlook

Under the current framework of flood control System, maintaining a stable riverbed elevation over time is crucial for achieving long—term stability in the lower reaches of the Yellow River. The water-sediment condition is the critical factor that determines sediment accumulation and riverbed elevation. Utilizing historical records, previ-ous research and measured data, this study analyzes flood occurrence frequencies in the lower Yellow River over the past 2200 years, as well as climate and socio—environmental changes on the Loess Plateau, and analyzes chan-ges of water and sediment of the Yellow River in different historical periods. The results show that from the Western Han Dynasty to the 1970s, there is a general trend of decreasing water volume and increasing sediment load. Dur-ing the Eastern Han Dynasty (70—907 AD), sediment load was only 400-550 million t/a, with downstream water volume exceeding 60 billion m /a. In the subsequent 127 years, sediment load increased to around 700 million t/a, while downstream water volume decreased to 58 billion m /a. From 1579 to 1918, sediment load increased to 1.5 billion t/a, while downstream water volume decreased to 57 billion m /a. The period from 1933 to 1979 was the pe-riod of maximum sediment yield on the Loess Plateau, with the measured sediment discharge at Tongguan Station reaching 1.62 billion t/a and the restored dammed sediment reaching 1.92 billion t/a. Since the 1980s, water and sediment discharge of the Yellow River has shown a decreasing trend, with the annual average measured sediment discharge of Tongguan Station being 0.234 billion t/a from 2000 to 2023, and reaching 0.55 billion t/a by restored dammed sediment, which is comparable to sediment discharge in the late Tang Dynasty. Downstream measured runoff was 29 billion m /a, accounting for 46% of runoff in the late Tang Dynasty. In the future, relying on sus-tained soil and water conservation, sediment discharge of the Yellow River may be controlled within 400—500 million t/a, reaching levels comparable to that in the earlier stage of the old course of the Yellow River of the Eastern Han Dynasty. However, due to downstream water volume unlikely to exceed 27 billion m /a, the operational lifes-pan of the current lower Yellow River channel may not match that of the old course of the Eastern Han Dynasty. © 2024 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press. All rights reserved.