Abstract Changes in riverine suspended and riverbed sediments have environmental, ecological and social implications. Here, we provide a holistic review of water and sediment transport and examine the human impacts on the flux, concentration and size of sediment in the Yangtze River in recent decades. We find that most of the fluvial sediment has been trapped in reservoirs, except for the finest portion. Furthermore, soil-conservation since the 1990s has reduced sediment yield. From 1956-1968 (pre-dam period) to 2013–2015 (post-dams and soil-conservation), the sediment discharge from the sub-basins decreased by 91%; in the main river, the sediment flux decreased by 99% at Xiangjiaba (upper reach), 97% at Yichang (transition between upper and middle reaches), 83% at Hankou (middle reach), and 77% at Datong (tidal limit). Because the water discharge was minimally impacted, the suspended sediment concentration decreased to the same extent as the sediment flux. Active erosion of the riverbed and coarsening of surficial sediments were observed in the middle and lower reaches. Fining of suspended sediments was identified along the river, which was counteracted by downstream erosion. Along the 700-km-long Three Gorges Reservoir, which retained 80% of the sediment from upstream, the riverbed gravel or rock was buried by mud because of sedimentation after impoundment. Along with these temporal variations, the striking spatial patterns of riverine suspended and riverbed sediments that were previously exhibited in this large basin were destroyed or reversed. Therefore, we conclude that the human impacts on sediment in the Yangtze River are strong and systematic.

中文翻译：

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人类对长江泥沙的影响：回顾与新视角

摘要 河流悬浮物和河床沉积物的变化具有环境、生态和社会意义。在这里，我们提供了水和泥沙输送的整体回顾，并研究了近几十年来人类对长江泥沙通量、浓度和大小的影响。我们发现，除了最细的部分外，大部分河流沉积物都被困在水库中。此外，自 1990 年代以来的土壤保持减少了沉积物产量。1956-1968年（建坝前）到2013-2015年（建坝后和水土保持），子流域的泥沙排放量减少了91%；干流中，向家坝（上游）、宜昌（上中游过渡）97%、汉口（中游）83%、大同（限潮）99%的泥沙通量下降. 由于排水受到的影响最小，悬浮泥沙浓度下降的程度与泥沙通量相同。中下游河床侵蚀活跃，地表沉积物粗化。沿河发现了悬浮沉积物的罚款，这被下游的侵蚀抵消了。沿700公里长的三峡水库，保留了上游80%的泥沙，河床砂砾或岩石因蓄水后淤积而被泥土掩埋。随着这些时间变化，之前在这个大盆地中表现出来的河流悬浮和河床沉积物的显着空间格局被破坏或逆转。因此，我们得出结论，人类对长江沉积物的影响是强烈和系统的。