Yangtze River of China: historical analysis of discharge variability and sediment flux
Yangtze River of China: historical analysis of discharge variability and sediment flux
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DOI：
10.1016/s0169-555x(01)00106-4
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发表时间：
2001-11-15
期刊：
影响因子：
3.9
通讯作者：
Wang, ZH
中科院分区：
文献类型：
--
作者：
Chen, ZY;Li, JF;Wang, ZH
收集了长江上游、中游和下游近百年的水文资料，分析了流域来水来沙的时空分布规律。不出所料，长江流量从上游流域向下游增加。据估计，只有50%的流量来自长江上游，其余的流量来自中下游的众多支流。然而，长江沿岸的泥沙分布与观测到的流量分布相反，大部分泥沙来自上游流域。由于上扬子岩段坡度的显著降低和向曲流型的转变，长江中游的泥沙量急剧减少(约0.8×10(8)t/年)。长江中游流域也发生了相当大的泥沙淤积，因为这条河穿过了一个巨大的内陆洞庭湖水系。长江下游输沙量明显低于上游，但由于邻近支流的附加作用，下游输沙量略高于中游。长江流域枯水期流量与输沙量之间存在着很强的相关性，因为枯水期水流携带的含沙量较低。在雨季，长江上游也存在很强的相关性，这是因为高流速使沙粒悬浮在河床上。然而，长江中下游河段的水流速度不能保持泥沙的悬浮，只能向下游输送细粒颗粒，因此长江中下游出现了负相关到较差的相关性。宜昌和汉口水文站的年输沙量呈下降趋势，同一站的年流量略有减少。这可以被解释为主要用于农业的调水的结果。大同下游泥沙比较稳定，不受流量略有减少的影响。此外，三个水文站的泥沙浓度增加，这可归因于人类活动加剧造成的泥沙流失，特别是在上游流域，例如砍伐森林和修建许多水坝。这30年的月平均输沙量比流量晚2个月左右，这意味着丰水期整个流域的泥沙输移是由大坝释放的。(C)2001 Elsevier Science B.V.保留所有权利。
Hydrological records (covering a 100-year period) from the upper, middle and lower Yangtze River were collected to examine the temporal and spatial distribution of discharge and sediment load in the drainage basin. The Yangtze discharge, as expected, increases from the upper drainage basin downstream. Only an estimated 50% of the discharge is derived from the upper Yangtze, with the rest being derived from the numerous tributaries of the middle and lower course. However, the distribution of sediment load along the Yangtze is the reverse of that observed for discharge, with most of the sediment being derived from the upper basin. A dramatic reduction in sediment load (by similar to 0.8 X 10(8) tons/year) occurs in the middle Yangtze because of a marked decrease in slope and the change to a meandering pattern from the upper Yangtze rock sections. Considerable siltation also occurs in the middle Yangtze drainage basin as the river cuts through a large interior Dongting Lake system. Sediment load in the lower Yangtze, while significantly less than that of the upper river, is somewhat higher than the middle Yangtze because of additional load contributed by adjacent tributaries. A strong correlation exists between the discharge and sediment load along the Yangtze drainage basin during the dry season as lower flows carry lower sediment concentration. During the wet season, a strong correlation is also present in the upper Yangtze owing to the high flow velocity that suspends sand on the bed. However, a negative to poor correlation occurs in the middle and lower Yangtze because the flow velocity in these reaches is unable to keep sand in suspension, transporting only fine-grained particles downstream.Hydrological data are treated for 30 years (1950-1980), when numerous dams were constructed in the upper Yangtze drainage basin. At Yichang and Hankou hydrological stations, records revealed a decreasing trend in annual sediment load, along with slightly reduced annual discharge at the same stations. This can be interpreted as the result of water diversion primarily for agriculture. Sediment load at Datong further downstream is quite stable, and not influenced by slightly reduced discharge. Furthermore, sediment concentration at the three hydrological stations increased, which can be attributed to sediment loss in association with intensifying human activity, especially in the upper drainage basin, such as deforestation and construction of numerous dams. Mean monthly sediment load of these 30 years pulses about 2 months behind discharge, implying dam-released sediment transport along the entire river basin during the high water stage. (C) 2001 Elsevier Science B.V. All rights reserved.