Evolution of the mid-channel bars in the middle and lower reaches of the Changjiang (Yangtze) River from 1989 to 2014 based on the Landsat satellite images: impact of the Three Gorges Dam
Evolution of the mid-channel bars in the middle and lower reaches of the Changjiang (Yangtze) River from 1989 to 2014 based on the Landsat satellite images: impact of the Three Gorges Dam
复制标题
基于Landsat卫星影像的1989-2014年长江中下游河道中坝的演变：三峡大坝的影响
DOI：
10.1007/s12665-018-7576-2
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发表时间：
2018-05-01
影响因子：
2.8
通讯作者：
Wei, Wen
中科院分区：
文献类型：
--
作者：
Lou, Yaying;Mei, Xuefei;Wei, Wen
河道中部坝长期以来被认为是世界各大河流的重要地貌，形态与流沙动力学之间的连通性的重要性一直受到高度重视。本研究利用1989年至2014年的遥感影像和相关水文数据，探讨长江中下游河道中坝的演化及其对世界最大水文工程三峡大坝的响应。结果表明，三峡工程前期，河道中部坝在汛期和枯季分别表现出沉积和侵蚀现象，而三峡工程后，则表现为轻度的洪水期沉积和枯季沉积。因此，中部通道酒吧区域的特点是“TGD 前时期季节性差异显着，TGD 后时期季节性模式温和”。季节特征的明显变化可以归因于2003年的三峡大坝调度。具体来说，三峡大坝调度后洪水持续时间的缩短和输沙量的减少抑制了汛期坝体的增长。 TGD 引起的输沙能力和悬浮泥沙浓度之间差异的变化导致了旱季沙坝的转变。同时，由于河流调整和支流补充，下游河中坝的变化趋势随着距三峡大坝距离的增加而变弱。此外，不同河型的河中坝呈现出不同的变化趋势，其中以鹅头型河型变化最为显着。研究结果为长江中下游河道整治提供了理论依据。
The mid-channel bars have long been identified as essential landforms in the large rivers of the world, and the significance of connectivity between morphology and flow-sediment dynamics has been intensively emphasized. In this study, remote sensing images and associated hydrological data from 1989 to 2014 were used to explore mid-channel bars evolution in the middle and lower reach of the Changjiang and their responses to the Three Gorges Dam (TGD), the world’s largest hydrological engineering. The results indicated that mid-channel bars, respectively, exhibited deposition and erosion in the flood and dry season in pre-TGD period, while mild deposition in flood season and deposition in dry season were found in post-TGD period. As a consequence, mid-channel bars area was characterized by ‘remarkable seasonal differences in pre-TGD period, mild seasonal pattern in post-TGD period’. The obvious shift in seasonal features could be attributed to the TGD operation in 2003. Specifically, flood duration decrease and sediment load reduction following TGD regulation suppressed the bars growth in flood season. TGD-induced variations in differences between sediment carry capacity and suspended sediment concentration resulted in the bars transformation in dry season. Meanwhile, the change trends of downstream mid-channel bars became weak as their locations’ distance to TGD increases because of the river adjustment and tributaries supplement. Moreover, mid-channel bars in different river patterns presented various change trends with the most remarkable variation being detected in goose-head-shaped river pattern. The results of this paper provide a theoretical basis for the river channel improvement in the middle and lower reaches of the Changjiang River.