Preprints
https://doi.org/10.5194/hess-2019-69
https://doi.org/10.5194/hess-2019-69
14 Mar 2019
 | 14 Mar 2019
Status: this preprint has been withdrawn by the authors.

Three-decadal dynamics of mid-channel bars in downstream of the Three Gorges Dam, China

Zhaofei Wen, Hong Yang, Changhong Ding, Ce Zhang, Guofan Shao, Jilong Chen, Mingquan Lv, Shengjun Wu, and Zhenfeng Shao

Abstract. The downstream of the world’s largest Three Gorges Dam (TGD) along Yangtze River (1560 km) hosts numerous mid-channel bars (MCBs). The morphodynamics of these MCBs are crucial to the river’s hydrological processing, local ecological functioning, and socioeconomic development. However, a systematic understanding of such dynamics and their linkages to the TGD across the entire downstream reach remain largely unknown. Using Landsat archive images and a thematic extracting scheme, the work presents comprehensive monitoring of MCB dynamics in terms of number, area, and shape, in the downstream of the TGD during 1985–2018. Total 140 MCBs were extracted and grouped into four types to represent small size (< 2 km2), middle size (2 km2–7 km2), large size (7 km2–33 km2) and extra-large size (> 33 km2) MCBs, respectively. Most of the MCBs in terms of number (70 %) and total area (91 %) were concentrated in the lower reach (Hankou to Estuary). The number of small size MCBs decreased after TGD closure and most of such decreasing events happened in the lower reach. Although all four types of MCBs showed overall increasing trends in area, small MCBs had smaller rate and received more influence by the TGD operation than the large MCBs. Small size MCBs tended to become relatively shorter and wider whereas the others became slimmer after TGD operation. Impacts from the TGD operation could decrease along with the increasing distance from TGD to Hankou (for shape dynamics) or to Jiujiang (for area dynamics). The quantified longitudinal and temporal dynamics of MCBs across the whole downstream of the TGD provides a crucial monitoring basis for continuous investigations of changing mechanisms in the morphology of the Yangtze River system.

This preprint has been withdrawn.

Zhaofei Wen, Hong Yang, Changhong Ding, Ce Zhang, Guofan Shao, Jilong Chen, Mingquan Lv, Shengjun Wu, and Zhenfeng Shao

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Zhaofei Wen, Hong Yang, Changhong Ding, Ce Zhang, Guofan Shao, Jilong Chen, Mingquan Lv, Shengjun Wu, and Zhenfeng Shao
Zhaofei Wen, Hong Yang, Changhong Ding, Ce Zhang, Guofan Shao, Jilong Chen, Mingquan Lv, Shengjun Wu, and Zhenfeng Shao

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Latest update: 24 Apr 2024
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This preprint has been withdrawn.

Short summary
The environmental effects of the world's largest Three Gorges Dam (TGD) have been received worldwide attentions. It is the first dynamics monitoring of mid-channel bars (MCBs) in the downstream of TGD at large spatiotemporal scale. The study shows most of the MCBs are located in the lower reach. Small MCBs become shorter and wider whereas the others became slimmer in post-TGD period. Impacts from the TGD operation on the MCB dynamics could decrease along with the increasing distance from TGD.