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From the headwater to the delta: a synthesis of the basin-scale sediment load regime in the Changjiang River

From the headwater to the delta: a synthesis of the basin-scale sediment load regime in the Changjiang River
From the headwater to the delta: a synthesis of the basin-scale sediment load regime in the Changjiang River

Many large rivers in the world delivers decreasing sediment loads to coastal oceans owing to reductions in sediment yield and disrupted sediment deliver. Understanding the sediment load regime is a prerequisite of sediment management and fluvial and deltaic ecosystem restoration. This work examines sediment load changes across the Changjiang River basin based on a long time series (1950–2017) of sediment load data stretching from the headwater to the delta. We find that the sediment loads have decreased progressively throughout the basin at multiple time scales. The sediment loads have decreased by ~96% and ~74% at the outlets of the upper basin and entire basin, respectively, in 2006–2017 compared to 1950–1985. The hydropower dams in the mainstem have become a dominant cause of the reduction, although downstream channel erosion causes moderate sediment load recovery. The basin-scale sediment connectivity has declined as the upper river is progressively dammed, the middle-lower river is leveed and river-lake interplay weakens. The middle-lower river has changed from a slight depositional to a severe erosional environment, from a sediment transport conduit to a new sediment source zone, and from a transport-limited to a supply-limited condition. These low-level sediment loads will likely persist in the future considering the cumulative dam trapping and depleted channel erosion. As a result, substantial hydro-morphological changes have occurred that affect the water supply, flood mitigation, and the aquatic ecosystem. The findings and lessons in this work can shed light on other large river systems subject to intensified human interference.

Changjiang, Sediment load, Sediment starvation, Source-to-sink
0012-8252
Guo, Leicheng
17e93f75-1537-481e-bba6-c9217b42428f
Su, Ni
8cbe5fcc-312a-4298-83b2-b41e6bb2828a
Townend, Ian
f72e5186-cae8-41fd-8712-d5746f78328e
Wang, Zheng Bing
0bf73ba6-eed4-4ebe-8175-929d35912e3d
Zhu, Chunyan
3b539a8b-319a-4662-aa39-7b4eab164acb
Wang, Xianye
19670c59-7669-4ed5-b5f9-05bc15328be0
Zhang, Yuning
ee0dbef1-7040-4936-861b-9c5e15493047
He, Qing
94baedd4-45f0-436e-83d4-4e2ebcd1bec3
Guo, Leicheng
17e93f75-1537-481e-bba6-c9217b42428f
Su, Ni
8cbe5fcc-312a-4298-83b2-b41e6bb2828a
Townend, Ian
f72e5186-cae8-41fd-8712-d5746f78328e
Wang, Zheng Bing
0bf73ba6-eed4-4ebe-8175-929d35912e3d
Zhu, Chunyan
3b539a8b-319a-4662-aa39-7b4eab164acb
Wang, Xianye
19670c59-7669-4ed5-b5f9-05bc15328be0
Zhang, Yuning
ee0dbef1-7040-4936-861b-9c5e15493047
He, Qing
94baedd4-45f0-436e-83d4-4e2ebcd1bec3

Guo, Leicheng, Su, Ni, Townend, Ian, Wang, Zheng Bing, Zhu, Chunyan, Wang, Xianye, Zhang, Yuning and He, Qing (2019) From the headwater to the delta: a synthesis of the basin-scale sediment load regime in the Changjiang River. Earth-Science Reviews, 197, [102900]. (doi:10.1016/j.earscirev.2019.102900).

Record type: Review

Abstract

Many large rivers in the world delivers decreasing sediment loads to coastal oceans owing to reductions in sediment yield and disrupted sediment deliver. Understanding the sediment load regime is a prerequisite of sediment management and fluvial and deltaic ecosystem restoration. This work examines sediment load changes across the Changjiang River basin based on a long time series (1950–2017) of sediment load data stretching from the headwater to the delta. We find that the sediment loads have decreased progressively throughout the basin at multiple time scales. The sediment loads have decreased by ~96% and ~74% at the outlets of the upper basin and entire basin, respectively, in 2006–2017 compared to 1950–1985. The hydropower dams in the mainstem have become a dominant cause of the reduction, although downstream channel erosion causes moderate sediment load recovery. The basin-scale sediment connectivity has declined as the upper river is progressively dammed, the middle-lower river is leveed and river-lake interplay weakens. The middle-lower river has changed from a slight depositional to a severe erosional environment, from a sediment transport conduit to a new sediment source zone, and from a transport-limited to a supply-limited condition. These low-level sediment loads will likely persist in the future considering the cumulative dam trapping and depleted channel erosion. As a result, substantial hydro-morphological changes have occurred that affect the water supply, flood mitigation, and the aquatic ecosystem. The findings and lessons in this work can shed light on other large river systems subject to intensified human interference.

Text
From the headwater to the deltaAccepted_manuscript_1_ - Accepted Manuscript
Restricted to Repository staff only until 13 July 2020.
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More information

Accepted/In Press date: 12 July 2019
e-pub ahead of print date: 13 July 2019
Published date: 1 October 2019
Keywords: Changjiang, Sediment load, Sediment starvation, Source-to-sink

Identifiers

Local EPrints ID: 433726
URI: http://eprints.soton.ac.uk/id/eprint/433726
ISSN: 0012-8252
PURE UUID: c2a84b24-71d2-4b74-91c1-6c018c72c362
ORCID for Ian Townend: ORCID iD orcid.org/0000-0003-2101-3858

Catalogue record

Date deposited: 02 Sep 2019 16:30
Last modified: 17 Dec 2019 01:51

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