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Sedimentation of overbank floods in the confined complex channel-floodplain system of the Lower Yellow River, China

Sedimentation of overbank floods in the confined complex channel-floodplain system of the Lower Yellow River, China
Sedimentation of overbank floods in the confined complex channel-floodplain system of the Lower Yellow River, China
The channel boundary conditions along the Lower Yellow River (LYR) have been altered significantly since the 1950s with the continual reinforcement and construction of both main and secondary dykes and river training works. To evaluate how the confined complex channel-floodplain system of the LYR responds to floods, this study presents a detailed investigation of the relationship between the tempo-spatial distribution of sedimentation/erosion and overbank floods occurred in the LYR. For large overbank floods, we found that when the sediment transport coefficient (ratio of sediment concentration of flow to flow discharge) is less than 0.034, the bankfull channel is subject to significant erosion, while the main and secondary floodplains both accumulate sediment. The amount of sediment deposited on the main and secondary floodplains is closely related to the ratio ofpeak discharge to bankfull discharge, volume of water flowing over the floodplains and sediment concentration of overbank flow, while the degree of erosion in the bankfull channel is related to the amount of sediment deposited on the main and secondary floodplains, water volume and sediment load in flood season. The significant increase in erosion in the bankfull channel is due to the construction of the main and secondary dykes and river training works, which are largely in a wide and narrow alternated pattern along the LYR such that the water flowing over wider floodplains returns to the channel downstream after it drops sediment. For small overbank floods, the bankfull channel is subject to erosion when the sediment transport coefficient is less than 0.028, while the amount of sediment deposited on the secondary floodplain is associated closely with the sediment concentration of flow. Over the entire length of the LYR, the situation of erosion in the bankfull channel and sediment deposition on the main and secondary floodplains occurred mainly in the upper reach of the LYR, in which a channel wandering in planform has been well developed.
1099-1085
3472-3488
Zhang, Min
b05c2fb3-97e7-49a1-9a42-ca8a7c0cc4f0
Huang, He Qing
09aac111-fc3f-48a0-91ac-1bebca3d36fc
Carling, Paul A.
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Zhang, Mingwu
b18313e6-22bf-435b-969e-0d630f8b6cb0
Zhang, Min
b05c2fb3-97e7-49a1-9a42-ca8a7c0cc4f0
Huang, He Qing
09aac111-fc3f-48a0-91ac-1bebca3d36fc
Carling, Paul A.
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Zhang, Mingwu
b18313e6-22bf-435b-969e-0d630f8b6cb0

Zhang, Min, Huang, He Qing, Carling, Paul A. and Zhang, Mingwu (2017) Sedimentation of overbank floods in the confined complex channel-floodplain system of the Lower Yellow River, China. Hydrological Processes, 31 (20), 3472-3488. (doi:10.1002/hyp.11260).

Record type: Article

Abstract

The channel boundary conditions along the Lower Yellow River (LYR) have been altered significantly since the 1950s with the continual reinforcement and construction of both main and secondary dykes and river training works. To evaluate how the confined complex channel-floodplain system of the LYR responds to floods, this study presents a detailed investigation of the relationship between the tempo-spatial distribution of sedimentation/erosion and overbank floods occurred in the LYR. For large overbank floods, we found that when the sediment transport coefficient (ratio of sediment concentration of flow to flow discharge) is less than 0.034, the bankfull channel is subject to significant erosion, while the main and secondary floodplains both accumulate sediment. The amount of sediment deposited on the main and secondary floodplains is closely related to the ratio ofpeak discharge to bankfull discharge, volume of water flowing over the floodplains and sediment concentration of overbank flow, while the degree of erosion in the bankfull channel is related to the amount of sediment deposited on the main and secondary floodplains, water volume and sediment load in flood season. The significant increase in erosion in the bankfull channel is due to the construction of the main and secondary dykes and river training works, which are largely in a wide and narrow alternated pattern along the LYR such that the water flowing over wider floodplains returns to the channel downstream after it drops sediment. For small overbank floods, the bankfull channel is subject to erosion when the sediment transport coefficient is less than 0.028, while the amount of sediment deposited on the secondary floodplain is associated closely with the sediment concentration of flow. Over the entire length of the LYR, the situation of erosion in the bankfull channel and sediment deposition on the main and secondary floodplains occurred mainly in the upper reach of the LYR, in which a channel wandering in planform has been well developed.

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Zhang_et_al-2017-Hydrological_Processes - Accepted Manuscript
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Accepted/In Press date: 19 June 2017
e-pub ahead of print date: 9 August 2017
Published date: 30 September 2017

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Local EPrints ID: 415085
URI: http://eprints.soton.ac.uk/id/eprint/415085
ISSN: 1099-1085
PURE UUID: 9fd3951f-ad5d-42a0-9821-6febf7b1e2b0

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Date deposited: 25 Oct 2017 16:30
Last modified: 07 Oct 2020 06:18

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