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Assessment of local outburst flood risk from successive landslides: case study of Baige landslide-dammed lake, upper Jinsha river, eastern Tibet

Assessment of local outburst flood risk from successive landslides: case study of Baige landslide-dammed lake, upper Jinsha river, eastern Tibet
Assessment of local outburst flood risk from successive landslides: case study of Baige landslide-dammed lake, upper Jinsha river, eastern Tibet
Two large landslides in October and November 2018 sequentially dammed the Jinsha river at Baige village, eastern Tibet, China. Subsequently, breaching of each dam induced massive outburst floods that posed a severe threat to downstream cities and infrastructure. Field investigation indicates volumes of the first and second landslide dam are about 24.5 × 106 m3 and 8.53 × 106 m3, respectively. However, the peak discharge of the flood generated from the second landslide (3.1 × 104 m3/s) was significantly larger than that from the first (1.0 × 104 m3/s). The second peak discharge would have been 5.15 × 104 m3/s if the dam breached naturally. In this study, we developed two geometry parameters: effective dam height He (elevation difference between overtopping level and river bottom) and a narrowing number distribution Nr(H) (measures the degree to which a river section is occupied by landslide materials to elevation H) which represents river section narrowing effects of successive landslides. Using numerical simulations, we show that He dominates peak discharge, and it has a linear relationship with peak discharge with slope of 1009.4 m2/s. Furthermore, the dam includes two sub-areas: a higher part (SB-1) and a lower part (SB-2). Two floods only eroded SB-2. However, breaching of SB-1 and breached SB-2 still narrowed the river. The narrowing effects of the first and second breached dam on the river channel are around 0.35 and 0.5, respectively. Spillway and landslide runup deposits increased the local flood risk by narrowing and lifting the local river section; the first landslide promoted the second landslide, which occupied the same area and forms a dam with high He value. Consequently, a more catastrophic flood could be triggered by a small subsequent landslide. Spatial superposition phenomenon of successive landslides increased the local flood risk. This research quantitatively analyzed the influence of the geometry of dam induced by successive landslides on the process of outburst floods and the risk.
Effective dam height, Multi-hazard chain, Narrowing effect, Successive landslides, Successive outburst floods
0022-1694
Liu, Dingzhu
3e85c90b-1f7d-4eea-b66d-f72dc9ec6d20
Cui, Yifei
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Wang, Hao
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Jin, Wen
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Wu, Chunhao
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Bazai, Nazir Ahmed
c5c39b50-391c-438a-a492-19dafac2d872
Carling, Paul
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Chen, Huayong
b2992bc5-640f-4f7d-8a9b-dd13e7219cf6
Liu, Dingzhu
3e85c90b-1f7d-4eea-b66d-f72dc9ec6d20
Cui, Yifei
36a4c4d3-f460-4b7a-94e9-4dc2e9717717
Wang, Hao
a43804be-e40e-408d-a09c-00fd069cdd30
Jin, Wen
d9f96a01-cbd6-4d70-add6-eca0d09e1f99
Wu, Chunhao
7ab0e8e2-b882-4619-9efd-7072878228cb
Bazai, Nazir Ahmed
c5c39b50-391c-438a-a492-19dafac2d872
Carling, Paul
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Chen, Huayong
b2992bc5-640f-4f7d-8a9b-dd13e7219cf6

Liu, Dingzhu, Cui, Yifei, Wang, Hao, Jin, Wen, Wu, Chunhao, Bazai, Nazir Ahmed, Carling, Paul and Chen, Huayong (2021) Assessment of local outburst flood risk from successive landslides: case study of Baige landslide-dammed lake, upper Jinsha river, eastern Tibet. Journal of Hydrology, 599, [126294]. (doi:10.1016/j.jhydrol.2021.126294).

Record type: Article

Abstract

Two large landslides in October and November 2018 sequentially dammed the Jinsha river at Baige village, eastern Tibet, China. Subsequently, breaching of each dam induced massive outburst floods that posed a severe threat to downstream cities and infrastructure. Field investigation indicates volumes of the first and second landslide dam are about 24.5 × 106 m3 and 8.53 × 106 m3, respectively. However, the peak discharge of the flood generated from the second landslide (3.1 × 104 m3/s) was significantly larger than that from the first (1.0 × 104 m3/s). The second peak discharge would have been 5.15 × 104 m3/s if the dam breached naturally. In this study, we developed two geometry parameters: effective dam height He (elevation difference between overtopping level and river bottom) and a narrowing number distribution Nr(H) (measures the degree to which a river section is occupied by landslide materials to elevation H) which represents river section narrowing effects of successive landslides. Using numerical simulations, we show that He dominates peak discharge, and it has a linear relationship with peak discharge with slope of 1009.4 m2/s. Furthermore, the dam includes two sub-areas: a higher part (SB-1) and a lower part (SB-2). Two floods only eroded SB-2. However, breaching of SB-1 and breached SB-2 still narrowed the river. The narrowing effects of the first and second breached dam on the river channel are around 0.35 and 0.5, respectively. Spillway and landslide runup deposits increased the local flood risk by narrowing and lifting the local river section; the first landslide promoted the second landslide, which occupied the same area and forms a dam with high He value. Consequently, a more catastrophic flood could be triggered by a small subsequent landslide. Spatial superposition phenomenon of successive landslides increased the local flood risk. This research quantitatively analyzed the influence of the geometry of dam induced by successive landslides on the process of outburst floods and the risk.

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Assessment of local outburst flood risk from successive landslides
Restricted to Repository staff only until 8 April 2023.
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Accepted/In Press date: 5 April 2021
Published date: 8 April 2021
Additional Information: Funding Information: This study was funded by the National Natural Science Foundation of China (41941019, 42077238) and the Research Fund Program of the State Key Laboratory of Hydroscience and Engineering (2020-KY-04). The authors would like to thank the National Natural Science Foundation of China (grant 41771045) and the CAS "Light of West China" Program. Publisher Copyright: © 2021 Elsevier B.V. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
Keywords: Effective dam height, Multi-hazard chain, Narrowing effect, Successive landslides, Successive outburst floods

Identifiers

Local EPrints ID: 450367
URI: http://eprints.soton.ac.uk/id/eprint/450367
ISSN: 0022-1694
PURE UUID: b3e0a718-be88-49f6-96ff-6f96b6098cfe

Catalogue record

Date deposited: 26 Jul 2021 16:31
Last modified: 25 Nov 2021 20:43

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Contributors

Author: Dingzhu Liu
Author: Yifei Cui
Author: Hao Wang
Author: Wen Jin
Author: Chunhao Wu
Author: Nazir Ahmed Bazai
Author: Paul Carling
Author: Huayong Chen

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