Journal of Geographical Sciences >
Flood assessment and early warning of the reoccurrence of river blockage at the Baige landslide
Gao Yunjian (1991-), PhD Candidate, specialized in geological engineering and geological hazards. E-mail: gaoyunjiansu@163.com |
Received date: 2020-09-15
Accepted date: 2021-05-27
Online published: 2022-01-25
Supported by
The Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0905)
National Key R&D Program of China(2018YFC15050004)
National Natural Science Foundation Projects(42007248)
Copyright
On 10th Oct. and 3rd Nov. 2018, two successive landslides occurred in the Jinsha River catchment at Baige Village, Tibet Autonomous Region, China. The landslides blocked the major river and formed the barrier lake, which finally caused the huge flood disaster loss. The hillslope at Baige landslide site has been still deforming after the 2018 slidings, which is likely to fail and block the Jinsha River again in the future. Therefore the investigation of 2018 flood disaster at the Baige landslide is of a great significance to provide a classic case for flood assessment and early warning for the future disaster. The detailed survey revealed that the outstanding inundations induced bank collapse disasters upstream the Baige landslide dams, and the field investigations and hydrological simulation suggested that the downstream of the Baige landslide were seriously flooded due to the two periods of the outburst floods. On these bases, the early warning process of potential outburst floods at the Baige landslide was advised, which contains four stages: Outburst Flood Simulating Stage, Outburst Flood Forecasting Stage, Emergency Plan and Emergency Evacuation Stage. The study offers a conceptual model for the mitigation of landslides and flood disasters in the high-relief mountainous region in Tibet.
Key words: Baige landslide; outburst flood; flood assessment; flood early warning; HEC-RAS
GAO Yunjian , ZHAO Siyuan , DENG Jianhui , YU Zhiqiu , RAHMAN Mahfuzur . Flood assessment and early warning of the reoccurrence of river blockage at the Baige landslide[J]. Journal of Geographical Sciences, 2021 , 31(11) : 1694 -1712 . DOI: 10.1007/s11442-021-1918-9
Figure 1 Geographical location (a. Submerged area of upper and lower reaches of the Baige landslide dam; b. Regional location of the study area; c. Longitudinal profile of the main channel downstream of the Baige landslide dam) |
Figure 2 Landslide profile (a. Geomorphic characteristic of the Baige landslide; b. Cross section of the entire Baige landslide (modified from Chen et al*2021); c. Cross section of the Baige landslide deposition) |
Figure 3 Flow chart of flood simulation for potential outburst floods |
Table 1 Manning coefficient of land-use types for flood simulation |
Parameter | Land-use type | Value |
---|---|---|
Manning coefficient | Farmland | 0.035 |
Housing land | 0.150 | |
Road | 0.030 | |
Forest land | 0.100 | |
Grassplot | 0.030 | |
Alluvial flat | 0.025 |
Figure 4 Barrier lakes at different elevations (a. Plan of flood area in upstream of barrier dam; b. Flood level of typical townships upstream of the barrier dam; c. Profiles of flood area in upstream of the barrier dam) |
Figure 5 The “10.10” bank slope disaster (a. 5 km downstream of Boluo Town; b. Tagong Village; c. Boluo Town) |
Figure 6 The “11.3” flood disaster (a. Boluo township government building; b. Boluo Temple; c. Jinsha Town) |
Figure 7 Landslides induced by the fluctuation of water level in barrier lake area |
Table 2 Statistics on the basic information of typical landslide deformation induced by barrier lake |
Landslide | Deposition zone (km2) | Volume (×106 m3) | Average slope (°) | Relative elevation (m) |
---|---|---|---|---|
Xiaomojiu | 0.71 | 12.70 | 29 | 710 |
Guili | 0.44 | 3.20 | 25 | 510 |
Figure 8 Discharge variation at the dam (a. The “10.10” break flood process of barrier dam; b. The “11.3” break flood process of the downstream dam) |
Figure 9 Flood disaster loss in the upstream and downstream of the dam |
Figure 10 Land type of flood inundated area in Shigu Town |
Figure 11 The field investigation area, as shown in Figure 10 (a. Right inundated area of Jinsha River, Shigu Town; b. Left inundated area of Jinsha River, Shigu Town) |
Figure 12 Flood simulation in the Shigu region (a. Section cross selection of simulated reaches; b. Flood inundation elevation) |
Figure 13 Time of flood arrival in the downstream catchment of the dam |
Figure 14 Warning process of outburst floods |
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