scholarly journals Experimental Investigation of the Outburst Discharge of Landslide Dam Overtopping Failure

2021 ◽  
Vol 9 ◽  
Author(s):  
Mingjun Zhou ◽  
Zhenming Shi ◽  
Gordon G. D. Zhou ◽  
Kahlil Fredrick E. Cui ◽  
Ming Peng
Keyword(s):  
Landslide Dam ◽  
Longitudinal Direction ◽  
Peak Discharge ◽  
Outburst Flood ◽  
Outburst Floods ◽  
Flume Tests ◽  
Loose Deposits ◽  
Overtopping Failure ◽  
Solids Content ◽  
Inflow Discharge

Research on the factors and mechanisms that influence outburst floods are essential for estimating outflow hydrographs and the resulting inundation. In this study, large flume tests are conducted to investigate the effects of the upstream inflow and the presence of loose erodible deposits on the breaching flow and the subsequent outburst floods. Experimental results reveal that hydrographs of the breaching flow and outburst flood can be divided into three stages where each stage is separated by inflection points and peak discharges. It is found that the larger the inflow discharge, the larger the peak discharge of the outburst flood and the shorter the time needed to reach the peak and inflection discharges of the outburst flood. The breaching flow decreases along the longitudinal direction at rates that increase with the inflow discharge. The ratio between the length of the upstream dam shoulder and the dam width is inversely related to the ratio of the outburst discharge to inflow discharge. We also show that the presence of loose deposits at the dam toe can amplify the peak discharge of outburst flood by increasing the solids content of the water flow.

scholarly journals Long-period variability in ice-dammed glacier outburst floods due to evolving catchment geometry

2021 ◽  
Author(s):  
Amy J. Jenson ◽  
Jason M. Amundson ◽  
Jonathan Kingslake ◽  
Eran Hood
Keyword(s):  
Peak Discharge ◽  
Water Volume ◽  
Flood Hazards ◽  
Outburst Flood ◽  
Ice Shelf ◽  
Outburst Floods ◽  
Flood Magnitude ◽  
Hydrological System ◽  
Basin Geometry ◽  
Glacier Flow

Abstract. We combine a glacier outburst flood model with a glacier flow model to investigate decadal to centennial variations in outburst floods originating from ice-dammed marginal basins. Marginal basins form due to retreat and detachment of tributary glaciers, a process that often results in remnant ice being left behind. The remnant ice, which can act like an ice shelf or break apart into a pack of icebergs, limits the basin storage capacity but also exerts pressure on the underlying water and promotes drainage. We find that during glacier retreat there is a strong, nearly linear relationship between flood water volume and peak discharge for individual basins, despite large changes in glacier and remnant ice volumes that are expected to impact flood hydrographs. Consequently, peak discharge increases over time as long as there is remnant ice remaining in a basin, the peak discharge begins to decrease once a basin becomes ice free, and similar size outburst floods can occur for very different glacier volumes. We also find that the temporal variability in outburst flood magnitude depends on how the floods initiate. Basins that connect to the subglacial hydrological system only after reaching flotation yield greater long-term variability in outburst floods than basins that are continuously connected to the subglacial hydrological system (and therefore release floods that initiate before reaching flotation). Our results highlight the importance of improving our understanding of both changes in basin geometry and outburst flood initiation mechanisms in order to better assess outburst flood hazards and impacts on landscape and ecosystem evolution.

scholarly journals Estimates of Peak Discharge from the Drainage of Ice-Dammed Ape Lake, British Columbia, Canada

1989 ◽  
Vol 35 (121) ◽  
pp. 349-354 ◽  
Author(s):  
Joseph R. Desloges ◽  
David P. Jones ◽  
Karl E. Ricker
Keyword(s):  
British Columbia ◽  
Flood Plain ◽  
Peak Discharge ◽  
Outburst Flood ◽  
Flood Peak ◽  
Lake Volume ◽  
Outburst Floods ◽  
Direct Measurements ◽  
Instantaneous Discharge ◽  
Method Yield

AbstractThe first known occurrence of outburst flooding at Ape Lake, British Columbia, was in October 1984 following the formation of a subglacial tunnel in an ice dam created by Fyles Glacier. Following tunnel closure, the lake refilled in 150 d and then a second outburst flood occurred in August 1986. During both events, 55% of the Apc Lake volume or 46 × 106m3was released in less than 24 h into the 50 km long, ungauged Noeick River, producing an average discharge of 540 m3s−1. Channel and flood-plain erosion, damage to access roads, bridges, a logging camp, and an airstrip were related to the peak or maximum instantaneous discharge. In the absence of direct measurements, and to facilitate planning for future flood events, several independent methods were employed to estimate peak discharge. A modified version of the Clague-Mathews formula and the slope-area method yield consistent estimates which approach 1600 m3s−1near the ice-dam outlet. Attenuation of the flood peak in Noeick River is as high as 25% in the upper 12 km due to channel and flood-plain storage. Results using Clarke’s (1982) physical-based model suggest lower discharges and may be related to the irregular morphology of Ape Lake. Since Fyles Glacier is in continuous retreat, drainage around the margin of the ice dam which began in the summer of 1987 is expected to continue and no further outburst floods are anticipated.

scholarly journals The formation processes and development characteristics of sandbars due to outburst flood triggered by landslide dam overtopping failure

2020 ◽  
Author(s):  
Xiangang Jiang ◽  
Haiguang Cheng ◽  
Lei Gao ◽  
Weiming Liu
Keyword(s):  
Failure Process ◽  
Landslide Dam ◽  
Dam Failure ◽  
Average Height ◽  
Formation Processes ◽  
Outburst Flood ◽  
Channel Changes ◽  
River Bed ◽  
Essential Form ◽  
Overtopping Failure

Abstract. Sandbars are an essential form of riverbed morphology which could be affected by landslide dams. However, few studies have focused on the formation processes and development characteristics of sandbars triggered by outburst flood. In such a way, eight group dam failure experiments with 4 to 7 times of dam length movable bed is carried out to study the temporal and spatial distributions of 25 sandbars along the riverbeds, the sandbars geometric characteristics, and the influence of outburst flow hydraulic characteristics on developments of sandbars. The results show that sandbars are formed after peak discharge of outburst flow. The number of sandbars is 0.4 to 1.0 times the ratio of river bed length to dam length. Besides, sandbars have the characteristic of lengthening towards upstream during the failure process. Sandbars' upstream edges have a more extensive development than sandbars downstream edges. The length of a sandbar along the channel changes faster than the sandbar's width and height. The sandbars' length and width are about 10 to 80 and 1 to 7 times of average height, respectively, and the average heights of sandbars are about 1 to 3.5 times the maximum particle size. Sandbars' lengths make a more significant impact on sandbars' volumes than widths and heights. It found that the Froude number has a significant influence on the sediment carrying capacity. And the sediment concentrations in volumes of the outburst flow at the upstream edges of all sandbars are greater than those at the downstream edges of sandbars. Meanwhile, the sediment carrying capacities of the outburst flow at the upstream edges of sandbars are smaller than those at the sandbars' downstream edges. And the differences between the sediment concentrations and the sediment carrying capacities determine the sedimentation or entrainment. The results can reference the research on the river channel's geomorphological characteristics affected by the outburst flood.

scholarly journals Reconstruction of the Catastrophic Outburst Floods of the Diexi Ancient Landslide-Dammed Lake in the Upper Minjiang River, Eastern Tibetan Plateau

2021 ◽  
Author(s):  
Junxue Ma ◽  
Jian Chen ◽  
Zhijiu Cui ◽  
Wendy Zhou ◽  
Ruichen Chen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Landslide Dam ◽  
Peak Discharge ◽  
The Tibetan Plateau ◽  
Lake Area ◽  
Ancient Landslide ◽  
Mountainous Regions ◽  
Minjiang River ◽  
Outburst Floods ◽  
Dammed Lake

Abstract Landslide-dammed lake outburst floods (LLOFs) may pose serious safety threats to nearby residents and their livelihoods, as well as cause major damages to the downstream areas in mountainous regions. This study presents the Diexi ancient landslide-dammed lake (DALL) in the Upper Minjiang River at the eastern margins of the Tibetan Plateau, which was known to an estimated previous maximal lake area of 1.1 × 107 m2 and an impounded volume of 2.9 × 109 m3. Then, at approximately 27 ka BP, the ancient landslide dam failed and catastrophic LLOFs occurred. It was determined that the peak discharge of the Diexi ancient LLOFs could be reconstructed using regression, parametric, and boulder competence approaches. The reconstructed maximum peak discharge might be 72,232.66 m3/s, with an average velocity of 17.23 m/s, indicating that the Diexi ancient LLOFs were the most gigantic outburst floods to occur in the Upper Minjiang River Valley since the Late Pleistocene Period. The differences in the widths and slopes within the former and the later reaches of the dam indicated that the geomorphic influences on the river channel resulting from the DALL and its LLOFs have existed for tens of thousands of years. These findings were of major significance in deepening the understanding of the existence and disappearances of important river-knickpoints on a time scale of tens of thousands of years.

scholarly journals Modeling Flood Peak Discharge Caused by Overtopping Failure of a Landslide Dam

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 921
Author(s):  
Hechun Ruan ◽  
Huayong Chen ◽  
Tao Wang ◽  
Jiangang Chen ◽  
Huibin Li
Keyword(s):  
Landslide Dam ◽  
Calculation Model ◽  
Peak Discharge ◽  
Mitigation Measures ◽  
Dam Failure ◽  
Jinsha River ◽  
Simulation Accuracy ◽  
Flood Peak ◽  
Overtopping Failure ◽  
Dam Overtopping

Overtopping failure often occurs in landslide dams, resulting in the formation of strong destructive floods. As an important hydraulic parameter to describe floods, the peak discharge often determines the downstream disaster degree. Based on 67 groups of landslide dam overtopping failure cases all over the world, this paper constructs the calculation model for peak discharge of landslide dam failure. The model considers the influence of dam erodibility, breach shape, dam shape and reservoir capacity on the peak discharge. Finally, the model is compared with the existing models. The results show that the new model has a higher accuracy than the existing models and the simulation accuracy of the two outburst peak discharges of Baige dammed lake in Jinsha River (10 October 2018 and 3 November 2018) is higher (the relative error is 0.73% and 6.68%, respectively), because the model in this study considers more parameters (the breach shape, the landslide dam erodibility) than the existing models. The research results can provide an important reference for formulating accurate and effective disaster prevention and mitigation measures for such disasters.

scholarly journals Estimates of Peak Discharge from the Drainage of Ice-Dammed Ape Lake, British Columbia, Canada

1989 ◽  
Vol 35 (121) ◽  
pp. 349-354 ◽  
Author(s):  
Joseph R. Desloges ◽  
David P. Jones ◽  
Karl E. Ricker
Keyword(s):  
British Columbia ◽  
Flood Plain ◽  
Peak Discharge ◽  
Outburst Flood ◽  
Flood Peak ◽  
Lake Volume ◽  
Outburst Floods ◽  
Direct Measurements ◽  
Instantaneous Discharge ◽  
Method Yield

AbstractThe first known occurrence of outburst flooding at Ape Lake, British Columbia, was in October 1984 following the formation of a subglacial tunnel in an ice dam created by Fyles Glacier. Following tunnel closure, the lake refilled in 150 d and then a second outburst flood occurred in August 1986. During both events, 55% of the Apc Lake volume or 46 × 106 m3 was released in less than 24 h into the 50 km long, ungauged Noeick River, producing an average discharge of 540 m3 s−1. Channel and flood-plain erosion, damage to access roads, bridges, a logging camp, and an airstrip were related to the peak or maximum instantaneous discharge. In the absence of direct measurements, and to facilitate planning for future flood events, several independent methods were employed to estimate peak discharge. A modified version of the Clague-Mathews formula and the slope-area method yield consistent estimates which approach 1600 m3 s−1 near the ice-dam outlet. Attenuation of the flood peak in Noeick River is as high as 25% in the upper 12 km due to channel and flood-plain storage. Results using Clarke’s (1982) physical-based model suggest lower discharges and may be related to the irregular morphology of Ape Lake. Since Fyles Glacier is in continuous retreat, drainage around the margin of the ice dam which began in the summer of 1987 is expected to continue and no further outburst floods are anticipated.

Influence of inflow discharge and bed erodibility on outburst flood of landslide dam

2019 ◽  
Vol 16 (4) ◽  
pp. 778-792 ◽  
Author(s):  
Ming-jun Zhou ◽  
Gordon G. D. Zhou ◽  
Kahlil Fredrick E. Cui ◽  
Dong-ri Song ◽  
Xue-qiang Lu
Keyword(s):  
Landslide Dam ◽  
Outburst Flood ◽  
Inflow Discharge

scholarly journals Brief communication: Observations of a glacier outburst flood from Lhotse Glacier, Everest area, Nepal

2017 ◽  
Vol 11 (1) ◽  
pp. 443-449 ◽  
Author(s):  
David R. Rounce ◽  
Alton C. Byers ◽  
Elizabeth A. Byers ◽  
Daene C. McKinney
Keyword(s):  
Satellite Imagery ◽  
Peak Discharge ◽  
Dam Failure ◽  
Outburst Flood ◽  
Recent Event ◽  
Triggering Mechanism ◽  
Flood Water ◽  
Outburst Floods ◽  
Field Assessment

Abstract. Glacier outburst floods with origins from Lhotse Glacier, located in the Everest region of Nepal, occurred on 25 May 2015 and 12 June 2016. The most recent event was witnessed by investigators, which provided unique insights into the magnitude, source, and triggering mechanism of the flood. The field assessment and satellite imagery analysis following the event revealed that most of the flood water was stored englacially and that the flood was likely triggered by dam failure. The flood's peak discharge was estimated to be 210 m3 s−1.

scholarly journals Mapping Outburst Floods Using a Collaborative Learning Method Based on Temporally Dense Optical and SAR Data: A Case Study with the Baige Landslide Dam on the Jinsha River, Tibet

2021 ◽  
Vol 13 (11) ◽  
pp. 2205
Author(s):  
Zhongkang Yang ◽  
Jinbing Wei ◽  
Jianhui Deng ◽  
Yunjian Gao ◽  
Siyuan Zhao ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Landslide Dam ◽  
Flood Mapping ◽  
Outburst Flood ◽  
Backscattering Coefficient ◽  
Sar Images ◽  
Jinsha River ◽  
Outburst Floods ◽  
Sar Data ◽  
Sentinel 2

Outburst floods resulting from giant landslide dams can cause devastating damage to hundreds or thousands of kilometres of a river. Accurate and timely delineation of flood inundated areas is essential for disaster assessment and mitigation. There have been significant advances in flood mapping using remote sensing images in recent years, but little attention has been devoted to outburst flood mapping. The short-duration nature of these events and observation constraints from cloud cover have significantly challenged outburst flood mapping. This study used the outburst flood of the Baige landslide dam on the Jinsha River on 3 November 2018 as an example to propose a new flood mapping method that combines optical images from Sentinel-2, synthetic aperture radar (SAR) images from Sentinel-1 and a Digital Elevation Model (DEM). First, in the cloud-free region, a comparison of four spectral indexes calculated from time series of Sentinel-2 images indicated that the normalized difference vegetation index (NDVI) with the threshold of 0.15 provided the best separation flooded area. Subsequently, in the cloud-covered region, an analysis of dual-polarization RGB false color composites images and backscattering coefficient differences of Sentinel-1 SAR data were found an apparent response to ground roughness’s changes caused by the flood. We carried out the flood range prediction model based on the random forest algorithm. Training samples consisted of 13 feature vectors obtained from the Hue-Saturation-Value color space, backscattering coefficient differences/ratio, DEM data, and a label set from the flood range prepared from Sentinel-2 images. Finally, a field investigation and confusion matrix tested the prediction accuracy of the end-of-flood map. The overall accuracy and Kappa coefficient were 92.3%, 0.89 respectively. The full extent of the outburst floods was successfully obtained within five days of its occurrence. The multi-source data merging framework and the massive sample preparation method with SAR images proposed in this paper, provide a practical demonstration for similar machine learning applications using remote sensing.

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