scholarly journals Landslide-lake outburst floods accelerate downstream slope slippage

2021 ◽  
Author(s):  
Wentao Yang ◽  
Jian Fang ◽  
Jing Liu-Zeng
Keyword(s):  
River Channel ◽  
Disaster Mitigation ◽  
Jinsha River ◽  
Mountainous Regions ◽  
Deformation Response ◽  
Outburst Floods ◽  
Dynamic Channel ◽  
One Year ◽  
Landslide Lake ◽  
Sentinel 2

Abstract. The Jinsha River, carving a 2–4 km deep gorge, is one of the largest SE Asian rivers. Two successive landslide-lake outburst floods (LLFs) occurred after the 2018 Baige landslides along the river. Using Sentinel-2 images, we examined the LLFs' impacts on downstream river channel and adjacent hillslopes over a 100 km distance. The floods increased the width of the active river channel by 54 %. Subsequently, major landslides persisted for 15 months in at least nine locations for displacements > 2 m. Among them, three moving hillslopes, ~80 km downstream from the Baige landslides, slumped more than 10 m one year after the floods. Extensive undercuts by the floods probably removed hillslope buttresses and triggered deformation response, suggesting a strong and dynamic channel-hillslope coupling. Our findings indicate that infrequent catastrophic outburst flooding plays an important role in landscape evolution. Persistent post-flood hillslope movement should be considered in disaster mitigation in high-relief mountainous regions.

scholarly journals Landslide-lake outburst floods accelerate downstream hillslope slippage

2021 ◽  
Vol 9 (5) ◽  
pp. 1251-1262
Author(s):  
Wentao Yang ◽  
Jian Fang ◽  
Jing Liu-Zeng
Keyword(s):  
River Channel ◽  
Disaster Mitigation ◽  
River Channels ◽  
Jinsha River ◽  
Mountainous Regions ◽  
Deformation Response ◽  
Outburst Floods ◽  
Dynamic Channel ◽  
Landslide Lake ◽  
Sentinel 2

Abstract. The Jinsha River, which has carved a 2–4 km deep gorge, is one of the largest SE Asian rivers. Two successive landslide-lake outburst floods (LLFs) occurred after the 2018 Baige landslides along the river. Using Sentinel-2 images, we examined the LLF impacts on downstream river channels and adjacent hillslopes over a 100 km distance. The floods increased the width of the active river channel by 54 %. Subsequently, major landslides persisted for 15 months in at least nine locations for displacements >2 m. Among them, three moving hillslopes ∼80 km downstream from the Baige landslides slumped more than 10 m 1 year after the floods. Extensive undercuts by floods probably removed hillslope buttresses and triggered a deformation response, suggesting strong and dynamic channel–hillslope coupling. Our findings indicate that infrequent catastrophic outburst flooding plays an important role in landscape evolution. Persistent post-flood hillslope movement should be considered in disaster mitigation in high-relief mountainous regions.

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.

scholarly journals Correction to: Using Sentinel-2 time series to detect slope movement before the Jinsha River landslide

Landslides ◽  
2019 ◽  
Vol 16 (7) ◽  
pp. 1325-1326
Author(s):  
Wentao Yang ◽  
Yunqi Wang ◽  
Shao Sun ◽  
Yujie Wang ◽  
Chao Ma
Keyword(s):  
Time Series ◽  
Slope Movement ◽  
Jinsha River ◽  
Sentinel 2

Special Issue on the 2016 Kumamoto Earthquakes

2017 ◽  
Vol 12 (sp) ◽  
pp. 645-645
Author(s):  
Haruo Hayashi
Keyword(s):  
Urban Areas ◽  
Peer Review Process ◽  
Extended Period ◽  
Seismic Intensity ◽  
Intensity Level ◽  
Special Issue ◽  
Mountainous Regions ◽  
The 2016 Kumamoto Earthquakes ◽  
One Year ◽  
2016 Kumamoto Earthquakes

At 9:26 pm on April 14, 2016, a magnitude 6.5 earthquake struck directly beneath Kumamoto prefecture, Japan, producing a seismic intensity level (JMA) of 7 in Mashiki Town. Although the earthquake damage forecasting system in operation at the time predicted that this earthquake would cause no damage, it resulted in extensive human casualties and property damage centered in Mashiki Town. Past midnight on April 16, 28 hours after the first shock, the second and main shock hit, which recorded magnitude 7.3 and was the strongest recorded urban earthquake in Japan since 1995. The hypocenter extended from Kumamoto prefecture to Oita prefecture, cutting across the island of Kyushu. Mount Aso also saw increased volcanic activities which led to several landslides. This resulted in the collapse of the Great Aso Bridge, an important transportation point, causing the loss of human lives as well as obstruction of traffic for an extended period. Much confusion arose in the process of implementing measures in response to the earthquakes, which produced damage in urban areas as well as hilly and mountainous regions, raising many issues and prompting several new approaches. Researchers in many fields have conducted various activities at the disaster sites in the one-year period following the earthquakes, and produced significant findings in many areas. In order to make these results available to the wider global community, JDR is releasing a special issue on the 2016 Kumamoto Earthquakes with excellent papers and reports to mark their one-year anniversary. While the submitted papers to this special issue went through our regular peer review process, no publication charge was imposed so as to encourage as many submissions as possible. It is our hope that this special issue will contribute to throwing light on the 2016 Kumamoto Earthquakes in its entirety.

scholarly journals Wind Speeds at Heights Crucial for Wind Energy: Measurements and Verification of Forecasts

2012 ◽  
Vol 51 (9) ◽  
pp. 1602-1617 ◽  
Author(s):  
Susanne Drechsel ◽  
Georg J. Mayr ◽  
Jakob W. Messner ◽  
Reto Stauffer
Keyword(s):  
Wind Speed ◽  
Low Cost ◽  
Good Choice ◽  
Mountainous Regions ◽  
Wind Speeds ◽  
Relative Contribution ◽  
Site Characteristics ◽  
One Year ◽  
Nwp Model ◽  
Ecmwf Model

AbstractWind speed measurements from one year from meteorological towers and wind turbines at heights between 20 and 250 m for various European sites are analyzed and are compared with operational short-term forecasts of the global ECMWF model. The measurement sites encompass a variety of terrain: offshore, coastal, flat, hilly, and mountainous regions, with low and high vegetation and also urban influences. The strongly differing site characteristics modulate the relative contribution of synoptic-scale and smaller-scale forcing to local wind conditions and thus the performance of the NWP model. The goal of this study was to determine the best-verifying model wind among various standard wind outputs and interpolation methods as well as to reveal its skill relative to the different site characteristics. Highest skill is reached by wind from a neighboring model level, as well as by linearly interpolated wind from neighboring model levels, whereas the frequently applied 10-m wind logarithmically extrapolated to higher elevations yields the largest errors. The logarithmically extrapolated 100-m model wind reaches the best compromise between availability and low cost for data even when the vertical resolution of the model changes. It is a good choice as input for further statistical postprocessing. The amplitude of measured, height-dependent diurnal variations is underestimated by the model. At low levels, the model wind speed is smaller than observed during the day and is higher during the night. At higher elevations, the opposite is the case.

Recent catastrophic landslide lake outburst floods in the Himalayan mountain range

2016 ◽  
Vol 41 (1) ◽  
pp. 3-28 ◽  
Author(s):  
Virginia Ruiz-Villanueva ◽  
Simon Allen ◽  
Manohar Arora ◽  
Narendra K Goel ◽  
Markus Stoffel
Keyword(s):  
Large Scale ◽  
Drainage System ◽  
Mountain Range ◽  
The Tibetan Plateau ◽  
Remotely Sensed Data ◽  
Discharge Data ◽  
Outburst Floods ◽  
High Resolution Satellite Images ◽  
Hydrometeorological Conditions ◽  
Landslide Lake

Among the more complex and devastating interactions between climate and hydromorphological processes in mountain environments are landslide lake outburst floods (LLOFs), resulting from mass movements temporarily blocking a drainage system. This work reviews these processes in the Himalayas and highlights the high frequency of this type of phenomenon in the region. In addition, we analyse two recent catastrophic trans-national LLOFs occurring in the Sutlej river basin during 2000 and 2005. Based on high resolution satellite images, Tropical Rainfall Measuring Mission (TRMM), Moderate-Resolution Imaging Spectroradiometer (MODIS) derived evolution of snowline elevation and discharge data we reconstruct the timing and hydrometeorological conditions related to the formation and failure of landslide dams. Results showed that the 2005 flood, originating from the outburst of the Parchu Lake, was not related to heavy precipitation, but was likely enhanced by the rapid and late snowmelt of an unusually deep and widespread snowpack. The flood in 2000 was triggered by the outburst of an unnamed lake located on the Tibetan plateau, identified here for the first time. In this case, the outburst followed intense precipitation in the lake watershed, which raised the level of the lake and thus caused the breaching of the dam. As stream gauges were damaged during the events detailed discharge data is not available, but we estimated the peak discharges ranging between 1100 m3 s−1 and 2000 m3 s−1 in 2005, and 1024 m3 s−1 and 1800 m3 s−1 in 2000. These events caused significant geomorphic changes along the river valleys, with observed changes in channel width exceeding 200 m. Results also demonstrate that remotely-sensed data enables valuable large-scale monitoring of lake development and related hydrometeorological conditions, and may thereby inform early warning strategies, and provide a basis for flood risk reduction measures that focus on disaster preparedness and response strategies.

Strike-variable coseismic and postseismic slips of the 12 December 2017 Mw 6.0 Hojedk (Iran) earthquake revealed by Sentinel-1/2 images: Implications for the local lithospheric structure

2020 ◽  
Author(s):  
Yingwen Zhao ◽  
Caijun Xu ◽  
Yangmao Wen
Keyword(s):  
Slip Distribution ◽  
Seismogenic Zone ◽  
Postseismic Deformation ◽  
Reverse Fault ◽  
Sar Images ◽  
One Year ◽  
The Moment ◽  
Depth Extent ◽  
Postseismic Slip ◽  
Sentinel 2

<p>On 12 December 2017, a shallow reverse earthquake ruptured an unrecognized fault located in a transpressional relay zone between Lakar Kuh and Gowk faults. Four tracks of Sentinel-1A/B interferometric wide swath SAR images are used to generate coseismic interferograms. The retrieved maximum line-of-sight (LOS) displacement is up to ~1 m toward the satellite for descending data. An offset tracking method within GAMMA software is used to generate range and azimuth offsets based on Sentinel-1 SAR images. Two Sentinel-2 images are processed with the COSI-Corr package to generate horizontal displacements. The calculated three-dimension deformation field shows that the east-west displacements have motions in different directions, the north-south shortening near the fault trace approaches ~2 m and the maximum uplift is over 1 m. Based on the rupture trace in Sentinel-2 image, a strike-variable fault is constructed to explain the LOS displacements. The estimated slip distribution shows that the peak slip is ~2.5 m located at a depth of ~1.5 km and the depth extent of rupture is 0-3 km with the length of rupture on the surface approaching ~7 km. There are both right-lateral and left-lateral slips occurring on the fault, which are consistent with field observations. The one year of postseismic displacements are estimated by a short baseline subset technique based on two tracks (ascending and descending) of Sentinel-1 SAR images. The maximum LOS displacements is up to ~7 cm toward the satellite for the descending data. The forward displacements show that the poro-elastic rebound in the upper crust does not explain the LOS data. The data can be fitted well in terms of afterslip. The estimated postseismic slip on this strike-variable fault is found to occur in portions of the fault where small slips on these patches are obtained in the coseismic slip inversion. Most of patches related to the postseismic slip are located below the main coseismic patches with the depth extent of rupture being 0.5-4 km. The cumulative slip distribution during one year has the peak slip of ~20 cm, releasing ~12% of the moment of coseismic rupture. Taking into account aftershock depths, the shallow postseismic slip is considered to occur aseismically and cause the most of postseismic deformation. The afterslip may result from some response to a stress concentration located at the periphery of main coseismic rupture. After the analysis on Coulomb stress change, it is possible that the former two Mw ~6 earthquakes occurred on 1 and 12 December cause stress perturbations in the seismogenic zone of this earthquake, which further may bring the local prestressed lithosphere to rupture. For this shallow event, a small shear modulus (less than 30 GPa) is needed to make the moment more comparable to seismic results. This earthquake can be interpreted as the accommodation of the northward motion in the form of oblique-slip reverse fault between right-lateral strike-slip fault systems. The unusually deformation patterns caused by the coseismic and postseismic slips of this earthquake may be indicative of differently local lithosphere structure in this transpressional relay zone.</p>

scholarly journals Development of Supraglacial Ponds in the Everest Region, Nepal, between 1989 and 2018

2019 ◽  
Vol 11 (9) ◽  
pp. 1058 ◽  
Author(s):  
Mohan Bahadur Chand ◽  
Teiji Watanabe
Keyword(s):  
Seasonal Variations ◽  
Winter Season ◽  
Landsat Images ◽  
Continuous Increase ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Good Potential ◽  
Accuracy Assessments ◽  
Fine Resolution ◽  
Sentinel 2

Several supraglacial ponds are developing and increasing in size and number in the Himalayan region. They are the precursors of large glacial lakes and may become potential for glacial lake outburst floods (GLOFs). Recently, GLOF events originating from supraglacial ponds were recorded; however, the spatial, temporal, and seasonal distributions of these ponds are not well documented. We chose 23 debris-covered glaciers in the Everest region, Nepal, to study the development of supraglacial ponds. We used historical Landsat images (30-m resolution) from 1989 to 2017, and Sentinel-2 (10-m resolution) images from 2016 to 2018 to understand the long-term development and seasonal variations of these ponds. We also used fine-resolution (0.5–2 m) WorldView and GeoEye imageries to reveal the high-resolution inventory of these features and these images were also used as references for accuracy assessments. We observed a continuous increase in the area and number of ponds from 1989–2017, with minor fluctuations. Similarly, seasonal variations were observed at the highest ponded area in the pre- and postmonsoon seasons, and lowest ponded area in the winter season. Substantial variations of the ponds were also observed among glaciers corresponding to their size, slope, width, moraine height, and elevation. The persistency and densities of the ponds with sizes >0.005 km2 were found near the glacier terminuses. Furthermore, spillway lakes on the Ngozompa, Bhote Koshi, Khumbu, and Lumsamba glaciers were expanding at a faster rate, indicating a trajectory towards large lake development. Our analysis also found that Sentinel-2 (10-m resolution) has good potential to study the seasonal changes of supraglacial ponds, while fine-resolution (<2 m) imagery is able to map the supraglacial ponds with high accuracy and can help in understanding the surrounding morphology of the glacier.

The maximum discharge of outburst floods caused by the breaching of man-made and natural dams

1986 ◽  
Vol 23 (3) ◽  
pp. 385-387 ◽  
Author(s):  
Stephen G. Evans
Keyword(s):  
Empirical Relationship ◽  
Landslide Dam ◽  
Dam Failure ◽  
Order Estimate ◽  
Mountainous Regions ◽  
Maximum Discharge ◽  
Outburst Floods ◽  
Debris Dams ◽  
Sudden Release ◽  
The Relationship

The sudden release of water impounded in natural and man-made reservoirs has been responsible for some major disasters in mountainous regions of the world. Recent natural damming events and failures of natural dams have illustrated the need to examine the nature and magnitude of outburst floods and the behaviour of debris dams in general. An empirical relationship between maximum discharge (Qmax) and volume of water released during the outburst event (Vmax) is established (Qmax = 0.72Vmax0.53) for man-made dams and the relationship is thought applicable to the breaching of natural debris dams (landslides and moraines). This relationship allows a first-order estimate to be made of Qmax in the vicinity of the breach for a given Vmax during the failure of a man-made dam or a natural debris dam. Key words: outburst floods, man-made dams, natural dams, landslide, dam failure.

Sign in / Sign up

Export Citation Format

Share Document