scholarly journals Calculation of the Coseismic Landslide Volume Using DEMs: An Example from the Yingxiu Area, Wenchuan, Sichuan, China

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaoli Chen ◽  
Yijian Chuan ◽  
Yankun Wei
Keyword(s):  
Wenchuan Earthquake ◽  
Volume Calculation ◽  
Affected Area ◽  
Preliminary Stage ◽  
Coseismic Landslides ◽  
Landslide Volume ◽  
Digital Elevation ◽  
Elevation Changes ◽  
Coseismic Landslide ◽  
Broad Region

Volume calculation is important for quantifying the erosion driven by coseismic landslides in geomorphology. With the advent of digital elevation models (DEMs), quantifying features of landslide bodies have become possible, permitting to calculate the landslide volume in terms of elevation changes. To further test this approach, this work calculates the volume of landslides near the epicenter of the 2008 Mw 7.9 Wenchuan earthquake in the Yingxiu region, Sichuan, China, by comparing pre- and postearthquake DEMs. Results suggest that effective application of this method needs to consider the DEM resolution and eliminates background errors of individual landslides. The volume of coseismic landslides calculated by the proposed method may represent a minimum value compared to that from the existing empirical V-A formulas. Considering that it is difficult to quantify the coseismic landslide volume throughout in a broad region, this method can be applied to the preliminary stage of characterizing coseismic landslides quantitatively for some key localities of the affected area of major earthquakes.

scholarly journals Beyond 2D inventories : synoptic 3D landslide volume calculation from repeat LiDAR data

2020 ◽  
Author(s):  
Thomas G. Bernard ◽  
Dimitri Lague ◽  
Philippe Steer
Keyword(s):  
Point Cloud ◽  
Volume Estimation ◽  
Airborne Lidar ◽  
Aerial Images ◽  
3D Point Cloud ◽  
Volume Calculation ◽  
Landslide Volume ◽  
Digital Elevation ◽  
Multi Temporal ◽  
Areal Mapping

Abstract. Efficient and robust landslide mapping and volume estimation is essential to rapidly infer landslide spatial distribution, to quantify the role of triggering events on landscape changes and to assess direct and secondary landslide-related geomorphic hazards. Many efforts have been made during the last decades to develop landslide areal mapping methods, based on 2D satellite or aerial images, and to constrain empirical volume-area (V-A) allowing in turn to offer indirect estimates of landslide volume. Despite these efforts, some major issues remain including the uncertainty of the V-A scaling, landslide amalgamation and the under-detection of reactivated landslides. To address these issues, we propose a new semi-automatic 3D point cloud differencing method to detect geomorphic changes, obtain robust landslide inventories and directly measure the volume and geometric properties of landslides. This method is based on the M3C2 algorithm and was applied to a multi-temporal airborne LiDAR dataset of the Kaikoura region, New Zealand, following the Mw 7.8 earthquake of 14 November 2016. We demonstrate that 3D point cloud differencing offers a greater sensitivity to detect small changes than a classical difference of DEMs (digital elevation models). In a small 5 km2 area, prone to landslide reactivation and amalgamation, where a previous study identified 27 landslides, our method is able to detect 1431 landslide sources and 853 deposits with a total volume of 908,055 ± 215,640 m3 and 1,008,626 ± 172,745 m3, respectively. This high number of landslides is set by the ability of our method to detect subtle changes and therefore small landslides with a carefully constrained lower limit of 20 m2 (90 % with A 

Changes of surface recovery at coseismic landslides and their driving factors in the Wenchuan earthquake-affected area

CATENA ◽  
2021 ◽  
pp. 105871
Author(s):  
Ming Chen ◽  
Chuan Tang ◽  
Mingwei Li ◽  
Jiang Xiong ◽  
Yuting Luo ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Driving Factors ◽  
Affected Area ◽  
Coseismic Landslides ◽  
The Wenchuan Earthquake

scholarly journals Glacier elevation and mass changes over the central Karakoram region estimated from TanDEM-X and SRTM/X-SAR digital elevation models

2016 ◽  
Vol 57 (71) ◽  
pp. 273-281 ◽  
Author(s):  
Melanie Rankl ◽  
Matthias Braun
Keyword(s):  
High Resolution ◽  
Snow Cover ◽  
Digital Elevation Models ◽  
Mass Balances ◽  
Freshwater Resources ◽  
Digital Elevation ◽  
Glacier Changes ◽  
Kinematic Waves ◽  
Elevation Changes ◽  
River Communities

AbstractSnow cover and glaciers in the Karakoram region are important freshwater resources for many down-river communities as they provide water for irrigation and hydropower. A better understanding of current glacier changes is hence an important informational baseline. We present glacier elevation changes in the central Karakoram region using TanDEM-X and SRTM/X-SAR DEM differences between 2000 and 2012. We calculated elevation differences for glaciers with advancing and stable termini or surge-type glaciers separately using an inventory from a previous study. Glaciers with stable and advancing termini since the 1970s showed nearly balanced elevation changes of -0.09 ±0.12 m a-1 on average or mass budgets of -0.01 ±0.02Gt a-1 (using a density of 850 kg m-3). Our findings are in accordance with previous studies indicating stable or only slightly negative glacier mass balances during recent years in the Karakoram. The high-resolution elevation changes revealed distinct patterns of mass relocation at glacier surfaces during active surge cycles. The formation of kinematic waves at quiescent surge-type glaciers could be observed and points towards future active surge behaviour. Our study reveals the potential of the TanDEM-X mission to estimate geodetic glacier mass balances, but also points to still existing uncertainties induced by the geodetic method.

scholarly journals 2001–2009 elevation and mass losses in the Larsen A and B embayments, Antarctic Peninsula

2011 ◽  
Vol 57 (204) ◽  
pp. 737-754 ◽  
Author(s):  
Christopher A. Shuman ◽  
Etienne Berthier ◽  
Ted A. Scambos
Keyword(s):  
Antarctic Peninsula ◽  
Loss Rate ◽  
Ice Shelf ◽  
Laser Altimetry ◽  
Ice Shelves ◽  
Ice Volume ◽  
Mass Losses ◽  
Digital Elevation ◽  
Modis Imagery ◽  
Elevation Changes

AbstractWe investigate the elevation and mass-balance response of tributary glaciers following the loss of the Larsen A and B ice shelves, Antarctic Peninsula (in 1995 and 2002 respectively). Our study uses MODIS imagery to track ice extent, and ASTER and SPOT5 digital elevation models (DEMs) plus ATM and ICESat laser altimetry to track elevation changes, spanning the period 2001–09. The measured Larsen B tributary glaciers (Hektoria, Green, Evans, Punchbowl, Jorum and Crane) lost up to 160 m in elevation during 2001–06, and thinning continued into 2009. Elevation changes were small for the more southerly Flask and Leppard Glaciers, which are still constrained by a Larsen B ice shelf remnant. In the northern embayment, continued thinning of >3 m a−1 on Drygalski Glacier, 14 years after the Larsen A ice shelf disintegrated, suggests that mass losses for the exposed Larsen B tributaries will continue for years into the future. Grounded ice volume losses exceed 13 km3 for Crane Glacier and 30 km3 for the Hektoria–Green–Evans glaciers. The combined mean loss rate for 2001–06 is at least 11.2 Gt a−1. Our values differ significantly from published mass-budget-based estimates for these embayments, but are a reasonable fraction of GRACE-derived rates for the region (∼40 Gt a−1).

scholarly journals Application and analysis of debris-flow early warning system in Wenchuan earthquake-affected area

2016 ◽  
Vol 16 (2) ◽  
pp. 483-496 ◽  
Author(s):  
D. L. Liu ◽  
S. J. Zhang ◽  
H. J. Yang ◽  
L. Q. Zhao ◽  
Y. H. Jiang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Early Warning ◽  
Early Warning System ◽  
Prediction Accuracy ◽  
Warning System ◽  
Sichuan Province ◽  
Affected Area ◽  
The Wenchuan Earthquake ◽  
New System

Abstract. The activities of debris flow (DF) in the Wenchuan earthquake-affected area significantly increased after the earthquake on 12 May 2008. The safety of the lives and property of local people is threatened by DFs. A physics-based early warning system (EWS) for DF forecasting was developed and applied in this earthquake area. This paper introduces an application of the system in the Wenchuan earthquake-affected area and analyzes the prediction results via a comparison to the DF events triggered by the strong rainfall events reported by the local government. The prediction accuracy and efficiency was first compared with a contribution-factor-based system currently used by the weather bureau of Sichuan province. The storm on 17 August 2012 was used as a case study for this comparison. The comparison shows that the false negative rate and false positive rate of the new system is, respectively, 19 and 21 % lower than the system based on the contribution factors. Consequently, the prediction accuracy is obviously higher than the system based on the contribution factors with a higher operational efficiency. On the invitation of the weather bureau of Sichuan province, the authors upgraded their prediction system of DF by using this new system before the monsoon of Wenchuan earthquake-affected area in 2013. Two prediction cases on 9 July 2013 and 10 July 2014 were chosen to further demonstrate that the new EWS has high stability, efficiency, and prediction accuracy.

scholarly journals Glacier topography and elevation changes from Pléiades very high resolution stereo images

2014 ◽  
Vol 8 (5) ◽  
pp. 4849-4883 ◽  
Author(s):  
E. Berthier ◽  
C. Vincent ◽  
E. Magnússon ◽  
Á. Þ. Gunnlaugsson ◽  
P. Pitte ◽  
...  
Keyword(s):  
Field Measurements ◽  
Ground Control ◽  
European Alps ◽  
Control Points ◽  
Mass Balances ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Stereo Imagery ◽  
Elevation Changes ◽  
Very High

Abstract. In response to climate change, most glaciers are losing mass and hence contribute to sea-level rise. Repeated and accurate mapping of their surface topography is required to estimate their mass balance and to extrapolate/calibrate sparse field glaciological measurements. In this study we evaluate the potential of Pléiades sub-meter stereo imagery to derive digital elevation models (DEMs) of glaciers and their elevation changes. Our five validation sites are located in Iceland, the European Alps, the Central Andes, Nepal and Antarctica. For all sites, nearly simultaneous field measurements were collected to evaluate the Pléiades DEMs. For Iceland, the Pléiades DEM is also compared to a Lidar DEM. The vertical biases of the Pléiades DEMs are less than 1 m if ground control points (GCPs) are used, but reach up to 6 m without GCPs. Even without GCPs, vertical biases can be reduced to a few decimetres by horizontal and vertical co-registration of the DEMs to reference altimetric data on ice-free terrain. Around these biases, the vertical precision of the Pléiades DEMs is ±1 m and even ±0.5 m on the flat glacier tongues (1-sigma confidence level). We also demonstrate the high potential of Pléiades DEMs for measuring seasonal, annual and multi-annual elevation changes with an accuracy of 1 m or better. The negative glacier-wide mass balances of the Argentière Glacier and Mer de Glace (−1.21 ± 0.16 and −1.19 ± 0.16 m.w.e. yr−1, respectively) are revealed by differencing SPOT5 and Pléiades DEMs acquired in August 2003 and 2012 demonstrating the continuing rapid glacial wastage in the Mont-Blanc area.

The sediment-landform assemblage in the forefield of the Gepatsch Glacier, Tirol, Austria and its preservation potential

2021 ◽  
Author(s):  
Daniel Le Heron ◽  
Bethan Davies ◽  
Lars Scharfenberg ◽  
Christoph Kettler ◽  
Michael Ketterman ◽  
...  
Keyword(s):  
Sedimentary Facies ◽  
Erosion And Deposition ◽  
Glacial Sediments ◽  
Time Period ◽  
Digital Elevation ◽  
Preservation Potential ◽  
Elevation Changes ◽  
Sand And Gravel ◽  
First Time

<p>Ongoing monitoring of the Gepatsch Glacier, Tirol (Austria) consists of a multifaceted, interdisciplinary project which aims to characterise short term (diurnal in the summer melt season) and longer term (annual to decadal) changes to the glacier snout and forefield in the context of a rapid retreating valley glacier. The glacial valley and forefield comprises amphibolites, para- and orthogneisses that have been smoothed and striated into whalebacks, compound bedrock-sediment bedforms (crag and tail structures), flutes, and annual moraines. The glacial sediments and landforms are undergoing incision and terrace development by meltwater streams. As part of a long term goal to characterise the rates of erosion, sedimentation, and re-deposition, we return to the same site each year in mid-July to collect airborne data with an UAV (Mavic Pro drone) that allows us to produce orthophotos and digital elevation models. We compute the daily and annual elevation changes, allowing us determine zones of erosion and deposition. Measureable evidence for erosion of flutes in the immediate glacial forefield has occurred over a 12-month time period. Till deposited within the last 20 years has undergone substantial mass wasting and re-deposition as subaerial mass flows, or reworked into stream deposits. The lee side of many whaleback structures completely lacks subglacial sediment, and contains instead a sand and gravel deposit interpreted to result from waterlain deposition. Thus, this case study area offers insight into the rates of erosion and deposition in a complex, proglacial setting, allowing some of these processes to be quantified for the first time. This approach is expected to yield a better understanding of the preservation potential of proglacial sedimentary facies, and hence their preservation potential in Earth’s sedimentary record.</p>

New evidence of glacier surges in the Central Andes of Argentina and Chile

2018 ◽  
Vol 42 (6) ◽  
pp. 792-825 ◽  
Author(s):  
Daniel Falaschi ◽  
Tobias Bolch ◽  
Maria Gabriela Lenzano ◽  
Takeo Tadono ◽  
Andrés Lo Vecchio ◽  
...  
Keyword(s):  
Satellite Imagery ◽  
Remote Sensing Data ◽  
Central Andes ◽  
Aerial Images ◽  
Mountain Ranges ◽  
The Andes ◽  
Digital Elevation ◽  
Heterogeneous Behavior ◽  
Elevation Changes ◽  
Glacier Surges

In contrast to the large surge-type glacier clusters widely known for several mountain ranges around the world, the presence of surging glaciers in the Andes has been historically seen as marginal. The improved availability of satellite imagery during the last years facilitates investigating of glaciers in more detail even in remote areas. The purpose of the study was therefore to revisit existing information about surge-type glaciers for the Central Andes of Argentina and Chile (32° 40′–34° 20′ S), to identify and characterize possible further surge-type glaciers, providing new insights into the mass balance and evolution of the velocity of selected glaciers during the surge phase. Based on the analysis of 1962–2015 satellite imagery, historical aerial images, differencing of digital elevation models and a literature survey, we identified 21 surge-type glaciers in the study area. Eleven surge events and six possible surge-type glaciers were identified and described for the first time. The estimation of annual elevation changes of these glaciers for the 2000–2011 period, which encompasses the latest surge events in the region, showed heterogeneous behavior with strongly negative to positive surface elevation change patterns (−1.1 to +1.0 m yr−1). Additionally, we calculated maximum surface velocities of 3±1.9 m d−1 and 3.1±1.1 m d−1 for two of the glaciers during the latest identifiable surge events of 1985–1987 and 2003–2007. Within this glacier cluster, highly variable advance rates (0.01–1 km yr−1) and dissimilar surface velocities at the surge peak (3–35 m d−1) were observed. In comparison with other clusters worldwide, surge-type glaciers in the Central Andes are on average smaller and show minor absolute advances. Generally low velocities and the heterogeneous duration of the surge cycles are common between them and glaciers in the Karakorum, a region with similar climatic characteristics and many known surge-type glaciers. As a definitive assertion concerning the underlying surge mechanism of surges in the Central Andes could not be drawn based on the remote sensing data, this opens more detailed research avenues for surge-type glaciers in the region.

Intensity–duration threshold of rainfall-triggered debris flows in the Wenchuan Earthquake affected area, China

Geomorphology ◽  
2016 ◽  
Vol 253 ◽  
pp. 208-216 ◽  
Author(s):  
Xiaojun Guo ◽  
Peng Cui ◽  
Yong Li ◽  
Li Ma ◽  
Yonggang Ge ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Affected Area ◽  
The Wenchuan Earthquake ◽  
Duration Threshold

scholarly journals Glacier-specific elevation changes in parts of western Alaska

2015 ◽  
Vol 56 (70) ◽  
pp. 184-192 ◽  
Author(s):  
R. Le Bris ◽  
F. Paul
Keyword(s):  
Mass Balance ◽  
Accurate Determination ◽  
Entire Region ◽  
Volume Changes ◽  
Sample Mean ◽  
Tidewater Glaciers ◽  
Digital Elevation ◽  
Elevation Changes ◽  
Global Sea Level

AbstractThe meltwater from glaciers in Alaska contributes strongly to global sea-level rise, but accurate determination is challenging as only two comparatively small glaciers have long-term measurements of annual mass balance (Gulkana and Wolverine). Simple upscaling of their values to the entire region is error-prone as their representativeness is unknown and might be biased. Alternatively, differencing digital elevation models (DEMs) from two epochs provides overall volume changes for a longer period of time that can be converted to mass changes using appropriate density assumptions. Here we combine outlines from two glacier inventories to determine glacier-specific elevation changes over a 50 year period for 3180 glaciers in western Alaska using DEM differencing. This allows us to determine the representativeness of the land-terminating Gulkana and Wolverine Glaciers for the entire region and to exclude calving glaciers (marine and lacustrine) from the sample. Mean changes for all land-terminating, lake-terminating and tidewater glaciers are –0.23 ± 0.44, –0.63 ± 0.40 and –0.64 ± 0.66 m a–1, respectively, and –0.7 and –0.6 m a–1 for the two mass-balance or benchmark glaciers. Thus fortuitously their changes better represent calving glaciers and the overall mean (–0.63 ± 1.14 m a–1) than the change of land-terminating glaciers, i.e. they are not representative for their own type. Different methods of considering potential DEM artefacts provide variable mean changes but the same general result.

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