Tracking the sediment plume from the 7th February 2021 Chamoli (Uttarakhand, India) hazard cascade

2021 ◽  
Author(s):  
Stuart Dunning ◽  
Simon Gascoin ◽  
Dan Shugar ◽  
Wolfgang Schwanghart
Keyword(s):  
Nuclear Power ◽  
Slope Failure ◽  
Mass Movement ◽  
Ganges River ◽  
Initial Event ◽  
Source Regions ◽  
Debris Flood ◽  
Chronic Threat ◽  
Automated Methods ◽  
Sentinel 2

<p>The 7<sup>th</sup> February Chamoli hazard cascade originated from a 25 million m³ rock/ice avalanche slope failure that transformed into a destructive, far travelled debris flow / debris flood. There has a been necessarily a significant science focus on the proximal and immediate part of the hazard cascade. Here we report on the larger spatial and temporal scale: the sediment plume that progressed over the following days and weeks along the Ganga (Ganges) River. At the time of submission this was still recognisable over 900 km from the landslide site and had passed through hydro and nuclear power schemes. Beyond the initial plume, which has implications for rapid sedimentation in hydropower schemes and water / aquatic habitat quality, the subsequent (or not) mobilisation of event sediments over future years is a possible medium term chronic-threat to some hydropower projects. We show spectral ‘recipes’ and semi-automated methods for tracking the mass movement sediment plume and quantifying celerity using Sentinel 2 imagery, infilled using high-temporal repeat optical imagery from Planet Labs. data. The plume averaged ~60 km/day and, as expected has begun to slow as the river gradient decreases, as well as becoming less distinctive as some sediment is deposited, and as other sediment-rich water joins the Ganga.</p><p>The tracking of sediment plumes from these hazard cascades can be extended over inventories of similar events using both Sentinel 2 and Landsat archives. Such approaches allow us to provide insight into the possibilities of automated detection of hazard cascade sediment plumes to identify previously unknown events from remote source regions, as plumes have a far larger spatial-temporal footprint than the initial event.</p>

Recurrent rock avalanches progressively dismantle mountain ridges in the Longmen Shan, China, most recently in the 2008 Wenchuan earthquake

2021 ◽  
Author(s):  
Janusz Wasowski ◽  
Maurice McSaveney ◽  
Luca Pisanu ◽  
Vincenzo Del Gaudio ◽  
Yan Li ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Ambient Noise ◽  
Slope Failure ◽  
Mass Movement ◽  
Rock Avalanche ◽  
Ground Vibration ◽  
Source Area ◽  
Slope Failures ◽  
Rock Avalanches ◽  
Beichuan County

<p>Large earthquake-triggered landslides, in particular rock avalanches, can have catastrophic consequences. However, the recognition of slopes prone to such failures remains difficult, because slope-specific seismic response depends on many factors including local topography, landforms, structure and internal geology. We address these issues by exploring the case of a rock avalanche of >3 million m<sup>3</sup> triggered by the 2008 Mw7.9 Wenchuan earthquake in the Longmen Shan range, China. The failure, denominated Yangjia gully rock avalanche, occurred in Beichuan County (Sichuan Province), one of the areas that suffered the highest shaking intensity and death toll caused by co-seismic landsliding. Even though the Wenchuan earthquake produced tens of large (volume >1 million m<sup>3</sup>) rock avalanches, few studies so far have examined the pre-2008 history of the failed slope or reported on the stratigraphic record of mass-movement deposits exposed along local river courses. The presented case of the Yangjia gully rock avalanche shows the importance of such attempts as they provide information on the recurrence of large slope failures and their associated hazards. Our effort stems from recognition, on 2005 satellite imagery, of topography and morphology indicative of a large, apparently pre-historic slope failure and the associated breached landslide dam, both features closely resembling the forms generated in the catastrophic 2008 earthquake. The follow-up reconstruction recognizes an earlier landslide deposit exhumed from beneath the 2008 Yangjia gully rock avalanche by fluvial erosion since May 2008. We infer a seismic trigger also for the pre-2008 rock avalanche based on the following circumstantial evidence: i) the same source area (valley-facing, terminal portion of a flat-topped, elongated mountain ridge) located within one and a half kilometer of the seismically active Beichuan fault; ii) significant directional amplification of ground vibration, sub-parallel to the failed slope direction, detected via ambient noise measurements on the ridge adjacent to the source area of the 2008 rock avalanche and iii) common depositional and textural features of the two landslide deposits. Then, we show how, through consideration of the broader geomorphic and seismo-tectonic contexts, one can gain insight into the spatial and temporal recurrence of catastrophic slope failures  in Beichuan County and elsewhere in the Longmen Shan. This insight, combined with local-scale geologic and geomorphologic knowledge, may guide selection of suspect slopes for reconnaissance, wide-area ambient noise investigation aimed at discriminating their relative susceptibility to co-seismic catastrophic failures. We indicate the feasibility of such investigations through the example of this study, which uses 3-component velocimeters designed to register low amplitude ground vibration.</p>

The Implementation of the Gradual Movement of Sliding Blocks to a New Method for Evaluating the Seismic Stability of Slopes Reinforced by Geotextile

2018 ◽  
Vol 12 (04) ◽  
pp. 1841010
Author(s):  
Tadashi Kawai ◽  
Makoto Ishimaru
Keyword(s):  
Seismic Performance ◽  
Nuclear Power ◽  
Power Plants ◽  
Slope Failure ◽  
Failure Process ◽  
Tohoku Earthquake ◽  
Seismic Stability ◽  
Centrifuge Tests ◽  
Stability Of Slopes ◽  
Design Basis

Evaluating the seismic stability of a rock slope typically involves searching for the minimum value of calculated safety factors (SF) for each supposed sliding block. Because only the transient equilibrium is evaluated, the likelihood of any slope failure can be deemed negligible if all the calculated SFs are greater than unity. However, even if some of the calculated SF are less than unity, it cannot be assumed that the slope will collapse. Recently, in the wake of extremely large earthquakes in Japan, the design earthquake standards for nuclear power plants (NPP) have been extended. After the experience of the 2011 off the Pacific coast of Tohoku Earthquake, the designer is expected to consider beyond design basis earthquakes to determine whether more can reasonably be done to reduce the potential for damage, especially where major consequences may ensue [IAEA (2011). IAEA international fact finding expert mission of the Fukushima dai-ichi NPP accident following the Great East Japan Earthquake and Tsunami, Mission report, IAEA]. With this in mind, the method employed to evaluate the seismic performance of the slope surrounding an NPP needs to be capable of doing more than determining the likelihood of failure: it must also consider the process toward failure in the event of an earthquake beyond the design basis. In this paper, a new evaluation flow which considers the failure process is proposed to evaluate the seismic performance of slopes surrounding an NPP. This is followed by confirming the validity of the concepts in the proposed flow chart by re-evaluating centrifuge tests in past literature and the numerical simulations designed for those tests.

Ultimate Heat Sink Sizing Requirements on a Month-to-Month Basis

2009 ◽  
Author(s):  
Dong Zheng ◽  
Allen T. Vieira ◽  
Julie M. Jarvis ◽  
George P. Emsurak
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Heat Sink ◽  
Nuclear Power ◽  
Meteorological Data ◽  
Meteorological Condition ◽  
Water Requirement ◽  
Next Generation ◽  
Worst Case ◽  
Automated Methods

The Ultimate Heat Sink (UHS) of a nuclear power plant is a complex cooling water system which serves the plant during normal and accident conditions. For some next generation nuclear plants, the UHS sizing is a major design and licensing analysis task. The analysis involves detailed modeling of the transient heat loads and the selection of worst-case meteorological data for the plant site. The UHS sizing requirements for a representative next generation nuclear power plant are evaluated on a month-to-month basis. This paper assesses the UHS water requirement for each month of year. The UHS analysis for a representative next generation nuclear plant with mechanical draft cooling towers and a water basin is used to determine the maximum evaporation of the basin for the worst-case meteorological data on a month-to-month basis. To size the cooling tower basin, automated methods have been developed which determine the highest evaporative losses from the basin and highest basin temperature over a 30-day design basis accident period. This paper also evaluates the month-to-month basin temperature changes. This assessment is done for a representative next generation nuclear power plant and considers the monthly historical meteorological data over 45 years. The result of this assessment of monthly UHS water requirement is of interest in assessing the margin in the UHS design. This monthly assessment is also useful in demonstrating that the automated methods used to establish the limiting 30-day meteorological condition are indeed accurate. In addition, these results may be useful in helping to plan plant maintenance activities.

Effect of Initial and Boundary Conditions on the Formation of Reactor Vessel Pressurized Thermal Shock

2013 ◽  
Author(s):  
Maksym Vyshemirskyi ◽  
Aleksander Mazurok ◽  
Anatoliy Nosovskyy
Keyword(s):  
Boundary Conditions ◽  
Thermal Shock ◽  
Nuclear Power ◽  
Reactor Vessel ◽  
Energy Agency ◽  
Detailed Model ◽  
Initial Event ◽  
Pressurized Thermal Shock ◽  
Initial And Boundary Conditions ◽  
Main Steam

The effect of initial and boundary conditions on the reactor vessel Pressurized Thermal Shock (PTS) was analyzed. For example unit 1 of South-Ukrainian Nuclear Power Plant (NPP) with WWER-1000/V-302 reactor was selected. Thermal-hydraulic analysis was made in accordance with methodology of Reactor Pressure Vessel (RPV) brittle fracture analysis by using RELAP5/mod3.2 code. Also, a detailed model of downcomer, which provides a realistic behavior of the fluid, including the mutual mixing of flows with different temperatures was used for these calculations. As an Initial Event (IE) the large secondary leak, namely Steam Generator (SG) Main Steam Line (MSL) break, was considered. According to the International Atomic Energy Agency (IAEA) recommendations all calculations were performed under conservative approach. Also, the asymmetric overcooling was considered. As a result of a series of thermal-hydraulic calculations the most conservative scenario for a group of IE associated with the secondary leaks was obtained.

scholarly journals Monitoring of recent mass movement activity in anthropogenic slopes of the Krušné Hory Mountains (Czech Republic)

2011 ◽  
Vol 11 (5) ◽  
pp. 1463-1473 ◽  
Author(s):  
J. Burda ◽  
L. Žižka ◽  
J. Dohnal
Keyword(s):  
Czech Republic ◽  
Slope Failure ◽  
Water Saturation ◽  
Mass Movement ◽  
Interdisciplinary Approach ◽  
Open Pit ◽  
Mass Movements ◽  
Slope Failures ◽  
The Czech Republic ◽  
Krušné Hory Mountains

Abstract. Recent mass movements currently comprise one of the main morphogenetic processes in the extensive anthropogenic relief of the foreground of the Krušné Hory Mountains in the Czech Republic. These mass movements result in several types of deep-seated slope failures, depending on the type of movement and the water saturation of the landslide material. This paper presents the results of a detailed geomorphic survey and orthophotograph analysis combined with geodetic monitoring data in an area affected by open-pit coal mining. An interdisciplinary approach has enabled an in-depth review of both the dynamics and development of recent slope failures. The article describes deep-seated landslide complex in this part of the foothills of the Krušné Hory Mountains. At the study site, mass movements occur in thick colluvial mantle and weathered Tertiary claystones. The main factors influencing their development include rainfall culminations, groundwater flowing from the valley of Šramnický Brook and former slope failures. All of the slope failures that have occurred here have originated at former slope failure sites.

scholarly journals Unravelling earth flow dynamics with 3-D time series derived from UAV-SfM models

2017 ◽  
Vol 5 (4) ◽  
pp. 791-806 ◽  
Author(s):  
François Clapuyt ◽  
Veerle Vanacker ◽  
Fritz Schlunegger ◽  
Kristof Van Oost
Keyword(s):  
High Resolution ◽  
Slope Failure ◽  
Drainage Basin ◽  
Time Lag ◽  
Mass Movement ◽  
Three Dimensional ◽  
Sediment Budget ◽  
Swiss Alps ◽  
Surface Displacements ◽  
Sediment Redistribution

Abstract. Accurately assessing geo-hazards and quantifying landslide risks in mountainous environments are gaining importance in the context of the ongoing global warming. For an in-depth understanding of slope failure mechanisms, accurate monitoring of the mass movement topography at high spatial and temporal resolutions remains essential. The choice of the acquisition framework for high-resolution topographic reconstructions will mainly result from the trade-off between the spatial resolution needed and the extent of the study area. Recent advances in the development of unmanned aerial vehicle (UAV)-based image acquisition combined with the structure-from-motion (SfM) algorithm for three-dimensional (3-D) reconstruction make the UAV-SfM framework a competitive alternative to other high-resolution topographic techniques. In this study, we aim at gaining in-depth knowledge of the Schimbrig earthflow located in the foothills of the Central Swiss Alps by monitoring ground surface displacements at very high spatial and temporal resolution using the efficiency of the UAV-SfM framework. We produced distinct topographic datasets for three acquisition dates between 2013 and 2015 in order to conduct a comprehensive 3-D analysis of the landslide. Therefore, we computed (1) the sediment budget of the hillslope, and (2) the horizontal and (3) the three-dimensional surface displacements. The multitemporal UAV-SfM based topographic reconstructions allowed us to quantify rates of sediment redistribution and surface movements. Our data show that the Schimbrig earthflow is very active, with mean annual horizontal displacement ranging between 6 and 9 m. Combination and careful interpretation of high-resolution topographic analyses reveal the internal mechanisms of the earthflow and its complex rotational structure. In addition to variation in horizontal surface movements through time, we interestingly showed that the configuration of nested rotational units changes through time. Although there are major changes in the internal structure of the earthflow in the 2013–2015 period, the sediment budget of the drainage basin is nearly in equilibrium. As a consequence, our data show that the time lag between sediment mobilization by landslides and enhanced sediment fluxes in the river network can be considerable.

Multi Tiered Approach to Slope Movement Management: Case Study

2012 ◽  
Author(s):  
Millan Sen ◽  
John Richmond ◽  
Aaron Dinovitzer ◽  
Abdelfettah Fredj
Keyword(s):  
Stress Analysis ◽  
Slope Failure ◽  
Action Plan ◽  
Large Diameter ◽  
Mass Movement ◽  
Strain Analysis ◽  
Slope Movement ◽  
Soil Movement ◽  
Slope Movements ◽  
Inspection Data

A major slope in southern Manitoba is currently experiencing deep seated movements of approximately 60mm per year. This 20m high × 70m long slope contains a pipeline right of way with five large diameter crude oil lines that were constructed from 1950–1998. It is estimated that the slope has moved over 3 meters since the pipeline installations. Management of the effects of this slope movement on the pipelines has involved cross-functional strategies that include geotechnical, integrity, and stress evaluations. The slope is assessed annually by a geotechnical engineer, and the most likely cause for the slope movements has been determined. Slope monitoring equipment has been installed at key locations and is monitored at frequent intervals. A toe berm has been installed to prevent lower slope failure at the creek bed that is located at the slope toe. A finite element stress analysis, which considers the interaction between the soil movement and pipeline, has been generated. This stress analysis evaluated the pipeline stresses due to the slope movements to date, and also due to a possible sudden mass movement. The results are backed up by a bending strain analysis based on inertial in-line inspection data was conducted for several of the lines. This paper presents an overview of the engineering assessment considering structural, material, geotechnical and operational concerns involved in developing an integrity management action plan.

Paleostress analysis of a gigantic gravitational mass movement in active tectonic setting: The Qoshadagh slope failure, Ahar, NW Iran

2013 ◽  
Vol 605 ◽  
pp. 70-87 ◽  
Author(s):  
I. Baroň ◽  
M. Kernstocková ◽  
M. Faridi ◽  
M. Bubík ◽  
R. Milovský ◽  
...  
Keyword(s):  
Slope Failure ◽  
Tectonic Setting ◽  
Mass Movement ◽  
Gravitational Mass ◽  
Nw Iran ◽  
Active Tectonic ◽  
Paleostress Analysis

scholarly journals Investigation of the probability of existence of defects with a size exceeding the allowed value

2020 ◽  
Vol 16 (5) ◽  
pp. 414-423
Author(s):  
Dmitry A. Kuzmin ◽  
Alexander Yu. Kuzmichevsky ◽  
Marina V. Vertashenok
Keyword(s):  
Nuclear Power ◽  
Control Point ◽  
Reactor Vessel ◽  
Actual State ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Work Permit ◽  
Residual Defect ◽  
Initial Event ◽  
Non Destructive

Relevance. Non-destructive testing of metal determines the actual state of the metal, the presence of discontinuities and their sizes, and also allows to determine what mechanisms of metal degradation were subjected to. One of the main characteristics of the quality of non-destructive testing is the detectability of discontinuities and defects. If no defects were missed, then its possible to guarantee the reliable operation of the facility until the next scheduled inspection. The article is devoted to the study of the probability function of detecting defects and determining the probability of the existence of a residual defect with a size exceeding the permissible value. The aim of the work - to develop a method to determine the probability of the existence of a residual defect with a size exceeding the permissible value after non-destructive testing and repairs of equipment and pipelines of a nuclear power plant. Methods. During the work formulas for the probability of detecting a defect and initial defectiveness, regulatory requirements in the field of certification of flaw detectors, and the results of research on non-destructive testing were used. Results. A method for determining the probability of defects with a size exceeding the allowed value, using the example of a reactor vessel, is presented. The method is based on residual defects, which takes into account the detectability of defects. The value of the coefficient that takes into account the influence of the human factor, instrument and methodological shortcomings or complexity of access to the control point is determined, which reduces the degree of uncertainty in determining the residual defect. The results of this work permit to evaluate the probability of the existence of a defect with a size exceeding the allowed value. The development of a residual defect to critical values characterizes the initial event for the destruction of the integrity of the structure. Thus, the probability of a residual defect can be used when performing a safety analysis of the water-water energetic reactor vessel.

scholarly journals The Spatio-Temporal Dynamics of the Ciprnik Complex Landslide, Tamar Valley, Julian Alps, Slovenia

2015 ◽  
Vol 49 (1) ◽  
Author(s):  
Andrej Šmuc ◽  
Karolina Janecka ◽  
Michał Lempa ◽  
Ryszard J. Kaczka
Keyword(s):  
Debris Flow ◽  
Slope Failure ◽  
Temporal Dynamics ◽  
Mass Movement ◽  
Active Phase ◽  
Slope Position ◽  
Translational Movement ◽  
Complex Landslide ◽  
Julian Alps ◽  
Spatio Temporal

AbstractMass movements represent important processes that shape relief in Alpine areas. In this article, we present the spatio-temporal dynamics of the Ciprnik landslide (Julian Alps, NW Slovenia) and interpret its triggering and evolution. In the study area, mass movement activity is characterised by two phases: normal deposition on the fluvial fans that dominated up to 2000, and a more active phase related to the triggering of the Ciprnik complex landslide and formation of an additional debris-flow fan. The Ciprnik landslide started as a translational movement over the discontinuity plane that was mobilised into a debris-flow. The triggering and slope failure resulted from a combination of tectonics (i.e. dip-slope position of the strata, and strong fracturing), lithology (alternation of thin beds of carbonates and fine-grained clastics), and accumulation of precipitation. The debris-flow fan remains active and interfingers with adjacent active fluvial fans.

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