Fig 6- - uploaded by Jean F. Schneider
Content may be subject to copyright.
Maximum flow depth computed with FLO-2D and RAMMS for dif-ferent lake outburst scenarios of Khavrazdara
Source publication
Glacial lake outburst floods (GLOFs) are potentially highly dangerous events and have contributed to numerous disasters in history. Today, computer models are standard tools to estimate the magnitude of hazardous events in the future and to support risk mitigation. The present paper explores the potentials and limitations of modelling for predictin...
Context in source publication
Context 1
... (before entrainment takes place), whilst increased values of μ = 0.05 were applied to ac- count for the higher sediment concentration expected in the lower section. ξ-values were held constant for the entire flow path. The spatial distribution of the maximum flow height simulated with RAMMS and FLO-2D for selected scenarios is illustrated in Fig. ...
Similar publications
Mountain shadows in optical satellite images complicate the mapping of glacial lakes. Due to the rugged topography in periglacial alpine regions, many glacial lakes, especially smaller lakes, are partially shaded by mountain shadows in remotely sensed images. Shadows not only reduce the accuracy of lake mapping but also make changes in lake area ha...
Citations
... (Anderson et al., 2008) iCRESTRIGRS , SIMTOP (Lee & Ho, 2009) CAPRA Landslide Tool (Hurtado, 2018) Seismic and landslide SpecFem3D (Komatitsch et al., 2010) CAPRA Landslide Tool (Hurtado, 2018) OpenLISEM Hazard (Bout et al., 2018) Slope Failure Surface Scoops3D (Reid et al., 2015), r.slope.stability (Mergili et al., 2014) Runout of several types of mass movements r.avaflow , RAMMS (Christen et al., 2010) EDDA (Chen & Zhang , 2015) Flo-2D (O'Brien et al., 1993), Landslide, River dams, Break out floods BREACH +SOBEK (Fan et al., 2012) BASEMENT+RAMMS (Byers et al., 2018) RAMMS + FL-2D (Mergili et al., 2011) AUT16+DAM10 (Clerici&Perego,2000 NWS DAMBRK (Alford, 2000) Integrated multi-hazard models ...
This paper discusses approaches to evaluate how landslide risk might change over time. Multi-hazard risk assessment (MHRA) is the quantitative estimation of the spatial distributions of potential losses for an area, of multiple natural hazards with different hazard interactions, with multiple event probabilities, for multiple types of elements-at-risks, and multiple potential loss components. The paper first discusses the various types of hazard interactions in which landslides are involved. An example is presented of a MHRA at district level in Tajikistan for a combination of seven hazard types (earthquakes, floods, windstorms, drought , landslides , mudflows and snow avalanches) and five types of elements-at-risk (Built-up area, buildings, people, agriculture and roads). After discussing problems involved in such types of static MHRA projects, the paper continues with describing the need for analyzing changing multi-hazard risk as a basis for decision-making. These changes may be related to changes in triggering or conditional factors, increasing exposure of elements-at-risk, and their vulnerability and capacity. Dynamic risk can be evaluated on the long term because of changes in climate, land use, population density, economy, or social conditions. Climate change scenarios still contain large uncertainties in the changes in return periods of extreme rainfall events, and their spatial variation in mountainous areas. In addition, feedback mechanisms between climate change and land use change play an important role, but are difficult to incorporate in the risk assessment. Changes in landslide risk might also be occurring in a short time frame, and assessed as a basis for impact based forecasting, and to analyze the consequences of hazard interactions after major events, for instance after the occurrence of wildfires, major earthquakes, volcanic eruptions, or extreme rainfall events, which alter the conditional factors for the occurrence of landslides. An overview is given of the tools available for multi-hazard assessment, stressing the importance for developing integrated physically based multi-hazard models. One of such models, OpenLISEM Hazard, is presented in some more detail. In addition, an overview is given of the tools for multi-hazard risk assessment, stressing the need to incorporate landslide risk within the existing models, as currently this is not taken into account at a sufficient level. One example is given of a Spatial Decision Support System for dynamic multi-hazard analysis, which aims to assist stakeholders in decision making of optimal risk reduction alternatives under various future scenarios. This is further illustrated with a case study for the city of Envigado, near Medellin in Colombia. The OpenLISEM Hazard model is used to generate hazard scenarios for flood, landslides, and debris flows for different return periods of triggering rainfall. Building footprints are updated and classified into occupational types, and structural types, and absolute vulnerability curves were generated. Current multi-hazard risk is analyzed. After that several future scenarios of climate change and population change are outlined, for which the changing risk is analyzed. Finally, three alternatives for risk reduction are presented, their risk reduction is calculated, and eventually the optimally performing alternative under different future scenarios is selected.
... RAMMS is suitable for avalanche modelling. It can compute material entrained by mass flows, but when the result of RAMMS was compared with the output obtained from FLO-2D for predicting motion of potential outburst flood (Mergili et al. 2011), it was reported to predict higher flow depths, smaller area of flood and stoppage of flow, which was in sharp divergence with the result of FLO-2D (Zhang and Liu 2015). FLO-2D solves mass and momentum conservation equations of sediment and water, but it cannot include material entrainment (Worni et al. 2014). ...
Moraine dams, impounding glacial lakes, are among the weak natural dams because of their slope, freeboard and composition. Glacial lake outburst floods occurring due to the failure of moraine dams are significant hazards for the valley downstream the failure, as they possess huge amount of hydraulic energy that can kill thousands and destroy infrastructures and riverine landscape. Also, the entrainment of debris to the flow from the breaching process and downstream channel may develop the flow into a much bigger disaster or even a series of hazard chain. Ice and rock avalanche or landslide, glacier calving, degradation of ice cores, earthquake and atmospheric events trigger the breaching phenomenon which generates a series of waves overtopping the dam or seepage causing the failure of the dam. Various approaches have been discussed in this review paper to produce an understanding of the failure mechanism of moraine dams: experimental works, empirical relationships, analytical solutions, and numerical modelling. No concrete experimental investigations and parametric solutions pertained to the failure mechanism of moraine dam is found in the review, but various empirical relationships are discussed and suitable approaches for numerical modelling are suggested as per the requirement of the task.
... Upon substantial development, hydrostatic force (when no trigger) or hydrodynamic force (when displacement waves are generated due to a trigger) could exceed lake strength causing a lake outburst (Korup and Tweed 2007;Massey et al. 2010). Moraine lakes are most prone to get breached due to the weak structure and may cause heavy flooding (Malone 2010;Mergili et al. 2011Mergili et al. , 2018Bolch et al. 2012). ...
In this study, the Glacier Lake Outburst Flood (GLOF) that occurred over Kedarnath in June 2013 was modeled using integrated observations from the field and Remote Sensing (RS). The lake breach parameters such as area, depth, breach, and height have been estimated from the field observations and Remote Sensing (RS) data. A number of modelling approaches, including Snow Melt Runoff Model (SRM), Modified Single Flow model (MSF), Watershed Management System (WMS), Simplified Dam Breach Model (SMPDBK) and BREACH were used to model the GLOF. Estimations from SRM produced a runoff of about 22.7 m 3 during 16-17, June 2013 over Chorabari Lake. Bathymetry data reported that the lake got filled to its maximum capacity (3822.7 m 3) due to excess discharge. Hydrograph obtained from the BREACH model revealed a peak discharge of about 1699 m 3/s during an intense water flow episode that lasted for 10-15 minutes on 17 th June 2013. Excess discharge from heavy rainfall and snowmelt into the lake increased its hydrostatic pressure and the lake breached cataclysmically.
... Sorg et al. (2012) state that 'by the end of the twenty-first century, however, total runoff is projected to be smaller than today' and that many parts of the region would suffer from unfavourable seasonal distribution. The disappearance of the glaciers would mean profound changes in livelihoods for a region highly dependent on meltwater from snow and glaciers (Mergili et al. 2011). ...
... The melting of the glaciers, as well as causing uncertainty and insecurity for the future of downstream countries, is already triggering various disasters in upstream countries. It may lead to fluvial floods or glacial lake outburst floods (Beniston 2003;Mergili et al. 2011;Bernauer and Siegfried 2012;Kundzewicz et al. 2014), with these phenomena themselves possibly leading to landslides, mudflows and erosion (Khakimov and Mahmadbekov 2007;Mergili et al. 2011;Babajanov et al. 2012;Chandonnet et al. 2016). According to the First National Communication of the Republic of Tajikistan Under the United Nations Framework Convention on Climate Change, 'Some 38% of the imminent processes in the republic are landslides, 31% mudflows and floods, 21% erosion processes. ...
... The melting of the glaciers, as well as causing uncertainty and insecurity for the future of downstream countries, is already triggering various disasters in upstream countries. It may lead to fluvial floods or glacial lake outburst floods (Beniston 2003;Mergili et al. 2011;Bernauer and Siegfried 2012;Kundzewicz et al. 2014), with these phenomena themselves possibly leading to landslides, mudflows and erosion (Khakimov and Mahmadbekov 2007;Mergili et al. 2011;Babajanov et al. 2012;Chandonnet et al. 2016). According to the First National Communication of the Republic of Tajikistan Under the United Nations Framework Convention on Climate Change, 'Some 38% of the imminent processes in the republic are landslides, 31% mudflows and floods, 21% erosion processes. ...
Increasingly, studies are considering Central Asia a ‘hot spot’ of climate change and a region prone to environmental migrations. Growing aridity and the shrinking of glaciers may have important impacts on food security, health, human security and infrastructure in the region and compel people to move. Drawing on the literature on environmental issues in Central Asia and on interviews conducted in the Kuhistoni-Badakhshan Autonomous Region of Tajikistan, this article provides a literature survey on environmental migrations in the region and positions Central Asia in the current debates within the broad environmental migrations literature. The article shows that environmental issues can stand out as an important push factor for out-migration in Central Asia, highlights the important role of the Soviet heritage of environmental management as well as of post-Soviet socio-economic transformations in understanding these issues, and discusses possible adaptation strategies.
... S jökulhlaup simulation in Northeast Iceland with a 2-D finite element model TELEMAC-2D, using a pre-defined hydrograph. Their results indicated that unsteady HEC-RAS modelling is feasible to a ca. 200-m horizontal accuracy in the simple routes at the peak discharge stage, but the 2-D model could be used for non-parallel gorges of the main channel. Mergili et al. (2011) compared RAMMS as a mass movement model and FLO-2D using an input hydrograph as a river hydraulics model for predicting the motion of potential future GLOFs in the Pamir Mountains of Tajikistan. They found that RAMMS predicted higher flow depths and smaller inundation areas in the uppermost section than did FLO-2D, and that RAMMS predic ...
Glacial outburst floods (GLOFs) in alpine regions tend to be relatively complicated, multi-stage catastrophes, capable of causing significant geomorphologic changes in channel surroundings and posing severe threats to infrastructure and the safety and livelihoods of human communities. GLOF disasters have been observed and potential hazards can be foreseen due to the newly formed glacial lakes or the expansion of existing ones in the Poiqu River Basin in Tibet, China. Here we presented a synthesis of GLOF-related studies including triggering mechanism(s), dam breach modeling, and flood routing simulation that have been employed to reconstruct or forecast GLOF hydrographs. We provided a framework for probability-based GLOFs simulation and hazard mapping in the Poiqu River Basin according to available knowledge. We also discussed the uncertainties and challenges in the model chains, which may form the basis for further research. © 2015, Xinjiang Institute of Ecology and Geography, the Chinese Academy of Sciences and Springer - Verlag GmbH.
... They generally occur on slopes covered by unconsolidated rock and soil, where a water supply sufficient to saturate the debris and an adequate slope inclination (Hungr et al., 2001(Hungr et al., , 2014) trigger a flow that suddenly pushes ahead with a vanguard of large boulders (Takahashi, 2007). This type of slope movements affects different natural environments, such as glacial (Lionel and Jackson, 1979;Clague et al., 1985;Narama et al., 2010;Mergili et al., 2011), volcanic (Pierson, 1985;Pierson et al., 1990;Scott et al., 1995;Vallance and Scott, 1997;Mothes et al., 1998), and alpine settings (Berti et al., 1999;Marchi et al., 2002;Hürlimann et al., 2003;Chiarle et al., 2007;Carrara et al., 2008;Bardou et al., 2011). A growing number of dangerous events are also threatening the populations of non-extreme environmental settings, especially in areas with a significant soil cover and subject to heavy precipitation. ...
Debris-flows are widespread natural phenomena characterized by high mobility (high velocity and long runout distance) and impact forces, which frequently cause human casualties and significant damage to infrastructure. To better understand the dynamics of such events, analyzing in particular the effect induced by the valley geometry on flow velocity, runout and mobilized volumes, in this work we reconstruct a real debris-flow event through numerical modelling. Specifically, we used a modified version of the BING model, a fluid-dynamic depth-integrated numerical model for debris flows, which has been properly modified to account for width changes along the valley. The studied event, which occurred in Scaletta Zanclea (Messina, north-eastern Sicily, Italy) on October 1st, 2009, is exceptionally well constrained by field and topographic information. In this respect the flow velocity, estimated from two specific locations on the basis of field evidence, the distribution of erosional and depositional areas along the Racinazzo valley, based on the comparison of pre- and post-event Digital Elevation Models (DEMs), and the runout distance were used as constraints to calibrate the model. Furthermore, we report a detailed description of the main event characteristics based on hydrological records and witness reports. The numerical modelling results are consistent with witness reports and the severe damage recorded in the Scaletta Marina village, and highlight the effect of the valley geometry on both the debris flow velocity and the erosion/deposition processes. The effect of changing valley width has been also quantified, resulting in accelerations of the debris in correspondence of the valley narrowing and stagnations at the plateaus. This article is protected by copyright. All rights reserved.
... Hyperconcentrated flows are common in volcanic settings (e.g., Pierson and Scott 1985;Smith 1986;Scott et al. 1995;Lavigne and Hiroshi 2004); however, hyperconcentrations are also found in nonvolcanic settings, both in mountainous regions and on low-lying areas typically with abundant clay, high soil erosion and low vegetation cover (Martin and Turner 1998;Jiongxin 1999;Svendsen et al. 2003;Hessel 2006;Worni et al. 2012). Hyperconcentrated flows not related to volcanic activity can result from the catastrophic breakthrough of rivers or lakes through dams made of either rock and sediments (Costa and Schuster 1988;Svendsen et al. 2003;Worni et al. 2012) or snow and ice (Costa and Schuster 1988;Chernomorets et al. 2007;Mergili et al. 2011). One of these catastrophic events, a glacier lake outburst flood, is typically driven by heavy rainfall, spring meltwater, mass ground movements, or earthquakes that cause a dammed glacial lake to overflow and the dam to ultimately fail (Costa and Schuster 1988;Worni et al. 2012). ...
... One of these catastrophic events, a glacier lake outburst flood, is typically driven by heavy rainfall, spring meltwater, mass ground movements, or earthquakes that cause a dammed glacial lake to overflow and the dam to ultimately fail (Costa and Schuster 1988;Worni et al. 2012). Some outburst floods can travel downslope at high speed for great distances (Scott et al. 1995;Chernomorets et al. 2007;Mergili et al. 2011;Schneider et al. 2014). It has been shown, however, that steep slopes are not required to maintain hyperconcentrated flows and that they can travel for long distances even over low gradients. ...
The Cretaceous coastal plain of Arctic Alaska contains the richest concentration of high-latitude dinosaurs on
Earth. Three bonebeds (Liscomb, Byers, Sling Point) are found in paleopolar (82u–85u N) coastal-plain deposits of the Prince Creek Formation on Alaska’s North Slope. 40Ar/39Ar analysis of a tuff below the oldest bonebed (Sling Point) returned an age of 69.2 ± 0.5 Ma indicating a maximum early Maastrichtian age for these bonebeds. Bonebeds are overwhelmingly dominated by partially articulated to associated late-stage juvenile Edmontosaurus sp. Bone is rarely found in channels; instead high density accumulations are preserved on floodplains in laterally extensive, muddy alluvium. Bone size grading is vertically nonuniform and most bones are in hydraulic disequilibrium with the surrounding clay-rich matrix. Bones exhibit little evidence of rounding, weathering, predation, or trampling, suggesting short-distance transport and rapid burial. Because these bonebeds are unlike typical debris-flow or streamflow deposits, the mechanism for bonebed emplacement remained poorly understood. All bonebeds contain a current-rippled siltstone containing the largest bone overlain by a distinctive mudstone encasing smaller bones, bone fragments, and subparallel-aligned plant fragments that appear ‘‘frozen in flow’’ within the muddy matrix. We recognize that these bonebeds exhibit a recurring facies pairing and bipartite division of flow consistent with deposition by fine grained viscous hyperconcentrated flows. We suggest that exceptional discharge events entrained mud and ash stored on point
bars and floodplains, increasing suspended-sediment concentrations in rivers and generating erosive hyperconcentrated flows that transported the remains of scores of juvenile dinosaurs onto floodplains adjacent to distributary channels.
... Sediment is a critical consideration in this study for two main reasons; 1) sedimentloading is highly influential on the characteristics of GLOFs, adding weight, complicating attempts at predicting flow routes and water behaviour (Awal et al., 2010;Mergili et al., 2011); 2) siltation of the Sutlej's HEPs has an influence over water flowing through them, as well as affecting the longevity of key mechanisms (i.e. Archer et al., 2010;Wulf et al., 2012), and affecting their resilience to flooding (CISMHE, 2010). ...
... Sporadic glacial lake outbursts may drain as powerful floods (Mergili et al., 2011), and are therefore considered the most important glacier-related hazard in terms of direct damage potential (Osti and Egashira, 2009). Glacial lake outburst floods (GLOFs) have killed thousands of people in many parts of the world (Carey, 2005; Clague and Evans, 2000; Richardson and Reynolds, 2000a), and some of the largest events occurred in the Himalayas (Bhargava, 1995; Osti and Egashira, 2009; Tashi, 1994; Vuichard and Zimmermann, 1986). ...
... For lake dams that are found to be susceptible to failure, magnitudes of potential GLOFs can be approximated with empirical relationships (Evans, 1986; Huggel et al., 2004; Kershaw et al., 2005) or calculated using empirical and physical models. Different types of dam breach and flood models have been applied to model glacial lake outburst scenarios and to assess potential downstream impacts (Bajracharya et al., 2007; Huggel et al., 2003; Mergili et al., 2011; Osti et al., 2012; Wang et al., 2008). For specific and local-scale scenario modeling the application of dynamic models is preferable to empirical models, as the latter represent an over-simplification of complex processes (Allen et al., 2009; Worni et al., 2012b). ...
Glacial lake hazards and glacial lake distributions are investigated in many glaciated regions of the world, but comparably little attention has been given to these topics in the Indian Himalayas. In this study we present a first area-wide glacial lake inventory, including a qualitative classification at 251 glacial lakes >0.01km(2). Lakes were detected in the five states spanning the Indian Himalayas, and lake distribution pattern and lake characteristics were found to differ significantly between regions. Three glacial lakes, from different geographic and climatic regions within the Indian Himalayas were then selected for a detailed risk assessment. Lake outburst probability, potential outburst magnitudes and associated damage were evaluated on the basis of high-resolution satellite imagery, field assessments and through the use of a dynamic model. The glacial lakes analyzed in the states of Jammu and Kashmir and Himachal Pradesh were found to present moderate risks to downstream villages, whereas the lake in Sikkim severely threatens downstream locations. At the study site in Sikkim, a dam breach could trigger drainage of ca. 16×10(6)m(3) water and generate maximum lake discharge of nearly 7000m(3)s(-). The identification of critical glacial lakes in the Indian Himalayas and the detailed risk assessments at three specific sites allow prioritizing further investigations and help in the definition of risk reduction actions.
... Moraine dams are inherently prone to failure because of their often weak structure, loose internal composition and lack of an engineered spillway. Sporadic glacier lake outbursts may drain as powerful floods (Mergili et al., 2011) and are considered the most important glacier-related hazard in terms of direct damage potential (Osti and Egashira, 2009). Glacier lake outburst floods (GLOFs) have killed thousands of people in many parts of the world (Clarke, 1982; Hewitt, 1982; Clague and Evans, 1994, 2000; Watanabe and Rothacher, 1996; Richardson and Reynolds, 2000a; Huggel et al., 2004; Carey, 2005) and with ongoing glacier retreat new, often unstable glacier lakes are likely to develop in the future (Frey et al., 2010). ...
Although moraine dams are inherently prone to failure because of their often weak structure, loose internal composition and lack of an engineered spillway, the understanding of dam breaching processes remains largely incomplete and appropriate modeling approaches are scarce. This paper analyzes a recent glacier lake outburst, caused by the failure of the terminal moraine of Ventisquero Negro (Patagonian Andes, Argentina) in May 2009. The dam breach trigger, breaching and lake emptying processes, plus the dynamics of the outburst flood were reconstructed based on field evidence and the application of a dynamic dam break model. Results indicate that the moraine failure was caused most probably by a rising lake level due to heavy precipitation, resulting in high lake outflow which led to dam erosion and finally to dam failure. The lake volume of ca. 10 x 10(6) m(3) was released in ca. 3 h, producing high-discharge (ca. 4100 m(3) s(-1)) debris flows and hyperconcentrated flows as the escaping water entrained large volumes of clastic material. The methodology presented in this paper provides valuable insights into complex dam breach and GLOF processes, and closes a critical gap in dynamic dam break modeling aimed at providing the lake outburst hydrograph. An accurate determination of outburst hydrographs constitutes one of the most crucial aspects for hazard assessment of unstable lakes and will gain further importance with ongoing glacier retreat and glacier lake formation.
