A Perspective on Rishiganga-Dhauliganga Flash Flood in the Nanda Devi Biosphere Reserve, Garhwal Himalaya, India
01 Apr 2021-Journal of The Geological Society of India (Geological Society of India)-Vol. 97, Iss: 4, pp 335-338
TL;DR: A ground-based and heliborne survey was conducted immediately after the disaster that took place on 7th February, 2021 in the Chamoli district of Uttarakhand as discussed by the authors.
Abstract: A ground-based and heliborne survey was conducted immediately after the disaster that took place on 7th February, 2021 in the Chamoli district of Uttarakhand. Based on these observations and freely available Google Earth imagery, we have arrived at plausible causes of this catastrophe as detachment of a sizeable rock mass and overlying hanging glacier in the Raunthi catchment that dammed the Rishiganga River and led to the devastation of roads, bridges and hydropower projects in downstream.
Citations
More filters
TL;DR: In this paper , the authors recommend forward-looking design and maintenance measures and sustainable sediment management solutions that can help transition towards climate change-resilient dams and reservoirs in High Mountain Asia, in large part based on improved monitoring and prediction of compound and cascading hazards.
Abstract: Global warming-induced melting and thawing of the cryosphere are severely altering the volume and timing of water supplied from High Mountain Asia, adversely affecting downstream food and energy systems that are relied on by billions of people. The construction of more reservoirs designed to regulate streamflow and produce hydropower is a critical part of strategies for adapting to these changes. However, these projects are vulnerable to a complex set of interacting processes that are destabilizing landscapes throughout the region. Ranging in severity and the pace of change, these processes include glacial retreat and detachments, permafrost thaw and associated landslides, rock–ice avalanches, debris flows and outburst floods from glacial lakes and landslide-dammed lakes. The result is large amounts of sediment being mobilized that can fill up reservoirs, cause dam failure and degrade power turbines. Here we recommend forward-looking design and maintenance measures and sustainable sediment management solutions that can help transition towards climate change-resilient dams and reservoirs in High Mountain Asia, in large part based on improved monitoring and prediction of compound and cascading hazards. Climate change is exacerbating geohazards in High Mountain Asia that pose a growing risk to hydropower and water infrastructure across the region.
50 citations
TL;DR: In this paper , a sequence of precursory signals of main failure/detachment preceded by a dynamic nucleation phase is found, which can be used for forecasting of flow events and hazard mitigation in the downstream.
Abstract: On 7 February 2021, Chamoli district (Uttarakhand, India) was devastated by a deadly rock-ice avalanche that led to a large causality of more than 200 people and a huge economic loss. We found noteworthy sequence of precursory signals of main failure/detachment preceded by a dynamic nucleation phase. The rock-ice avalanche appears to have been initiated by seismic precursors which were continuously active for 2:30 h prior to main detachment. The seismic amplitude, frequency characteristics and signal-to-noise ratio variation of detected tremors indicate static to dynamic changes in nucleation phase located at the source of detached wedge. The characteristics of seismic data distinguished debris flow and hitting obstacles from other seismic sources and allowed the estimations of debris flow speed. We analyzed and verified the seismic signals with field evidences to estimate the associated impacts and velocity of dynamic flow. The proximal high-quality seismic data allowed us to reconstruct the complete chronological sequence and evaluate impacts since the initiation of nucleation phase to its advancement. Furthermore, we suggest that real-time seismic monitoring with existing network and future deployment of integrated dense network can be used for forecasting of flow events and hazard mitigation in the downstream.
11 citations
TL;DR: In this paper , a catastrophic flood occurred on 7 February 2021 around 10:30 AM (local time) in the Rishiganga River, which has been attributed to a rockslide in the upper reach of the Raunthi River.
Abstract: Abstract A catastrophic flood occurred on 7 February 2021 around 10:30 AM (local time) in the Rishiganga River, which has been attributed to a rockslide in the upper reach of the Raunthi River. The Resourcesat 2 LISS IV (8 February 2021) and CNES Airbus satellite imagery (9 February 2021) clearly show the location of displaced materials. The solar radiation observed was higher than normal by 10% and 25% on 6 and 7 February 2021, respectively, however, the temperature shows up to 34% changes. These conditions are responsible for the sudden change in instability in glacier blocks causing deadly rock-ice slides that led to the collapse of the hanging glacier as a wedge failure. The displaced materials mixed with ice, snow, and debris caused catastrophic floods downstream within no time that destroyed critical infrastructure and killed human lives. The hydrodynamic modelling (HEC-RAS software) shows mean flow velocity up to 22.4 ± 8.6 m/s with an average depth of 16.3 ± 6.5 m that caused deadly devastation in the source region and along the rivers due to the flow of water in the valley.
9 citations
TL;DR: In this article, the authors synthesize the results and inferences of several studies carried out in the Indian Himalayan Region (IHR) using in situ data, remotely sensed data, and model-based meteorological observations.
Abstract: The Himalaya, by virtue of its location and stupendous height, acts as a great climatic divide and regulates meteorological conditions in the subcontinent regions of South Asia. However, the associated complexities and their effects are yet to be resolved to understand the meteorology of the Indian Himalayan Region (IHR). In this review volume, we synthesize the results and inferences of several studies carried out in the IHR using in situ data, remotely sensed data, and model-based meteorological observations. Results provide insights into climate change, scientific gaps, and their causes in deciphering meteorological observations from the last century to recent decades and envisage impacts of climate change on water reservoirs in the future. Warming trend of air temperature, in contrast to global temperature, has been projected in recent decades (after 1990) with a greater warming rate in the maximum temperature than the minimum temperature. This drifting of air temperature from the beginning of last century accelerates the diurnal temperature range of the Himalayas. An elevation-dependent warming trend is mostly perceived in the northwest Himalayan region, implicating an increased warming rate in the Greater Himalaya as compared to the lower and Karakoram Himalaya. No definite trends of precipitation have been observed over different regions of the IHR, suggesting heterogeneous cryosphere-climate interaction between western and central Himalaya. In this review, we have tried to emphasize to the scientific community and policy-makers for enhancing the knowledge of physical and dynamical processes associated with meteorological parameters in the Himalayan terrain.
8 citations
TL;DR: In this article , an early warning system based on geospatial technology to minimize loss of life, particularly for the workers employed in the engineering projects in the vicinity of the risk zone was proposed.
Abstract: This study, motivated by the flood disaster that took place at the glaciated region in Rishi Ganga Basin of Nanda Devi Biosphere Reserve (NDBR), Uttarakhand on 7th February 2021, intends to identify the altitudinal and sequential changes in the glacier region using satellite imageries. Our results suggest that 21.50 km2 and 34.70 km2 glacier area was lost from the region during the period 1976–2013 and 1976–2020 respectively. Besides this, out of the 106 High Altitude Glacial Lakes (HAGLs) found at an altitude of 4500 m above mean sea level (amsl), 14 potential spots are identified which can be a reason for future calamities. Our analysis of snow cover extents for the decade 2010–2021 suggests a considerable decrease of (16–28%) in winter snow cover. The unpredictable temperature fluctuations especially during the last few decades have also affected the freezing and thawing processes in the high-altitude areas. The changing behavior of the weathering processes quite often results in landslides, a major reason for disasters in the higher Himalaya. There is, thus, an urgent need to identify the high-risk sites in higher Himalaya which may be potential zones for future landslides. In anticipation to mitigate the resulting damages, the study emphasizes developing an early warning system based on geospatial technology to minimize loss of life, particularly for the workers employed in the engineering projects in the vicinity of the risk zone.
5 citations
References
More filters
TL;DR: It is shown that meltwater is extremely important in the Indus basin and important for the Brahmaputra basin, but plays only a modest role for the Ganges, Yangtze, and Yellow rivers, indicating a huge difference in the extent to which climate change is predicted to affect water availability and food security.
Abstract: More than 1.4 billion people depend on water from the Indus, Ganges, Brahmaputra, Yangtze, and Yellow rivers. Upstream snow and ice reserves of these basins, important in sustaining seasonal water availability, are likely to be affected substantially by climate change, but to what extent is yet unclear. Here, we show that meltwater is extremely important in the Indus basin and important for the Brahmaputra basin, but plays only a modest role for the Ganges, Yangtze, and Yellow rivers. A huge difference also exists between basins in the extent to which climate change is predicted to affect water availability and food security. The Brahmaputra and Indus basins are most susceptible to reductions of flow, threatening the food security of an estimated 60 million people.
2,754 citations
University of Arizona1, University of Washington2, University of Dayton3, California Institute of Technology4, Nagoya University5, Scott Polar Research Institute6, ETH Zurich7, Marshall Space Flight Center8, International Centre for Integrated Mountain Development9, NASA Headquarters10, Mountain Institute11, United States Geological Survey12, Tribhuvan University13, University of Victoria14, California State University, Long Beach15, Utrecht University16, Chinese Academy of Sciences17, University of Oslo18, Goddard Space Flight Center19, Nanjing University20, University of Texas at Austin21, Nanjing Normal University22, Texas A&M University23, University of Colorado Boulder24, Kathmandu25, Wadia Institute of Himalayan Geology26, MacDonald, Dettwiler and Associates27, University of California, Santa Barbara28, Hunan University of Science and Technology29, Kansas State University30, Steward Health Care System31, Northwest Normal University32, University of California, Davis33, Cooperative Research Centre34
TL;DR: Satellite imaging isolated hazard potential for earthquake-triggered landslides after the 2015 Gorkha earthquake in Nepal and provided information to relief and recovery officials as emergency operations were occurring, while supported by one of the largest-ever NASA-led campaigns of responsive satellite data acquisitions over a vast disaster zone.
Abstract: The Gorkha earthquake (M 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9,000 and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes’ induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision makers. We mapped 4,312 co-seismic and post-seismic landslides. We also surveyed 491 glacier lakes for earthquake damage, but found only 9 landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.
338 citations
TL;DR: In this paper, the role of these lakes as terrestrial storage for glacial meltwater is unknown and not accounted for in global sea level assessments, and they use scaling relations to estimate that global glacier lake volume increased by around 48%, to 156.5 km3, between 1990 and 2018.
Abstract: Glacial lakes are rapidly growing in response to climate change and glacier retreat. The role of these lakes as terrestrial storage for glacial meltwater is currently unknown and not accounted for in global sea level assessments. Here, we map glacier lakes around the world using 254,795 satellite images and use scaling relations to estimate that global glacier lake volume increased by around 48%, to 156.5 km3, between 1990 and 2018. This methodology provides a near-global database and analysis of glacial lake extent, volume and change. Over the study period, lake numbers and total area increased by 53 and 51%, respectively. Median lake size has increased 3%; however, the 95th percentile has increased by around 9%. Currently, glacial lakes hold about 0.43 mm of sea level equivalent. As glaciers continue to retreat and feed glacial lakes, the implications for glacial lake outburst floods and water resources are of considerable societal and ecological importance. Warming is increasing glacial lakes, and scaling relations show a 48% increase in volume for 1990 to 2018. All measures—area, volume, number—increased, providing water storage but also representing a potential hazard with the risk of outburst floods.
219 citations
TL;DR: In this article, the authors developed a HMA Glacial Lake Inventory (Hi-MAG) database to characterize the annual coverage of glacial lakes from 2008 to 2017 at 30'm resolution using Landsat satellite imagery.
Abstract: . Climate change is intensifying glacier melting and lake development in High Mountain Asia (HMA), which could increase glacial lake outburst flood hazards and impact water resource and hydroelectric power management. However, quantification of variability in size and type of glacial lakes at high resolution has been incomplete in HMA. Here, we developed a HMA Glacial Lake Inventory (Hi-MAG) database to characterize the annual coverage of glacial lakes from 2008 to 2017 at 30 m resolution using Landsat satellite imagery. It is noted that a rapid increase in lake number and moderate area expansion was influenced by a large population of small glacial lake (≤ 0.04 km2), and faster growth in lake number occurred above 5300 m elevation. Proglacial lake dominated areas showed significant lake area expansion, while unconnected lake dominated areas exhibited stability or slight reduction. Small glacial lakes accounted for approximately 15% of the lake area in Eastern Hindu Kush, Western Himalaya, Northern/Western Tien Shan, and Gangdise Mountains, but contributed > 50 % of lake area expansion in these regions over a decade. Our results demonstrate proglacial lakes are a main contributor while small glacial lakes are an overlooked element to recent lake evolution in HMA. Regional geographic variability of debris cover, together with trends in warming and precipitation over the past few decades, largely explain the current distribution of supra- and proglacial lake area across HMA. The Hi-MAG database are available at: https://doi.org/10.5281/zenodo.3700282 , it can be used for studies on glacier-climate-lake interactions, glacio-hydrologic models, glacial lake outburst floods and potential downstream risks and water resources.
84 citations