{"id":370560,"date":"2026-08-28T19:49:57","date_gmt":"2026-08-28T14:19:57","guid":{"rendered":"https:\/\/forumias.com\/blog\/?p=370560"},"modified":"2026-08-28T19:49:57","modified_gmt":"2026-08-28T14:19:57","slug":"danger-from-above-on-the-nepal-flood","status":"publish","type":"post","link":"https:\/\/forumias.com\/blog\/danger-from-above-on-the-nepal-flood\/","title":{"rendered":"Danger from Above: On the Nepal Flood"},"content":{"rendered":"

UPSC Syllabus: Gs Paper 3- <\/strong>Disaster, and disaster management<\/p>\n

Introduction<\/strong><\/h2>\n

The devastating flash floods along the Nepal-Tibet border show the growing danger of disasters originating in the high Himalayas. The event was initially linked to an earthquake or rainfall, but satellite evidence pointed towards a glacial collapse or ice-rock avalanche<\/strong>, followed by destructive downstream flooding. It highlights the risks from unstable glaciers, debris blockages, glacial lakes and vulnerable infrastructure in a rapidly warming Himalayan region.<\/p>\n

Nepal Flood Disaster: Causes and Sequence of Events<\/strong><\/h2>\n
    \n
  1. Glacial collapse as the trigger:<\/strong> Satellite imagery and scientific assessments indicate that a glacier collapse or ice-rock avalanche<\/strong> triggered the destructive flood, while the seismic event resulted from the collapse.<\/li>\n
  2. Possible river blockage and breach:<\/strong> Ice, rock and sediment may have temporarily blocked the river before accumulated water broke through, intensifying downstream flooding.<\/li>\n
  3. Rapid spread through river valleys:<\/strong> The flood entered the Lhende Khola<\/strong>, flowed into the Bhote Koshi<\/strong>, and then travelled south through the Trishuli river system.<\/li>\n
  4. Sudden rise in water level:<\/strong> Water in the Trishuli River reportedly rose by about 9 metres within 30 minutes<\/strong>, showing the extreme speed of the flood.<\/li>\n
  5. Human and infrastructure losses:<\/strong> The disaster caused hundreds of deaths and many missing persons<\/strong>, while settlements, hydropower and monitoring infrastructure suffered extensive damage.<\/li>\n
  6. Continuing secondary flood risk:<\/strong> A newly formed barrier lake upstream created fears of another breach and further flooding in downstream areas.<\/li>\n<\/ol>\n

    ,<\/strong><\/h2>\n
      \n
    1. Meaning of glacial collapse: <\/strong>It involves the detachment of a large mass of glacier ice, often carrying rock, sediment and water, from its bed.<\/li>\n
    2. Different forms of failure: <\/strong>Such gravity-driven events can include glacier detachments, ice avalanches and rock-ice avalanches on steep mountain slopes.<\/li>\n
    3. Transformation into debris flows: <\/strong>The collapsed material can move rapidly downhill as an ice-rich avalanche or a highly destructive debris flow.<\/li>\n
    4. High-altitude fall: <\/strong>Satellite observations suggested that part of the glacier broke off at about 5,200 metres and fell roughly 1,200 metres into the valley.<\/li>\n
    5. Role of melting snow: <\/strong>Available imagery indicated that a substantial amount of snow may have melted during the 24 hours before the disaster.<\/li>\n
    6. Barrier lake formation: <\/strong>Landslide and avalanche debris can block mountain rivers, creating temporary lakes that store large volumes of water.<\/li>\n
    7. Sudden barrier failure: <\/strong>When such blockages fail, stored water, mud, rock and debris can surge downstream as a catastrophic flood.<\/li>\n
    8. Difficulties in escape: <\/strong>High-speed flows of mud and water leave very little time for evacuation and can overwhelm roads and vehicles.<\/li>\n<\/ol>\n

      Glacier-Related Disasters: Evidence from the Himalayas and Beyond<\/strong><\/h2>\n
        \n
      1. South Lhonak Lake disaster: <\/strong>In October 2023, a Glacial Lake Outburst Flood in Sikkim released water, debris and rock, severely damaging the State’s largest hydropower project.<\/li>\n
      2. Long-term build-up of risk: <\/strong>Subsequent analysis showed that the South Lhonak disaster had developed over several years rather than appearing suddenly.<\/li>\n
      3. Aru glacier collapses in Tibet: <\/strong>In 2016, two major glacier collapses released about 68 million and 83 million cubic metres of ice, killing people and animals.<\/li>\n
      4. Sedongpu Basin events: <\/strong>Ice-rock avalanches in 2018 blocked the Yarlung Tsangpo River, creating a dangerous temporary lake and downstream flood threat.<\/li>\n
      5. Bukadaban Feng collapse: <\/strong>In 2022, around 40 million cubic metres of glacier ice detached and generated a 13-metre-high wave after entering a lake.<\/li>\n
      6. Ronti Peak disaster: <\/strong>In 2018, about 27 million cubic metres of rock and glacier ice collapsed in Uttarakhand, killing more than 200 people.<\/li>\n
      7. Rare but serious events: <\/strong>Glacial collapses remain unusual and site-specific, but Tibet has emerged as a location of several major documented collapses.<\/li>\n
      8. Risk beyond the Himalayas: <\/strong>The Blatten collapse in Switzerland also showed how combined rock, soil and ice failures can destroy settlements.<\/li>\n<\/ol>\n

        Climate Change and Increasing Himalayan Cryosphere Risks<\/strong><\/h2>\n
          \n
        1. Rapid glacier loss: <\/strong>Glaciers across the Hindu Kush Himalaya lost ice 65% faster between 2011 and 2020 than during the previous decade.<\/li>\n
        2. Shrinking glaciers in Nepal: <\/strong>Nepal’s glaciers lost close to one-third of their ice volume in roughly three decades, according to United Nations estimates.<\/li>\n
        3. Glacial retreat and instability: <\/strong>Rising temperatures can increase glacier retreat, alter mountain slopes and contribute to conditions favourable for glacier-related hazards.<\/li>\n
        4. Permafrost reduction: <\/strong>Warming can reduce permafrost, weakening high-altitude slopes and increasing the possibility of landslides and ice-rock failures.<\/li>\n
        5. Growing danger of glacial lakes: <\/strong>Melting glaciers can create or enlarge glacier-fed lakes, increasing the risk of Glacial Lake Outburst Floods (GLOFs).<\/li>\n
        6. More heat-related pressures: <\/strong>There is high confidence that increasing heatwaves, glacier retreat and permafrost loss will raise Himalayan hazard risks.<\/li>\n
        7. Hazards are location-specific: <\/strong>Even under a warming climate, the immediate causes of individual glacial collapses must be examined separately for each site.<\/li>\n<\/ol>\n

          Challenges in Monitoring and Predicting Himalayan Disasters<\/strong><\/h2>\n
            \n
          1. Large monitoring challenge:<\/strong> The Indian Himalayas contain nearly 7,500 glacial lakes and about 15,000 glaciers, making comprehensive monitoring extremely difficult.<\/li>\n
          2. Limits of remote sensing: <\/strong>Satellites can detect changes and reconstruct disasters, but they cannot fully determine the stability of every glacier or lake.<\/li>\n
          3. Need for field assessment: <\/strong>Accurate assessment often requires site visits, but remote terrain makes access difficult and limits the period for expeditions.<\/li>\n
          4. Short fieldwork window: <\/strong>High-altitude expeditions are generally feasible only from July to September, restricting detailed on-ground observations.<\/li>\n
          5. Difficulty of precise forecasting: <\/strong>Even with satellite data, predicting exactly when and where a glacier will collapse remains extremely difficult.<\/li>\n
          6. Limits of conventional flood warnings: <\/strong>The absence of rainfall before the Nepal disaster shows that rainfall-based warning systems may fail to detect such sudden events.<\/li>\n
          7. Risk of ineffective warnings: <\/strong>Warnings may also have limited value when residents cannot relocate because of habit, livelihood needs or lack of alternatives.<\/li>\n
          8. Role of advanced technology: <\/strong>Satellites, drones, unmanned aerial vehicles and thermal imaging can help assess damage, locate survivors and identify high-risk areas.<\/li>\n<\/ol>\n

            Way Forward<\/strong><\/h2>\n
              \n
            1. Improve glacier health monitoring: <\/strong>Governments should invest in better tracking of glaciers, glacial lakes and unstable mountain areas through remote sensing and field studies.<\/li>\n
            2. Identify vulnerable zones: <\/strong>Scientific monitoring should be used to map areas exposed to glacier collapse, GLOFs, landslides and debris-blocked rivers.<\/li>\n
            3. Integrate risk into development: <\/strong>Disaster assessments must become part of long-term development planning instead of being considered only after a disaster.<\/li>\n
            4. Restrict construction in high-risk areas: <\/strong>Settlements and large infrastructure projects should be discouraged in zones already identified as vulnerable to major natural outbursts.<\/li>\n
            5. Strengthen construction standards: <\/strong>Governments should enforce appropriate construction codes to reduce damage to roads, bridges and other infrastructure.<\/li>\n
            6. Protect hydropower infrastructure: <\/strong>Dams and hydropower projects in Himalayan valleys require greater attention because they are often among the first assets damaged.<\/li>\n
            7. Prepare for cascading hazards: <\/strong>Disaster planning must consider secondary risks, including temporary barrier lakes, river breaches and repeated downstream flooding.<\/li>\n
            8. Go beyond relief and rescue: <\/strong>Long-term prevention, continuous monitoring and safer development are necessary to address disasters worsened by passive neglect.<\/li>\n<\/ol>\n

              Conclusion<\/strong><\/p>\n

              The Nepal flood shows how a disaster high in the Himalayas can quickly turn into a major downstream crisis through glacial collapse, debris flow and river blockage<\/strong>. Climate change is increasing the wider risks, even if its direct role remains uncertain. Better monitoring, safer construction and risk-based development can reduce future losses and prevent natural hazards from becoming larger human disasters.<\/p>\n

              Question for practice:<\/strong><\/p>\n

              Discuss the causes, growing risks and challenges associated with glacier-related disasters in the Himalayan region, with special reference to the Nepal flood.<\/p>\n

              Source<\/strong>: The Hindu<\/p>\n","protected":false},"excerpt":{"rendered":"

              UPSC Syllabus: Gs Paper 3- Disaster, and disaster management Introduction The devastating flash floods along the Nepal-Tibet border show the growing danger of disasters originating in the high Himalayas. The event was initially linked to an earthquake or rainfall, but satellite evidence pointed towards a glacial collapse or ice-rock avalanche, followed by destructive downstream flooding.… Continue reading Danger from Above: On the Nepal Flood<\/span><\/a><\/p>\n","protected":false},"author":10320,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"footnotes":""},"categories":[1230],"tags":[411,216,10498],"class_list":["post-370560","post","type-post","status-publish","format-standard","hentry","category-9-pm-daily-articles","tag-disaster-management","tag-gs-paper-3","tag-the-hindu","entry"],"jetpack_featured_media_url":"","views":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts\/370560","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/users\/10320"}],"replies":[{"embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/comments?post=370560"}],"version-history":[{"count":0,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts\/370560\/revisions"}],"wp:attachment":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/media?parent=370560"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/categories?post=370560"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/tags?post=370560"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}