Biodiversity Heritage Sites

Context: The Karnataka Biodiversity Board has decided to declare four more areas in the State as biodiversity heritage sites, namely,

  1. Antaragange Betta in Kolar;
  2. Aadi Narayana Swamy Betta in Chickballapur;
  3. Mahima Ranga Betta in Nelamangala, Bengaluru; and
  4. Urumbi area on the Kumaradhara river basin in Dakshina Kannada.
  • Biodiversity heritage sites are considered unique and fragile ecosystems that can be marine ecosystems, coastal and inland waters, or terrestrial areas.
  • For Biodiversity Heritage Sites of India refer to 11th Oct file.

5. Glacial Lake Outburst Floods (GLOF) (TH)

Context: Using remote sensing data, researchers from Germany have mapped the evolution of Gya glacial lake that outburst in 2014 and note the cause of the flood.

  • Most interesting was finding the cause of the flood —here the flooding did not happen due to the spillovers due to an avalanche or landslide, rather there was a thawing of the ice cores in the moraine [a field of dirt and rocks that have been pushed along by the glacier as it moves] which drained through the subsurface tunnels.

Analysis

  • As glaciers retreat, the formation of glacial lakes takes place behind moraine (glacial debris left behind after the ice has retreated), rock or ice dam.
  • In particular moraine dams, which is the most common dam type in the Himalayan region, are potentially weak and can breach suddenly, leading to a discharge up to millions of cubic meters of water and debris.
  • Glacial Lake Outburst Floods (GLOF) is a term used to describe a sudden release of water retained in a glacial lake that can be located in front, at the side, underneath, within, or on top of a glacier.
  • Large lakes located in front of the glacier are mainly dammed by loose moraine and these lakes are generally considered to be potential flood sources.
  • Different types of lakes may have different levels of hazard potential.
  • For instance, moraine-dammed lakes located at the snout of a glacier have a high probability of breaching and thus may have high hazard potential, whereas rock dam’s lakes have little chances of breaching and thus have a lower hazard potential.
  • Much of the damage caused during GLOF events are associated with large amounts of debris / boulders that accompany the floodwaters. 
  • Continued climate change is expected to alter and potentially increase the likelihood of lake outbursts in the future, as:
  1. Glacial lakes grow in size and number,
  2. Stability of steep slopes is weakened due to changes in thermal and mechanical conditions, and
  3. Heavy rainfall increases landslide activity.
  • In total, there are about 9,575 glaciers in the Indian Himalayan Region (IHR), spread across 6 states and union territories i.e., Jammu-Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh.
  • In some cases, cloudbursts can also trigger glacial lake outburst flood events like in the Kedarnath disaster in 2013.
  • While these events have been regarded as a major risk in the central Himalayan region including Sikkim, the arid Trans-Himalayan regions of Ladakh have received attention only recently.
  • Here the glaciers are located at high altitudes not lower than 5,200 m and most glaciers are of small size. Likewise, the glacial lakes are quite small in size.
  • GLOFs are recognized in the National Disaster Management Plan (NDMP) 2019 of India as a potential climatological disaster.
  • Early Warning Systems (EWS) has a prominent role in the international policy agenda and is aligned directly with Priority 4 of the Sendai Framework on Disaster Risk Reduction (DRR), and UN Sustainable Development Goal (SDG) 13 on Climate Action.
  • Four key elements of Early Warning Systems, according to the UNISDR are:

    i) Risk Knowledge;
    ii) Monitoring and Warning Service;
    iii) Dissemination and Communication; and
    iv) Response Capability.

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