Glacial Lake Outburst

The false-color images above show a glacial lake in the Himalayas nearly doubling in length over 30 years. Ice is represented as light blue, while significant meltwater is dark blue. Rocks are brown; vegetation is green. The growth of glacial lakes can increase the risk of flooding in nearby valleys. Image: NASA.

Definition

“Glacial lake outburst flood” (GLOF) is a phrase used to describe a sudden release of a significant amount of water retained in a glacial lake, irrespective of the cause. GLOFs are characterized by extreme peak discharges, often several times in excess of the maximum discharges of hydrometeorological induced floods, with an exceptional erosion/transport potential; therefore, they can turn into flow-type movements, e.g. GLOF-induced debris flows (Emmer).

Facts and figures

A GLOF may have diverse causes and subsequent mechanisms, for example accordingly on how water is released. Specific causes are related to specific mechanisms and not all their combinations are realistic scenarios. Moreover, specific subtypes of glacial lakes are susceptible to specific causes and subsequent mechanisms of outburst floods. Numerous studies have investigated the causes of lake outburst floods for specific lake subtypes and regions ; however, systematic investigation of the causes and mechanisms of GLOF, as well as database construction, are required in order to better understand the complex processes and, in turn, provide more effective hazard and risk management (Emmer).

 

The following direct causes of glacial lake outburst floods were documented:

  • Rapid slope movement into the lake
  • Heavy rainfall/snowmelt
  • Cascading processes (flood from a lake situated upstream)
  • Earthquake
  • Melting of ice incorporated in dam/forming the dam (including volcanic activity-triggered jökulhlaups)
  • Blocking of subsurface outflow tunnels (applies only to lakes without surface outflow or lakes with a combination of surface and subsurface outflow)
  • Long-term dam degradation (Emmer).

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Noticias

Satellite image of the Tibetan Plateau. Image: Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC

A study conducted by Swiss and Chinese scientists assesses the flood danger posed by glacial lakes across the Tibetan Plateau using an automated satellite survey. 

Glacial lake outburst floods (GLOFs) are a major concern throughout the Third Pole Environment, where thousands of glacial lakes have formed and continue to expand in response to climate warming and glacial retreat. This is particular true in the Himalaya, where several disasters occurring over the past century have caused significant loss of life and damage to infrastructure. The fear is that these lakes can overtop their barriers and send floods downstream that overrun settlements.

The study looked at 1,300 of these water bodies that have built up in front of ice streams and which are dammed by rocky debris, and identified 210 lakes (16 per cent) with a potential to threaten communities. This information facilitates targeted local monitoring and other risk reduction... read more

Publishing date: 23/04/2019
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The Sentinel Hub Custom Script Contest is a remotely run hackathon engaging data... read more

Publishing date: 23/04/2019

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Publishing date: 01/04/2019

Data Source

Publishing institution: European Space Agency (ESA)
ESA's Earth Observation Thematic Exploitation Platform (TEP) is a browser for satellite imagery and specific products on an environmental topic. The TEP platforms are divided into 7 categories: Coastal; Forstry; Geohazards; Hydrology; Polar; Urban; and Food Security. Each platform is a collaborative, virtual work environment providing access to EO data and the tools, processors and Information and Communication Technology resources required to work with them. TEP aims to bridge the gap between the users and the data and tools.

SAM Satellite

ALTIKA, the altimeter and prime payload of the SARAL mission, will be the first spaceborne altimeter to operate at Ka-band (35.75 GHz, 500 MHz). The high-resolution AltiKa altimeter has a dual-frequency radiometric function which allows the altimetry measurements to be corrected for the effects due to the signal passing through the wet troposphere

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