QUESTION Identify different factors that trigger Glacial Lake Outburst Floods. Also, suggest certain measures that need to be taken to minimize their impact. 8 Marks 120 words
|DIRECTIVE : Define Glacial Lake Outburst Floods.
Enumerate its triggering factors.
Mention measures that are required to minimize the impact of these floods.
|Glacial Lake Outburst Floods(GLOFs) refer to release of melt water, moraines and the entire content of the ice-dam glacial lake due to dam failure. GLOFs often result in catastrophic flooding downstream, with major geomorphic and socio-economic impact.
|Causative Triggers for the Glacial Lake Outburst Floods:-
1. Glacial retreat due to Global Warming increases the number of glacial lakes and also expands the size of existing ones. Rapid Slope Movement into the lake and melting of ice incorporated into the dams are linked to glacial retreat. The exorbitant size and content becomes difficult to contain.
2. Anthropogenic factors which greatly alter the radiative balance- For example in the Himalayan region anthropogenic activities such as mass tourism; developmental interventions such as roads and hydropower projects has resulted in faster glacial melting and resultant GLOFs.
Other factors – Surface heating impact of the Black Carbon, Earthquakes, blocking of subsurface outflow tunnels and long term dam degradation are other trigger points for the same.
Access to early warning system and timely information is the key to minimizing the impact. In addition, continuous monitoring may be done using remote sensing.
Prevention or mitigation of the magnitude of the flood by dam remediation like artificial dams, tunnels, open cuts, concrete outflows, flood protection walls.
Other measures include GLOF hazard mapping, identification of GLOF safe evacuation sites, identifying vulnerable communities, community preparedness including community based early warning systems etc.
|ISRO among other organizations are already engaged in monitoring of glacial lake and other water bodies in the Himalayan region of Indian River basins.
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