Glacial Retreat and Glacial Hazards in the Himalayas

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1. Introduction 33.. Glacial Hazards 4. Mitigation of Hazards

• Glaciers cover 17% of the Himalayas (Xu et al, • Moraine-dammed lakes are highly unstable • Siphoning of lake water to reduce the lake level

2009) and act as a freshwater reservoir for more due to unconsolidated material. (Tsho Rolpa in 1995).

than a billion people (Prasad et al, 2011). • Excavation of spillways to direct water away

• Retreat of these glaciers leads to the formation from villages (Tsho Rolpa in 2000).

of unstable glacial lakes, which can burst their • Tunnelling to allow safe water flow.

moraines to form glacial lake outburst floods • Early warning systems (19 sirens installed in 17

(GLOF) and threaten water resources. villages downstream of Tsho Rolpa in 1997)

(Kattelmann 2003).

2. Causes of retreat

5. Conclusion

• Global warming and changes in atmospheric

• Himalayan glaciers are retreating rapidly due to

composition (aerosols) increase ablation and

Figure 2: Image of the ImjaGlacial Lake in 2004 (Fujita et al, 2009) anthropogenic influences. This has led to the

decrease accumulation on glaciers (figure 1).

formation of dangerous glacial lakes, which

• GLOFs can be triggered by avalanches, rockfalls

could result in GLOFs. More studies need to be

Figure 1:

and the collapse of steep moraines.

response of conducted into understanding the threat level

world glaciers • 1977 NareDrangka GLOF was caused by the

(figure 3).

to climate change

collapse of an ice-cored moraine.

(Rasul et al, 2008)

• 1985 Dig Tsho GLOF was caused by an ice

avalanche into the lake that generated a

displacement wave. The flood killed 5 people.

• The Imja Glacial Lake (figure 2) is a large glacial

lake (area of 0.54km2 ) that is dammed by an

ice-cored moraine (Watanabe et al, 1994).

Figure 3: Potential flood volume of Himalayan glacial lakes (Fujita et al, 2013).

• The Siachen Glacier has retreated 1.9km in 30 • It is likely to suffer a GLOF due to the large

References:

years due to military activity causing a 4oC volume of water and the melting of the ice-

Fujita et al., 2009, Enviro. Research letters, 4(4); Fujita et al., 2013, Nat. Hazards & Earth Sci. Syst., 13(7);

Kattelmann., 2003, Natural Hazards 26(1), pp. 145-154; Prasad et al., 2011, Planet Earth 2011 –Global Warming

temperature rise (Rasul et al, 2008). cored moraine and unstable lateral moraines. Challenges. ; Rasul et al., 2008, Pakistan Journal of Meteorology, 5(9). ; Watanabe et al., 1994, Mountain

Research and Development, pp. 329-340; Xu et al., 2009, Conservation Biology, 23(3), pp. 520-530.