Sustainable Mountain Development No. 56, ICIMOD, Winter 2009
The Himalayas –
water storage under threat
Ouyang Hua, Integrated Water and Hazard Management, ICIMOD, houyang@icimod.org
T
he Hindu Kush-Himalayan region has the most the monsoon as well as the number and frequency of
extensive high altitude areas on Earth and extreme precipitation events.
the largest areas covered by glaciers and
permafrost outside the polar regions – the ‘Third Pole’.
One of the main concerns in relation to climate change
These mountains are now recognised to be a hotspot
in the Himalayan region is the reduction of snow and
of climate change (Dyurgerov and Meier 2005), but
ice, which reduces the region’s water storage capacity.
they still receive signifi cantly less attention than the
Changes in the intensity and distribution of rainfall
Arctic or Antarctic.
may also lead to changes in the uptake of rainwater
by soils and the recharge of aquifers. Climate change
The region’s ranges and foothills encompass a wide may affect people‘s wellbeing in numerous ways. For
spectrum of ecological zones with great socioeconomic example, it is very likely to aggravate the existing food
potential. They contain signifi cant biodiversity hotspots insecurity and problems of irrigated farming systems,
and a unique array of plants and animals of global especially in the Tarim and Indus river basins. The Indus
importance. Furthermore, the wetlands, rangelands, Irrigation Scheme in Pakistan depends 50% or more
and forests provide valuable ecosystem services such as on runoff originating from snowmelt and glacial melt
plant-based production, soil retention, climate regulation, from the eastern Hindu Kush, Karakoram, and western
and carbon sequestration. Himalayas (Winiger et al. 2005).
The ranges form a barrier to the easterly monsoon winds
and are the origin of ten of the largest rivers in Asia. The
“The huge water storage
huge water storage capacity of the mountains provides
a lifeline for millions of people in the region and
capacity of the mountains
downstream; more than 1.3 billion people are estimated
to depend directly or indirectly on Himalayan waters.
provides a lifeline for millions”
Climate change
The Himalayas as the water tower of Asia
The Himalayas are experiencing a general warming
The Hindu Kush-Himalayan mountains are the major
trend. The mean maximum temperature in Nepal
source of stored water in the region. Water is retained
increased by 0.06°C per year between 1977 and
in the form of ice and snow in the high mountains, as
2000. Similarly, the Tibetan Plateau has experienced
well as being stored in natural lakes, wetlands, and
warming in the range of 0.02°C to 0.03°C per
groundwater aquifers, and behind constructed dams.
year over the last fi fty years (Yao et al. 2006) -- much
greater than the global average of 0.74°C total over The Himalayas have a total glaciated area of around
the last 100 years (IPCC 2007). Based on regional 33,000 sq.km (Eriksson et al. 2009) which provides
climate models, it is predicted that the temperatures on important short- and long-term water storage facilities.
the Indian sub-continent will rise between 3.5°C and “There is about 12,000 cu.km of fresh water stored in
5.5°C by 2100, and on the Tibetan Plateau 2.0°C by the glaciers throughout the Himalayas -- more fresh water
2050 and 5.0°C by 2100 (Rupa Kumar et al. 2006). than in Lake Superior” (Thompson 2007). Compared
Monsoon rainfall in India and Nepal has been found to glaciers in other mountain ranges, the Himalayan
to be highly correlated with large-scale climatological glaciers are retreating at higher rates, and these rates
phenomena such as El Niño. There are already signs are accelerating. Projections of glacier retreat in the
of changes in the dates of the onset and retreat of region (IPCC 2007) suggest that the projected increase
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