Water Storage - A strategy for climate change adaptation in the Himalayas

Sustainable Mountain Development No. 56, ICIMOD, Winter 2009
cu.m of groundwater recharge takes place in the Bhabar combination of natural and artiﬁ cial systems could be
zone, the piedmont deposit north of Nepal’s Terai belt, selected to meet the water needs of the community.
and another 8800 million cu.m in the Terai belt itself.
It is necessary, however, to turn the natural storage
Generally, the rate of recharge from vertical percolation
options, including ponds, lakes and aquifers, from a
is much higher in the Bhabar zone than in the Terai. The
passive source to a planned and active source of water
Bhabar zone is also the main recharge site for the Terai,
storage. To this end, the knowledge gap concerning the
but there is no clear information available on the exact
cryosphere and biosphere will have to be addressed.
demarcation and area of the zone.
The changes in glacial volume and snow cover must
Reservoirs
also be examined further, and information sought on the
contribution of snow meltwater to stream ﬂ ow in river
Since constructed reservoirs can have a wide range of
basins. Scientiﬁ c investigations to assess and monitor
capacity for water storage, it would be helpful to think in
groundwater resources in the region, including the
terms of small and large reservoirs. The standard deﬁ nition
three transboundary aquifers of the Indus, Ganges, and
of small dams is for structures less than 15 metres high
Brahmputra basins, must also be launched.
with an embankment volume generally less than 0.75
million cu.m. Small reservoirs can be built at a low cost in
Traditional institutional mechanisms for community water
a short period. Their proximity to the point of use makes
governance play a very important role for the success of
them easily manageable by the local community. The
water storage capacity development initiatives. Institutional
evaporation loss in these small reservoirs is, however, high
mechanisms may also be necessary to encourage the
due to the high surface area to volume ratio.
downstream beneﬁ ciaries of aquatic ecosystem services
to reward and compensate the upstream communities in
Both upstream and downstream communities can take
managing watersheds or wetland conservation projects.
advantage of ‘positive externalities’ by choosing to
Furthermore, institutional mechanisms for transboundary
build storage projects of a multipurpose type. A number
cooperation are vital for taking advantage of ‘positive
of large dams have been built in in the HKH areas of
externalities’ and making compromises on the ‘negative
China and India during the last six decades to service
externalities’ of large reservoirs.
storage type hydropower plants . Water storage
capacity in the hydropower plants of China and India
To conclude, it is necessary to close the knowledge
has been found to be large enough to provide irrigation
gaps concerning the cryosphere and biosphere and to
water beneﬁ ts as well. The storage capacity in the
craft appropriate institutional mechanisms to successfully
hydropower plants of Bhutan and Nepal, however, is
harness the water storage potential of the HKH region
relatively small with the projects providing hydroenergy
for adapting to climate change.
beneﬁ ts only.
References
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Conclusion
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