Agriculture Reference
In-Depth Information
Water from both permanent snow and ice and seasonal snow is re-
leased by melting, some to be temporarily stored in high altitude wetlands
and lakes, but most flowing directly downstream in the large river sys-
tems, giving a distinct seasonal rhythm to annual stream flow regimes in
these rivers. The contribution of snow and glacial melt to the major rivers
in the region ranges from 2 to 50% of the average flow. In the 'shoulder
seasons,' before and after precipitation from the summer monsoon, snow
and ice melt contribute about 70% of the flow of the main Ganges, Indus,
Tarim, and Kabul rivers (Barnett et al., 2005; Kattelmann, 1987; Singh
and Bengtsson, 2004). The rivers of Nepal contribute about 40% of the
average annual flow in the Ganges Basin, which alone is home to 500 mil-
lion people, about 10% of the total human population of the region. Even
more importantly, they contribute about 70% of the flow in the dry sea-
son (Alford, 1992). In western China, glacial melt provides the principal
water source in the dry season for 25% of the population (Xu, 2008). The
Indus Irrigation Scheme in Pakistan depends 50 percent or more on runoff
originating from snow melt and glacial melt from the eastern Hindu Kush,
Karakoram, and western Himalayas (Winiger et al., 2005) (Table 19.3).
TABLE 19.3
Glaciated Areas in the Himalayan Range (Qin, 2002)
Drainage basin
Number of glaciers
Total area (km
2
)
Total ice reserves (km
3
)
Ganges River
6694
16,677
1971
Brahmaputra River
4366
6579
600
Indus River
5057
8926
850
Total
16,117
32,182
3421
19.9 OBSERVED AND PROJECTED EFFECTS OF CLIMATE
CHANGE
Climate change is currently taking place at an unprecedented rate and is
projected to compound the pressures on natural resources and the environ-
ment associated with rapid urbanization, industrialization, and economic
development. It will potentially have profound and widespread effects on
