Agriculture Reference
In-Depth Information
which is mainly based on measurements of rainfall in the valley bottoms,
is not representative for the area, and the use of these data results in sig-
nificant underestimates.
A substantial portion of the annual precipitation falls as snow, particu-
larly at high altitudes (above 3000 amsl) feeding the Himalayan glaciers.
The high Himalayan and inner Asian ranges have the most highly glaciated
areas outside the polar regions (Dyurgerov and Meier, 2005; Owen et al.,
2002). Glaciated areas in the greater Himalayan region cover an area of
more than 112,000 km
2
. The Himalayan range alone (a subregion) has a
total area of approximately 33,000 km
2
of glaciers or 17% of the mountain
area (as compared to 2.2% in the Swiss Alps) with a total ice volume of
3,420 km
3
which provides important short and long-term water storage fa-
cilities. These figures are very tentative, however, and need to be followed
up with more research. Glaciers undergo winter accumulation and summer
ablation in the west, but predominantly synchronous summer accumulation
and summer melt in the east. The main melting occurs in high summer;
however, when this coincides with the monsoon, it may not be as critical
for water supply as when the melting occurs in the shoulder seasons: spring
and autumn. When the monsoon is weak, delayed, or fails, melt water from
snow and ice may limit or avert catastrophic drought (Table 19.2).
TABLE 19.2
Glaciated Areas in the Greater Himalayan Region (Dyurgerov and Meier,
2005)
Mountain range
Area (km
2
)
Tien Shan
15,417
Pamir
12,260
Qilian Shan
1,930
Kunlun Shan
12,260
Karakoram
16,600
Qiantang Plateau
3,360
Tanggulla
2,210
Gandishi
620
Nianqingtangla
7,540
Hengduan
1,620
Himalayas
33,050
Hindu Kush
3,200
Hinduradsh
2,700
Total
112,767
