Agriculture Reference
In-Depth Information
Irrawaddy
8024
a
Not avail-
able
413,710
79
32,683
7742
Mekong
9001
a
~ 7
805,604
71
57,198
4963
Salween
1494
a
~ 9
271,914
22
5982
7876
Tarim
1262
a
Up to 50
1,152,448
7
8067
4933
Yangtze
28,811
a
~ 18
1,722,193
214
368,549
2465
Yellow
1438
a
~ 2
944,970
156
147,415
308
Total 1,345,241
a
The data were collected by the Global Runoff Data Centre (GRDC) from the following most
downstream stations of the river basins:Chatly (Amu Darya), Bahadurabad (Brahmaputra),
Farakka (Ganges), Pakse (Mekong), Datong (Yangtze), Huayuankou (Yellow).
b
Estimation of the melt water contribution is difficult and varies in an upstream and down-
stream situation; approximates are given here.
Source
: Chalise and Khanal (2001); Tarar (1982); Chen et al. (2005).
19.8
HIMALAYAN CLIMATE AND WATER
The Himalayas display great climatic variability. The mountains act as
a barrier to atmospheric circulation for both the summer monsoon and
the winter westerlies. The summer monsoon dominates the climate, last-
ing eight months (March-October) in the eastern Himalayas, four months
(June-September) in the central Himalayas, and two months (July-Au-
gust) in the western Himalayas (Chalise and Khanal, 2001). The east-west
variation is based on the dominance of different weather systems, which
in turn cause the monsoon to weaken from east to west. The monsoon
penetrates northwards along the Brahmaputra River into the south-east
Tibetan Plateau, but rarely as far as the Karakoram (Hofer and Messerli,
2006; Rees and Collins, 2006). The highest annual rainfall in the region
occurs in Cherrapunji in India, amounting to more than 12,000 mm. The
monsoon rainfall is mainly of an aerographic nature, resulting in distinct
variations in rainfall with elevation between the southern slopes of the
Himalayas and the rain shadow areas on the Tibetan Plateau (Mei'e et al.
,
1985). On the meso-scale, the impacts of climate are mainly due to local
topographic characteristics (Chalise and Khanal, 2001) with dry inner val-
leys receiving much less rainfall than the adjacent mountain slopes as a
result of the lee effect. This suggests that the currently measured rainfall,
