Brahamaputra Basin
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<strong>Brahamaputra</strong> <strong>Basin</strong><br />
2. Hydrological units<br />
2.1 Sub-basins<br />
The Brahmaputra <strong>Basin</strong> is further divided into two major sub basins- Brahmaputra Upper and<br />
Brahmaputra Lower sub basin, as shown in Map 2. Contributing Percentage drainage area of each<br />
sub basin is given in Figure 4. Subansiri, Buri Dihing, Dihang, Dhansiri, Diyung, Neo Dihing, Lohit,<br />
Dibang, Disai, Disang, Jhanzi, Dikrang, Dikhow are some major tributaries contributing to the Upper<br />
Brahmaputra sub basin. The upper Brahmaputra sub basin is larger than the lower Brahmaputra sub<br />
basin which covers 98,972.87 Sq.km of geographical area as shown in Table 6.<br />
Lower Brahmaputra sub basin covers about 87,392.22 Sq.km. of the total geographical area of the<br />
<strong>Basin</strong>. Major tributaries contributing to the Lower Brahmaputra sub basin are Teesta, Kopilli,<br />
Jaldhaka, Kameng, Torsa, Kalung, Jinjimm, Kulsi, Sonai, Manas, Umiam, Champamati, Digaru etc.<br />
2.2 Watersheds<br />
Figure 4. Sub-basins and percent drainage area<br />
There are 180 watersheds in the Brahmaputra basin. The Brahmaputra Upper and the Lower Sub<br />
<strong>Basin</strong> compromised of 97 and 83 Watersheds respectively (Map 9a & 9b). Number of watersheds<br />
and their size ranges are given in Table 6.<br />
Table 6. Sub-basin wise watersheds<br />
Sl.no. Sub <strong>Basin</strong> Area (Sq. km.) Size Range of Watershed No. of Watersheds<br />
1 Brahmaputra Lower 87392.22 429.01 - 1490.01 83<br />
2 Brahmaputra Upper 98972.87 488.58 - 1473.03 97<br />
Source: India-WRIS<br />
www.india-wris.nrsc.gov.in 28