Brahamaputra Basin

Brahamaputra Basin
3. Surface water resources
The Brahmaputra and its tributaries carry more than 30% of the total water resources potential of
the country. Besides, this region has the highest per capita and per hectare availability of water in
the country. The Average annual water potential and the Utilizable Surface Water of the Basin are
537.24 BMC and 24BCM respectively.
3.1 Surface waterbodies
Surface water bodies have traditionally played an important role in Brahmaputra basin used for
irrigation, drinking water supply, navigation and other domestic uses. But water bodies (total
number, capacity as well as quality) are decreasing day by day due to mainly siltation and disposal of
untreated waste in that waterbodies.
The basin is blessed with optimal amount of rainfall. Storage of water in pond both in the settlement
and agricultural fields is the own water saving/storing strategy of the local population of this basin. It
is observed that there are sufficient number of pond in thisregion followed by lakes which is
generally used for fish cultivation and agricultural activity. Most of the waterbodies in the basin is
less than 25 ha. A detail of water bodies according to their water spread area is given in Table 7.
The floodplains of the Brahmaputra, is dotted with a large number of wetlands. This undrained
depressions, generally known as ‘Bils/ Beels’ or beels (lakes), possess tremendous ecological
significance as unique habitats for an exquisite variety of flora and fauna.These beels function as
flood water retention basins and traditional fisheries. They have importance for the groundwater
recharge also. Important wetlands of the Brahmaputra basin are - Deepar Beel, Sola Beels (Saru Sola
& Bor Sola), Chandubi Lake etc. Most of the wetlands are now in degraded condition while a
considerable number have been totally destroyed due to siltation, eutrophication, harmful land use
practices and encroachment for settlement, construction of roads, railways, embankments etc.
Oxbow lakes generated from the abandoned channels/ channel cut-offs covers is very frequent in
this basin. Considerable 5.86% of the total surface water of Brahmaputra basin is covered by this
class. Several large reservoirs of considerable size have also been constructed in the Brahmaputra
Basin associated with the dams and barrages. Some large reservoirs of this basin are - Umium,
Subansiri Lower, Ranganadi, Doyang etc.
Table 7. Number and size of waterbodies
Sl. No. Size Range (ha) No. of Waterbodies
1 0 - 25 15766
2 25 - 50 174
3 50 - 100 57
4 100 - 250 28
5 250 - 500 5
6 500 - 1000 5
7 1000 - 2500 2
8 More than 2500 0
Source: India-WRIS
www.india-wris.nrsc.gov.in 31