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Saturday 21 January 2012

Heritage sites face threat from projects on Brahmaputra

20 January 2012
by Moushumi Basu


The looming threat to the world heritage sites of Kaziranga and other national parks in Assam is not from poachers or encroachers. But according to a study conducted by experts it is from the 70 dams and hydro electric power projects that are coming up on River Brahmaputra and its tributaries in the North-East region of the country.

The study was conducted Bibhab K Talukdar, Secretary General of Aaranyak, member organisation of National Board For Wildlife (NBWL) and Partha J Das who heads the Water, Climate & Hazard Programme of the organisation. The 70 large dams proposed by the Government of India are to come up on the basins of the Rivers Siang (20), Lohit (11), Dibang (17) and Subansiri (22).

According to them, these upcoming dams in the region will have serious impacts on the life-sustaining ecosystems and the fragile environment of the region which has the largest forest cover in India. The area includes 24.6 per cent of the country’s total forest area in a relatively small area of 7.76 per cent of the country’s total geographical area. The effects of the dams would also affect the Indo-Burma biodiversity hotspot, which is one of the 34 in the world.

The situation in Kaziranga, is particularly precarious, Talukdar pointed out. It is located in the floodplain of the Brahmaputra and known for its population of the greater one-horned rhino, elephants and tigers as well as many other important species of flora and fauna. “The threat to the sanctuary comes from a number of power projects which are in various stages of development”, he stressed.

These include the Lower Subansiri Hydroelectric Project (2000 MW) on river Subansiri, the Lower Siang HEP (2700 MW) on river Siang (the mainstream of the Brahmaputra that flows from Tibet, the Demwe Lower HEP (1750 MW) on river Lohit and the Dibang Multipurpose Project (3000 MW) on river Dibang, projects.

Das further pointed out that these run of the river projects will create daily variations in the rate of water flow creating a cycle of high flow and low flow cycle on a daily scale rather than the natural seasonal scale.

This daily occurring contrast in flow of water will drastically vary the hydrostatic pressure on the riverine and inner aquatic habitats constantly, putting severe stress specially on the aquatic wildlife of Kaziranga, felt Das.

Further, increase in rate of river bank erosion and uncertainty over anticipating the areas likely to be hit by erosion is commonly observed in alluvial plains downstream of dams, said Talukdar.

Any increase in bank erosion along the riparian stretch of Kaziranga will lead to loss of area of the wildlife habitat. It can also cause excessive sedimentation of inland water bodies and grasslands during annual peak floods.

“Similar impacts are inevitable during those sure but unpredictable cases of release of flood (excess) water during extreme rainfall, landslide or dam outburst floods in upstream of these basins”, pointed out the experts.

According to them, such changes in the local hydrological characteristics of the Brahmaputra which will be caused by the dams will gravely affect the Kaziranga ecosystem reducing their productive and carrying capacity to sustain different species of flora and fauna.

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