The main threat to Kaziranga National Park in the next 25 years will come not from poachers or encroachers, but the 70 dams that are being built in the Eastern Himalayas of India’s Northeast. Experts who have just completed a study of the region fear that Kaziranga National Park and Manas National Park, both World Heritage Sites of natural importance, might be adversely affected by dam-building on the Brahmaputra and its tributaries.
Partha J Das (Head, Water, Climate & Hazard Programme) and Bibhab K Talukdar (Secretary General) of Aaranyak say that the 168 dams planned in the region will have serious impacts on the life-sustaining ecosystems and the fragile environment to various degrees in the the entire region which has the largest forest cover in India (24.6 per cent of the country’s forest area) in a relatively small area (7.76 per cent of the country’s total geographical area) as well as an integral part of the Indo-Burma biodiversity hotspot, one of the 34 in the world.
For Kaziranga, 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 comes from 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. All these are in various stages of development.
Diurnal fluctuations in flow discharge and water level due to calculated pattern of release of water from these run-of-the river projects will create a high flow-low flow cycle on a daily scale rather than the natural seasonal scale. As a result of this high flow-low contrast occurring every day, the hydrostatic pressure on the riverine and inner aquatic habitats will vary drastically all the time pushing the wildlife of Kaziranga, especially the aquatic wildlife to severe stress.
Increase in rate of river bank erosion and uncertainty in anticipating the places where banks will be eroded is commonly observed in alluvial plains downstream of dams. Any increase in bank erosion along the riparian stretch of Kaziranga will lead to loss of area of the wild habitat and even might lead to excessive sedimentation of inland water bodies and grasslands during annual peak floods and during those sure but unpredictable cases where floods are created by release of water in the event of extreme rainfall or landslide dam outburst floods in upstream of these basins.
In simple worlds, the Kaziranga ecosystem may undergo such changes that may reduce their productive and carrying capacity to sustain different species of flora and fauna due to changes in the local hydrological characteristics of the Brahmaputra which will be caused by the dams. If the cumulative impact of these dams is added to those due to the Chinese ones reportedly under construction, the impacts could still be more adverse than being assessed at present.
The scary part is that a total of 70 large dams have been proposed by the Government of India over the basins of the Siang (20), Lohit (11), Dibang (17) and Subansiri (22).
