Subansiri dams may impact aquatic life
The endangered Mahseer fish and river dolphins may face grave danger from the proposed hydroelectric power projects, with a critical study of the Subansiri Sub Basin recommending development of an integrated biodiversity conservation plan.
The two-volume report, released by the Ministry of Environment and Forest (MoEF), was prepared by the Central Water Commission (CWC). Titled ‘Cumulative Impact and Carrying Capacity Study of Subansiri Basin, Including Downstream Impact in Brahmaputra River Valley’, the study was made with an objective to assess the cumulative impacts of hydropower development in the basin.
Among its several recommendations, the report has said that the MoEF may associate other institutions in Arunachal Pradesh, besides Botanical Survey of India, Zoological Survey of India, State Pollution Control Board and research and development organisations, among others, while drafting the conservation plan.
According to the Central Electricity Authority (CEA) estimate, the Subansiri basin has 6,092 MW hydropower generation potential (60 per cent load factor) with a probable installed capacity of 13,767 MW. This potential is planned to be harnessed by setting up about 18 hydropower projects, while 16 small HEPs, totalling 35.85 MW, are already commissioned in Subansiri Basin.
The report said that based on the data availability of biodiversity on the proposed HEPs, it can be inferred that the Subansiri sub basin is the most important basin from the point of view of having the highest number of HEPs with the highest installed capacity, the highest estimated loss of forest area and reported presence of endemic and threatened species.
About the threats faced by the endangered species, the report said that the proposed dams may obstruct the migration route of the Mahseer species. In addition, certain species of Schizothorax (Snow trout) also undertake migration from upper reaches during winter months for feeding and breeding. Amongst the aquatic animals, it is the fish life that would be most affected. The migratory fish species, like Mahseers and snow trouts, are likely to be adversely affected due to obstruction to be created by the proposed dams, the reports said.
The Subansiri Basin is rich in fish resources and other aquatic animals, like river dolphin (Platanista Gangetica), otter and therefore, there is a need to continuously maintain aquatic flow downstream of all proposed dams, so that there is no shortage of water at downstream of Lower Subansiri, where important fauna thrives because of continuous water flow in the Subansiri river, the report added.
KALYAN BAROOAH
NEW DELHI, October 9, 2015
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