Backgrounders

The Northeast is blessed with the highest hydro power potential in the country on account of the mighty Brahmaputra and its immumerous tributaries. This power potential is estimated to be about 48000 MW. Although this constitutes as much as 30 per cent of the total reserves of India, less than even 3 per cent of this has so far been harnessed. Besides, there are considerable thermal power potentials. Given below are the statewise and basinwise summary of the study on proposed hydel projects in the Brahmaputra river system conducted by The Ecologist Asia. BASIN/STATE

This is an indicative list of some major projects commissioned, under construction and proposed to come up in this region. Many of the proposed projects indicated here are in an advanced stage of planning and clearance. Pakke (NEEPCO): 105 MW, proposed in the Preliminary CEA ranking. Preliminary survey being carried out. Reported to cause submergence within Pakke Wildlife Sanctuary. Kolodyne (NEEPCO): 120 MW, proposed in the Preliminary CEA ranking. Kaldan: 545 MW, proposed in the Preliminary CEA ranking. Emra II: 870 MW, proposed in the Preliminary CEA ranking.

The issue of dams is intrinsically contentious. The Frequently Asked Questions (FAQs) section here settles many of the points that are used by dam proponents to disinform and misinform people. Q. What is a large dam? How many large dams are there? A: A large dam is defined by the dam industry as one higher than 15 metres (taller than a four-story building). There are more than 40,000 large dams worldwide. There are more than 300 major dams - giants which meet one of a number of criteria on height (at least 150 metres), dam volume and reservoir volume. Q: Which countries have the most large dams?

The World Commission on Dams has proposed a new approach to decision-making based on recognising the rights of, and assessing the risks to, all stakeholders. This means that all stakeholders whose rights might be affected, and all stakeholders who have risks imposed upon them involuntarily, should be included in decision-making on development. The WCD believes that this approach "offers an effective way to determine who has a legitimate place at the negotiation table and what issues need to be included on the agenda." The WCD developed seven strategic priorities for this new approach to development. Effective implementation of these strategic priorities depends on applying the respective policy principles.

Freshwater is an essential natural resource on which all humans depend. Dams have been used for thousands of years to regulate river flows and ensure adequate supply of water during dry periods. In the future, as populations increase and water consumption rises many people believe there will be a need for more dams. However, in recent years proposals for new dams have, in many places, aroused intense opposition. There are many social and economic arguments used against dams, but underpinning many of these arguments is the fact that dams, particularly large dams, produce major ecological changes in river ecosystems.

Land and water are ecologically linked in a natural system called a watershed. From the smallest droplet to the mightiest river, water works to shape the land, taking with it sediment and dissolved materials that drain to watercourses and, in most cases, eventually to the sea. So, too, is the river a product of the land it inhabits--the type of rock and soil, the shape of the land, and the amount of vegetation are some of the factors that determine the river's shape, size and flow.

Farmers in the foothills of the Zagros mountains on the eastern edge of Mesopotamia may have been the first dam builders. Eight thousand-year-old irrigation canals have been found in the area and it is not unlikely that small weirs of brushwood and earth were used to divert water from streams into the canals. By 6,500 years ago the Sumerians were criss-crossing the plains along the lower Tigris and Euphrates with networks of irrigation canals. Again no physical evidence of dams has been found from this period but it is likely that they were used to control flows of irrigation water.

Dams have two main functions. The first is to store water to compensate for fluctuations in river flow or in demand for water and energy. The second to raise the level of the water upstream to enable water to be diverted into a canal or to increase 'hydraulic head' -- the difference in height between the surface of a reservoir and the river downstream. The creation of storage and head allow dams to generate electricity (hydropower provides nearly a fifth of the world's electricity); to supply water for agriculture, industries and households; to control flooding; and to assist river navigation by providing regular flows and drowning rapids. Other reasons for building large dams include reservoir fisheries and leisure activities such as boating.