Construction of large dams always faced resistance and criticism from local people, environmentalists and social activists. On the other side, some economists, engineers, agronomists and development planners are in favor of large dams. There are valid arguments and explanations for both sides.
Effect on local people :-
The main argument for those who are protesting against large dams is the displacement of thousands of local people and the loss of their livelihoods. Koel-Karo project in Eastern India expected to destroy 200 tribal villages. Most of these displaced people are rural poor and belongs to Scheduled Tribes. They are expected to give up their land for anonymous beneficiaries. Their attachment to the land that they have nurtured all their lives is treated as insignificant. Most of these displaced people migrate to overcrowded urban areas in search of livelihood. Some of them stay at the construction site for temporary jobs and are forced to leave once the construction of dam is finished. Not all displaced people are given promised land. According to government estimates, only one fourth of the displaced people are rehabilitated.
Agronomists opine that large dams have the potential to save the country from critical food shortages. Large dams can increase the are under cultivation and improve irrigation facilities. However care should be taken by governments to ensure greater participation of local people in the projects. Benefits should also be spread to local people. Those who support large dams argue that rehabilitation is not done properly because of the delays of projects in turn caused by social activists.
Effect on Ecology :-
Moreover Large dams lead to permanent destruction of vast expanse of forests, wetlands and wildlife. In Chattisgarh, destruction of forests forced wild animals to enter into villages in search of food, killing several people in the incident. Loss of forest cover have many other consequences such as loss of migratory birds. Stopping the flow of rivers by dams will intercept the cycle of breeding in fishes. Other than that, restricting the river flow leads to the formation of heavy amounts of sediment in the reservoir. The downstream of river denied of its quota of water, affects the fertility of the soil. To reduce the pressure, reservoirs release water periodically. This further worsens the soil of river downstream, disturbing the ecosystem in that place.
Defenders of large dams argue that small dams take up large amount of land, sometimes more than the amount of land they irrigate. This results in heavy impact on ecology. Dams also save ground water from over-exploitation. Moreover large dams contribute to Eco-living by producing Hydel power, which is a cleanest and cheapest source of energy.
Effect on Economy :-
Critic of large dams construction of dams is absorbing huge financial investments. State is taking loans form world bank and from people by bonds. This huge investments are leading to less investments for the other development sectors like welfare schemes, education sector, health sector etc. Apart from the investment, environment loss worth crores of rupees is happening due to the construction of large dams.
Economists opine that small dams are uneconomic, because of low profit to cost ratio. Defenders of large dams argue that investments on dams is increasing because of the delays in the construction caused by the protests of social activists. Small dams cannot approach the scale of benefits of the larger dams.