Big dams benefits and problem
Introduction: Big dams are plain bad. They flood people out of their homes and off their lands; wipe out endangered habitats and species; spread water-borne diseases; deprive flood plains of the water and sediments of life-giving floods (while increasing the damage floods cause to people); ruin beautiful landscapes and submerge places of great cultural or spiritual importance. And that’s just a partial charge sheet.
Big dams even cause earthquakes (because of the weight of water in reservoirs), release greenhouse gases (because of the rotting of flooded vegetation), destroy marine fisheries (because they disrupt river-borne flows of freshwater and nutrients into oceans) and lead to coastal erosion (because the sediments that eventually fill reservoirs would previously have flowed out through estuaries and then been washed back by waves to protect the shoreline). Occasionally, they collapse and drown people. In the world’s worst dam disaster – a mega-catastrophe that struck central China in 1975 when two large dams burst – as many as 230,000 people died.
- River valley projects with big dams play a key role in the development process due to their multiple uses.
- These dams aim at providing employment for tribal people and raising the standard and quality of life.
- Dams can help in checking floods and generate electricity and reduce water and power shortage, provide irrigation water to lower areas, provide drinking water in remote areas and promote navigation, fishery.
Problems: The impacts of big dams can be upstream as well as downstream levels. The upstream problems include the following.
- Displacement of tribal people
- Loss of forests, flora and fauna
- Changes in fisheries
- Saltation and sedimentation of reservoirs
- Loss of non-forest land
- Stagnation and water logging near reservoir
- Breeding vectors and spread of vector –borne diseases
- Reservoir induces seismicity causing earthquakes
- Microclimatic changes
- Growth of aquatic weeds.
Downstream problems include the following:
- Water logging and salinity due to over irrigation
- Microclimatic changes
- Reduced water flow and slit deposition in river
- Flash foods
- Salt water intrusion at river mouth
- Loss of land fertility
- Outbreak of vector-borne diseases like malaria.
DAMS AND THEIR EFFECTS ON FORESTS AND PEOPLE: Big dams and rivers valley projects have multi-purpose uses and PanditJawaharlal Nehru used to refer to these dams and valley projects as “Temples of modern India”. However, these dams are also responsible for the destruction of vast areas of forests. India has more than 1550 large dams, the maximum being in the state of Maharashtra (more than 600), followed by Gujarat (more than 250)and Madhya Pradesh (130). The highest one is Tehri dam, on river Bhagirathi inUttaranchal and the largest in terms of capacity is Bhakra dam on river Satluj in Himachal Pradesh. Big dams have been in sharp focus of various environmental groups all over the world which is mainly because of several ecological problems including deforestation and socio-economic problems related to tribal or native people associated with them. The Silent valley hydroelectric project was one of the first such projects situated in the tropical rain forest area of Western Ghats which attracted much concern of the people. The crusade against the ecological damage and deforestation caused due to Tehri dam was led by Shri. Sunder lal Bahaguna, the leader of Chipko Movement. The cause of Sardar Sarovar Dam related issues have been taken up by the environmental activist Medha Patkar, joined by Arundhati Ray and Baba Amte. For building big dams, large scale devastation of forests takes place which breaks the natural ecological balance of the region. Floods, droughts and landslides become more prevalent in such areas. Forests are the repositories of invaluable gifts of nature in the form of biodiversity and by destroying them (particularly, the tropical rain forests) .