Big dams are often regarded as a symbol of national development. However, there are several other issues and problems related to these.
River valley projects with big dams have usually been considered to play a key role in the development process due to their multiple uses. India has the distinction of having the largest number of river – valley projects. The tribals living in the area pin big hopes on these projects as they aim at providing employment and raising the standard and quality of life. The dams have tremendous potential for economic upliftment and growth. They can help in checking floods and famines, generate electricity and educe water and power shortage, provide irrigation water to lower areas, provide drinking water in remote areas and promote navigation, fishery etc.
ENVIRONMENTAL PROBLEMS :
The environmental impacts of big dams are also too many due to which very often the big dams become a subject of controversy. The impacts can be at the 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 and the spawning grounds
- Siltation and sedimentation of reservoirs
- Loss of non forest land
- Stagnation and waterlogging near reservoir
- Breeding of vectors and spread of water borne diseases
- RIS causing earthquakes
- Growth of aquatic weeds
The downstream impacts include the following :
- Water logging and salinity due to over irrigation
- Micro-climatic changes
- Reduced water flow and slit deposition in river
- Flash floods
- Salt water intrusion at river mouth
- Loss of land fertility along the river since the sediments carrying nutrients get deposited in the reservoir
- Outbreak of vector – borne diseases like malaria
Thus, although the dams are built to serve the society with multiple uses, but it has several serious side effects. That is why, now there is a a shift towards construction of small dams or mini-hydel projects.