Geography

Disadvantages of Multipurpose Project
1. High Cost : The initial cost of building the dams is very high. It requires a lot of capital and engineering skills and modern machinery which is not available in India.
2. Adverse Impact on Environment : A vast variety of flora and fauna as well as human settlements get submerged in the water of reservoir formed by the dam.
3. Adverse effect on the fertility of the soil : Due to construction of dams there are no annual floods in the river. And because of this the soil of the down stream region does not get nutrient rich “silt”. This decreases the fertility of the soil.
4. Adverse Impact on aquatic life : Due to construction of dam on the river, the fish in the down stream area do not get sufficient nutrient material.
5. Non-availability of water throughout the year : Most of the rivers in India flow only for few months. So water is not sufficient to build a dam.
6. Disputes between different states : States have disputes over sharing of water, height of the dam and so on.
7. Displacement of local communities : The local people often have to give up their land and livelihood and their meagre access and control over resources for the greater food for the Nation.
8. Change in cropping pattern : They provide assured means of irrigation to farmers. Due to this most of the farmers have changed the cropping pattern shifting to water intensive and commercial crops. This has led to salinisation of soil leading to ecological imbalance.
9. (i) Regulating and damming of rivers affect their natural flow causing poor sediment flow and excessive sedimentation at the bottom of the reservoir, resulting in rockier stream beds and poorer habitats for the rivers aquatic life.
(ii) Dams also fragment rivers making it difficult for aquatic fauna to migrate, especially for spawning. The reservoirs that are created on the floodplains also submerge the existing vegetation and soil leading to its decomposition over a period of time.