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DAM AND IT’S IMPACT

Recently Narmada Control Authority (NCA) has cleared the final raising of Sardar Sarovar Dam (SSD) in Gujarat. This has raised concerns that Raising the Sardar Sarovar dam to its full height will result in more large-scale submergence of habitations. Once the dam is at its full height, it will submerge one town and at least 176 villages, displace close to 20,000 families, flood productive agricultural land, and destroy hundreds of acres of biodiverse forest.

In this context we shall look at benefits and its cost including environmental and at society level. In particular we shall look at issues related to Sardar sarovar dam.

Pros and cons of a Multi-purpose river Project

Dams provide a range of economic, environmental, and social benefits, including recreation, flood control, water supply, hydroelectric power, waste management, river navigation, and wildlife habitat.

  • Flood Control - In addition to helping farmers, dams help prevent the loss of life and property caused by flooding. Flood control dams impound floodwaters and then either release them under control to the river below the dam or store or divert the water for other uses. For centuries, people have built dams to help control devastating floods.
  • Water Storage (Fire & Farm Ponds) - Dams create reservoirs that supply water for many uses, including industrial, municipal, and agricultural.
  • Irrigation – Agriculture land is irrigated using water stored behind dams.
  • Electrical Generation – Dam provide Clean, efficient, and reliable form of energy. India's economically exploitable and viable hydroelectric potential is estimated to be 148,701 MW. An additional 6,780 MW from smaller hydro schemes (with capacities of less than 25 MW) is estimated as exploitable. India is the 7th largest producer of hydroelectric power in the world. As of 30 April 2017, India's installed utility-scale hydroelectric capacity was 44,594 MW
  • Navigation - Dams and locks provide for a stable system of inland river transportation throughout the heartland of the Nation.
  • Recreation - Dams provide prime recreational facilities. Boating, skiing, camping, picnic areas and boat launch facilities are all supported by dams.

Dams are built worldwide to store water for irrigation, flood control, and to generate electricity. However, there are some negative environmental effects of building large hydroelectric dams. These affects are as follow:

  • Siltation Issue - Apart from directly reducing water storage capacity, siltation also decreases water capacity due to increased evaporation loss. As a result, the capacity to generate hydropower is affected. A dam choked with silt creates a river prone to risky situations of potential flooding in the backwaters.

Siltation of dam reservoir - All rivers contain sediments: a river, in effect, can be considered a body of flowing sediments as much as one of flowing water. When a river is stilled behind a dam, the sediments it contains sink to the bottom of the reservoir. As the sediments accumulate in the reservoir, so the dam gradually loses its ability to store water for the purposes for which it was built.

  • Rehabilitation issue - Compensation to the displaced, when given, has often come in the form of land unsuitable for farming or living, located either on riverbed at the risk of flooding, or in rocky areas which cannot be ploughed. Resettlement sites lack basic facilities: no wells, drinking water pipelines, or grazing land for cattle, let alone schools or road facilities.
  • Bio-diversity challenge - Once the dam is constructed flow of water is reduced in the river. This creates challenge for habitat and biodiversity on downstream course of the river. The Narmada valley is biodiversity rich. The dams along the Narmada have changed this, blocking normal water flow, leading to downstream habitat change and impacting biodiversity. The Narmada estuary, where the river meets the sea, has become increasingly saline because of the decrease in fresh water flow after the dams came up. This imposes a cost on society which is not properly reflected in environment impact assessment report because it is difficult to calculate true cost of damage.
  • Other effects - Dams serve as a heat sink, and the water is hotter than the normal river water. This warm water when released into the river downstream can affect ecosystem; Dams restrict sediments that are responsible for the fertile lands downstream. Farmers use chemical fertilizers and pesticides to compensate for the loss in productivity.

Sardar Sarovar dam Issue

The Sardar Sarovar Dam is a gravity dam on the Narmada river near Navagam, Gujarat in India. It is a part of the Narmada Valley Project. One of the 30 dams planned on river Narmada, Sardar Sarovar Dam (SSD) is the largest structure to be built. Following a number of controversial cases before the Supreme Court of India (1999, 2000, 2003), by 2014 the Narmada Control Authority had approved a series of changes in the final height. The recent decision to increase height has been taken in June, 2017. The project will irrigate more than 18,000 km2 (6,900 sq mi), most of it in drought prone areas of Kutch and Saurashtra. The total installed capacity of the power facilities is 1,450 MW.

The argument in favour of the Sardar Sarovar Project is that the benefits are so large that they substantially outweigh the costs of the immediate human and environmental disruption. The project has the potential to feed as many as 20 million people, provide domestic and industrial water for about 30 million, provide valuable peak electric power in an area with high unmet power demand. It will also provide flood protection to riverine reaches. However, the dam is one of India's most controversial, and its environmental impact and net costs and benefits are widely debated.

Conclusion

The benefits of a dam are easy to monetize as most of the benefits have a market to serve which help in correctly valuing the value of services it provide. For ex – Electricity produced by dam has per unit cost which is decided by dynamics of demand and supply of electricity. This helps in exactly determining benefits of a dam project in terms of electricity produced and revenue generated. However, in case of cost it is difficult to estimate as it is difficult to value true cost of environment degradation or cost of rehabilitation. So it is highly important to improve economic techniques of valuing costs of a dam so that true value is known and policymakers can correctly access net benefit before undertaking a project.

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