Dams in India

Water is a renewable resource however much of it is not usable. Usable freshwater comes from rivers and groundwater which is replenished from surface run-off. Dams were invented to maximise the use of this usable water for human consumption and irrigation. They also helped in tackling both floods and droughts. India has a long history of dams one of the oldest dating 1st century BC in Sringaverapura near Allahabad to channelise the flood waters of Ganga. Later the Mauryan ruler Chandragupta made many dams and lakes. Famous manmade structures include the Bhopal Lake dated 11th Century and Hauz Khas by Iltutmish in 14th Century. During independence, Jawaharlal Nehru looked upon dams as the ‘temples of modern India’ due to their multipurpose role and they were the vehicles for development of the country. He hoped that they would boost development of agriculture with industrialization leading to integrated growth for rural and urban India.

Simply put, a dam is the reservoir which is constructed after redirecting or obstructing the flow of water. Dams have a spillway which allows release of water either regularly or intermittently. Dams have today become multipurpose projects used for drinking water, for irrigation, industrial and domestic use, flood control, electricity generation, recreation, fishing and inland navigation. E.g. the Bhakra Nangal Dam is used for hydropower and irrigation in Himachal Pradesh and the Sardar Sarovar Dam will supply water to drought prone desert areas of Gujarat.

• Based on Material Used: Timber dams, embankment dams or masonry dams
• Based on Height: Large or major dams, medium height dams and low dams.
• Based on Use: Storage, Detention or Diversion.

There are many disadvantages of multipurpose projects due to which there is rising resistance against them and alternatives like indigenous rain-water harvesting methods are being explored for their socio-economic and environmental viability.

• Sedimentation: Daming of rivers leads to poor sediment flow as most sediments get accumulated in the dam.
  • Affecting Soil Fertility: Flood plains are deprived of silt which is a natural fertilizer leading to land degradation.
  • Robs Nutrients from Flora & Fauna: This results in poor aquatic life in rivers
  • Causes Floods: due to sedimentation water overflows.
  
  
• Aquatic Ecosystem Disrupted: Dams fragment rivers leading to poor migration for reproduction in aquatic animals.
• Destruction to Ecosystem: Dams submerge large areas which slowly degrade under water.
• Rehabilitation & Loss of Livelihood: ‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’ are some examples of resistance from local communities which are displaced. While they are promised compensation, it sometimes doesn't arrive. It raises ethical questions of causing distress to minority in large interest of majority.
• Land Degradation
  • Water Irrigation has also changed the cropping pattern of many regions with farmers shifting to water intensive and commercial crops.
• Inter-State & Regional Conflicts:
  • States frequently fight over the costs of construction and share of resources from dam e.g. Karnataka and Tamil Nadu over the Mullaperiyar dam. The Interstate River Water Disputes Act, 1956 was enacted to tackle this issue.
  • Disputes within region like farmers in Sabarmati basin objected to diversion of river water to urban areas during a drought.
• Ineffective in Flood Control: During excess rainfall dams have aggravated the issue as release of water from dams causes flood in downstream areas e.g. in Maharashtra and Gujarat in 2006.
• Disaster: Induce earthquakes, cause water borne diseases and pollution resulting from excessive use of water
• Better Alternatives: Some argue that India has a history of indigenous water harvesting methods which are beneficial for local ecological conditions and their water needs. E.g.
  • Western Himalayas have irrigation channels like the ‘guls’ or ‘kuls’ through which water is diverted.
  • Water tankers are created out of fields in arid regions of Rajasthan like ‘khadins’ & ‘Johads’ which allow the water to moisten the soil
  • Meghalaya uses the locally available bamboo to create pipes which transfer water from streams to the fields.
  • Rooftop rainwater harvesting and storage in tankers is popular in Rajasthan and made compulsory in Tamil Nadu.

• Tehri Dam: in Uttarakhand on river Bhagirathi is the highest Dam of India (Height = 260.5 m)
• Indira Sagar Dam: in Madhya Pradesh on river Narmada is the largest dam in India (in terms of water storage)
• Nagarjuna Sagar Dam: in Telangana on river Krishna is the second largest dam in India and the highest masonry dam in the world.
• Bhakra Nangal Dam: At the Himachal Pradesh & Punjab border on river Sutlej is the second highest dam in India after Tehri Dam(226m). It creates the Gobind Sagar reservoir which is the third largest reservoir in India. It is the second largest concrete dam in the world.
• Hirakud Dam: in Odisha on the river Mahanadi is the longest dam in India (Length = 25.79 km). It is the longest earthen dam of the world.
• Kallanai Dam: in Tamil Nadu on river Kaveri is the oldest dam of India (Built in 2nd CE by King Karikala Chola of the Chola Dynasty)
• Gayaji Dam: in Bihar on river Falgu is the longest rubber dam in India

Dam Failure: Despite their monumental benefits, dams also carry inherent risks, and dam failures can have catastrophic consequences.

• Causes of such failures: Natural calamities like earthquakes, excessive rainfall, or sedimentation can strain dam structures, compromising their integrity. Design flaws or structural deficiencies can lead to breaches, while poor maintenance or inadequate surveillance can heighten the risk.
• Tackling Dam Failure: Robust maintenance practices, regular inspections, and adherence to stringent safety protocols are indispensable in averting catastrophic failures.
• Dam Safety Act, 2021: was passed to provide a system for surveillance, inspection, operation, and maintenance of dams across the country. It provides following:-
  • The National Committee on Dam Safety (NCDS) to evolve uniform dam safety policies, protocols, and procedures.
  • The National Dam Safety Authority (NDSA) to implement the policies and resolve State disputes.
  • The State Dam Safety Organisations (SDSOs) for surveillance, inspection and day to day oversight of dams.
  • The State Committee on Dam Safety oversees state-level dam rehabilitation programs, reviews the activities of the SDSO, and monitors the progress of measures recommended to ensure dam safety, among its various functions.
  • Dam Owners to conduct inspection and prepare an emergency action plan
  • Penalties both monetary and jail term provided for non-implementation.

In India, dams and multipurpose projects have played a crucial role in meeting various developmental needs, including irrigation, power generation, and water supply. However, their future is increasingly being scrutinized due to environmental, social, and economic concerns. Environmentalists argue that large-scale dam construction disrupts ecosystems, alters river courses, and can lead to adverse ecological consequences. Additionally, displacement of local communities and the associated socio-economic challenges have raised ethical questions about the viability of such projects.

Indian government have thorough Environmental Impact Assessment, 2020 procedures to check the viability of a dam to ensure sustainable development. Stakeholder consultation has become a part of this process also. Further, emergency action plans are mandated under the Dam Secutiy Act, 2021. Future lies in embracing innovative technologies to improve efficiency of these multipurpose projects and embrarcing indigenous water storage methods.