The Problem of Ageing Dams

Context: India’s ageing dams can threaten water security, affect farmers’ income, and increase flooding.

Issues with dams in India:

• Aging and replacement of dam water by silt or sediments: India is ranked third in the world in terms of building large dams.
  • Of the over 5,200 large dams built so far, about 1,100 large dams have already reached 50 years of age and some are older than 120 years.
  • By 2050, 80% of the nation’s large dams face the prospect of becoming obsolete as they will be 50 years to over 150 years old.
• Flawed design: underestimated the rate of siltation and overestimated live storage capacity.
  • High siltation rate: like in Bhakra dam, it is 139.86% higher than originally assumed.
  • Similarly, the actual siltation rate observed for the Hirakud, Maithan, and Ghod dams is higher at 141.67%, 808.64%, and 426.59%, respectively.

Associated consequences:

• On cropping in the area: with siltation, supply gets chocked resulting in
  • Reduced availability of water.
  • Reduced net sown water area or increases exploitation of already stressed groundwater.
  • Affects crop yield and disrupting farmer's income.
  • Affecting adaption plan to counter climate change.
• Increase frequency of floods downstream of dams: due to early depletion of designed flood cushion within several reservoirs.
  • For example: The flooding of Bharuch in 2020, Kerala in 2018 and Chennai in 2015 are attributed to downstream releases from reservoirs

Conclusion: All stakeholders must come together to address this situation in order to meet the demand for water in the 21^st century to feed the rising population, grow abundant crops, create sustainable cities, and ensure growth.