The Problem of Ageing Dams

The Hindu     1st February 2021     Save    

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 21st century to feed the rising population, grow abundant crops, create sustainable cities, and ensure growth.