. Recently, a UN University report titled “Ageing water infrastructure: An emerging global risk”, held that by 2050, most people on Earth would live downstream of tens of thousands of large dams built in the 20th century, many of them including India’s already operating at or beyond their design life, putting lives and property at risk.
Ageing signs of dams include increasing cases of dam failures, progressively increasing costs of dam repair and maintenance, increasing reservoir sedimentation, and loss of a dam ’s functionality and effectiveness.
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.
Moreover, hundreds of thousands of medium and minor dams are even more precarious as their shelf life is even lower than large dams. India’s aging dams can threaten water security, affect farmers’ income, and increase flooding. Thus, there is an urgent need to tackle this crisis.
Issues Related to Ageing Dam
¾ Faster Rate of Storage Loss
As dams age, soil replaces the water in the reservoirs. Therefore, the storage capacity cannot be claimed to be the same as in the 1900s and 1950s.
Impact of Climate Change
The rising frequency and severity of flooding and other extreme environmental events can overwhelm a dam’s design limits and accelerate a dam’s ageing process.
Consequences of Ageing Dams
Impacting Food Security
When soil replaces the water in reservoirs, supply gets choked. In this case, the cropped area may begin receiving less and less water as time progresses.
The flawed siltation rates reinforce the argument that the designed flood cushion within several reservoirs across many river basins may have already depleted substantially, due to which floods have become more frequent downstream of dams.