Some planning needed
Today the world is claiming fresh technologic breakthroughs every now and then, but at the same time a brazen violation is happening as the infrastructure that has been build years back is being ignored with no idea about how disastrous it can prove if something bad happens.
A United Nations report which has been made public few months back has pointed out to such brazen neglect as the report claims that by 2050, most people on Earth will live downstream of tens of thousands of large dams built in the 20th century, many of them already operating at or beyond their design life.
The analysis includes dam decommissioning or ageing case studies from the USA, France, Canada, India, Japan, Zambia and Zimbabwe. The concern gets worse as over a thousand large dams in India will be roughly 50 years old in 2025 and such aging structures across the world pose a growing threat.
The report, titled ‘Ageing water infrastructure: An emerging global risk’ and compiled by United Nations University’s Canadian-based Institute for Water, Environment and Health, says most of the 58,700 large dams worldwide were constructed between 1930 and 1970 with a design life of 50 to 100 years.
This simply means that at 50 years, a large concrete dam would most probably begin to express signs of ageing and this stands true for all the nations which have an increasing number of dams that are now becoming more vulnerable and prone to damages.
Ageing signs 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.
According to the report, the world is unlikely to witness another large dam-building revolution as in the mid-20th century, but dams constructed then will inevitably be showing their age.
Interestingly, 32,716 large dams (55 per cent of the world’s total) are found in just four Asian countries: China, India, Japan, and South Korea – a majority of which will reach the 50-year threshold relatively soon.
The same is true of many large dams in Africa, South America, and Eastern Europe. However, in India, there are over 1,115 large dams that will be roughly 50 years old in 2025, more than 4,250 large dams in the country will be over 50 years old in 2050 and 64 large dams will be more than 150 years old in 2050.
It needs no imagination to picture a disaster in case majority of these dams fail or show signs of ageing that may require immediate replacement or even creation of alternatives.
Worldwide, the huge volume of water stored behind large dams is estimated at 7,000 to 8,300 cubic kilometres – enough to cover about 80 per cent of Canada’s landmass under a meter of water.
Ironically, the pace of large dam construction has dropped dramatically in the last four decades and continues to decline in part because the best locations for such dams globally have been progressively diminishing as nearly 50 per cent of global river volume is already fragmented or regulated by dams. This scenario calls for paying immediate attention towards dams that have been constructed years back and have almost lived their utility.