It’s Time To Let Our Rivers Flow Freely Again

The undeniable evidence now being documented about the adverse effects of dams has led to a strong movement in most of the developed world for the decommissioning of dams and allowing the free flow of rivers in their natural state.

Decommissioning Dams And Re-Wilding The Rivers

There is a quiet revolution taking place in the world, but as is usual with most good things, it is passing India by. This movement, about fifteen years old but gathering momentum, is variously known as Re-wilding of Rivers or as Dams Decommissioning. Its premise is that dams belonged to a different era of environmental ignorance and now, with climate change and global warming our primary concerns, they need to go. Technology too has made them largely obsolete.

Dams, especially large ones, have provided benefits in terms of irrigation, power and flood control. But their downsides have also become evident over the years: the constant threat to downstream populations, adverse effect on fish spawning and migration, design flaws resulting in dam failures and flooding, release of huge quantities of methane from the reservoirs, displacement of populations, damage to biodiversity and river eco-systems. The most pernicious, however, has been the obstruction of the natural flow of rivers. Rivers are the arteries of a country, carrying water and nutrients to large areas, and their obstruction upsets the rhythms of nature. Today there are hardly any free flowing rivers left in the world.

One of the most adverse effects of dams is the obstruction to the natural flow of sediments carried by rivers. This cyclic sedimentation has nurtured civilisations for centuries along the rivers- the Nile, Ganges, Euphrates, Mississippi, the Congo, Brahmaputra and so on. It has created vast and fertile deltas where cities have flourished. But with most rivers now being subjected to multiple dams, the silt load has diminished with alarming consequences in some cases.

An example is the mighty Sunderbans, sprawling over 10000 sq. kms, the largest continuous mangrove forest in the world. Most of us aware that it is now threatened by global warming and rising sea levels. But what we don’t know is that its land mass is being slowly declining because of reduced sedimentation by the Ganges, the result of the hundreds of large dams on this river . A path breaking research paper, based on satellite data, by Faiz Rehman (Indiana University) and Basil El Masry (Murray State Univ.) shows that the accretion of sediments in the Sunderbans has declined from 10 sq. km per year between 1973 and 1989 to 4 sq. km per year between 1989 to 2010. Their studies reveal that it has lost 170 sq. km. of land in the last 37 years. A similar fear about erosion of the Nile delta is one of the reasons why Egypt is opposing the new dam built by Ethiopia on the Blue Nile.

Dam removal: the Marmot Dam on the Sandy River in Oregon (USA) was demolished in 2007 using dynamite (Photo: Wikipedia)

The undeniable evidence now being documented about the adverse effects of dams has led to a strong movement in most of the developed world for the decommissioning of dams and allowing the free flow of rivers in their natural state. The scientific view now is that dams should be dismantled / decommissioned when they pose a safety risk, no longer serve their intended purpose, or no longer meet the current social/ environmental/ economic values. For example, with renewable energy (like solar or wind power) expanding and becoming cheaper every year, the need for hydel power may no longer be so vital or pressing.

It has been estimated that dams have caused a 90% decline in migratory fish like salmon, herring and eels, and an 80% decline of fresh water fish (the Gangetic dolphin and our own Mahaseer are prime examples), by blocking their spawning routes. Safety of downstream populations from floods can also be illusory: as reservoirs silt up fast the flood cushion supposed to be provided by dams is also reduced, forcing the dam management to release huge volumes of flood waters, causing devastation downstream. This happened in Chennai in 2015 and in Kerala in 2018- in fact, this has become almost an annual ritual in Kerala. The Rishi-Ganga disaster in Uttarakhand a couple of years back is exclusively attributable to the dam on this river.

This realisation is most visible in the United States and Europe., where planners are working with agencies like WWF, World Fish Migration Foundation, Wetlands International and the Nature Conservancy to decommission dams and river barriers. The USA has 90000 dams and Europe has 150000 barriers on its rivers. 1700 dams have been removed by the USA so far, and 600 have been dismantled in Europe: the latter’s target is to restore 25000 kms of free flowing rivers by 2030.

In contrast, India is doing just the opposite- we are still on a dam building spree, even though all data points to a rethink on the subject. The country has 5202 large dams, of which 1100 have completed 50 years of their life, with some being older than 120 years, well past their safe life. By 2050 as many as 4400 dams will have completed 50 years and 80% will have become obsolete. But we continue to build more dams on an unprecedented scale: 90 large dams have been constructed in the last 10 years alone, and 411 dams are under construction at the moment.

The worst effected are the Himalayan states, which have the highest dam density in the world: 600 dams have been constructed, are under construction or are planned in this highly seismic region. But governments, both central and states, are yet to consider a decommissioning policy. The union government has passed a Dam Safety Bill in 2019 and in 2020 has notified a Dam Rehabilitation and Improvement Project (DRIP). But these are only intended to extend the life of existing dams and fall far short of the global trend of restoring rivers to their free flowing status.

Not only this, the central government is actually encouraging the construction of more dams by treating hydel projects as a renewable energy source, in order to meet its ambitious renewable energy targets. In 2019 it has reclassified dams above 25 MW as an RE source and has extended the debt repayment period to 18 years, apart from offering other incentives to project developers. This kind of tunnel vision and subterfuge ignores all environmental, safety and economic evidence to the contrary.

With the exponential fall in solar power tariffs and increasing time and cost overruns in hydel projects, dams are becoming uneconomic. A typical, and instructive, example is the controversial Etalin HEP (3097 MW) in Arunachal Pradesh which has been on the drawing board for more than 15 years ! It has been estimated that power from this project, when completed, will cost between Rs. 8.00 and Rs. 9.00 per unit, whereas solar power tariff is currently between Rs. 2.00 and Rs. 3.00 per unit. Himachal Pradesh provides another example of the fact that hydel projects have outlived their utility but our policy makers will not accept the hard figures: just last month the HP govt. cancelled 26 projects and provided extension to another 191 to complete formalities. Most of these are likely to become stranded projects like Etalin.`

The sooner Indian policy makers accept the inevitability of the environmental, safety and economic logic of discontinuing with dams and allowing rivers to flow freely again, the better it shall be for our ecology, health and downstream populations. It is high time to put in place a selective dam decommissioning policy and emerge from the comfort zone of contractors, tenders, and outdated and tired thinking. The planet is changing fast and so should our policy prescriptions.

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