In the unfolding debate over the deadly effects of the great torrent of Uttarakhand, the construction of dams in an earthquake-prone area of fragile, deforested mountain sides is hotly contested. And so it should.
There are 45 hydropower projects in Uttarakhand, according to Uttarakhand Jal Vidyut Nigam (UJVN), a state government company. If that sounds like a lot in a state only just larger than Punjab, consider that unlike richer states, such as Punjab, Uttarakhand—carved out of Uttar Pradesh 13 years ago—hopes its bountiful rivers and steep mountain sides can meet not just its needs but generate a surplus that it can sell to its chronically power-starved neighbours, even distant Delhi. So, more than 230 hydel projects, from micro to mega, 0.2 MW to 376 MW, are under development, according to UJVN (Right to Information queries over the last three years put the figure at more than 500).
This would seem like a good idea. Hydel power is considered clean and planet friendly, a good way to reduce carbon emissions in an age of global warming and produce more electricity in a country desperately short of it. Urja Pradesh, land of electricity, is a moniker that the state government likes to bandy about to prospective investors.
The flipside of hydel power, particularly large and medium dams, is the disruptive impact they can have on forests and wildlife. In addition, there is growing awareness that while large dams drastically cut carbon emissions, they can just as drastically increase methane, another so-called greenhouse gas that heats up the planet. “If a large amount of vegetation is growing along the riverbed when a dam is built, it can decay in the lake that is created, causing the buildup and release of methane,” says the US Environmental Protection Agency on its website.
A solution to such devastation, it was thought, is to make small run-of-the-river dams with far smaller environmental footprints. Now, a study in the journal Water Resources Research says this is a flawed assumption. The construction of small dams may reduce greenhouse-gases, but it can cause unforeseen habitat and biodiversity loss, cumulatively 100 times larger, per MW, than a big dam in some cases. “The preference of small to large dams assumes, without justification, that small hydropower dams entail fewer and less severe environmental and social externalities than large hydropower dams,” says an abstract of the study, published online last week.
The study of 31 small dams running on the Chinese stretch of the Nu river is one of the most comprehensive of its kind. Researchers from the Oregon State University (OSU) spent five years studying the Nu river, which flows from to Myanmar and Thailand from China. The Nu river basin is considered one of the most ecologically fragile and diverse places in the world. The findings could be equally applicable to other countries, such as India. “Results reveal that biophysical impacts of small hydropower may exceed those of large hydropower, particularly with regard to habitat and hydrologic change,” the study said.
“The result can be profound…there is damage to streams, fisheries, wildlife, threatened species and communities,” Desiree Tullos, an OSU associate professor and water resources engineer was cited as saying in a university release. “The energy may be renewable, but this research raises serious questions about whether or not the overall process is sustainable.”
Does this mean we should focus on large dams instead? Not really, especially not in Uttarakhand, where large dams could destabilize a land that is already geologically unstable. This instability emerges from the shifting nature of the Himalayas, which continue to grow as they grind against the Asian landmass.
Obviously, stripping the slopes of forests, which bind the soil and stabilize slopes, does not help. Over the last five years, Uttarakhand has seen a particular rush of deforestation and unregulated construction on river banks and hill slopes.
The combined effect of dams and development has been to unsettle one of India’s most delicate areas. Yet, it would be premature to say the tragedy in Uttarakhand was “man-made”, as many television channels and commentators insist. Even if building codes—if indeed they exist—were followed, the slopes were not damned and the valleys not dammed, the cloudburst over Uttarakhand was so extraordinary that floods were inevitable. There was similar devastating inundation in parts of Canada and Germany. What could have been mitigated were the effects of the Uttarakhand floods. Certainly so many people need not have died and so many buildings need not have been washed away.
Uttarakhand’s development choices, most of which centre around its water resources, are limited. Big dams will generate lots of electricity but devastate forests and at a time of extreme weather and climate change, they are prone to disasters (days ago, two large dams were filled to 500% over capacity). As for small dams, India clearly needs to study them more closely than ever.
Samar Halarnkar is a Bangalore-based journalist. This is a fortnightly column that explores the cutting edge of science and technology. Comments are welcome at firstname.lastname@example.org. To read Samar Halarnkar’s previous columns, go to www.livemint.com/frontiermail