Reservoirs and global warming
The nation's first Prime Minister Jawaharlal Nehru was a staunch advocate of rapid industrialisation and national development, which underpin economic growth and surplus. He once said that dams are the temples of modern India and that big dams would address India’s hunger and poverty. History has proved him right to a major extent.
On the joint venture of the Punjab, Haryana and Rajasthan states, designed to harness the precious water of the Sutlej, Nehru observed: “Bhakra Nangal Project is something tremendous, something stupendous, something which shakes … Bhakra today is the symbol of India’s progress… This dam has been built with the unrelenting toil of man for the benefit of mankind and therefore is worthy of worship.
May you call it a temple or a gurdwara or a mosque, it inspires our admiration and reverence". It was no hyperbole. For, the project comprises: (i) two dams at Bhakra and Nangal, (ii) Nangal Hydel Channel, (iii) power houses with a combined installed capacity of 1,204 megawatt (MW), (iv) Electric transmission lines and (v) Bhakra canal system for irrigation. The dam has created a huge reservoir of water which is 88 km long and 8 km wide with a storage capacity of 986.8 crore cubic metres.
This reservoir is named as Gobindsagar Lake after Guru Gobind Singh, the 10th guru of the Sikh community. Be that as it may, scientists have now found that reservoirs also contribute to global warming. According to a new study conducted by researchers from Washington University, reservoirs are huge contributors in the generation of global warming. The study noted that reservoirs produce the equivalent of about one gigatonne of carbon dioxide a year or 1.3% of all greenhouse gases produced by humans.
They are a particularly significant source of methane-- a greenhouse gas that is 34 times more potent than carbon dioxide over the course of a century. Reservoir methane production is comparable to rice paddies or biomass burning, both of which are included in emission estimates of the Intergovernmental Panel on Climate Change. "We had a sense that methane might be pretty important, but we were surprised that it was as important as it was," said Bridget Deemer, WSU research associate and lead author.
"It is contributing right around 80% of the total global warming impact of all those gases from reservoirs. It is a pretty important piece of the budget," observed Deemer. The researchers acknowledge that reservoirs provide important services like electrical power, flood control, navigation and water. However, reservoirs have also altered the dynamics of river ecosystems, impacting fish and other life forms.
Only lately have researchers started to look at reservoirs’ impact on greenhouse gases. Unlike natural water bodies, reservoirs tend to have flooded large amounts of organic matter that produce carbon dioxide, methane and nitrous oxide as they decompose. The research was published in the journal BioScience.