London: Dams and irrigation considerably raise the global human consumption of freshwater by increasing evapotranspiration – an effect that increases the loss of freshwater to the atmosphere, thereby reducing the water available for humans, societies and ecosystems on land.
“Small things that we do on the surface of the Earth can have large global effects. Previously, the global effects of local human activities such as dams had been underestimated.
This study shows that, so far, the effects are even greater than those from atmospheric climate change,” said one of the researchers Fernando Jaramillo from Stockholm University in Sweden.
For the study, the researchers compiled and analysed data from 1901 to 2008 for climate, hydrology and water use in one hundred large hydrological basins spread over the world.
Their results raise the previous estimate of the global human freshwater footprint by almost 20 percent.
The increase in total freshwater loss from the landscape to the atmosphere from human activities is calculated to be around 4,370 cubic kilometres per year. This corresponds to two-thirds of the annual flow of the Amazon River, the world’s largest river by discharge, the study said.
“Our study shows that we have already passed a proposed planetary boundary for freshwater consumption. This is serious, regardless of whether we have crossed a real boundary or if the boundary has been underestimated,” Gia Destouni, the professor at Stockholm University, pointed out.
The golden mahseer of Bhutan is also known as ‘Tor putitora’
The Bhutan government is taking steps to conserve it by allocating hatcheries right besides the dams where these fishes are usually found
This doesn’t stop the Bhutanese government from building hydroelectric dams
One of the best known fish found in South Asian waters is the golden mahseer or ‘Tor putitora’. Growing to a length of nine feet and weighing up to 40kg, makes it one of the most sought-after gaming fish in the world. At one point, the fish was found along the whole Himalayan belt, from northern Pakistan to present-day Myanmar. It was also found in the waters of Iran and Thailand.
Unfortunately, environmental degradation and unrestricted fishing have had a catastrophic impact on its population. Today, it is listed on the International Union of Conservation of Nature’s Red List of threatened species. In India, the private company, Tata Power has spearheaded a campaign to breed and release fishes into the rivers. In Nepal, it continues to face severe challenges as laws go unenforced.
“The rivers of southern Bhutan are its greatest hope for survival, as long as action is taken soon to keep the threats to mahseer at bay” states a World Wildlife Fund report. The health of the big fish is also a measure of the health of the river ecosystems of Bhutan, which impact all the flora and fauna living in and around the water bodies.
For Bhutan, a Buddhist country, the golden mahseer has religious significance as well, as the fish is one of the eight auspicious signs associated with Buddhism as practised in the Himalayan region.
The challenge of dams
This iconic fish is found in the Punatsangchhu river, which runs for 320 km from its source in Bhutan to the point where it meets the Brahmaputra in India. Two major hydroelectric dam projects – Punatsangchhu-I and Punatsangchhu-II – are being built on the river.
“The golden mahseer migrates all the way from India to upstream rivers in Bhutan for breeding and feeding that since no proper scientific study had been conducted, there is no way of knowing how the dams will affect the fish. Nevertheless, since the fish have been sighted upstream in Punatsangchhu earlier, the dams may prevent the mahseer from migrating for spawning and feeding.” Singye Tshering, programme director at the National Centre for Riverine and Lake Fisheries told thethirdpole.net.
There is no official record kept of the fish in the area, but according to Kinley, who was posted by the Bhutanese government, 15 years ago to keep track of the iconic fish, the number has declined since the hydroelectric projects commenced.
Singye Tshering told thethirdpole.net “while this may not be an ideal mitigation measure, it is recommended especially for conditions found in Bhutan, where gorges, rugged terrain and swiftly flowing rivers mean that fish passages and fish ladders will not work to offset the blockages created by dam construction. He said fish migrating upstream for breeding are collected and bred artificially in the hatchery near the dam and later released back into the river. That way, we can ensure that the fish are able to breed and sustain their population.” Officials from National Centre for Riverine and Lake Fisheries and environment officials at the Punatsangchhu project identified alocation for a hatchery at Harrachu, a few kilometres away from Punatsangchhu-II, in November 2015. The golden mahseer hatchery project is being built at an estimated cost of $2.8 million.
The management plan includes the identification of spawning and feeding grounds and declaring them as sanctuaries as well as promoting and developing fish-based tourism to promote a sense of ownership among the people to protect fishery resources. With World Wildlife Fund funding, the ministry of forest and agriculture has started a scientific remote radio telemetry study on the golden mahseer to understand its habitat. The project also hopes to establish baseline data for the mahseer population and identify migration patterns. The study is underway in the Manas river basin covering the Mangdechhu and Dangmechhu rivers.
Taking steps to conserve mahseer, Bhutan continues to build hydroelectric dam which is the main source of their economy.