Troubled waters as dam builders threaten world rivers

LAST DAYS OF THE MIGHTY MEKONG Brian Eyler UNRULY WATERS: How Rains, Rivers, Coasts and Seas Have Shaped Asia’s History Sunil Amrith

We will hear more about rivers in the years ahead. Almost all the waterways on which our civilisations were built are under threat in the Anthropocene era, from the Nile and the Euphrates to the Ganges, the Yangtze and the Murray-Darling.

The main villains in Brian Eyler’s lament for southeast Asia’s most important river, Last

Days of the Mighty Mekong, are not industrial polluters or the fossil-fuel producers that have contributed to climate change and glacier-melt on the Tibetan plateau but the hydroelectric dam builders of China and Laos.

Eyler, director of the southeast Asia programme at the Stimson Center in Washington, concludes that ecologically and commercially hydropower is fast becoming an “obsolete technology”.

Eyler’s wanderings down the Mekong and his encounters with those who live on and from the river leave no doubt that the dams interfere with the vast fish migrations that supply Cambodians with most of their protein. Cambodia’s Tonle Sap lake, fed for the past five millennia by a reversible Mekong tributary that ebbs and flows with the seasonal monsoon pulse of the main river, produces 500-million tons of fish a year — more than all the lakes and rivers of North America.

We will be lucky if we ever see again the likes of the Mekong giant catfish caught by Thai fishermen in 2005; it was 2.7m long, weighed 293kg and is the largest freshwater fish yet recorded.

China, which has not hesitated to exploit the upper reaches of the great Asian rivers that rise in Tibet, already operates 10 dams on the upper Mekong and has nine more due to be completed by 2030. Laos plans nine dams on the main stream of the Mekong and 130 more on its tributaries as part of a drive to export electricity and become the “battery of Asia”.

Humanity’s obsession with dams, first for irrigation and later for electricity, is not new. In Unruly Waters, Sunil Amrith, a professor of South Asian studies at Harvard University, examines the dilemma from a historical perspective, meticulously researching the colonial and postcolonial attempts to control the region’s rivers for human ends. It was Jawaharlal Nehru, the first prime minister of independent India, who called dams “the new temples of India”.

Few can begrudge southeast Asia, China or India the infrastructure investment that underpin their growing prosperity. After independence in 1947, Amrith says, India built 3,500 large dams and China 22,000. And in the Mekong region of southeast Asia, as Eyler acknowledges, “the average person has never been healthier, more educated or relatively better off than today”.

Yet dams have dire consequences for rivers and their role in the circulation of water and soil fertility that we are only now beginning to appreciate, which is why (along with the fact that the best spots for hydroelectricity have been taken) big new dams are being shunned by rich countries and some developing nations.

Overextraction of water for agriculture for the world’s growing population has dried up thousands of rivers in Asia, while silt deposition behind dam walls, with rising sea levels, threatens fertile river deltas such as those of the Ganges, the Indus and the Mekong with erosion, subsidence and saltwater intrusion.

One contemporary issue that merits further study is the tension between upstream nations that dam the upper reaches of rivers — in Asia that is usually China because it controls Tibet — and the dependent downstream states. Eyler spent years living in Kunming, China, and quotes many people and academic studies critical of Chinese water policies but, in his largely anecdotal book, he is disappointingly reluctant to analyse these policies in detail or draw conclusions about what China really wants to do. Michael Buckley’s polemical

Meltdown in Tibet (2014) pulled no punches — he accused China of “ecocide ”— but the seriousness and multiplicity of the threats to the rivers on which hundreds of millions of Chinese, Indians and other Asians depend suggest there is much more travelling and research to be done.

DAMS HAVE DIRE CONSEQUENCES FOR RIVERS AND SOIL FERTILITY THAT WE ARE ONLY NOW BEGINNING TO APPRECIATE