Friday, 4 May 2018

Artificial Rain on the Tibetan Plateau for More Water in China

                                                                                                                                 * By Dechen Palmo

By Dechen Palmo
Due to water scarcity in major Chinese cities, Chinese scientists are coming up with different techniques to acquire more water to satisfy their growing demand.

According to a recent news report published on 22 March, 2018 in South China Morning Post, "China needs more water. So it's building a rain-making network three times the size of Spain," China is testing a weather modification system developed by the state-owned China Aerospace Science and Technology Corporation. The scientists have designed and constructed chambers using cutting-edge military rocket engine technology to develop this system. This is a cloud seeding method to bring more rain on the Tibetan plateau.

Tibet is the home of largest store of accessible freshwater outside the North Pole and South Pole, it is also the source of the six most important rivers of Asia. Since Tibet is self-sufficient in water, there is no need for the Tibetan plateau to induce such artificial rain-making system.  These burners are set up by Chinese on the Tibetan plateau to increase rainfall in order to feed the Drichu (Yangtze) and Machu (Yellow), which are the lifeline of Chinese people.

So far, according to the news, China has built over 500 burners on Tibetan mountains. Furthermore, they are planning to build tens of thousands of more such burners. Cloud-seeding is a method used by scientists to alter rainfall pattern. Water in clouds need to form into heavy droplets to precipitate. But often, the droplets in the clouds are just too small to precipitate. This technique involves an enormous network of fuel burning chambers which burn solid fuel to produce silver iodide, a cloud-seeding agent with a crystalline structure, much like that of an ice

Image: Snowy hydro

These chambers are installed high on the Tibetan mountain ridges facing the moist monsoon from South-Asia. As wind hits the mountains, it produces an upward draft and sweeps the particles into the cloud to induce rain and snowfall. This practice is not new and it is used in many countries. Even Beijing famously used it during the Olympics in 2008. But the matter to be concerned about is that the Chinese government is considering setting up what would be the world's largest cloud-seeding operation and keep these chambers operating in a near-vacuum conditions for months, or even years, without requiring maintenance on the Tibetan plateau.

Other cloud-seeding methods such as using planes, cannons and drones to blast silver iodide into the atmosphere won't have much environmental impact as the process of "blast" is for a short duration and induce rain only when it is required. But the type of chambers built on the Tibetan plateau that operate for months and years might have more impact over other methods. This cloud-seeding technique sounds good in theory, but the question is, does the technique work and what would be the long-term effects on the Tibetan plateau?

Whether cloud-seeding is a sustainable method is a controversial subject. A study in 2016 by the Wyoming Weather Modification Pilot Programme found that, although the technique can increase precipitation if wind and other conditions are ideal, it cannot do so reliably over a long period or on a large scale. Much of the literature on this substantiate that not only does cloud-seeding fail to achieve the desirable effect, it also could yield harmful consequences. Some of these consequences include rain suppression, flood, tornado and silver iodide toxicity.

In Australia, scientists consider three or five years to be the bare minimum period required to obtain a reliable data from the area of seeding trial.  However, Australia has stopped cloud-seeding due to environmental reasons.

The Tibetan plateau is very fragile and any weather modification could be fraught with unintended consequences. Before tens of thousands of chambers are to be built at select locations across the Tibetan plateau, the Chinese government should wait for at least three to five years to get reliable data from these 500 burners which have already been set up. They also should carry out a thorough scientific study of its use and conduct an Environmental Impact Assessment (EIA) before giving the green light to such project.

        *The author is an environment Research Fellow at the Tibet Policy Institute

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