Cloud seeding helps alleviate drought
By Wang Jian (China Daily)
Updated: 2004-07-24 00:23

To draw rain from the heavens, ancient Chinese once used to offer their best in sacrifice. Apart from oxen and sheep, legend has it that beautiful virgin girls were also thrown into rivers to please the water dragon, who would then show mercy and release the rain.

Today, Chinese meteorologists believe that cloud seeding, either by using artillery to fire shells containing rain-inducing chemicals into the cloud cover or by dropping the chemicals from aircraft, is a more scientifically effective approach.

Cloud seeding has been regularly used to ease the drought situation in North China.

Despite the diversity of opinions on the feasibility of the technology, primarily because of the difficulties in assessing its results, the prevailing opinion is that it has reached a relatively advanced stage of application, and it can be considered one of the technologies capable of contributing to the augmentation of freshwater supplies in arid regions.

In a bid to address Beijing's growing water shortages, the city has decided to take every possible measure to increase water supplies, including precipitation inducement technology, Zhang Qiang, an official with the Beijing Office of Artificial Weather Inducement, told China Daily.

Zhang said the city uses specially modified Military Aviation Xia Yan IIIA and An-26 aircraft for this purpose.

In the first half of the year, Beijing meteorologists carried out several cloud seeding operations. Aircraft, rockets, artillery shells, meteorological balloons and mountain-top-based devices have been employed to scatter silver iodide particles into gathering clouds to induce precipitation in the form of rain or snow over the city.

According to statistics, precipitation last year was increased by 25 per cent, 23.77 millions cubic metres of water to the Miyun, Guanting and Chaobai reservoirs, Beijing's main sources of drinking water 23.77 million cubic metres.

"Although it may be an exaggeration to attribute all of the increase to cloud seeding, we believe it has worked,'' said Zhang.

In order to make more rain and expand water reserves for the Chinese capital, experts and rain-making workers have been stationed upstream of the Miyun and Guanting reservoirs this summer. "Cloud seeding shells will continue to be fired into the skies above Beijing in the hope of breaking a prolonged dry spell," Zhang said.

Nationwide application

Cloud seeding has been widely used in other parts of China as well.

According to statistics from the China Meteorological Administration (CMA), from January to the end of June, China used 227 aircraft putting in 529.8 hours of flight time in cloud seeding operations in 15 provinces and regions, covering an area of about 1.66 million square metres, and scattered chemicals in clouds using 12,464 rockets and 66,000 large-calibre artillery shells in 30 provinces and cities, producing 10 billion cubic metres of water.

"I believe that nearly every time it has rained in Beijing or northern China this spring, cloud seeding technologies have been used," said Hu Zhijin, an expert with the Institute of Artificial Rain under the China Meteorological Administration.

According to a report by Qin Dahe, the top official of the China Meteorological Administration, from 1995 to 2003, 23 provinces around the country conducted precipitation enhancement (PE) operations using 4,231 flights of aircraft with a total flying time of 9,881 hours; and many provinces employed artillery and rockets for their PE work. The total area of operation covered more than 3 millions square kilometres and precipitation was about 2,100 billion cubic metres.

In 2003 alone, more than 3,800 rocket launchers, about 7,000 antiaircraft guns and many airplanes were used for various weather modification operations to enhance precipitation in more than 1,800 counties throughout China. More than 35,000 people were involved.

Last year, 413 million yuan (US$49 million) was injected into the programme.

At the national level, the Second National Co-ordination Meeting on Weather Modification was held on February 27, 2004.

The meetings are held to organize, coordinate and guide weather modification activities across the country. Many ministries and committees took part in this meeting, held at the China Meteorological Administration.

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