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The per capita amount of water in China is only 2,200 tons, about one-fourth the world average of 7,300 tons. Even worse, the distribution of the scanty resources is uneven, with northwest and north China suffering a severe water shortage.
Facing such a grim situation, the development of water resources in the air to improve the efficiency of atmospheric precipitation should be high on the national agenda, according to Zhang Rongming, vice-chairman of the Central Committee of the China Democratic National Construction Association.
Zhang made the proposal during the current session of the Ninth CPPCC National Committee, which began on March 3.
Water was essential for the survival of mankind, for social development and the maintenance of ecological balance is mainly from atmospheric precipitation, he said.
According to some estimates, annual seawater evaporation can lead to precipitation of some 453,000 billion tons, 90% of which returns to sea; the remaining 41,000 billion tons forms runoff on the ground. With the southwest monsoon, the annual accumulation of vapor above the land in China stands at some 20,000 billion tons, of which some 6,000 billion tons forms precipitation. The runoff is some 2,700 billion tons.
If appropriate measures are adopted, scientists forecast it would be possible to have 10 percent more rainfall, which would amount to 600 billion tons of water annually. If one-third of this amount flows into northwest and north China, said Zhang, it will have remarkable impact in easing the regional water shortage.
Tapping the air for water resources, therefore, is a significant way for China to the shortage problem in the 21st century, he noted.
Artificial precipitation began in China in the 1950s and the nation now has some 6,000 special cannons and a large team of professionals. But artificial precipitation has served just as a technical means to combat drought, and has never been considered as a strategic resource to be developed. As a result, no studies have been made nor primary information accumulated, according to the CPPCC National Committee member.
Technically speaking, said Zhang, the wide application of remote sensing and detecting technologies, the birth of powerful computers, the popularization of digital transmission systems, the appearance of fixed-position unmanned spacecraft, maturing synthetic technology of various catalytic agents as well as the established networks of meteorological, radar navigation and microwave transfer stations have all created various favorable conditions for the applied basic studies and technology development in relation to scientific and scaled artificial rainfall.
Economically speaking, he said, the cost on one ton of artificial rainfall in Israel is currently about four cents (some 0.24 yuan); but the cost on each ton of water diverted from south to north China along whichever of the three proposed routes is between 1-2 yuan. It is obvious that, with large-scale input of human and material resources to integrate and improve the usable technical resources, it would be possible to master the law of turning clouds into rain and apply the technology into the development of air water resources. To this end, he suggests:
-- To regard the development and utilization of air water resource as a strategic project to be programmed and studied. Water conservancy work in China used to be focused on dredging and damming surface water. With the development of deep well technology in modern times, the focus shifted to excess extraction of underground water, causing many underground funnels and surface subsidence. “Facing the grim situation of water shortage, we must change our vision strategically from ground to sky, and the state must make strategic input in this respect.”
-- To pay close attention to basic studies on the development of water resources in the sky. The current focus should be on physics and technology of precipitation from cloud and mist; the distribution, operation and transformation of steam in the country; the detection technology and forecasting system of water resources; determination of the critical state of cloud precipitation, choice and development of cheap, but highly effective catalytic agents; the design and application of units for spraying catalytic agents; etc.
-- To consider the development of water resources in the sky and the utilization and regulation of ground water resources in a comprehensive way in accordance with objective law. The construction of water works should be regulated in light of rainfall distribution.
-- To organize forces from the sectors of water conservancy, meteorology, universities, national defense, agriculture, forestry, telecommunications and aviation, and to train qualified personnel to gradually set up a unified detection and forecasting network, and an overall regulation and command system in the country.
“We have no other choice than beginning the undertaking at an earlier date,” said Zhang. “It’s better for us to take the initiative.”
(www.keyanhelp.cn 03/12/2001)
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