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."
(CIIC 03/12/2001)
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