By Zhang Liang, Gu Shuzhong & Wang Yufei, Research Team on "water development Countermeasures for adapting priority zones ", Research Institute for Resources and Environment Policies of DRC

Research Report No. 222, 2012 (Total 4224)

Cloud water resources refer to the total of liquid and solid water in the atmosphere that can be directly developed and utilized through artificial intervention. Scientifically and reasonably developing and utilizing cloud water resources is one of the effective solutions to water shortage in China. It has been made clear in No.1 Document of the Central Government, 2011 that "construction of demonstration areas for artificial precipitation (snowfall) should be strengthened and cloud water resources should be developed and utilized in a scientific way." In August 2012, the General Office of the State Council printed and distributed the Views on Further Improving the Work on Weather Modification, specifying more clearly the important task of "reasonably developing cloud water resources".

I. Developing and Utilizing Cloud Water Resources Is of Vital Importance and Has Great Potential for Development

1. As one of the major non-traditional water sources, cloud water resources are an important channel for alleviating water shortage in China

Development and utilization of clouds water resources can directly increase the total amount of water resources and can be an effective solution to the seasonal water shortage in regions where rainfalls are fewer or are excessively concentrated. In appropriate weather conditions, artificial precipitation (snowfall) can turn cloud water resources into ground water resources, and experiences and theories both at home and abroad have demonstrated that it is an effective method for developing cloud water resources. Calculation shows that, in the spring of 2009 alone, an increase of 9.3 billion tons of artificial rainfall was generated in winter wheat areas in 11 provinces (regions and municipalities) in north China, a remarkable contribution to drought alleviation, and after the promulgation and implementation of the Weather Modification Regulations in 2002, the countrywide artificial precipitation reached an accumulative total of nearly 490 billion tons, equivalent to the total storage capacity of 12 Three Gorges reservoirs.

2. Higher input-output ratio from the development of cloud water resources

Scientific experiments show that artificial precipitation (snowfall) is a low-cost and efficient job. The present internationally recognized benefit-cost ratio is 1:20~1:25 and the highest can be 1:40, and other benefits including the ecological benefit of artificial precipitation (snowfall) are much more inestimable.

3. Huge potential for the development of cloud water resources

Currently, China's average annual amount of cloud water resources (including water vapor) comes to 22 trillion tons or so, yet the precipitation efficiency is only 28% or so (15% or so in northwest China), with 87% of the clouds water resources fluttering out of China. In view of present technical conditions, if the countrywide cloud water can be completely developed, the latent amount of artificial precipitation will then reach 280 billion tons or so a year. Since the artificial precipitation (snowfall) is very short-cycled (only 8.7 days), water in the air can circulate 42 times a year, the amount of water in the air will then reach 1176 trillion tons, more than 8 times that of surface water.

II. Remarkable Successes Have Been Achieved in Explorations and Practices in the Development and Utilization of Cloud Water Resources by Foreign Countries

Scientific bases for the development and utilization of cloud water resources through artificial precipitation (snowfall) have been demonstrated by a wealth of laboratory experiments, theoretical studies and field experiments. World Meteorological Organization (WMO) points out that weather modification (including artificial precipitation (snowfall)) should be taken as part of water resource overall management strategy.

1. Successful explorations and practices in the development of cloud water resources in developed countries

The modern artificial precipitation (snowfall) began in 1946. Currently, more than 30 countries, including USA, Russia, Israel and Australia, are carrying out this work. Due to economic development, the State of California of the United States was much water-starved. During 1976~1987, government organs, such as the Bureau of Reclamation (USBR), developed cloud water resources through joint efforts by using the silver iodide generator on the plane to catalyze orographic clouds to generate a precipitation of 50,000 cubic meters within the cloud modification areas. In addition, artificial precipitation experiments were also conducted over Rocky Mountains in Colorado, Cascade Range in Washington and Wasatch Range in north of Utah, increasing the precipitation by 15%~20%. In 1975, Israel started artificial precipitation in its northern part to increase its water resources, with the increment reaching 13%~15%. Australia has been involved in catalyzing precipitation through oceanic cloud tests for 12 years, with the rainfall up by 30%. Economic analysis shows that each ton of precipitation costs about 4~5 cents, which generates an input-output ratio of about 1:30 and leads to a good economic benefit.

2. Marked effects have been achieved by China related to artificial precipitations (snowfalls)

Since 1958, China has conducted a raft of artificial precipitations (snowfalls), making great contribution to drought mitigation and increase in crop yields, and rich technical experiences have been accumulated in this course. The organizing and management system under the leadership of governments at all levels and under the guidance of competent meteorological organs has been formed gradually, the structure of professionals has been constantly optimized and the quality of personnel has been gradually improved. After the implementation of the Weather Modification Regulations in 2002, particularly since the 2nd National Weather Modification Conference held in 2004, China's artificial precipitation (snowfall) work has been enhanced at a faster pace, and the operational capability and the service efficiency have been improved notably. According to statistics, in 2011 the area of countrywide artificial precipitation regions reached more than 5 million square kilometers and the area of artificial hail suppression regions surpassed 500,000 square kilometers, up by 60% and 25% respectively over 2002. At present, weather modification work has been conducted in 2,235 counties (municipalities, districts, and farms) in 30 provinces (regions and municipalities), including the regiment-level farms of Xinjiang Production and Construction Corps and the General Bureau of Land Reclamation of Heilongjiang. There are 47,700 weather modification workers and a total of 6,902 cannons and 7,034 rocket launchers in those counties, with over 50 aircrafts being used each year.

III. Main Problems Currently Existing in the Development and Utilization of Cloud Water Resources in China

1. More attention should be paid to the development and utilization of cloud water resources

Firstly, China's Water Law prescribes that water resources are owned by the state, but the Law does not clearly define the ownership of the cloud water resources and has not categorized cloud water as water resources under law, thus leading to an increasingly fierce scramble for cloud water resources among various localities. In addition, China uses artificial precipitation mainly as a technical means to fight against drought and does not develop and utilize cloud water resources as important water resources. Finally, guidance on the state level has been few and far between as regards the development and utilization of cloud water resources. Although some plans, policies and laws touch upon the development and utilization of cloud water resources, they have not stressed the development and utilization of such water resources from the perspective of the development of strategic resources. Besides, there is a lack of guidance plans. Therefore, regardless of overall interests, each locality acts in its own way in developing and utilizing cloud water resources across China.

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