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INTRODUCTION
Water is one of the most important needs of mankind. With the rapid development of industry and agriculture, as well as with the increasing population and the daily demands of people, water consumption has been increasing constantly. In China, the gulf between the increasing demand for water and the shortage of water resources is becoming increasingly wide. Water shortage is becoming an important limiting factor for the development of industry, agriculture and the economy.
Meanwhile, water pollution due to the discharges of waste water from homes and industry aggravates the gulf between the demand for water and its supply. Water pollution started in China in the late 1950s with the development of industry and has become more and more serious since the 1970s(2). The discharges of waste water into aquatic environments are increasing year by year. In terms of the survey, the waste water quantity was 30.16 billion cubic metres in 1980, and in 1985 it had increased by more than 13 per cent to 34.2 billion cubic meties. Most of the waste water is discharged into rivers, lakes and seas without any treatment. Of these discharges, 75-80 per cent is from industry, while only 22 per cent of industrial wastewater is treated before discharging. According to a statistical survey of cities in China, about 63 per cent have been polluted by waste water to differing extents, 43 per cent of groundwater reserves having been polluted. In the case of river systems, 32 per cent are being threatened by environmental pollution(3).
The Chinese Government attaches great importance to environmental protection and has made great efforts to solve these problems. Several important laws relating to environmental protection have been enacted since the 1970s(4,5). Environmental protection has become one of the national basic policies since 1987.
WATER RESOURCES
DISTRIBUTION OF WATER RESOURCES
China covers an area of 9.6 million square kilometres, while its annual average rainfall is approximately 6,190 billion cubic metres (Table I), i.e. 648 mm in rainfall depth, which is 20 per cent less than the global average value of 800 mm. (Table I omitted) Only 44 per cent of the rainfall forms surface or groundwater run-off. The annual average of reserves in China is 2,800 billion cubic metres; this ranks sixth in the...