水是不可替代的自然资源,是自然环境的重要组成部分,在经济建设、社会发展和人民生活中占有极其重要的地位。合理开发利用水资源,防治水环境污染和破坏,是我国的一项重要政策。我国人均占有的淡水资源不丰富,而且因时空分布不均衡,相当一部分地区的水资源十分缺乏。随着经济建设、城乡建设的发展和人口的增加,用水量持续增长,水的供需矛盾将日益突出。同时,由于大量的工业废水和生活污水排入水体,使水环境质量恶化,地表水和 Water is an irreplaceable natural resource and an important part of the natural environment. It occupies an extremely important position in economic construction, social development and people’s livelihood. Rational development and utilization of water resources, prevention and control of water pollution and damage, is an important policy in our country. The per capita fresh water resources in our country are not abundant, and due to the uneven distribution of time and space, a considerable part of China’s water resources are in short supply. With the economic construction, urban and rural development and population growth, water consumption continues to grow, water supply and demand conflicts will become increasingly prominent. At the same time, due to the large amount of industrial wastewater and domestic sewage discharged into the water body, the quality of the water environment is deteriorated. Surface water and