我国水资源形势严峻.已成为影响经济与社会发展的一个严重制约因素。据统计.我国640多个城市中有300多个缺水全国农村每年缺300亿立方米.并有6000多万人口常年饮水困难。随着我国人口增加和经济社会的发展.预计2010年将缺水315亿立方米。若不采取有效对策，我国引世纪的可持续? The situation of water resources in our country is grim and has become a serious constraint on economic and social development. According to statistics, there are over 300 billion cubic meters of water shortages in more than 640 cities in China every year, and more than 60 million people have difficulties in drinking water all year round. With the increase of population and economic and social development in our country, it is estimated that there will be a water shortage of 31.5 billion cubic meters in 2010. If we do not take effective countermeasures, the sustainable development of our century?