我国水资源的时空分布极不平衡,河流径流量逐年变大。水资源状况严重制约着我国农业的发展。随着当今世界人口、环境、资源问题的日益突出,水更是严重威胁着人类的生存。我国每年用水总量为5 000亿m~3,农业用水占80%,而水稻又是耗水的第一大农作物,每年水稻用水量占全国用水总量40%以上。因此,节水对水 The spatial and temporal distribution of water resources in our country is extremely unbalanced, and the runoff of rivers has been increasing year by year. The status of water resources severely restricts the development of agriculture in our country. With the increasingly prominent problems of population, environment and resources in the world today, water is a serious threat to the survival of mankind. The total water consumption in China is 500 billion m 3 per year, while the agricultural water accounts for 80%. However, rice is also the largest water-consuming crop. Annual rice water consumption accounts for more than 40% of the national total. Therefore, save water on the water