自然界的水资源由大气水、地表水、地下水三个部分组成。三者之间有密切的内在联系,并在一定条件下相互转化构成水体循环。自然界水体循环是按照以下方式进行的:海洋表面受到太阳能的作用使海水蒸发变成水汽进入大气中,水汽被气流带至大陆上空以雨或雪的形式降落到地面上,最后通过江河又(?)到海洋中去,这就是水的大循环。最近Rob xt P.Amlxoggi 教授1978年的论文中把自然界水资源按水循环运动速度分为两类: Natural water resources by the atmospheric water, surface water, groundwater in three parts. There is a close relationship between the three, and under certain conditions, each other into the water cycle. The circulation of water in nature is carried out in the following way: the surface of the ocean is exposed to the action of solar energy to evaporate seawater into water vapor and enter the atmosphere. The water vapor is brought to the upper reaches of the continent by air currents and falls onto the ground in the form of rain or snow. Finally, To go to the ocean, this is the water cycle. In a recent paper by Professor Rob xt P.Amlxoggi in 1978, the nature of water resources was divided into two categories according to the speed of the water cycle: