Water is essential for human life.
Although we may be able to find alternate energy sources, there is no substitute for potable water. Excluding water contained in the oceans and various forms of ice such as glaciers and polar ice caps, the vast majority of the remaining water is ground water. The Earth has approximately 70 times more ground water than surface water. Hydrogeology is the study of water below the land surface. Water availability and quality are strongly dependent upon the geology.