Hydrology ( from Greek : YÎ Ï Ï , hudÅ r , `` water '' ; and Î '' Ï Î Î Ï , logos , `` study '' ) is the study of movement , distribution , and quality of water throughout the Earth . The term hydrology is from Greek : á 1\/2 Î Ï Ï , hydÅ r , `` water '' ; and Î '' Ï Î Î Ï , logos , `` study '' .