Hydrology: The Basics

The word "water" is derived from the older English word “waeter”, or proto-German “water” or German “Wasser”. All these words derived from various languages mean "wet." The word water basically refers the liquid state of the compound. Water exists in various forms. Water is termed as “ice” when it is in solid form, as “steam” when it is in the gas form. Super-critical fluid is formed by water under definite conditions. Hydrology can be defined as the studies related to the movement and the further distribution of the quantities of water above and/or below the surface of the earth. Water cycle or hydrologic cycle is the process of the form of water which continually changes and circulates between the oceans, atmosphere and land. The water of the earth circulates in three media like hydrosphere, atmosphere and the upper part of lithosphere. Water circulates from ocean to the atmosphere, then to lithosphere and finally from lithosphere to the ocean through a complex and interdependent processes which includes evaporation, transpiration, run off, ground water flow, precipitation etc. To have a simple understanding, water rises above the sea level reaching the surface of the earth in the form of vapour. Then clouds are formed from the water vapor which further falls on the earth’s ground as rain.  Some amount of rain water gets penetrated into the ground while some other parts of rain water are joined to the moving water systems like streams and rivers.