The science of studying the different forms of water available above the earth surface or below the earth surface is known as hydrology. Even Hydrology includes those portion of the science which deals with the estimation of runoff and its transportation from one place to another.
Importance of Hydrology
The study of Hydrology is useful for the design and operation of engineering projects for the control and use of water. The knowledge of hydrology is very essential for the applications:
(a). Determination of the capacity of a reservoir from the rainfall records and the yearly discharge observation of a river.
(b). Determination of peak flow of a river.
(c). Determination of suitable site for hydro-electric power generation.
(d). Sources of water supply in a town or city.
(e). Methods to be adopted for the flood control.
The water from the surface sources like lakes, rivers, ocean, etc. converts to vapour by evaporation due to solar heat. The vapour goes on accumulating continuously in the atmosphere. This vapour is again condensed due to the sudden fall of temperature and pressure. Thus clouds are formed. These clouds again causes the precipitation (i.e Rainfall).Some of the vapour is converted to ice at the peak of the mountains. The ice again melts in summer and flows as rivers to meat the sea or ocean. These processes of evaporation, precipitation and melting of ice go on continuously like an endless chain and thus a balance is maintained in the atmosphere. This phenomenon is known as Hydrologic cycle.
Component of Hydrologic cycle –
1 . Evaporation
2 . Transpiration by plant
3 . Condensation
4 . Precipitation
5 . Interception
7 . Ground water flow
8 . Surface flow
Hydrology & Hydrologic cycle – Book Irrigation Engineering, Writer – N N Basak