Question

State the significance of following terms : i) Hydrology ii) Surface run-off iii) Evaporation iv) Precipitation

Answer 1

i) Hydrology:- It may be defined as the science which deals with the depletion and replenishment of water resources. 

OR 

 To study hydrological cycle i.e. i.e. evaporation, precipitation and to estimate the yearly possible flow.

ii) Surface run-off:- It is that portion of precipitation (rain fall) which actually flow towards stream, lake, river or ocean. 

 Run-off = Total precipitation – Total evaporation of water 

iii) Evaporation:- It is the transfer of water from liquid state to vapour state.

iv) Precipitation:- Precipitation is nothing but rain fall. This includes all the water that falls from atmosphere (sky) to the earth surface. 

Answer 2

(i) Hydrology: It may be defined as the science which deals with the depletion and replenishment of water resources. Hydrology deals with the occurrence and distribution of water over and under earth’s surface. It is helpful for managing the water resources. 

(ii) Surface runoff: It is that portion of precipitation (rain fall) which actually flow towards stream, lake, river or ocean. Run-off can be possible only when the rate of precipitation is more than rate of absorption of water in soil and also evaporation losses. Run-off = Total precipitation – total evaporation of water The collection of water in lake, river and ocean depends upon the surface run-off. 

(iii) Evaporation: It is the transfer of water from liquid state to vapor state. It includes all the rainfall that is returned to atmosphere from the land and water surfaces. 

(iv) Precipitation: Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. It is the primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth. It is mainly of two types: 

a) Liquid precipitation (Rainfall) 

b) Solid precipitation (Snow, Hail)