HYDROLOGY



The branch of physical geography which deals with the origin, distribution, and properties of water of the earth surface is called hydrology.

Engineering hydrology deals with the field of hydrology which is mainly concerned with the wind and operation of engineering projects for the control and use of water . Indeed , the engineer makes use of hydrology as agriculturists , foresters, etc . do

The Hydrological cycle

Water goes on changing from one state to another in a cyclic order . This cycle is visualised at beginning with the evaporation of water from the oceans and lakes. The resulting vapoura are transported by the wind and under proper conditions, these vapours get condensed to form clouds which contribute to the precipitation . The precipitation which falls upon the land is disposed of in several ways as discussed below:

(1) the greater part is temporarily retained in the soil on which it falls and is ultimately returned to the atmosphere either by evaporation or by transpiration by the plants.

(2) A partion of water finds its way over and through the surface soil to stream channels 

(3) A partion of the water penetrates farther into the ground and becomes a parts of the earth's ground water supply.

Uses of hydrology

A study of hydrology ise useful for the following
  • For proper design and operation of hydraulic structures 
  • For ascertaining flood flows expected at a spillway , or at a highway culvert or in a city drainage system 
  • For ascertaining reservoir capacity to ensure adequate water for irrigation or municipal water supply during draughts 
  • For ascertaining the effect of reservoirs , levees and other control works in flood flow in a stream

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