Hydrology is defined as the study of different forms of water that is available on the earth surface or below the earth's surface. 

The study of hydrology have the following objectives:

  1. To measure the precipitation or rainfall.
  2. To estimate the run-off and peak flow.
  3. To study the water losses caused due to evaporation, absorption, infiltration and transpiration.
  4. To estimate the river training works.
  5. To check the availability of underground water.
  6. To forecast flood and decide flood control works.
  7. To conduct river gauging procedure.
  8. To prepare hydrograph and prepare maximum flood discharge.

What is the Importance of Hydrology?


The knowledge of hydrology is very important for the following applications:
  1. To determine the peak flow of a river
  2. To determine the sources of watersupply in a town or a city
  3. To determine the methods necessary for flood control.
  4. To determine the suitable site for hydro-electric power generation.
  5. To determine the capacity of the reservoir from the rainfall records and the yearly discharge observation of a river.

Terms Related to Hydrology


The important terms related to hydrology are:
  1. Catchment Area : The catchment area of a river is the area from where the surface runoff flows to that river either through tributaries, streams, springs etc. The area is bounded by watershed line.
  2. Runoff: When it rains, some portion of the rainfall moves and infiltrates into the soil and some is intercepted by vegetation. Some portion of rainfall can evaporate or flow over the ground water and finally joins the rivers, streams, lakes etc. The portion of rainfall that flows over the ground is called as surface runoff or runoff. The surface runoff is also called as rainfall excess or the effective rainfall.
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