science that deals with the water above, on and below the land surface of the earth
Water covers 70% of the Earth's surface
Vew of Fernando de Noronha, Brazil

Hydrology [1] is the study of movement, distribution, and quality of water throughout the Earth.[2] A person who studies hydrology is called a hydrologist.

The central theme of hydrology is how the water circulates. This is called the water cycle. The most vivid illustration of it is the water evaporation from the ocean with the formation of clouds. These clouds drift over the land and produce rain.[3]

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  1. from Greek: Yδωρ, hudōr, "water"; and λόγος, logos, "study"
  2. What is hydrology and what do hydrologists do?
  3. Basic Ground Water Hydrology