Themes
The central theme of hydrology is that water circulates throughout the Earth through different pathways and at different rates. The most vivid image of this is in the evaporation of water from the ocean, which forms clouds. These clouds drift over the land and produce rain. The rainwater flows into lakes, rivers, or aquifers. The water in lakes, rivers, and aquifers then either evaporates back to the atmosphere or eventually flows back to the ocean, completing a cycle. Water changes its state of being several times throughout this cycle.
The areas of research within hydrology concern the movement of water between its various states, or within a given state, or simply quantifying the amounts in these states in a given region. Parts of hydrology concern developing methods for directly measuring these flows or amounts of water, while others concern modelling these processes either for scientific knowledge or for making prediction in practical applications.
Read more about this topic: Hydrology
Famous quotes containing the word themes:
“In economics, we borrowed from the Bourbons; in foreign policy, we drew on themes fashioned by the nomad warriors of the Eurasian steppes. In spiritual matters, we emulated the braying intolerance of our archenemies, the Shi’ite fundamentalists.”
—Barbara Ehrenreich (b. 1941)
“I suppose you think that persons who are as old as your father and myself are always thinking about very grave things, but I know that we are meditating the same old themes that we did when we were ten years old, only we go more gravely about it.”
—Henry David Thoreau (1817–1862)