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Chapter 3: Hydrological Processes in Riparian Areas
The Hydrologic Cycle
- The hydrologic cycle can be described as follows:
- Water is moved from the earth's surface to the atmosphere as water vapor through evaporation and transpiration.
- Water vapor condenses and falls as precipitation (rain, snow, hail etc.), that either travels laterally and downhill across the land surface as runoff, or infiltrates through the soil surface.
- Water that infiltrates may continue its downward movement (percolation), to underground aquifers, and travel laterally underground as groundwater flow that may occasionally surface as springs (figure below).
- Surface water collects in streams which join to move water into larger water bodies such as rivers, lakes and oceans.
- Globally, the same water has been transferred around since the origin of the earth.
- The hydrologic cycle is driven by the sun, which provides energy, and gravity, which keeps water moving vertically and horizontally.
- The science dealing with these topics is termed hydrology, and the processes that act to move water through the atmosphere and the earth are termed hydrologic processes.
Figure 3.2. The hydrologic cycle.
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