The water cycle

The water cycle

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Uploaded 16 Feb 2012 by GRID-Arendal
Year: 2008
From collection: Vital Water Graphics 2
Author: Philippe Rekacewicz , UNEP/GRID-Arendal
Description:
Environment water transport system. The water cycle consists of precipitation, vapour transport, evaporation, evapo-transpiration, infiltration, groundwater flow and runoff. Figure 1 explains the global water cycle, illustrating how nearly 577,000 km3 of water circulates through the cycle each year. A table of estimated residence times shows the approximate times that water resources exist as biospheric water, atmospheric water and so on. The world’s surface water is affected by varying levels of precipitation, evaporation and runoff, in different regions. Figure 2 illustrates the different rates at which these processes affect the major regions of the world, and the resulting uneven distribution of freshwater. Water is transported in various forms within the hydrologic cycle. Shiklomanov in Gleick (1993) estimates that each year about 502,800 km3 of water evaporates over the oceans and seas, 90% of which (458,000 km3) returns directly to the oceans through precipitation, while t ...
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