Forested_urban_water_balance2.jpg(800 × 384 pixels, file size: 60 KB, MIME type: image/jpeg)

This figure illustrates how the hydrologic cycle and water balance change as a result of urbanization. In a forested setting with no urbanization, about one-third of annual precipitation is returned to the atmosphere through evapotranspiration, while approximately another third infiltrates deeply into soil and recharges groundwater. Very little overland runoff occurs. Impervious surfaces created through urbanization results in 30 percent of annual precipitation rapidly being conveyed via overland flow. Recharge and evapotranspiration are greatly reduced. Note that the runoff amount will vary with the extent and connectedness of impervious surface. Ultra-urban settings may result in runoff exceeding 70 percent of annual precipitation.

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current21:13, 30 October 2012Thumbnail for version as of 21:13, 30 October 2012800 × 384 (60 KB)Admin (talk | contribs)