Effects on the Hydrosphere

Flow of Water into Streams

As cities grow, natural groundcover changes dramatically. Natural vegetation and undisturbed soil are replaced with concrete, asphalt, brick, and other impermeable surfaces. This means that, when it rains, water is less likely to be absorbed into the ground and, instead, flows directly into river channels. Not only does more water reach the stream channels, but it arrives far more quickly after a storm. Natural vegetation slows run-off, concrete and asphalt speed the flow. The result diagrammed below indicates how urbanization speeds run-off and produces higher peaks of flow.


adapted from Detwyler 1971, 208

created 3/9/2002; last revised 5/1/2002 - Matt Kuhn & Andreas von der Dunk