Thursday, September 25, 2008

Unintended consequences on Arizona hydrology

A new article in the journal BioScience by a team of ASU scientists found that creation of artificial lakes and canal systems along with extensive groundwater pumping have had "unintended impacts on nutrient cycling." [above, Tempe Town Lake. Photo by Greg Folley]

The study concludes that water systems such as canals "cut across stream channels, disrupting the flow of water and sediments from tributary networks to the main channel. In pristine streams, sandbars and other patches created where these sediments collect are often ideal places for nutrient cycling. By starving streams of their historic supply of this material, canals accidentally alter the way nutrients are cycled in stream ecosystems."

The authors report that "surface and subsurface hydrologic network is short circuited with water entering the channel from well and canal sources, and water leaving by evaporation, seepage, and canal redirection."

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