Posted by: Michael Ritter PhD | April 22, 2009

As World Warms, Water Levels Dropping in Major Rivers

colorado-river_usgs-large

Colorado River. Courtesy USGS.

A new study by the National Center for Atmospheric Research (NCAR) indicates that rivers in some of the most populous regions on earth are losing water, and it may be due to climate change. Reduced river discharge could potentially threaten supplies of water and food in the future. An examination of river flows between 1948 and 2004 found significant changes in one-third of the largest rivers.  Many of these rivers provide water resources to large populations in China, West Africa, and the southwestern United States. Increased stream flows were found in sparsely populated areas of the Arctic where snow and ice are rapidly melting as regional temperatures rise. Dam construction and water diversion for agriculture can affect river discharge. However, the NCAR research team found reduced flows in several cases related to altered patterns of precipitation and increased evaporation rates caused by climate change.

Beyond the impact on water resources for human activities, reduced flows impact the delivery of dissolved nutrients and minerals to oceans. Freshwater flows into the ocean also affects ocean circulation patterns that are driven by salinity and temperature, which in turn affects global climate. Flows into the Pacific decreased by 6% and the Indian Ocean by 3%. Discharge into the Arctic Ocean increased by 10%.

Trends in River Flow 1948 - 2004. Courtesy: Journal of Climate, UCAR

Trends in River Flow 1948 - 2004. Courtesy: Journal of Climate, UCAR

For more see:As World Warms, Water Levels Dropping in Major Rivers” at Science Daily or the news release from the National Science Foundation.

The Physical Environment link: Stream Flow

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