Study: Human-Made Ponds Dramatically Changed Drainage Patterns

Human-made ponds in the United States have dramatically changed drainage patterns, collecting up to quarter of all run-off sedimentation that would have otherwise been deposited in river valleys and deltas, according to a study by Kansas Geological Survey researchers at the University of Kansas.

The researchers are the first to develop estimates of the number of ponds in the nation and their impact on siltation. Their report recently received a major award from the Association of American Geographers, officials announced on March 9.

"These ponds capture the runoff from about 20 percent of the area of the United States," said Jeremy Bartley, a geographic information systems specialist at the Survey and one of the paper's authors. "Most large-scale studies of sedimentation haven't taken these small water bodies into account. Taken together, they have a dramatic impact."

Based on their analysis of satellite imagery, the researchers estimate that there are 2.6 million ponds in the continental United States.

Most of these ponds are fairly small, covering less than 1.5 acres. Many were constructed during the 1900s, mainly to provide water for livestock and for recreation. Thousands more are built each year. Many of these are in the Great Plains or in the southeastern U.S., where natural lakes are relatively rare.

The researchers estimate that ponds capture 430 million cubic meters of sediment per year, a quarter of the amount that large reservoirs collect but still enough to fill more than 3 million railroad boxcars with dirt each year.

"Before these ponds were built, much of that sediment was deposited in river valleys," Bartley said. "Now it goes into these small impoundments, changing the nature of sedimentation and drainage in this country."

Bartley and Robert Buddemeier, senior scientist at the Survey, authored the report along with William Renwick of Miami University in Oxford, Ohio, and Stephen Smith of the Center for Scientific Investigation in Mexico.

Their report was given the 2006 G.K. Gilbert Award for Excellence in Geomorphic Research from the Association of American Geographers at their annual meeting in Chicago this month. The award is named for Grove Karl Gilbert, a geologist who in the late 1800s and early 1900s worked extensively in the field of geomorphology, the study of the landscape and its change over time.

Kansas Geological Survey: http://www.kgs.ku.edu

Jeremy Bartley: jbartley@kgs.ku.edu

This article originally appeared in the 03/01/2006 issue of Environmental Protection.

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