News Release, Kansas Geological Survey, March 7, 2006
LAWRENCE--More than 2.5 million man-made ponds now cover the American landscape, dramatically changing drainage patterns and the movement of sediment that erodes off the land.
That's the finding of four researchers, including two at the Kansas Geological Survey based at the University of Kansas, who developed one of the first estimates of the number of ponds in the country and their impact on siltation. Their work, published in the scientific journal Geomorphology, recently received a major award from the Association of American Geographers.
Based on their analysis of satellite imagery, the researchers estimate that there are 2.6 million ponds in the continental U.S.
"These ponds capture the runoff from about 20% of the area of the U.S.," said Jeremy Bartley, a geographic information systems specialist at the Survey and one of the paper's authors. "These ponds catch an estimated 25% of the sediment load eroded each year."
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.
"Most large-scale studies of sedimentation haven't taken these small water bodies into account," said Bartley. "Taken together, they have a dramatic impact."
The researchers estimate that ponds capture 430 million cubic meters of sediment per year. That's less than 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," said Bartley. "Now it goes into these small impoundments, changing the nature of sedimentation and drainage in this country."
The papers other authors William Renwick, Miami University, Oxford, Ohio; Stephen Smith, Center for Scientific Investigation, Mexico; and Robert Buddemeier, KU's Kansas Geological Survey.
The paper 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 in early March. 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.