2.6 Million Manmade Ponds Have 'Dramatic Impact'

[tocqueville]

http://news.yahoo.com/s/space/20060313/sc_space/26millionmanmadepondshavedramaticimpact

LiveScience Staff

LiveScience.com
Mon Mar 13, 10:00 AM ET

The United States is dotted by about 2.6 million man-made ponds that significantly alter natural runoff schemes by trapping a previously unknown amount of sediment.


The number was generated in a new review of satellite images. Most of the ponds are less than 1.5 acres in size, but they add up.


"These ponds capture the runoff from about 20 percent of the area of the U.S.," said Jeremy Bartley of the Kansas Geological Survey. "Most large-scale studies of sedimentation haven't taken these small water bodies into account. Taken together, they have a dramatic impact."


The ponds collect about a quarter of the sedimentation that would otherwise end up in rivers and deltas, Bartley and his colleagues report in the journal Geomorphology. The trapped sediment could fill more than three million railroad boxcars a year.

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wonders is this impact plays a role for NOLA.... probably

[ayeshahaqqiqa]

1. Ponds also alter local weather

It's a lot more foggy around here, and folks put it down to the number of ponds that have been built.

[lakeguy]

2. would all this sediment be heading to rivers under natural

conditions or is this mitigating human impact? i would think the main alteration to natural runoff was completed when we moved in and these ponds are helping to mitigate the peak flows and sediment loads resulting from all the beatiful tar and concrete we have laid down.

[benburch]

3. It should be noted that many are required by fire codes.

The reason you so often see a pond with a fountain next to a large office building is that the fire codes require that pond as a source of water for firefighting in case the building burns.