Thursday, May 2, 2013

Caution Karst Below!

Sinkholes have been a hot topic in the news recently, click here for a story from Illinois.  Did you know we have them here in Iowa?  They're actually quite common in northeast Iowa and stretch down to southeast Iowa.

Photograph from Northeast Iowa RC&D website:

Sinkholes commonly form when the earth beneath the surface erodes away forming a gap that the surface can slowly recede or quickly collapse into.  Because they are an easy path for water to drain from the surface, the Iowa Department of Natural Resources maps sinkholes in Iowa to protect groundwater from high levels of manure contamination, investigate how chemical runoff can affect ground water, and to better understand the geology of Iowa.
The image above uses DNR data to show areas with sinkhole potential in Iowa.  Area identified as green is within 1000 feet of a known sinkhole, and the blue shows area greater than 1000 feet but less than a mile from a known sinkhole or an area with carbonate bedrock close to the surface.

The layers are available in the DNR GIS Library if you want to examine them yourself (Potential Karst, Current and Historic Sinkhole Points, Current Sinkhole Polygons.)

Is your home near a sinkhole?

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