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 Ground-Water Flooding in Glacial Terrain of Southern Puget Sound, Washington Ground-water flooding occurs in low-lying areas when the water table rises above the land surface. Ground-water flooding is an unusual phenomenon because it typically occurs only in terrain shaped by continental glaciers. The unique geomorphic history of Puget Sound, Washington, leads to the unusual phenomenon of ground-water flooding when wet conditions persist for much more than a year. In the central Pierce County area of Southern Puget Sound, some relic drainage channels — legacies of melting glaciers at the conclusion of the last Ice Age — now convey only ground water. When wet conditions prevail, ground-water flooding can be observed moving progressively "downstream" in these channels. This is called "transient" ground-water flooding and is even more unique than "static" ground-water flooding that is usually due to persistent wet climate conditions raising the water levels in relatively large aquifers. The geomorphic history of Southern Puget Sound, the channels that were created, and transient ground-water flooding in 1997 are described in U.S. Geological Survey Fact Sheet 111-00 (4 pages). The Fact Sheet is in PDF format (PDF: 954 KB/4 pages). You will need to have Adobe Acrobat Reader installed on your system to read PDF files http://www.adobe.com/products/acrobat/readstep.html |
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