PORTLAND, Ore. -- Using a simple, yet sophisticated computer analysis, Oregon researchers have determined that flood-control dikes in the Columbia River floodplain and reduction of peak water flows have reduced shallow water habitat for juvenile salmon by about 62 percent during the crucial May to July period when salmon most need such shallow waters for their transition to the Pacific Ocean. The computer models, developed by environmental scientists at Oregon Health & Science University's OGI School of Science & Engineering, are efficient for the very long simulations needed to understand historic changes and climatic impacts on shallow water habitat.

"This is the first study to separate the effects of flow regulation and diking on salmon habitat loss in the Columbia River, Oregon's largest river," said Tobias Kukulka, M.S., the lead author of the study who is now in doctoral studies at the University of Rhode Island. "Taken individually, diking and flow-cycle alteration would have reduced spring-freshet shallow water habitat by 52 percent and 29 percent respectively."

The two-part study, funded by the United States Army Corps of Engineers Portland District and NOAA Fisheries, was conducted under the direction of David Jay, Ph.D., associate professor of environmental and biomolecular systems in the OGI School of Science & Engineering. The studies were posted online Sept. 22, 2003, on the American Geophysical Union's (AGU) Web site (http://www.agu.org/pubs/crossref/2003/2003JC001829.shtml and http://www.agu.org/pubs/crossref/2003/2002JC001382.shtml) and will be published soon in the AGU's JGR-Oceans.

Columbia River hydrology has changed drastically in response to human activities and climate at the same time that salmon populations have greatly decreased. To better understand the impacts of hydrolo
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Contact: Sydney Clevenger
clevenge@ohsu.edu
503-748-1546
Oregon Health & Science University
23-Sep-2003

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