Friday, January 18, 2008

Plan for 500 Years

A core principle of our organization is that the Auburn Dam should be built as it will protect the Parkway from the degradation high waters cause along the Parkway and will provide a 500 year level of flood protection to the region.

It is good to see public leadership reaching the same conclusion after so long being satisfied with 200 or even a 100 year level of flood protection when New Orleans had a 250 year level prior to Katrina hitting.

Study: Plan for bigger floods
By Matt Weiser -
Published 12:00 am PST Friday, January 18, 2008

A major new study of flood risk in California's Central Valley urges communities to use worst-case scenarios to build up their levees, rather than setting arbitrary targets based on flood probability.

Sacramento, known to have the worst flood risk of any major metropolitan area in the nation, is working to erect levees strong enough to withstand a 200-year flood, a catastrophic flood predicted to have a half-percent chance of striking in a given year.

The plans to fortify citywide levees by 2015 have ignited a levee war between local and federal officials because they call for restrictions that could result in a building moratorium in the city's fast-growing Natomas basin.

But instead of setting 200-year safety goals, the new study suggests even stronger flood-protection measures – guidelines that may invite even more controversy in the future.

Citing the Valley's "severe" flood risk, the report by a national panel of experts urges California to go further than the legislative steps taken last year to control floodplain development and improve levees.

One of those new laws pushes communities toward that 200-year flood protection, or about double what exists today in most of the Sacramento region.

The report released Thursday instead urges California communities to prepare for the "probable maximum flood," which defines a worst-case storm using historical weather records, storm behavior and runoff intensity.

This would result in protection that exceeds the 200-year threshold and may reach 500-year protection, said the panel's chairman, Gerald Galloway, a former brigadier general at the U.S. Army Corps of Engineers.