Tag Archives: Flood

Map of sea level predictions can assist waterfront owners

A sophisticated analysis of sea-level rise in Puget Sound and along the Washington Coast offers shoreline residents and land-use planners a new map-based tool to assess potential flood hazards for the coming years.

Click on map to access online interactive map
Map: Washington Coastal Hazards Resilience Network

Sea-level rise depends on two factors: how fast the oceans rise and the rate of vertical land shifts. Uplift, such as what occurs along the Washington Coast, slows the rate of sea-level rise relative to waterfront property. Subsidence, which occurs in Central Puget Sound, results in elevated tides sooner than in stable or uplifting areas. One map on this page shows the measured uplift and subsidence and another shows the uncertainty in that measurement.

Ian Miller, a coastal hazards specialist at Washington Sea Grant, has worked on studies that describe sea-level rise in Island County and on the Olympic Peninsula. The new report, titled “Projected Sea Level Rise for Washington State” (PDF 10.4 mb) goes well beyond what he and his colleagues have done before. It takes a more detailed look at where the land is uplifting and subsiding, according to Miller, the lead author on the new report that involves work by scientists at Sea Grant and the University of Washington’s Climate Impacts Group.

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Be alert for tidal flooding and King Tide photos

Some of the highest tides of the year, combined with a strong low-pressure system, could provide “King Tide” observers with ideal conditions tomorrow (Monday) for taking pictures of near-flood conditions or even flooding in some places.

This is the third year the Washington Department of Ecology has put out a call for photos of high-tide conditions.

Photo of Poulsbo waterfront taken during “King Tides” Dec. 28, 2011.
Photo by James Groh, Poulsbo

“Documenting how very high tides affect the natural environment and our coastal infrastructure will help us visualize what sea level rise might look like in the future,” states Ecology’s “Climate Change” blog.

The King Tide photo initiative began in Australia in January 2009. Washington and British Columbia joined in 2010, followed by Oregon and California in 2011.

Tide tables predict that tides in Bremerton and Port Orchard will reach 13.4 feet at 8:28 a.m. tomorrow. Check on other locations and other days in Washington state at Saltwater Tides.

The National Weather Service has issued a coastal flood advisory for Western Washington because of low-pressure conditions, which could add 1.5 feet to the tide table prediction. That would put the Bremerton area at 14.9 feet. Check out the Weather Service advisory and the Kitsap Sun story.

While it looks like we’ll have a very high tide, it probably won’t be a record. I was unable to find historical data for Bremerton, but the record high tide for Seattle is 22.4 feet on Jan. 27, 1983. The tide tables predict that Seattle will reach 12.5 feet tomorrow, or 14 feet with the added 1.5 feet because of the low pressure.

Historical data can be found on NOAA’s “Tides and Currents” webpage after selecting a station.

Shortly after I posted this, Jeff Adams of Washington Sea Grant sent me an email to point out that NOAA’s numbers need to be corrected by subtracting 7.94, because NOAA uses a different baseline than we commonly use in this area. That would place the record in Seattle at 14.5 feet, much closer to what we may see tomorrow. I should have known that something was amiss with that data. For more on this point, check out Jeff’s blog, Sea Life. 

King Tides will continue through this week, declining slightly each day, then will return on Jan. 14.

I’m certainly not hoping for high water levels, but where they occur it would be great to have some photos. Feel free to send them to me at cdunagan, as well as uploading to the Flickr page called “Washington King Tide Photo Initiative.”