Submitted map The community of Bay Center on Willapa Bay in Southwest Washington will be virtually an island if the current mean tide level (yellow line) changes with rise in ocean level to the mean high water (red line).
Submitted map The area of Tera Mar just north of Oysterville on the Long Beach Peninsula will become submerged during high tides if ocean levels rise.
Maps reveal extent of worries for Bay Center, Oysterville
By ELIZABETH LONG East Oregonian Publishing Group
Washington’s Pacific County covers 928 square miles, but by 2100, based on predictions of ocean level rise caused by global climate change, the county could lose 20 square miles to the ocean.
With forewarning and planning, hazards can be reduced.
Good long-range planning requires accurate and specific information. Usually planners use historical data to anticipate where dangers lie. Areas that have had earthquakes or flooding in the past are likely to have them again. Building codes or zoning laws are adjusted to help minimize the damage.
But global climate change brings new dangers, and the historical maps may no longer be an accurate guide for good planning. Areas that previously were designated 100-year flood plains may become flooded far more frequently. Coastal ranges may become more susceptible to erosion and storm damage. Lake levels may rise as a result of an increase in the water table, threatening homes.
As the title of a global warming conference held in Seattle in October 2005 states, “The future ain’t what it used to be.” The past is no longer a reliable guide.
A Geographic Information System analysis of Pacific County was done using a projected rise in ocean level of 3.4 feet by 2100. The Intergovernmental Panel on Climate Change estimates an approximate rise in ocean level of three feet by 2100, and a Canadian study suggests the Pacific Northwest may experience half as much again again as the global average.
The analysis uses the current mean tide level, shown as the yellow line on the maps, as a baseline. That level, which measures 4.78 feet above the mean lower low water level, is the average of all high and low tides. Sometimes the water level is higher, sometimes lower. If, as predicted, the ocean rises 3.4 feet, the mean tide level will shift to the current mean high water level, shown as the red line on the maps.
At one time, a bayfront development was planned for Tera Mar, just north of Oysterville on the Long Beach Peninsula. But the analysis shows potential property owners might be wise to avoid the area.
Bay Center, bracketed by Willapa Bay and a river, will become a virtual island at high tide. Tides will push further up the drainage canal in Ocean Park, with accompanying erosion. But knowing areas that will be affected by a sea level rise, such as in Tera Mar, Bay Center, and Ocean Park, can help planners mitigate those effects.
As a similar case study for Charleston, S.C., concludes, “No one knows how many other coastal communities must make decisions in the near future that depend on the risk of future sea level rise.
“But in view of the substantial future costs that could be avoided by cost-effective design modifications today, it would be prudent for all master drainage studies in coastal areas to assess the implications of future sea level rise and climate change.”
