|"As we continue to refine studied data, we will have something that will illustrate how the shoreline may look in the future, and help planners avoid the same disasters we're experiencing today."|
Washington Department of Ecology
After years of watching sand build on Washington beaches, coastal resource managers were caught off guard when severe erosion began putting communities in danger. With no scientific data on which to base response decisions, a massive erosion study was embarked upon to help guide managers in long-term planning.
"We realized there was an overall lack of coastal data to help managers and planners make decisions," says Brian Voigt, National Oceanic and Atmospheric Administration coastal management fellow working for the Washington Department of Ecology. "Without information to do wise and effective planning, there was a real danger that we could get into a bigger nightmare and experience some additional disasters along the coast."
The Southwest Washington Coastal Erosion Study is utilizing new technology to examine coastal geology, processes, and natural hazards, and to predict and avoid emergencies along the coast between Tillamook Head, Oregon, and Point Grenville, Washington. The U.S. Geological Survey (USGS) Coastal and Marine Geology Program and the Washington Department of Ecology are jointly directing the five-year study.
Historically, Voigt says, Washington's beaches have been some of the only ones on the west coast to experience accretion. Because of this, coastal management activities in the state have been focused primarily on the Puget Sound.
This changed in 1993 when a jetty breach occurred in one of the state's harbors. Pounding waves carved a trench that cut through a state park and "seriously jeopardized" the city of Westport's water-treatment plant, aquifer, and water wells, Voigt says. The following year, the Department of Ecology began inventorying the beaches in southwest Washington and found chronic erosion at nearly all the headland points. By 1995, erosion was beginning to undermine an area of state highway and was threatening commercial cranberry bogs.
With evidence of escalating erosion, the vulnerable counties joined with the Department of Ecology to approach the state legislature about funding a study that would document historical and current shoreline change rates, and assess and ultimately predict the effects that sediment supply has on the position of the shoreline.
Voigt says it wasn't difficult to persuade the lawmakers that the study was needed. "The Westport crisis developed an awareness of the potential for disaster along the coast. It really woke a lot of people up to the fact that we need to understand what's going on with our coasts." The fact that communities were already spending millions of dollars on temporary mitigation measures was another influential factor, he says.
The focus of the study is the Columbia River littoral cell. Sand from the Columbia River traditionally has been the source of accretion along the 100-mile stretch of coastline that is now under investigation, says George Kaminsky, coastal engineer for the Washington Department of Ecology. Now, major dams along the river's path and hundreds throughout the drainage basin may be slowing the water flow enough to cause a substantial decrease in sediment reaching the ocean. The construction of jetties at the Columbia River and Grays Harbor also has impacted the configuration of the coastline.
Scientists from the USGS are "looking at the past 4,000 years," investigating sediment budgets, framework geology, and inner continental shelf processes, Voigt says. The Department of Ecology is conducting physical monitoring to determine changes in the shoreline and beaches.
New technology is making it possible for Department of Ecology researchers to measure the entire beach, not just individual lines, and to produce a surface map of beach topography, Voigt says. For instance, to complete a beach profile survey, a scientist with Global Positioning System (GPS) equipment mounted on a backpack walks from the dunes to the water. To generate a three-dimensional topographic map of the beach surface, researchers are using the CLAMMER (Coastal All-terrain Morphology Monitoring and Erosion Research vehicle), which is a small, six-wheel-drive vehicle that features GPS equipment mounted to the frame, and an on-board laptop computer to store the data. To map shallow water bathymetry, depth finders and GPS are attached to wave runners. These surface maps are then directly compared within a geographic information system (GIS).
"When we add all the different pieces together we will be able to see if there is an overall reduction of sand in the system," Voigt says. "When we get all the numbers, we'll be able to feed the information into modeling systems to project future coastal conditions. As we continue to refine studied data, we will have something that will illustrate how the shoreline may look in the future, and help planners avoid the same disasters we're experiencing today."
Now two-and-a-half-years into the study, preliminary findings suggest that the erosion hot spots are resulting from long-term regional erosion trends, Kaminsky says. "It appears that the rapid beach accretion enjoyed for so long by our coastal communities has largely ended, and long-term trends will be governed by the amount of sediment in the system."
Some of the study's initial products include historical shoreline change maps, aerial photo mosaics, a network of 77 survey monuments, beach and nearshore surveys, and informational reports. A video, web site, and other information pieces about the study also have been produced to help inform the general public.
"We're really developing an original data set that is critical for managers and planners to be aware of," Voigt says. "What we will be able to do is show people a projection of how the beach will change over time. If we'd had this information 20 years ago, we would not have been caught by surprise."
For more information on the Southwest Washington Coastal Erosion Study, point your browser to http://www.ecy.wa.gov/programs/sea/coast/erosion/study.html, or contact Brian Voigt at (360) 407-6568, or email@example.com.