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USGS Collaboration with the NPS: Mapping Coastal Vulnerability to Future Sea-Level Rise within the National Parks
Rob Thieler, Jeff Williams, Erika Hammar-Klose, and Greg Booma of the USGS Woods Hole Field Center are mapping the relative vulnerability of the coast to forecast future sea-level rise within the National Parks using a Coastal Vulnerability Index, or CVI. The project is part of the National Assessment Project and is being conducted in cooperation with the Geologic Resources Division of the National Park Service. Based on previous national-scale work by Thieler and Hammar-Klose, the index highlights regions of the National Parks where the physical effects of coastal change might be the greatest. The CVI quantifies the physical contribution to sea-level rise-related coastal change of: 1) geomorphology, 2) regional coastal slope, 3) rate of relative sea-level change, 4) historical shoreline change rates, 5) mean tidal range, and 6) mean wave height. Each variable is ranked on a linear scale. Rankings for all variables are combined to calculate an index value for 1-minute (~2-km) grid cells covering each park. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's vulnerability to the effects of sea-level rise.
To date, the index has been applied at Cape Cod National Seashore (see figures above), Gulf Islands National Seashore, Sleeping Bear Dunes National Lakeshore, and Olympic National Park. Once an initial index is calculated for each park, field checks and meetings with park superintendents, natural resource staff, and NPS geologists take place. These meetings have demonstrated a high level of interest in and need for this type of assessment. NPS staff are using the CVI data for long-term resource management plans, park facilities planning (such as relocating coastal buildings or roads), and assessing long-term threats to cultural resources. For example, data from the Olympic National Park CVI study are being integrated into the park's General Management Plan, the major long-term planning document for a park. These data also provide a quantifiable assessment of shoreline change, one "geoindicator" of ecosystem health, and have been integrated into studies of human impacts on geologic processes within Sleeping Bear Dunes National Lakeshore and Olympic National Park. Preliminary results from the USGS investigations show that there are important differences within and among parks in terms of their vulnerability to coastal change due to future sea-level rise. For example, Cape Cod National Seashore consists of high glacial cliffs, beaches, sand spits, and salt-marsh wetlands. Here, the areas most vulnerable to sea-level rise have the lowest regional coastal slopes, geomorphologic types that are susceptible to inundation, and the highest rates of shoreline change. Conversely, Gulf Islands National Seashore is a low-lying barrier-island system. Within the park, washover-dominated barrier islands with high erosion rates are at the greatest risk. The few dune-ridge barrier-island segments with the lowest erosion rates have the least risk. In some cases, park areas that are at the greatest risk are also culturally significant or the most popular. In Gulf Islands National Seashore, Civil War-era Fort Massachusetts is at great risk due to high rates of soundside erosion, the low-sloping coastal plain and washover-dominated island morphology. In contrast, most of Cape Cod National Seashore's infrastructure is located on high elevation uplands away from the shore, with most high visitor use areas accessible only by foot. The long-term evaluation of such sites has shown that the CVI is useful as an objective tool for scientists and park managers. In the future, the following parks will be investigated: Fire Island, Colonial, Cape Hatteras, Dry Tortugas, Jean Lafitte, Padre Island, Apostle Islands, Point Reyes, American Samoa, and Kenai Fjords.
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in this issue:
Author of Organic Geochemistry Novel Visits |
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U. S. Department of the Interior | U.S. Geological Survey
cover story:
