One of the key early steps in preparing for sea-level rise and storm surge is ensuring that the geodetic “backbone,” the National Geodetic Survey (NGS) benchmarks, have long-term viability and provide complete coverage for park coastal zones. This task was just completed for the northeast coastal national parks by the University of Rhode Island and the National Park Service (NPS). Selected existing NGS benchmarks, screened for stability and survey quality, and new benchmarks, installed to augment the network, are positioned at 5-km intervals to provide complete coverage of the park’s coastal zone. Final surveys of each new benchmark used 4 hours of Real Time Kinematic (RTK) Global Positioning System (GPS) data, collected in the field and then processed with National Geodetic Survey tools to ascertain elevation values to within 2–4 cm. Now each park has benchmarks of consistent high quality and stability that are well distributed to support site-specific work such as archaeological surveys, endangered species habitat monitoring, and other NPS activities in the coastal zone. The benchmark data are available in a useful assortment of Web maps, viewers, databases, and services, including the Online Positioning User Service (OPUS) and the NGS geodetic monumentation database (see referenced Web site below for more information). In OPUS, the data are maintained as part of the NGS network. Associated NPS protocols and guidance for installation, survey, processing, and related data standards are available online. This “backbone” provides ground control for many specific follow-on projects: interagency lidar collection following Hurricane Sandy, determining elevations of buildings in flood zones, and calculating sediment budgets for threatened salt marshes. Elevations for hundreds of additional sites, surveyed off this geodetic backbone, are used along with lidar (funded through the American Recovery and Reinvestment Act and Hurricane Sandy Recovery) and other data to model inundation risk for key NPS resources and infrastructure. The NPS plans to extend this geodetic backbone throughout all coastal national parks. The 10 NPS sites benefitting from this initial project are listed below.
- Statue of Liberty National Monument, NY & NJ (including Ellis Island)
- Governors Island National Monument, NY
- Assateague Island National Seashore, MD & VA
- Fire Island National Seashore, NY
- Gateway National Recreation Area, NY & NJ
- Acadia National Park, ME
- Boston Harbor Islands National Recreation Area, MA
- Cape Cod National Seashore, MA
- Colonial National Historical Park, VA
- George Washington Birthplace National Monument, VA
Geodetic backbone sites for Fire Island National Seashore.