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Beach Morphology Monitoring Program
Global Positioning System
Geodetic Control
In order to reference all beach monitoring data to consistent horizontal and vertical datums, a dense network of 76 geodetic control monuments was established during the summer of 1997. Monuments are spaced approximately 3-4 km apart throughout the littoral cell. The network has been referenced to the Washington State Plane (South) North American Datum of 1983 (NAD 83) and the land-based North American Vertical Datum of 1988 (NAVD 88). The Washington Coastal Geodetic Control Network has been reviewed and adjusted by the National Geodetic Survey (NGS). Since its establishment, the geodetic network has been utilized by local and county governments for a variety of projects.
- The Department of Ecology publication Washington geodetic control network: Report and station index (#99-103), is available through the Department of Ecology's Publication's Office. The report provides a description of survey methodology and a complete list of the NGS Data Sheets for monuments in the littoral cell.
- Map of the Columbia River littoral cell geodetic control network
Using GPS to monitor coastal change
Beach morphology monitoring is being conducted using Real Time Kinematic Differential Global Positioning System (RTK DGPS) surveying techniques, widely accepted as an accurate and efficient means to collect coastal morphology data (Morton et al., 1993). The GPS setup includes a disc antenna mounted on a tripod which receives data from satellites, an antenna to transmit the information, and a roving receiver that collects the data on the beach. When surveying beach profiles or walking along a scarp, the roving receiver is contained in a backpack that is worn by the surveyor. Topographic and bathymetric mapping, however, involve the use of a motorized vehicle to make it possible to cover large areas in a minimal amount of time. When performing these surveys, the receiver is attached to either the CLAMMER (topographic mapping) or the Coastal Profiling System (bathymetric mapping). Survey techniques are described in greater detail in their respective sections. A map of the monitoring program sampling locations can be viewed here.
References
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Morton, R.A., Leach, M.P., Paine, J.G., and Cardoza, M.A. 1993. Monitoring beach changes using GPS surveying techniques, Journal of Coastal Research, 9(3), pp. 702 - 720.
