Beach surveys











Oregon Beach and Shoreline Mapping and Analysis Program: Pacific Northwest Estuaries and Shores  


The Rockaway Littoral Cell on the northern Oregon coast in Tillamook County


Beach Surface Topography.


Repeated surveys of beach profile sites provide important information on the 2-Dimensional response of the beach over a variety of time and space scales.  However, in order to understand larger-scale changes in the shape and configuration of the beach, which may include effects such as the development of rip embayments, hotspot erosion areas due to El Nios, rip currents, or from major storms, or the movement of sand waves along the beach, mapping of much larger stretches of shore is required.  To achieve this, a Trimble 5800 GPS unit is mounted on a 6 wheel amphibious ATV vehicle and the vehicle is navigated along pre-determined survey transect lines.  The transect lines are spaced approximately 15 - 20 m (50 - 65 ft) apart and extend for some 3 - 4 km (1.9 - 2.5 miles) in length along the shore.  The region that is covered typically includes the low tide line up to the toe of the dunes or bluffs.  The driver is able to navigate along the beach at speeds of 10 - 15 km/h using a Survey Controller TSCe Computer mounted inside the vehicle, which displays the survey lines.  Since the GPS unit samples at a rate of 1 sec, the surface mapping can generate a dataset consisting of some 10 - 15,000 survey points within each study area.



Surface Mapping Locations.


The accompanying map identifies three locations where the beach surface mapping is being undertaken.  The sites include the central part of BayOcean Spit, north of the Tillamook Jetties, and the south-central part of Nehalem Spit.  These data are presently not available as image maps.