The “Beach Bill,” signed by Oregon governor Thomas McCall in 1967, was created to codify the fight for public beach access and to preserve “such public easements as a permanent part of Oregon’s recreational resources.” The Oregon Department of Transportation performed a control and premark survey, and later a photogrammetric survey, both of which are valuable records of the state of the Oregon coastline in 1967. In the half century since the Beach Bill was passed, significant sea cliff erosion has occurred. A study in the Journal of Surveying Engineering, “Recovery and Readjustment of Historical Ocean Coast Control Stations in Oregon,” sought to combine the historical records with current survey data, to form a complete picture of the erosion that has affected the coastline over the past 50 years.
Researchers Jaehoon Jung, Christopher E. Parrish, Brady Callahan, and Michael L. Dennis needed to obtain updated coordinates for the 1967 shore control survey and developed a three-step procedure to identify the 2D coordinates. The coordinates produced were significantly different, but the authors posit that the discrepancy is a result of poor coordinate quality during the 1967 control. Despite the differences, the team was able to successfully demonstrate the feasibility of using historical survey observations, alongside new GNSS observations to obtain accurate coordinates relative to modern geodetic datums. While this study focuses on the 2D coordinates, the authors also discuss extension to 3D using lidar data. Learn more about this study and how researchers can apply historical survey data in the ASCE Library at https://doi.org/10.1061/(ASCE)SU.1943-5428.0000387. The abstract is below.
Abstract
In 1967, as directed by the Oregon Beach Bill, the Oregon State Highway Department undertook a survey of the entire coast to delineate the shore zone boundary. Survey control points and photo control were established for an aerial survey that same year, but only hardcopy records currently exist. If the 1967 survey coordinates can be accurately updated, the aerial imagery can be processed in modern photogrammetric software to produce digital elevation models of the entire coast, which will enable volumetric coastal change analysis over a period of half a century. The goal of this study was to develop and test a procedure for combining historic and current horizontal traverse survey data to update the 2D control survey coordinates (with the intent to add leveling data and extend the procedures to obtain 3D coordinates in a later study). First, a custom workflow and algorithms were developed to convert the historical survey records to machine-readable format. GNSS data—both static postprocessed and real-time network (RTN)—were then acquired for recoverable marks. An adjustment of the traverse data constrained to RTN coordinates was compared against an independent adjustment of the static GNSS data performed in the National Geodetic Survey OPUS-Projects software. The results show that the methods can produce updated horizontal coordinates for the 1967 survey accurate to within two centimeters.
