Morphological Monitoring of a High Energy Beach System Using GPS and Total Station Techniques, Runkerry, Co. Antrim, Northern Ireland

Abstract

Methodological aspects of GPS (Global Positioning System) and Total Station (Electronic Distance Measurement) surveying techniques were examined as part of a beach monitoring programme which was used to assess morphological variation of a high-energy beach system at Runkerry, Co.Antrim, Northern Ireland. The accuracy of the instruments as well as data processing methods concerning data conversion in different plane coordinates systems is discussed. GPS with Real Time Kinematics (RTK) provides high-resolution control on topographical surveying within limits on the order of centimeter-level accuracy in the horizontal and 2 cm in vertical dimension. Total station (EDM) also demonstrated high accuracy during its use in the monitoring programme. The model of EDM used in this work had a 5 to 6 degrees offset angle for the orientation due to the inherent characteristics of the instrument. A threshold-narrowed point selecting treatment was used to form a beach profile point set for the profile plot and any further processing. This work demonstrates that a two-dimensional translation and rotation for horizontal dimension data conversion is preferable over linear regression method; while the linear regression method for the vertical dimension data is still acceptable. It is suggested therefore that when a conversion of beach surveying data from one plane coordinate system to another is required, then this combined approach should be adopted in the analysis.