A high-resolution sub-aerial and sub-aqueous laser based laboratory beach profile measurement system

Abstract

This note presents a new method for high resolution beach profiling in,small and medium scale laboratory wave flumes. The combined use of laser distance sensors for elevation (z) measurements and a barcode reader for cross-shore (x) coordinates provides a non-contact, rapid and accurate method to measure beach profiles through the water surface. The system reduces errors from wheeled or contact sensors and eliminates the need to drain the wave tank to perform measurements. The need for a bed follower or motorised traverse and encoder is also eliminated. The system resolves the beach profile both below and above the waterline, with x and z coordinates provided with 1 mm resolution and repeatability of +/-1 mm, so also resolving wave ripples to a high level of detail. The method is demonstrated with an array of 8 sensors spaced across a 1 m wide tank, which enables accurate calculation of the cross-shore distribution of the total sediment transport at short intervals using multiple beach profiles to account for minor cross-tank variation in the bed elevation. (C) 2015 Elsevier B.V. All rights reserved