Laser Ranging for Monitoring Water Waves in the New Deltares Delta Flume

Abstract

Currently a new wave flume for hydraulic experiments near to prototype scale is under construction at Deltares. In the flume, modern measurement equipment will be installed. One of the potential sensor techniques is Terrestrial Laser Scanner (TLS) based range measurements of water waves. TLS range measurements are a very fast and accurate method for solid surfaces, providing temporal and spatial high resolution profile measurements. The conditions under which measurements of water surfaces with TLS are possible are however less well understood. The main objective of this work is to explore possibilities to apply TLS based range measurements of water waves in the new Delta Flume facility. Hence, influencing parameters on TLS based range measurements from water waves in the laboratory are identified from literature. The influencing parameters are further investigated in a test featuring the SICK LMS 511 and measuring the water surface in the 50 m TU Delft wave flume. Analysis of the results provides an insight into the possibilities and potential problems of the new measurement method. The obtained profile measurements from a originally straight still water surface showed a tendency to bend upwards at the side of the profile. For that reason a surface correction method based on the refraction of the laser beam when entering the water is elaborated. This method is part of the derived wave field reconstruction method. Finally, an optimized water wave measurement set-up for the new Delta Flume proposed.