Field measurements of very oblique wave run-up and overtopping with laser scanners

Abstract

This paper presents the first field measurements with an innov[1]ative laser scanner system, during a severe winter storm. The goal of this paper is to validate this system for measuring wave run-up and wave overtopping parameters during storms with very oblique wave attack. To this end, the paper describes the analysis of the data obtained during storm Ciara (10 - 12 February 2020) and validates the results with data from overtopping tanks and video recordings. Storm Ciara was a highly unique and complex storm, with offshore-directed wind and alongshore-directed waves at the dike. This posed large challenges for measuring the front velocities. The wave run-up heights and the overtopping discharges could be measured accurately with the laser scanners. Reasonable results were achieved for the run-up depths. This has led to several new insights into the probability distribution of oblique wave run-up and the run-up depths of up-rushing oblique waves. The 2D front velocities that were derived from laser data deviated more from a commonly used equation. The wave angle of incidence could not be determined as accurately for storm Ciara, as in previous calibration tests and numerical simulations with less oblique wave attack. This arose from the very oblique wave attack during storm Ciara.