Optical Techniques for Measuring Swash Zone Morphodynamics

Abstract

The use of different optical systems based on computer vision approach, for measuring swash zone morphological changes, is here proposed. In particular, such techniques are able to achieve quite accurate 2D and 3D reconstruction of the sandy bottom in dynamic conditions under regular waves. They are considered truly non-invasive, since there is no interaction of the hardware with the water motion. The optical techniques have been applied both at small and at large scale facilities for the investigation on the seabed interaction with the fluid motion within the swash zone. The performances of well-established more traditional measurement instruments have been compared with the proposed optical instruments both at small and large scales. In both cases satisfactory results have been gathered during the present experimental campaign.

High-resolution single-camera photogrammetry: incorporation of refraction at a fluid interface

“…Within the study of fluid motion, photogrammetry has been used for surface flow visualization (Karthikeyan and Venkatakrishnan 2011) and for measurements of the shape of free surface water waves (Rupnik et al 2015). The capability of photogrammetry to measure surfaces in a non-intrusive way makes it a good alternative to quantify changes in sediment beds in laboratory experiments (Baglio et al 2001;Peter Heng et al 2010;Rieke-Zapp and Nearing 2005;Stancanelli et al 2011;Stojic et al 1998).…”

“…Recent studies have used photogrammetry to measure changes in the morphology of a sediment bed inside a flume (Butler et al 2002;Stancanelli et al 2011). However, measuring through the water interface is a common problem, which depends on the amplitude of the disturbances and on the distance from the measurement plane to the interface (as discussed by Akutina et al 2018, for particle tracking velocimetry measurements through a free surface ).…”