VIDEO-DERIVED OBSERVATIONS OF ALONGSHORE CURRENTS

Introduction
Alongshore currents drive changes of coastal morphology and also embody a potential threat for
swimmer safety. This explains the interest of coastal managers and scientists in cost-efficient
techniques to quantify alongshore flow patterns. Traditional in-situ methods like electro
magnetic flowmeters are expensive, time-consuming, dangerous to deploy during rough wave
conditions and lack synoptic coverage. Recently a new technique was developed which
quantifies flow velocities from intra-wave video observations of the nearshore (Chickadel et al.,
2003). This Optical Current Meter (OCM) was successfully tested against extensive field
experiments at a swell-dominated, intermediate to reflective beach at Duck, NC (USA). In this
paper, we investigate the applicability of the OCM at a dissipative beach at Noordwijk (the
Netherlands), characterized by shorter waves and a mild beach slope.
The Optical Current Meter (OCM)
The OCM was developed at Oregon State University...