Abstract:
Video camera systems have been used over nearly three decades to monitor coastal
dynamics. They facilitate a high-frequency analysis of spatiotemporal shoreline mobility. Video
camera usage to measure beach intertidal profile evolution has not been standardized globally and
the capacity to obtain accurate results requires authentication using various techniques. Applications
are mostly site specific due to di erences in installation. The present study examines the accuracy of
intertidal topographic data derived from a video camera system compared to data acquired with
unmanned aerial vehicle (UAV, or drone) surveys of a reflective beach. Using one year of 15-min
video data and one year of monthly UAV observations, the intertidal profile shows a good agreement.
Underestimations of intertidal profile elevations by the camera-based method are possibly linked to
the camera view angle, rectification and gaps in data. The resolution of the video-derived intertidal
topographic profiles confirmed, however, the suitability of the method in providing beach mobility
surveys matching those required for a quantitative analysis of nearshore changes. Beach slopes were
found to vary between 0.1 and 0.7, with a steep slope in May to July 2018 and a gentle slope in
December 2018. Large but short-scale beach variations occurred between August 2018 and October
2018 and corresponded to relatively high wave events. In one year, this dynamic beach lost 7 m. At this
rate, and as also observed at other beaches nearby, important coastal facilities and infrastructure will
be prone to erosion. The data suggest that a low-cost shore-based camera, particularly when used in
a network along the coast, can produce profile data for e ective coastal management in West Africa
and elsewhere.
