Video Oberservation of Waves and Shoreline Change on the Microtidal James Town Beach in Ghana

The morphology of sandy beaches is highly dynamic. They are influenced by the geology of the coastal area and external hydrodynamic forcing. On long timescales (years to decades), it is more efficient and convenient to monitor beach evolution through remote sensing technics rather than through direct field measurements. Erosion is a major problem along the coastline of Ghana with over 25 erosion hotspots, including James town. Here, tides, ECMWF EraInterim re-analysis wave data and images covering the beach area have been obtained for the 2013-2014 period. This paper presents preliminary results of the first efforts in processing video-derived observations of waves and shoreline change in Ghana. The pilot application shows a strong potential of the video system in providing fair quality wave data for beach management purposes where video wave characteristics are in good agreement with EraInterim global reanalysis (daily RMSE = 0.8 m and 0.7 m for H-b and T-p, respectively). Shorelines extracted from video suggest large monthly variability driven by wave seasonality while shoreline change shows a subsequent erosion/accretion cycle.