Application of Video and Unmanned Aircraft Systems to Study Morphology of a Reflective Beach at Dzita, Ghana

The use of video camera systems (VCS) to monitor coastal dynamics has been in existence for close to three decades. VCS enable a high spatiotemporal frequency analysis of shoreline migration. Video camera usage to measure beach intertidal profile evolution has not been standardized globally and the capacity to obtain accurate results requires authentication by various techniques. Applications are mostly site specific due to differences in installation.

This study examines the accuracy of the intertidal topographic data derived at a data deprived site from a video camera system compared to unmanned aircraft system (UAS) surveys of a low-energy reflective beach. Using one year of 15-minute VCS data and one year of monthly UAS observations, the data shows a good agreement (r ~ 0.7; p~0) between UAS and VCS intertidal profiles and RMSE of 0.8 m. Intertidal profile elevations that are underestimated in VCS are linked to camera view angle and gaps in data. Beach slopes are found to vary between 0.1 and 0.5, with steep beach in May to July and gentle beach in December. High Dzita beach dynamics occur between August and September that corresponds with high wave conditions. Erosion rates are estimated at 7 m/yr. At this rate, important facilities including an NGO infrastructure are scheduled to be eroded in the next three decades. The data suggest the steep nature of the beach could influence offshore sediment drift that is related to the high erosion rates. The resolution of the video-derived intertidal topographic profiles confirmed the suitability of the method in providing beach surveys with evolution matching that required for a quantitative analysis of nearshore changes. The data suggests that VCS measurements could make it possible to produce profile data for effective coastal management.