Short-term seasonal changes of the Dzita beach of Ghana using geographic information system and photogrammetry

Abstract

Coastal erosion has become an issue globally. As the sea level continues to rise due to global warming, projections are that erosion would increase. To address the issue sustainably, relevant scientific information such as sediment transport and shoreline dynamics is required at local scales. Over the years, erosion at the eastern coast of Ghana has been mainly evaluated using low-resolution imagery due to the challenges in retrieving high-resolution data in the nearshore region. An unmanned aerial vehicle (UAV) approach was used to assess beach evolution on a seasonal and short-term basis between May 2018 and December 2019. Using the UAV approach, shoreline changes, sediment volume changes, and profile elevation parameters were extracted for the Dzita beach of Ghana. Shoreline changes indicated the dominance of erosion during the first and third phases (May 2018–December 2018 and June 2019–December 2019, respectively) at a rate of −7.23 ± 0.23 and −4.85 ± 0.23 m/yr, whereas the second phase (January 2019–June 2019) showed accretion of +8.44 ± 0.23 m/yr. Beach profiles from the first, second, and third phases had steep and gentle slopes, respectively. From these observations, it was recommended that soft engineering approaches such as beach nourishment should be implemented to protect the shoreline and strict prevention of nearshore sand mining and gravel mining. It is also possible that the beach could go through a cycle of changes. Further studies using this same approach should be done as well as probing into other parameters such as nearshore bathymetry to have a better understanding of beach dynamics as envisaged.