lithological responses to sea erosion along the coasline from gold hill (Komenda) to Amissano (Saltpond)

Abstract

Sea erosion, attributed to sea level rise and human activity, has become a threatening phenomenon confronting many coastal settlements worldwide. It has caused destruction to many coastal resources. Measures employed to mitigate sea erosion have been to build defence walls, groynes and revetment. However, these structures only dissipate the wave energy and cause further erosion on the coastline. The eastern shoreline of Ghana is the most vulnerable as a result of the increase in fetch distance eastwards and other offshore factors. However, other portions of the country’s coastline are experiencing high erosion activity. There is therefore the need to understand lithological responses to sea erosion to inform policy makers about the processes of sea erosion. The study assessed the extent of sea erosion along the coast of Komenda to Saltpond in the Central Region of Ghana. Sampled beaches were observed for sea erosion activities. In addition, particle size analysis was done by means of the Trask's Sorting Index and the Cailleaux Roundness and Flatness indices on sand and pebble samples from selected localities. The analysis revealed that particle size reduced while erosion increased with increased fetch distance. A field measurement conducted on cliff profiles resulted in an estimated annual rate of erosion to be 4 cm-8 cm. As a consequence, the coastline of the study area, especially the sandy coastline, is expected to lie from 10 m to 15 m inland from the current shoreline, by the year 2100.