Grain Size Analysis of Beach Sand around Eastern Dahomey Basin, Southwestern Nigeria: Implications for Coastal Flooding and Erosion

Erosion vulnerability in Coastal areas around the eastern Dahomey Basin, southwestern section of Nigeria, has constituted momentous threats to the resident communities in this area, thereby resulting in colossal destruction to their infrastructure hence to address the courses and proper remedies to it. The study aimed to examine the grain size constraints of beach sand within the eastern Dahomey Basin. A total of 50 beach sand sediments were obtained from several locations and probed using laser diffraction techniques. Results show a dominant medium-grained sand of 96.0 per cent and 4.5 per cent coarse grained sand, while the fine-grained sand is 0.5 per cent, respectively. Statistical analysis results for grain size distribution revealed the average mean size to be medium-grained (1.63, Mz), sorting to be moderately well sorted (0.717, M. w. st), kurtoses to be symmetrical (0.06864, Syt) and skewness to be mesokurtic (1.44288 Msk) respectively. These also indicate polymodal distributions, otherwise mixed sediment sources. Further probe into this reveals major correlations between grain size parameters and coastal erosion susceptibility. Findings suggest that areas with loose, medium grain sizes and moderately well sorted are more susceptible to coastal flooding than erosion episodes.