Grain size analysis of beach sediment along the barrier bar lagoon coastal system, Lagos, Nigeria; its implication on coastal erosion

Abstract

Beach sediments were collected from four selected beaches along the barrier bar lagoon coastal system Lagos Nigeria namely Badagry, Takwa, Alpha and Eleko beaches. The sediments were texturally analyzed in order to determine the statistical parameters of their grain size distribution. The result shows that Badagry and Alpha beach sands are medium grained with average mean values of (1.10 Ф and 1.14Ф respectively). Eleko beach sediment is coarsely grained with an average mean value of (0.56 Ф) while Takwa Bay beach sediment is fine grained and very well sorted with an average mean value of (2.25 Ф.). This suggest that Eleko beach sediment being coarse grained is deposited in a high energy condition hence less vulnerable to erosion compared to Takwa bay beach sediment which is fine grained and deposited in low energy condition hence more vulnerable to erosion. Alpha and Badagry beach sediment are medium grain and deposited in a moderate energy condition hence more stable to erosional forces than Takwa bay beach sediment. The grain size and amount of sand on a beach depends on wave energy and geological sensitivity of the sediments to the forces of erosion

KEYWORDS: Barrier Bar Lagoon, Beach Sediments, Grain Size Distribution, Erosion.