Shoreline Change Analysis in Parts of the Barrier–Lagoon and Mud Sections of Nigeria Coast

Abstract

This study assesses the short- and long-term changing position of the shorelines along the barrier lagoon and mud section of the Nigeria coast using remote sensing techniques. Five shoreline positions, covering a 30-year period (1986–2016), were extracted from medium resolution multi-spectral Landsat satellite imageries using both manual and semi-automatic shoreline extraction methods. Approximately, 533 orthogonal transects were cast using DSAS at simple right angles along the entire coast at 250-m interval. The shoreline change analysis was calculated using the Net Shoreline Movement and the End Point Rate techniques. The results show that the shoreline is highly dynamic; with the average rate of erosion estimated to be 28.08[Formula: see text]m/year and the average rate of accretion estimated to be 20.56[Formula: see text]m/year. While the persistence of erosional tendencies was found mainly in the Okesiri-Abereke-Aiyetoro parts of the mud section of the shoreline, the accretional tendencies was found mainly in the Aboraji-Araromi (barrier lagoon) and the Ajegunle-Jinriwo-Awoye (mud section) parts of the shoreline. The high dynamism of the shoreline is mainly attributed to the increasing frequency of storm surges in the area with over 13 incidents experienced within this period. This study submits that addressing coastal erosion and flooding problems in Nigeria should be based on the system boundary model where the coastal process and dynamics are constantly monitored holistically rather than locally or regionally as it is currently being done. This will also ensure the incorporation of the extent, frequency and intensity of extreme event in the development of adaptation measures.