Coastal Land Subsidence and Morphological Changes within Nigerian Coastal Areas

Nigerian coastline is increasingly subjected to a number of geomorphic, structural, and morphological changes due to a combination of several processes and change factors. Land subsidence is one of the major events causing geomorphic and morphological changes in the coastal areas. This study utilized GIS techniques, multi-date remote sensing data, auxiliary data, and fieldwork to examine, identify and estimate varying degrees of subsidence in the Nigerian coastal region. A total of 503 study stations were randomly generated along 853 kilometers stretch and 15 kilometers inland trajectory. The subsidence or elevation differentials at each station were computed as the arithmetic difference of the two digital terrain data sets (Aster 2001 and SRTM 2008). Correlation analyses were performed on the subsidence and distance of study stations to oil wells and corresponding land use types around the study stations. Subsidence was found to be positively correlated with distance to oil wells (0.557) while it has a weak negative correlation with land-use types(-0.0610). The study concluded that subsidence taking place in the Nigerian coastal area is compensated by river discharge in the delta region, and sand filling in the Lagos end, and construction of shoreline protection, jetty, and sand filling in the eastern end.