Spatial analysis of wetland dynamics and Sea level rise effects on Nigerian coastal area: Case study of Ilaje local government area, Ondo state

Abstract

Coastal wetlands are among the most productive ecosystems globally, providing essential ecological, economic, and social services. The effects of coastline changes mostly becoming noticeable on the coastal wetlands. The study of the hydrodynamics of the coastal wetlands can serve as pointer to the evaluation of the sea level rise. The study assessed the dynamics of wetland resources in Ilaje Local Government Area (LGA), Ondo State, Nigeria, over a 30-year period (1995 - 2025) to extract information on the changes taking place in the shoreline and the effects on wetland resources. The study utilized geospatial analyses on satellite remote sensing data. Findings reveal that marshy land and marine vegetation, which constituted the dominant wetland class in 1995, experienced significant reduction over the study period. A net loss of approximately 20, 153ha of wetland was recorded between 1995 & 2025, representing an annual decline of -671.78ha. Normalized Difference Vegetation Index (NDVI) results indicated shifts in vegetation health, reflecting the dual influence of settlement expansion, shoreline erosion, and recurrent flooding. Water bodies expanded considerably within the period under consideration indicating large volume of water incursion into the previous vegetation area. The landuse projection to year 2035 shows that water body will significantly increase to 11,281ha , the highest change projected. The study confirm sea level rise and coastal subsidence in Ilaje Local government area and the urgent need to reduce incursion of sea water into the marine ecosystem. The study recommends community-based coastal landscape management in order to reduce the negative effects of sea level rise and wetland loses in the project area.