Effect of coastal land use change on coastline dynamics along the Nigerian Transgressive Mahin mud coast

Abstract

Over the last ten decades, the coastal zone has been experiencing population growth and incomparable developments that are in discordance with the dynamic nature of the coastal system. This makes imperative the understanding of complex processes influencing the coastal system. The present study focused on the coastline changes and associated land use/land cover (LULC) patterns along the ∼89 km Mahin mud section of the Nigerian Coast in the Gulf of Guinea of the North Atlantic Ocean during the last 30 years (1987–2017). The study utilized ten multispectral Landsat TM/OLI 8 images in the geographic information system (GIS) environment for the coastline changes and the LULC patterns using maximum likelihood classifier (MLC) algorithm. Net rates of coastline change, on short-term and long-term periods, were calculated from endpoint rate (EPR) and linear regression rate (LRR) statistical methods, respectively. Results showed that the entire Mahin Mud coast is undergoing serious erosion. Over the entire study period (1987–2017), 58% (50.7 km) coastline of the study area experienced retreat. This rapid rate of coastline retreat has triggered land loss of 10.64 km2 to the Atlantic over the last 30 years. The study found that although the changing wave climate has a strong influence on the observed patterns of erosion and accretion along the Mahin mud coast, both marine and anthropogenic processes are acting in concomitance to influence coastal retrogradation along the coast. Therefore to curtail the ongoing coastal retrogradation along the mud coast, there is a need to fashion out the most sustainable approach that will facilitate the realization of the twin objectives of safeguarding the mud coast whilst at the same time maintaining and improving the socio-economic development of the area. Further, there is a need for strengthened spatial planning regulations that would control human activities and specify roles of the various coastal stakeholders in mitigating coastal retrogradation and other related coastal hazards in the study area. Finally, we propose a long-term policy of managed retreat that will curtail communities' exposure to coastal hazards, save lives, and lessen the expenditure of public fund on vulnerable infrastructure and response mechanisms.