Assessment of Shoreline Change Along the Coast of Lagos, Nigeria

Abstract

Shorelines and adjoining land remain an important site for the intensive interplay of socioeconomic development and natural processes. Unfortunately, the Lagos, Nigeria shoreline is always subjected to varied morphological changes in response to small (short term) and large-scale (long term) events as triggered by natural processes and human development. Thus, there is the need to accommodate these changes through a combination of the relative permanence of urban infrastructure and shoreline defense efforts. The study assesses the evolution of the Lagos coast over 20 years, with reliance on archived Google Earth imageries dated between 2001 and 2020 to estimate and visualize the magnitude of erosion and accretion along the Lagos coastline with a focus on sections extending from the east mole to Victoria Island end, which form part of the Eti-Osa Local Government Area (LGA). This was achieved using the Analyzing Moving Boundaries Using R (AMBUR) software package, an R programming language add-in. Over the 20-year period, the Lagos shoreline cumulatively records a mean rate of change of + 0.93 m/year, mean erosion rate of − 1.94 m/year, and mean accretion rate of + 4.84 m/year. Focusing on Victoria Island where shoreline change is observed to be the highest, a mean shoreline change rate of + 6.24 m/year, depicting accretion activities is observed. Victoria Island also recorded a mean erosion rate of − 5.2 m/year and a mean accretion rate of 81.99 m/year. The high accretion rate and positive mean rate of change for Victoria Island and the entire Lagos coast results from land reclamation activities undertaken within the period of study. Further analysis of temporally segmented data into pre-reclamation, reclamation, and post-reclamation periods at Victoria Island reveals that eastward of Victoria Island is an active and unabated erosional activity resulting in disappearing beaches and urban developmental structures during the post-reclamation period. A post-reclamation period overall mean rate of − 4.73 m/year, with maximum erosion rate of 51.25 m/year are recorded for Victoria Island over a pre-reclamation period overall mean rate of − 1.41 and a maximum erosion rate of − 11.8 m/year. Therefore, an appropriate land use and land cover management plan needs to be adopted along the Lagos shoreline region, especially for Victoria Island.

Assessment of coastal change detection on an urban coastline: A case study in metropolitan Manila, Philippines

“…Similar to the study of Adeaga et al [41], which assessed shoreline changes along the coast of Lagos, Nigeria, and utilized the findings to urge the integration of a coastal protection strategy, this study can be used to establish a management plan for protecting Metro Manila's urban coastline. In light of unfavourable changes in land use and the country's need for more sustainable development, this study of Metro Manila's urban coastline and LULC mapping will help decision-makers in identifying vulnerable zones, finding better solutions to existing coastline threats, and implementing policies that will protect the environment from further degradation.…”

Shoreline Change and Coastal Erosion in West Africa: A Systematic Review of Research Progress and Policy Recommendation

“…Boye and Fiadonu [91] underlined that in the western region of Ghana, few areas of the shoreline are accreting, while most areas with a rocky shoreline are eroding at varying rates. Moreover, Adeaga et al [92] indicated that the Lagos, Nigeria, shoreline cumulatively recorded a mean rate change of 0.93 m/year, a mean erosion rate of −1.94 m/year, and a mean accretion rate of 4.84 m/year. The researchers again told us that the Victoria Islands recorded a mean erosion rate of −5.2 m/year and a mean accretion rate of 81.99 m/year over a 20-year period [92].…”

“…Similarly, in Lekki, Nigeria, Danladi et al [87] alluded to policymakers about the need for continuous inspection of the entire Lekki coast and the construction of environmentally friendly coastal defenses like dune barriers and sand replenishment. Again, in the Eti-Osa local government area of Victoria Island, Nigeria, Adeaga et al [92] mentioned to authorities the need to institute appropriate land use and land cover management plans for the area. Considering the serious nature of shoreline change and coastal erosion in Nigeria, Oloyede et al [99] suggested to coastal planners the practicability of their study in identifying the vulnerable portions of the Nigerian coast and subsequently aiding in the development of appropriate adaptation and mitigation plans.…”