CLIMATE CHANGE AND MEGACITIES
FLOODING ALONG THE URBANISING ATLANTIC COASTLINE OF LAGOS, NIGERIA
Keywords:
Sea-level rise, low-lying areas, policy and planning, coastal inundation, sustainability.Abstract
The identification of risk regions is important for prioritising their risk mitigation and response efforts. In this paper, we simulate flooding and identify flood-prone as well as inundation areas between 1986 and 2023 in Lagos, Nigeria, using geospatial tools available in the Digital Earth Africa (DEA) Sandbox. By leveraging satellite imagery from Landsat and Sentinel-2 through the Water_extent_WOFS and Water_extent_sentinel notebooks, we evaluated longterm and seasonal water extent using the Modified Normalised Difference Water Index (MNDWI). A 3D terrain model was developed to assess water flow, accumulation, and coastal inundation risk. Also, through document analysis, we identified key policy options that can be strengthened within the study area. Overall, we found that some areas that were inundated with water before 2023 were revealed to be land in 2023, suggesting that
water has either receded from these regions or they are being sandfilled. Meanwhile, some areas that were inundated before 2023 have remained flooded to date. These areas might have certain characteristics, such as natural depressions or poor
drainage, that make them more prone to prolonged water presence. Also, we found new areas that have only become flooded
in recent times, possibly due to changes in land use, climate patterns, or other factors. The implementation of the DEA sandbox geospatial resources shows the utility of the toolbox for environmental resource monitoring and city planning. With respect to the developing Lagos Megacity, our findings highlight the importance of paying attention to the flood-prone areas of the city to ensure sustainable megacity development. The paper concludes with recommendations for policy, urban planning and climate adaptation.
