EFFECTS OF URBAN EXPANSION ON VEGETATION COVER LOSS IN LAGOS STATE, NIGERIA

Abstract

Urbanization is a significant human activity affecting the environment. The study analyzes land use/land cover changes and examines built-up expansion through multi-temporal Landsat images spanning 1985 to 2015. In order to assess the pattern of urbanization, land consumption ratio (LCR) and land absorption coefficient (LAC) have been estimated. In 1985, vegetation cover occupied 54.70%, water bodies accounted for 22.10%, and built-up/open area accounted for 15.80% of the total study area. However, in 2015, vegetation and water bodies reduced drastically to 42.60% and 17.90% while there was a geometric progression in built-up/open area accounting for 39.50% of the entire study area. Also, between 1985-2015, vegetation cover and water bodies declined by 0.74% and 0.63% while the built-up/open area increased at an average rate of 4.99% per annum. The analysis of land consumption ratio revealed that built-up expansion has led to a high level of consumption of vegetation cover and water bodies at the rate of 0.016, 0.007 and 0.006 in 1985, 2000 and 2015 respectively. Similarly, land absorption coefficient accounted for 0.002 and 0.005 between the periods of 1985-2000 and 2000-2015. The rate of land acquisition indicates that development is high over the 30 years leading to a decline of green areas. If the present trend continues, it will lead to severe degradation of urban micro-biome, especially wetland resources, hence the call for a proper land-use policy for Lagos and other similar megacities in Nigeria.