Effects of Urbanisation on Land Use and Land Cover Changes in Ibadan and Owerri Metropolitan Cities in Rainforest Ecological Zone of Nigeria

Abstract

This study assessed the effect of urbanisation on land use/land cover changes, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built up Index (NDBI) in Ibadan and Owerri Metropolis located in the Rainforest Ecological Zone of Nigeria. Landsat imageries of the two cities from 1990 to 2019 were acquired from the Earth Explorer and Global Visualizations (GLOVIS) database of the United States Geological Survey (USGS), processed and analysed using the maximum likelihood supervised classifier algorithm of the Idrisi Terrset., while the NDVI and NDBI for the locations were computed using ArcMap 10.8. The study established that in Ibadan, built-up increased by 726.64km2 from 312.90km2 in 1990 to 1039.54km2 in 2019 while bare surfaces increased by 134.26km2 from 155.0km2 in 1990 to 289.27km2 in 2019. Forest cover, light vegetation, agricultural lands and water bodies decreased from 712.66km2, 1316.21km2, 891.51km2 and 14.70km2 respectively in 1990 to 253.05km2, 1092.51 km2, 715.55km2 and 12.73km2 respectively in 2019. In Owerri, built-up and agricultural lands increased from 70.32km2, and 78.79km2 respectively in 1990 to 209.16km2 and135.94km2. Forest, bare surfaces, light vegetation and water bodies decreased in areal coverage from 70.16km2, 59.98km2, 255.09km2 and 9.11km2 respectively in 1990 to 21.35km2, 29.12km2, 141.52km2 and 6.19km2 in 2019. The study also revealed that Owerri had a higher mean NDVI value (0.1137) than Ibadan (-0.0422), while Ibadan had a higher mean NDBI value (0.1578) than Owerri (0.0589). The study concluded that urbanisation occurs rapidly in both cities to the detriment of other land cover types and has resulted in drastic depletion in vegetal cover and alterations in other biophysical parameters of the cities as a result of rapid urbanisation. The study therefore suggests strict implementation of the development plans of the cities, and adoption of urban improvement measures.