THE IMPLICATION OF URBANIZATION ON LAND USE/LAND COVER AND RUNOFF TRENDS DYNAMICS IN ABEOKUTA (1988-2018)

Abstract

This paper investigates the implication of urbanization on land use/land cover and runoff inAbeokuta from 1988-2018. Land use/Land-cover changes in the study area were quantifiedby extracting data from satellite imagery; the flow data of the Ogun River from 1988-2018was also evaluated. The study shows gross changes in the 6 land cover types identified in thestudy area which were estimated for Landsat imagery (1988, 1998, 2008, and 2018); withsome of the land cover types increasing while others decreased. An estimated increase in thebuilt-up area occurred within the space of 30 years from 38.8km2 in 1988 to 109.3km2 in2018; light forest increased from 6.1 8km2 in 1988 to 118km2 in 2018 while denseforest/swamp decreased from 66.8 8km2 in 1988 to 398km2 in 2018. The Mann-Kendallstatistical technique was used to identify significant decreasing, increasing, and stabletrends in time series data. The study shows both increasing and decreasing trends in thedifferent land use types identified; also that urbanization affects the trend of runoff inAbeokuta from 1988 - 2018, it was discovered that the increase in runoff trend is directlyproportional to the increase in impervious surfaces. The implication of this is the recurrentincidence of flood, loss of lives and properties, loss of arable lands, and humandisplacement. The paper suggests ways of reducing impervious surfaces in the study arealike increasing green spaces, land reclamation, etc. and mitigating the effects of floods likelegislation against building on floodplains, introduction of forest reserves, etc.