LAND USE CHANGE IMPACT ON FLOOD OCCURENCE IN SOME PARTS OF BENIN METROPOLIS

ABSTRACT

This project evaluated land use change impact on flood occurence in some parts of Benin metropolis with a view to understanding some of the factors responsible for incessant flooding in the city. This study was done by obtaining cloudless satellite imageries from United States Geological Survey at different points in time (1990, 1999, 2009 and 2019) and the Secure Copy Protocol plugin on Quantum Geographic Information System (QGIS) was employed to classify these images using the supervised classification method. ROIs were created and assessed, then classes (Water bodies, Built Up areas and Vegetation) were assigned to them so as to be able to properly represent them for the study and a change detection was done for the years to get a proper detailed result to show the effect of Urbanization in Benin City and its Environs under the Land Cover Classes employed in this study. The noticeable changes were tabulated, and the percentage differences were then calculated. Precipitation data were collected from previous work while runoff was calculated from the precipitation data. It was noted that vegetation has significantly reduced over time, from 819.91mi 2 in 1990 to 213.73mi 2 in 2019 which represents a 73.93% reduction and built up areas significantly increased over time, from 93.75mi 2 in 1990 to 700.01mi 2 in 2019 which represents a 646.6% increase. Rainfall also increased significantly within the period (700mm to 2105mm per annum) under review as the three year moving average showed no cyclicity in the pattern of rainfall. Antropogenic activities has greatly impacted on the soil and the bare surfaces are either paved or made impervious with little or no infilteration after precipiation. This has resulted into flooding and it was recommended that government agencies should ensure that land developers stick to environmental friendly approach in carrying out their work.