Evaluating urban sprawl and land consumption rate in Ilorin metropolis using multitemporal landsat imagery

Abstract

This study examines the rate and pattern of urban expansion from 1991 to 2021 using Landsat imageries of 1991, 2002, and 2021. First, the images were classified into a built-up area, open land, vegetation, and water bodies utilizing the supervised Maximum Likelihood classification algorithm. Subsequently, the classified images were used to determine land use/cover change between 1991 and 2002, and also between 2002 and 2021. The result has shown that the city expands radially from 1916.77 ha in 1991 to 3284.82 ha in 2002, and 8770.79 ha in 2021, representing 5.84%, 10%, and 26.72%, respectively, at a growth rate of 9.98% (1991-2002) and 40.02% (2002-2021). It is equally revealed that between 1991 and 2021, the vegetated land decreased from 56.33% to 20.64% whereas the open land from 36.4% to 51.52%. This study allowed measuring the pattern and rate at which urban expansion had occurred in Ilorin. The pattern of sprawling in Ilorin is radial with amplified development along the major roads that lead to the city. This has largely impacted the natural ecosystem and associated environmental problems, including soil degradation, erosion, and reduction in the available land for crop production. It is, therefore, important to implement sustainable measures that evolve policies stimulating urban regeneration, integrated into the ongoing development of Kwara State geographic information system (GIS) to effectively plan, allocate land resources, and monitor development in near real-time.