Multi-temporal land use/land cover change detection and urban watershed degradation in Olorunda Local Government Area, Osun State, Nigeria

Abstract

In recent years, land use/land cover change has become a critical issue in areas where population-driven urbanization portends a serious threat to urban watersheds particularly in fast-growing cities of developing countries. The emerging urban land use change enhances the degradation process of the urban watershed environment that may result in devastating environmental challenges. This study therefore assesses multi-temporal land use/land cover change detection and the underlying drivers of rapid urban land use change in relation to the watershed environment. Data used include Landsat TM 1986, ETM + 2002 and (OLI/TIRS) 2018, SRTM elevation data, and structured questionnaire. The imageries were processed and classified using the supervised image classification technique. Change detection analysis was further carried out using the post-classification comparison technique. DEM was extracted from the Shuttle Radar Topography Mission data using the ArchHydro extension package of ArcGIS. A normalized difference water index was performed to unfold the surface water availability in the study area. Responses obtained from the questionnaire administration were analyzed using SPSS 15.0 package. The study revealed a 1.1% rate of deforestation per annum, a monumental change in built-up area covered at the rate of 13.2% per year and a remarkable decrease of 78.1% in the area covered by water body over a period of 32 years. It was found that factors of residential land development contributed immensely to the emerging urban land use changes that have impacted the hydrological processes. A conscious watershed conservation policy implementation is required to ensuring water security and preventing flood disasters in cities of developing countries.