SPATIAL MODELLING OF URBAN VEGETATION AND LAND SURFACE TEMPERATURE: A CASE STUDY OF AKURE METROPOLIS.

Abstract

Urban forest provides environmental amelioration and ecological services such as air pollution removal and carbon storage than bare land surfaces. The coupling relationship between urban vegetation and higher atmospheric/surface temperatures in urbanized areas is therefore of great interest to a variety of urban planners and environmental scientists. One of the ecological consequences of dramatic urban growth and land use conversion is the significant decrease of urban vegetation and increase of the land surface temperature (LST). This study focuses on determining the relationship between urban vegetation and LST in Akure metropolis, Ondo State. Normalized Difference Vegetation Indices (NDVI) and LST were derived from Landsat images downloaded from the United States Geological Survey (USGS) website. Landsat TM (1986), ETM+ (2002) and OLI/TIR (2018) images were acquired, and then NDVI and LST maps were produced for evaluation. The correlation analysis between NDVI and LST for the study area was investigated. The results show negative correlation (Built up -0.91, Vegetation -0.20, Bare land -0.97), which implies that LST is increasing with decreasing NDVI in the study area. Increase in temperature over the years are notable in areas associated with commercial and residential activities, and bare lands with no vegetation cover; whereas places with vegetation cover exhibited decrease in temperature over the years. It can also be deduced from the results obtained that surface temperature rates increased about 2°C between 1986 and 2002, and about 3°C between 2002 and 2018. Meteorological data supports the increase in temperature. The effects of increasing surface temperature are devastating. It causes discomfort to the people living in the middle of the city owing to the excessive heat; people with little enduring capability undergo heat stress which can result to illness as well as death.