Assessment Of Landuse Induced Land Surface Temperature Changes In The Greater Accra Region, Ghana

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This study explored the application of geospatial technology in understanding change pattern of Land use/Land cover (LULC) and associated Land Surface Temperature (LST) variability in the Greater Accra region between 1986 and 2018. Landsat satellite imagery between the months of December and February (dry season) were used for LULC analysis and LST Estimation. MODIS LST data for 1986, 2002 and 2018 were also utilized for the validation of satellite derived LST. The aim of this research was to investigate how LULC changes affects LST. The results of analysis show that LULC in Greater Accra region has changed significantly over the 32-year period. Four major LULC types identified were; vegetation, built-up, bare land and waterbody. Bare land cover type indicated decrease from 1986 to 2018 of 60.22%. Water bodies experienced varying trend of 7.84% decrease representing 9.11 Km2. Vegetation cover indicated 16.20% increase in 2002 and 28.02% decrease in 2018. This amounted to a total of 11.82% decrease in vegetation cover. On the contrary, built-up increased by 654.03% (724.3 Km2) between 1986 and 2018. LST was observed to have increased by 3.05 over the 32-year period of this study across the Greater Accra region. with the highest LST of 36.95 and the lowest of 20.19 , both recorded in 2002. The trend however indicated a significant increase between 1986 and 2002 but a decrease in LST from 2002 to 2018. The increasing trend in LST over time was found to be consistent with the observed urban expansion of the study area. High temperatures are also more apparent along the coastal belt of the region stretching northwards as development spread in the same direction. Total change in LST for the entire period of the study show increases of 3.53 , 3.04 , 2.78 and 2.65 for bare land, vegetation, built-up and waterbody land use/land cover types respectively. LULC association with LST shows that bare land experienced the highest negative change of 60.22% and this corresponded to the highest increase in LST of 3.53 over the same period. Correlation analysis and Coefficient of variation indicated largely that, MODIS LST data validated derived LST from Landsat satellite imagery. Trend of both LST values follow identical pattern with few instances where derived LST is greater than MODIS LST. Both NDBAI and NDBI exhibited a positive correlation with LST. NDVI demonstrated a negative linear correlation while NDWI indicated the strongest negative linear correlation with LST. Land use/Land cover change can be linked to rising Land Surface Temperature Changes in the Greater Accra region of Ghana. The research stresses the need to ensure effective land use planning by relevant regulatory bodies to control urban development and address anthropogenic causes of surface temperature changes.
A Thesis submitted to the Department of Geomatic Engineering, Kwame Nkrumah University of Science and Technology, Kumasi in partial fulfilment of the requirements for the degree of MASTER OF PHILOSOPHY IN GEOGRAPHIC INFORMATION SYSTEMS