Study on Land Surface Temperature and Land Use / Land Cover Distribution in Weligama DS Division, Matara, Sri Lanka

Abstract

Land use/ Land cover (LULC) changes are mainly related to the reduction in vegetation cover and increased built-up areas in terms of urbanization. One of the significant implications of urbanization is the increase of land surface temperature (LST). The main objective of the study was to assess the spatial and temporal changes in LST with LULC dynamics in Weligama DSD, Matara for the period 2005-2020 using Thermal infrared bands (TIR) of Landsat images. The study further aimed at mapping the spatial and temporal distribution of NDVI and NDBI of the study area and developing relationships between LST and NDVI and NDBI to assess the environmental changes in Weligama DS Division, Matara. The LULC analysis revealed that vegetation (46%) is the abundant land use in the study area, followed by built-ups (32%). Water bodies contribute a smaller percentage (06%). LST map showed a gradual increase in land surface temperature from 2005 to 2020. LST analysis revealed that higher surface temperature in built-up and bare surfaces and low in healthy vegetative areas. The minimum LST ranged from 23-24°C, maximum LST ranged from 32-32.4°C and average LST ranged from 25-27°C from 2005 to 2020. The NDBI and NDVI maps showed a gradual increase in built-up areas and a decrease in vegetation, respectively. Further it indicated that the impact of urbanization was high around the coastal line of Weligama city whereas, the inlands of the study area are occupied with vegetative lands. The developed LST regression model showed a strong positive relationship with NDBI (r2 = 0.73, 0.61, 0.76 and 0.64) and moderate inverse relationship with NDVI (r2 = 0.45, 0.60, 0.59 and 0.59) in 2005, 2010, 2015 and 2020, respectively.