Analyzing the Urban Heat Island Scenario Using Satellite Imagery: A Case Study of Matara Municipal Council

Abstract

Urban Heat Island (UHI) is an increasingly prevalent phenomenon in rapidly urbanizing areas, resulting from the conversion of natural landscapes into impervious built-up surfaces, which absorb and retain more solar radiation than vegetated or natural environments. This study assesses the spatio-temporal dynamics of UHI within the Matara Municipal Council (MMC) area in Sri Lanka by analyzing changes in Land Surface Temperature (LST) between 2016 and 2024. Employing Landsat 8 satellite imagery, key indices such as LST, Normalized Difference Vegetation Index (NDVI), and Normalized Difference Built-up Index (NDBI) were derived following rigorous image pre-processing procedures. UHI intensity was quantified by calculating the temperature differential between urban and surrounding rural areas. The results indicate a marked increase in LST over the period, with the maximum LST rising by 3.69°C and the mean LST by 2.51°C, largely attributable to urban expansion and concomitant vegetation loss. Spatial analysis revealed that densely built-up zones exhibit elevated surface temperatures, whereas areas with higher vegetation density show significantly lower LST values, underscoring the mitigating influence of green cover. Correlation analyses confirmed a moderate negative association between LST and NDVI and a strong positive correlation between LST and NDBI, reinforcing the role of urban infrastructure in exacerbating surface heating. These findings emphasise the critical impact of urbanization on UHI intensification, which poses significant environmental and public health challenges, including increased energy demands for cooling and heightened pressure on water resources. The study advocates for the incorporation of green infrastructure and sustainable urban planning measures to alleviate UHI effects. Mapping the spatial distribution of UHI provides essential insights for policy interventions aimed at fostering resilient and climateadaptive urban environments in Matara