Change in Impervious Surfaces and its Impact on Humidity and Atmospheric Temperature

Background and Objective: Impervious surfaces are, mainly, artificial structures that are covered by water-resistant materials such as paved roads, roofs, residential rooftops and walkways. Accelerated urbanization has converted natural areas into impervious surfaces at an alarming rate everywhere in the world. The result of this trend is very harmful to the environment as well as the well-being of humans. Therefore, this study attempts to analyze the increase of impervious surfaces in the Western Province of Sri Lanka which can be considered as a metropolitan area in the country. Materials and Methods: This study analyses the impact of changes in the land surface on atmospheric temperature and relative humidity. For this study, Landsat images were used taken in the years 2000, 2005, 2009, 2015 and 2021. And these images were classified using the supervised classification technique based on the threshold values, which were calculated using 500 ground sample points. Atmospheric temperature and relative humidity maps were prepared using the data from the Meteorological Department of Sri Lanka. Statistical methods such as correlation analysis method was employed to assess the relationship between the factors. Results: The atmospheric temperature has a correlation coefficient more than +0.7 for all the years (+0.7302 in 2000, +0.7994 in 2005, +0.7504 in 2009, +0.7799 in 2015 and +0.7244 in 2021) and it indicates that the relationship is strong positively in between the factors. Also, it can be identified that the relative humidity has a strong negative correlation with the impervious surfaces (-0.6485 in 2000, -0.7847 in 2005, -0.7025 in 2009, -0.7368 in 2015 and -0.79436 in 2021. Conclusion: Increasing temperature and decreasing relative humidity have a significant influence on environmental changes and climate changes and it is a threat to the health of living organisms and their existence. Therefore, environmentalists and urban planners should consider the remaining open spaces for better ecological conditions.