Title: Remote Sensing and GIS approach to evaluate the UHI effect in Colombo city using Landsat satellite data from 2001 to 2019.
Abstract:
This study discusses the emergence of the heat island effect in Colombo, the capital city of Sri Lanka, due to rapid development activities. The factors contributing to this effect include urbanization and construction, reduced vegetation, increased energy consumption, heat-trapping surfaces, and waste heat.
The expansion of buildings and infrastructure in Colombo leads to the absorption and storage of heat, which is released at night, resulting in higher temperatures. The removal of vegetation decreases the city's ability to naturally regulate temperature. Increased energy consumption from air conditioning, industrial processes, and transportation further exacerbates the heat island effect. Heat-trapping surfaces like concrete and asphalt, along with waste heat generated from various sources, intensify temperature rise in the city.
The study analyzed the relationship between Land Surface Temperature (LST), Normalized Vegetation Difference Index (NDVI), Normalized Difference Building Index (NDBI), and albedo to understand the factors influencing the Urban Heat Island (UHI) effect. The findings show that the UHI effect expanded towards the north, east, and southeast of Colombo City from 2001 to 2019. NDVI demonstrated an inverse correlation with LST, suggesting that vegetation can mitigate the UHI effect. Conversely, NDBI showed a positive association with LST, indicating that built-up areas contribute to the UHI effect. The analysis of albedo revealed that lower values have a greater impact on the formation of the UHI effect, as they result in higher temperatures due to increased solar radiation absorption.
Based on an environmental assessment using the Urban Thermal Difference Index (UTFVI), it was found that 27% of the region experiences high thermal stress. Therefore, the text suggests that future urban planning in Colombo should include mitigation measures to improve residents' quality of life and environmental conditions.
To address the heat island effect, the text proposes strategies such as urban greening, cool roofs and pavements, sustainable urban planning, energy efficiency, and public awareness and education. These measures aim to increase vegetation, promote reflective surfaces, adopt sustainable practices, reduce energy consumption, and inform the public about the impacts of the heat island effect.
Successful implementation of these strategies requires collaboration between policymakers, urban planners, and residents to create a more sustainable and resilient urban environment in Colombo. By addressing the heat island effect, the city can mitigate the adverse effects of high temperatures and promote a more comfortable and livable urban environment.
