Monitoring the Impacts of Urbanisation on Environmental Sustainability Using Geospatial Techniques: A Case Study in Colombo District, Sri Lanka

In recent years, a critical understanding of the sustainable urban environment has become central to many urban studies, leading numerous scholars to employ geospatial tools and techniques to examine the sustainability of growing cities in the developing world. In this study, the Colombo district where the capital city of Sri Lanka is located, was selected with the prospect of monitoring the impacts of urbanization on environmental sustainability. The study uses the spectral indices of remote sensing, including the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built-Up Index (NDBI), Land Surface Temperature (LST), and Environmental Criticality Index (ECI) to detect the aspects of urbanization and environmental sustainability of the study area. The results show that there has been a dramatic increase in environment criticality from 1997 to 2008, and a slight decrease indicated from 2008 to 2017, coinciding with the government urban planning initiatives. However, the decline of environmental sustainability of the city center and along the transport corridors could be identified in the context of this study. Finally, by drawing attention of the landscape and land use planners, the study emphasizes the aspects that should be considered in future urban planning.