Can GIS and Remote Sensing Techniques Reveal the Impact of Open Landfills on Air Quality?: A Case Study of Colombo, Sri Lanka

Rapid urbanization and continuous population growth in Sri Lanka have led to increasing waste generation, with open landfills becoming a significant environmental concern. Air quality indices, where available, show moderately high values and there is no feasible method to monitor the overall urban air quality in Sri Lanka, mainly due to financial constraints. Hence, this study investigates the impact of open landfills in the Colombo district on urban air quality using GIS and Remote Sensing techniques. Supervised image classification identified the open landfills, and Sentinel-5P Satellite data were used to extract Methane (CH4) and Carbon Monoxide (CO) concentration through Google Earth Engine. Pearson correlation was performed to assess the relationship between the pollutant levels and the proximity to the open landfills, while multivariate linear regression analysis was performed to assess the in-fluence of wind speed and distance from open landfills. The results revealed an increase of open landfill areas as a result of population growth and poor waste management. Spatial trends in CH4 were not detectable due to data limitations in Sentinel-5P, while seasonal effects were evident in CO distributions. Weak Pearson correlations were observed due to the low spatial resolution satellite data while multivariate linear regression analysis highlighted the influence of wind speed on pollutant concentration. The study recommends downscaling satellite data to enhance the spatial and statistical analyses accuracy.