Spatiotemporal Assessment of Surface Water Quality and Pollution Index in the Buriganga River Using Geospatial Modelling

The Buriganga River, the lifeline of Dhaka, has suffered severe pollution due to rapid urbanization and industrial discharge. This study evaluates surface-water quality and pollution dynamics from 2010 to 2023 using a GIS-based multi-criteria approach. Three Water Quality Index (WQI) methods such as National Sanitation Foundation (NSF), Canadian Council of Ministers of the Environment (CCME), and the Weighted Arithmetic (WA) were applied to long-term monitoring data from four key stations (Mirpur Bridge, Hazaribagh, Kamrangir Char, Sadarghat). In addition, Comprehensive Pollution Index (CPI) and Organic Pollution Index (OPI), were also computed to capture overall and organic pollution loads. The findings present consistently poor water quality, with NSF-WQI values of 22.35–31.16 (“Very Bad – Bad”), CCME-WQI 41.60–52.38 (“Marginal – Bad”), and WA-WQI 310.41–606.13 (non-potable). Both CPI and OPI values indicate severe contamination, particularly during the dry season, with Hazaribagh and Kamrangir Char being the most polluted zones. Spatial–temporal mapping confirms industrial and domestic effluents as dominant stressors. Among the evaluated models, the CCME-WQI proved most suitable for the Buriganga context due to its sensitivity to seasonal and spatial variability. The findings highlight an urgent need for strengthened effluent regulation, sustainable wastewater management (SDG 6), and continuous GIS-based monitoring to reestablish this vital urban river (SDG 11).