ASSESSING SPATIOTEMPORAL WATER QUALITY CHANGES IN THE KARNAPHULI RIVER IN BANGLADESH USING REMOTE SENSING TECHNIQUES

Abstract

The major rivers and lakes of Bangladesh are increasingly threatened by pollution resulting from rapid urbanization and the effects of climate change. This study assessed the water quality of the Karnaphuli River using remote sensing techniques, focusing on three key parameters—chlorophyll-a, turbidity, and surface temperature—analyzed through Landsat imagery for the years 2000, 2007, and 2015. These parameters were measured across three representative months (March, July, and November), spaced at four-month intervals, and observed at 15 georeferenced stations. The results revealed a notable decline in chlorophyll-a concentrations between 2007 and 2015 and a steady increase in turbidity levels, indicating a deterioration in water quality from moderate to severe conditions. While remote sensing proved valuable for capturing large-scale Kaiser Mostafiz, Shishir Kumar Das, Mohammad Noor Uddin https://iaeme.com/Home/journal/IJCIET 14 editor@iaeme.com temporal and spatial patterns, its inherent limitation in accurately detecting chemical properties such as salinity, alkalinity, and pathogens highlights the importance of integrating ground-based laboratory measurements. A hybrid approach—combining remote sensing with in-situ data collection—can enhance the accuracy of regression models and allow for the calibration and validation of satellite-derived estimates. Field surveys revealed that many river users have already reduced or ceased their use of river water and are inclined to shift to alternative sources if available, underscoring growing public concern over water safety. If current pollution trends persist, the Karnaphuli River may become unsuitable for domestic use within the next 15 years. These findings emphasize the need for continuous, integrated water quality monitoring and management strategies to safeguard river systems and support long-term water resource sustainability in the region.