A Study on the Flux of Total Suspended Matter in the Padma River in Bangladesh Based on Remote-Sensing Data

The flux of total suspended matter (TSM), FTSM, output by several large rivers in Asia, has been in decline due to human activities. As the estuary of the Ganges–Brahmaputra River, the Padma River transports a significant amount of suspended matter (SM) to the Bay of Bengal each year. In this study, the TSM concentration (CTSM) and FTSM in the Padma River in the period 1991–2019 were calculated based on the data acquired by the Landsat series satellites and an empirical TSM algorithm model for large, high-turbidity rivers. The results showed that the maximum and minimum FTSM values (318 ± 62 and 73 ± 29 mt, respectively) in the Padma River occurred in 2011 and 2015, respectively. On average, FTSM in the Padma River decreased at an annual rate of 3.3 mt (p < 0.01). The impact of human activities on CTSM contributed more significantly to the changes in FTSM (R = 0.76) than natural factors (R = 0.44). Due to a lack of water conservancy facilities within the river basin, changes in the water and soil retention capacity due to the changes in vegetation coverage were an important human factor (R = −0.79).