Yes, it is heavy sedimentation. Each year the Ganges, Jamuna, and Meghna Rivers of Bangladesh transport more than one billion tonnes of sediment from their catchments in India, China, Nepal, and Bhutan to this delta region.
Now, let me do some math on the approximate volume of 1 billion tons of sediment. A cubic meter (m3) of soil weighs approximately 1.8 tons. So, if it is 1 billion (1,000,000,000) tons, then the volume is about: 1,000,000,000 tons/1.8= 550,000,000 m3.
Our Seaepths near the shorelines are shallow, less than 20 meters deep. For the sake of argument, if we assume this depth at 50m, the sedimentation would create a new land area of 10 km2 every year.
Someone can do his/ her math because I did it in a hurry.