Sediments Grain Size Sensitiveness of the Thakuran River Basin of the Sunderbans

Geomorphologically defined areas like mid-channel bars or flood-tidal delta, river mouth bar or ebb-tidal delta, point bar, swash platform, wash-over flat and river banks (levee) have been identified in the Thakuran River of the estuarine Sunderbans. These areas are delineated based on studies of the granulometric properties. A coarsening of graphic mean size (MZ), betterment of sorting (ó1), and negative to positive skewness (SK1) have been noticed from the seaward to landward direction. Variations of these textural parameters are related to decreasing energy levels along the same direction. A bipartite granulometric model of sedimentation having sand-to-mud from the seaward to the landward direction of the tidal creek has been discerned. This is in contrast to a tripartite granulometric model typical of estuaries.