Identification of littoral cell and its impact on shoreline dynamics along the Purba Medinipur–Balasore coastal stretch, Bay of Bengal, India: A numerical modelling and geospatial study

Abstract

The northern boundary of Bay of Bengal, between Subarnarekha and Rasulpur River is divided into five coastal sectors by the four inlets, namely, Talsari, Ramnagar, Jaldha, and Pichaboni. Each sector being characterized by severe coastal erosion, beach lowering and narrow beach segments. To bring such coastal areas under proper coastal management, delineation of littoral cell and sub-cell boundaries and assessment of sediment budget is required. This study attempts to identify these hydrodynamic characteristics, by investigating the wave-induced radiation stress of dominant wave, derived from offshore wave in order to simulate longshore current and associated sediment transport using the two-dimensional deterministic MIKE 21/3 Coupled Model that is based on two dimensional shallow water, Reynolds averaged Navier–Stokes equations and fully spectral wave action conservation equation. The shoreline dynamics in terms of shoreline retreat or spit formation, is quantified by Digital shoreline analysis system (DSAS)The result of the simulation shows the dominant westerly and comparatively weaker easterly longshore flow and the resultant bed level changes. By analysing the diverging and converging flow pattern of littoral current, rate of bed level change and magnitude of shoreline oscillation, six and five littoral sub-cell (LSC) have been identified for westerly and easterly circulation respectively. The coastal inlets indirectly influence the flow direction through the development of different depositional features at mouth. Because of that inlet mouths often function as littoral cell boundaries.Periodic observation reveals that the introduction of shore-normal engineering structures has positive impact on beach nourishment and inlet stability.