Morphodynamics of Barrier Spits and Tidal Inlets of Subarnarekha Delta: a study at Talsari-Subarnapur spit, Odisha, India

Abstract

The barrier-inlet system along the shoreline of Subarnarekha deltaic coast of Odisha state has most diverse morphologies of any barrier system in Indian coast. The delicate adjustment between wave and tide generated processes on the moderate energy coast allows only slight to moderate changes in either of these processes to result in significant and dynamically developing morphologic responses. Some of the natural phenomena such as cyclones induced opening of tidal inlets across the barrier spits, closure of inlets due to longshore transport of sediment, and changes in sediment input into the coastal zones are the result of responses produced by the interaction of energy levels and availability of materials in the coast. Tidal basin behind the barrier spits of Subarnarekha delta plays a significant role in controlling inlet morphology as well as tidal prisms. The various modifications by development have resulted in important morphodynamic changes in the barrier inlet system. These include the fishery ponds, fishing harbours in the basin, hardening of the coast along the banks of inlets by engineering structures, and construction of earthen embankments along the basin fringe areas. Such activities have inhibited normal coastal processes in the region. Severe erosion of barrier spits at the southwest corner adjacent to the inlet mouth, and cliffing of the barrier based beach ridge-dune complex on the seafront areas are examples of instability in the system. Impacts of above activities and basin filling by sediments with associated change in energy levels inhibit the environment of barrier spits and tidal inlets of Subarnarekha delta from responding to open coast processes of the Bay of Bengal at present.