Abstract

Mudbanks are the unique coastal phenomena with distinct patches of turbid and calm water with a high load of suspended sediment appearing close to the shore during rough sea. The occurrence and migration of mudbanks influence the coastal dynamics and coastline stability significantly. A typical mudbank formation was recently identified along the southern end of the east coast of India near Vedaranyam after the occurrence of Tsunami in 2004. A detailed study was carried out on the coastal morphology, geology, waves, currents, tides and other oceanographic parameters in the sea between Vedaranyam and Velankanni covering 35 km stretch during 2015 to 2016. The extent of clay deposition on the seabed and the formation of mudbank is more on the south side near Vedaranyam and reduce towards north near Velankanni. Such mudbank phenomenon was not existing before the occurrence of Tsunami in 2004. A lot of sediments washed into the sea elsewhere by the Tsunami waves got deposited in Palk Bay is found to be the primary reason for the recent formation of mudbank between Vedaranyam and Velankanni. It is noticed that during southwest monsoon season July and August, there is a deposition of mud composed of silt and clay at nearshore brought from the Palk Bay and also from the offshore deposits. The formation of mudbanks as clay deposit at nearshore gets retreated and disappears with the onset of northeast monsoon in October. This paper presents the detailed study on the reasons for the formation and behavior of this mudbank supported by various field observation.