Suitable Coastal Protection Measures for a Vulnerable Coastal Site Using Numerical Techniques

Abstract

Due to human intervention and nature’s fury, coastal morphology is continuously changing. Some time, longshore transport equilibrium is disturbed due to manmade coastal structure or due to natural wave attack. In such conditions, heavy erosion or accretion takes place at the coastal site. Coastal erosion is loss of land area due to action of waves, currents, winds and gradual increase in the sea level due to global warming. Coastal erosion is a severe problem needing immediate attention to this in an effective manner with a scientific base for evolving suitable design of coastal protective structure. In present paper, some coastal protection measures were evolved for the vulnerable site Sasihithlu, Dakshina Kannada District Karnataka along the west coast of India. Some shops and other buildings have been totally demolished by the severe shore erosion at the present site. Near the site, there is a combined river mouth for two rivers named as Sambhavi river and Nandani river. The mouth is located in the open coast and subjected to high waves of up to 4 m associated with the significant littoral drift. As a result, the severe erosion has been taking place at the south of the river mouth near Sasihithlu. In order to stabilize the shoreline near Sasihithlu, suitable coastal protection measures were suggested by using numerical model LITPACK. For shore protection at Sasihithlu, the performance of two types of protective measures, i.e. groyne field and offshore breakwaters, was assessed through model studies. From model studies, it was found that with six groyne in series, maximum 10 m of accretion would take place between the groyne fields after 10 years. While with offshore breakwaters, maximum 4 m of accretion would occur between the shore and offshore breakwaters in 10 years. The suggested coastal protection works are expected to stabilize the eroding coast line at Sasihithlu.