Coastal Protection Measures for a Barrier Island Along East Coast of India - Physical Modelling

Barrier islands are shore parallel sand deposits formed by the action of waves and winds and are separated from the mainland by tidal creeks, bays, and lagoons. These narrow strip of sand bars are most vulnerable to sea level rise and storm surges which are the consequences of changing Earth’s climate. As barrier islands are formed because of wind and waves, which shift according to weather patterns and local geographical features, they are most dynamic and complex in nature. As a case study, the barrier island of Sriharikota along East Coast of India stretching about 44 km parallel to pullicat lake (second largest lagoon in India) and Bay of Bengal is chosen as the study location. From the last two decades, the shore front of the island is experiencing rapid erosion causing high risk to the infrastructure on the island. So, there is an immense need of long-term shoreline management strategies which are environmentally friendly and sustainable solutions. The present study pertains to an experimental study on submerged rubble mound breakwater with a scaled model of 1:21 for three water depths of 0.4 m, 0.45 m, and 0.5 m. The wave heights are varied in the range of 0.05 m to 0.2 m with corresponding wave periods of 1.0 to 2.4 seconds. The performance of the submerged breakwater has been assessed by analyzing the hydrodynamic coefficients (i.e., wave reflection, transmission and loss characteristics) using two probe method. The results of the experimental study showed the significant impact of relative submergence, crest width, wave steepness and sea bed slope on the hydrodynamic performance of the structure.