Assessment of Performance of a Groin Constructed on Puducherry Coast - A Case Study

India, having coastline of about 7500 kms, is facing severe problems of erosion, threatening millions of lives. Construction of planned ports, harbours, and industries accelerate the erosion and degrade the environment along India's coastline. The reduced rainfall, due to changes in the monsoon pattern over the years, has in turn lessened the sediment inflow into the oceans. This reduction in the sediment flow leads to considerable erosion along the coastlines. Groins are typically built to stabilize a number of natural or manmade beaches against erosion, mainly due to a net loss of beach material. The influence of a groin is accretion of the beach material on the updrift side and erosion on the downdrift side. Puducherry, a Union Territory, is facing severe coastal erosion problems along some of the stretches, especially to the north of Puducherry harbour. In this study, the status and impact of a 60 m long groin constructed at Vaithikuppam, on Puducherry coastline is studied. A coupled and fully integrated 2D model for waves, currents and sediment transport is used for the assessment. The hydrodynamic processes and morphological stability near the groin are studied using field observations and bathymetric data. The numerical model results were validated and found to be in good agreement with the field data. The hydrodynamic conditions and sediment transport patterns are predicted using the model results and the impact of the groin on the morphological characteristics are established and presented.