Modelling coastal erosion: A case study of Yarada beach near Visakhapatnam, east coast of India

Prediction of coastal erosion is a challenging field of research with immense application potential in coastal management plans. In the present study, we simulated coastal morphological changes that occurred under normal and extreme wave conditions during a four-month winter monsoon period along a pocket beach at Yarada near Visakhapatnam city. We used Xbeach, a process-based numerical model to simulate the morphological changes by forcing the model with buoy observed wave parameters. Initial beach topography was generated from DGPS profiles surveyed in November 2014 at regular spatial intervals. Model simulated changes in the beach elevation due to accretion and erosion are validated by DGPS profiles re-surveyed in March 2015. During the four-month period, the net sediment transport at Yarada is generally southerly and becomes strong during high wave activity inducing erosion at the northern sector and accretion at the southern sector. The model has simulated the changes in elevation with a high degree of accuracy for the eroded northern sector, and with some disparity along the accreted southern sector. The swash and nearshore processes responsible for the coastal erosion were found to exist throughout the simulation period and intensified during the high wave condition. The paper highlights the importance of modelling studies for conceptual understanding of the beach response to normal and extreme conditions, and for identifying vulnerable sectors of a beach so that appropriate measures can be taken to prevent coastal erosion and loss of land.