Tsunami impacts on morphology of beaches along south Kerala coast, west coast of India

The present study is based on the post tsunami survey conducted in January 2005 along the southwest coast of India. Although tsunami affected the whole coastline of Kerala, it devastated the low-lying coastal areas of Kollam, Alleppey and Ernakulam districts leading to the loss of life and property. This paper illustrates the variation of tsunami intensity along the coasts of these districts and the consequent morphological changes occurred in the coastal area during tsunami. Topographic survey data showed that the coastal inundation was rampant along the worst affected regions where the coastal areas are like a narrow strip of land of width 100-400m, lying between the Arabian Sea and the backwaters and the down slope of the coastal area increases towards the backwater side. The data on run-up height showed a variation of 1.9 - 5 m along the study area. Post tsunami beach profiles showed erosion of the foreshore and backshore and landward transport of beach material during the run-up of waves at Puthu-Vypeen. The erosion of the backshore (berm) in several places along the coast was quite evident in the study. This has caused reduction in the elevation which may make these areas more vulnerable to breaching by the high waves, particularly during the monsoon and also during certain spring tides which is a matter of serious concern.