Post tsunami rebuilding of beaches and the texture of sediments

Abstract

Under CS1R-CMRI Network Programme of Coastal Placer Mining beach sand samples have been collected along the Poompuhar-Nagoor beaches of Central Tamil Nadu, India. Representative samples of 2003, 2005 and 2006 have been analysed for grain size and textural statistic studies. In view of the presence tsunami in between, the beach sand composition and texture have been drastically changed, the studies on beach re-building effort has been initiated in continuing the beach sand sample collection to 2006 at regular intervals. The textural statistics have clearly shown the shift in the mean, standard deviation, skewness and kurtosis for both low-tide and high-tide samples. The binary plots have distinctly placed each group of samples according to the period of collection such as pre-tsunami, immediately after tsunami and post-tsunami. Even after giving lapse of one year, the transformed sands though slowly ebbing to reach the 2003 stage of distribution, reaching to the pre-tsunami conditions could not be achieved by the sands. CM pattern also reflects similar condition. However, it shows that the 2003 and 2006 sands have reached similar pattern of distribution, hut the grain size is coarser in 2006 when compared to 2003. Probably, in the next 2 to 3 years, it may reach the pre-tsunami condition.