Wave and Littoral Processes at Thengapattanam Coast, Kanyakumari District, Tamil Nadu State, SW India

The field investigations were carried out on the beach profiles, breaking wave parameters and longshore currents for a period of 25 months from December 2006 to December 2008 to study the beach dynamics of Thengapattanam coast, Kanyakumari district, Tamilnadu state, SW India. The Thengapattanam beach is well known for its long history, estuary, tourism, manmade structures and fishing activities. Monthly measurements were prepared on littoral environmental observations (LEO) and beach level variations. Longshore sediment transport rates were estimated based on the observed data. The estimated annual gross longshore sediment transport rate was higher due to recent manmade structures and the net transport was towards southerly direction . The beach profile level was lowest in July and high in April and the variation was 35 m. The total volume of sand transported was 840 m3/yr during 2007 and 710 m3/yr during 2008. The wave heights varied between 0.4 to 2.5 m during 2007 and 0.45 to 1.8 m during 2008, whereas wave period was between 8 sec to 15.5 sec and 7 sec to 21 sec for 2007 and 2008 respectively. The study concluded that the beach is experiencing significant erosion. Thengapatanam beach is being subjected to erosion phase during both monsoon seasons and get stable profiles by fair weather seasons. Longshore currents were stronger in June, July and August and steady during rest of the year. The net southerly transport was 1.2*106 m3/yr during 2007 and 0.577*106 m3/year during 2008. The volume variations of the sediments, an account of accretion/erosion were estimated considering the January 2007 profile as the base reference over which the values of other months were compared. The study area is highly vulnerable due to its erosion and other factors.