Shoreline Change Studies Due to Construction of Breakwaters at Ariyankuppam River Mouth in Puducherry – a Union Territory of India, South India

Abstract

Objectives: In the present investigation, the shoreline change studies were carried out along the Pudhuchery coast using an online model such as DHI-LITPACK modules suite. Methods/Statistical Analysis: The study area covers 5 km on the southern side and 10 km on the northern side of the Ariyankuppam river port breakwaters. One year measured data off Puducherry coast at 15 m water depth was used for the estimation of littoral drift and to predict the shoreline changes along the Puducherry coast. The predicted shoreline changes using one-line model show good agreement with historical shoreline changes along the Puducherry coast. Findings: The shoreline change studies with existing coastal structures shows that, on the seawall northern end, the shoreline experiences erosion up to 10m, 20m, 35m, 45m, 55m and 60m after a period of 1, 2, 5, 10, 15 and 20 years respectively and the erosion is noticed for a distance of 1400m along the coast. The shoreline changes study with sand bypassing the net annual littoral sediment of 0.13 x106 m3 from the southern side of the south port breakwater to the northern side of the north breakwater show that shoreline erosion is limited to 20 m and extends 500 m along the coast on the northern end of the seawall. In order to avoid shoreline erosion along the Puducherry coast, the initially implemented sand bypassing operation with beach nourishment has to be carried out with the sand bypassing volume of 0.13 x106 m3 per year at the rate of 0.0188 x 106 m3 per month from March to September. Application/Improvements: After monitoring shoreline behavior with sand bypassing operation for few years, a long term arrangement can be worked out. Moreover, the study indicates that the DHI-LITPACK modules are suitable tools for the estimation of littoral drift and shoreline change studies.