Short Term and Seasonal Observation on Shoreline Changes from Kanagachettikulam to Veerampattinam of the Puducherry Coastal Region Using GPS Technique

Abstract

AbstractThe Shoreline oscillations are the response of natural endeavours such as wind, wave and storm which are termed as short term or temporary modification. Shore line changes are the phenomenon of permanent modification to a coast induced by natural calamities such as Tsunami, sea level rise and by human intervention such as the improper implication of structures like the groin, detached breakwaters, seawalls and coastal related activities such as dredging and beach nourishment. In this study, an attempt has been made for the assessment of shoreline position, rate of sediment movement, short term shoreline oscillation and volumetric changes using a most reliable and accepted system of data acquisition and manipulation. Land based survey method was found to be more effective and reliable system for an real time monitoring the response of a beach to seasonal changes and enhances the prediction of an accurate short term shoreline changes which could be confidently used in the development of beach response models of any desired stretch of coastline. Using conventional land based surveying system poses a challenge to the coastal engineer since its tediousness and cumbersome in acquiring, storing and representing the valuable data. The recent developments in land based data acquisition system such as GPS survey can overcome the problems posed by the conventional system which is found to be more swift and reliable. For the above study, a stretch of about 16 km from Kanagachetticulam to Veerampattinam of the Puducherry coastal region situated along the East coast of South India was selected. The selected coastal stretch has been accustomed to abnormal shoreline change from the past few decades and has lost valuable coast and its upland. The assessment study pertaining to the above study area was conducted using GPS surveying technique for an effective real time observation on the periodical shoreline position for both parallel and normal oscillation of the coast. From the observation, it was found that, the coast has experienced tremendous erosion on the Northerly side, maybe due to the construction of the harbour, seawall, and reef structure at the southern side. A mathematical model study was developed for short term shoreline movement using real time data which was very much comparable with real time shoreline observation. In justification to the above, the periodical data’s collected from the study area revealed that, the steepness of the coast has transformed from steep to gentle slope during the Northeast monsoon with only a modest development of beach. During the South west monsoon it was observed that the beach has recessed and the steepness has increased than usual which showed a sign of erosion. A slow recession of beach was observed during the non monsoon period. From the real time observation and model study it was concluded that the coast has witnessed severe erosion along the Northern side of the study area.