ABSTRACT
Coasts are dynamic systems, undergoing changes in form and processes spatially and temporally with respect to marine conditions and geomorphic features. A shoreline change is one of the major indicators to understand the nature of coastal processes/landforms and sea level variations. It also helps to assess intensities of coastal hazards in the geological past. Accurate shoreline change detection helps to delimit prograding and degrading coastlines that enables to suggest appropriate mitigating measures to protect the most vulnerable coastlines. The shoreline detection also helps to understand the impacts of human interventions and development projects along the coastlines. We attempted multi-hazard analysis to identify the most vulnerable coastal watersheds in Tamil Nadu. The results show that the coastal watersheds of Kollidam, Vellar and Godilam are very susceptible to coastal hazards in Tamil Nadu. Hence, these vulnerable coastal watersheds took in this study for detailed shoreline change detection analysis. The satellite images of Google Earth from 2003 to 2019 have been used for shoreline change detection using Digital Shoreline Assessment System (DSAS) in GIS. The study used Shoreline Change Envelope (SCE), Net Shoreline Movement (NSM), End Point Rate (EPR) and Linear Regression Rate (LRR) statistical methods for measuring the shoreline dynamics. A strong rate of erosion (< -1.00 m/yr) is observed in majority of sections of the coastlines. The results indicates that the structural measures constructed along the coastlines, frequency of cyclones and associated storm surge impacts and degradation of wetlands are the major attributable factors which affects the coasts of these watersheds. The scope of this work enables coastal managers to gain a deeper insight into significance of coastlines changes in these watersheds and suggest sustainable measures to protect the coasts.
