Multi-decadal shoreline change analysis in coast of Thiruchendur Taluk, Thoothukudi district, Tamil Nadu, India, using remote sensing and DSAS techniques

Abstract

Shoreline position has been forwarding or retrograding due to many factors, among them climate change and human interferences play a major role. The shoreline changes can be analyzed by various methods. In the present study, Linear Regression Rate (LRR) method is applied for the demarcation of rate of shoreline changes along the coast of Thiruchendur Taluk, Thoothukudi district, by using Digital Shoreline Analysis System (DSAS). It is an extension tool in ArcGIS. The length of the coast is 45 km. The coastal zone is further divided into three coastal zones based on their administrative division (panchayat union). The zones are Alwarthirunagiri coast, Thiruchendur coast, and Udankudi coast. These zone divisions are done for detailed mapping. Multi-date of remotely sensed data was used for mapping the details. These data are georeferenced with the UTM projection of WGS1984 and digitized the shorelines with the FCC color image. Transect lines were generated using DSAS tool. The transect lines starting from 752 to 1210 were used for present study to assess the shoreline changes. The tool had generated the LRR Statistic reports on each transect lines for all shorelines. The statistic report has been classified into five classes, viz., high erosion, low erosion, stable, low accretion, and high accretion. Finally, the shoreline has classified with LRR reports. The overall result shows that, low accretion has notied at 36 km (79%), high accretion perceived at 8.7 km (8.7%), and stable has observed in 8.3 km (8.3%), along the coast. Whereas, low erosion was noticed around 1.4 km (3.1%), and no high erosion was noticed along the study area. Thiruchendur and Udankudi coastal zones are mostly perceived low rate of shoreline changes with the rate from 1.02 to 3.96 m/year, happen in 18.9 km and 16.5 km, respectively. But, Alwarthirunagiri coast zone, low rate of erosion is noticed along the 1.4-km length of the shore. The study has concluded that, most of the Thiruchendur Taluk coastal areas are under the low-rate accretion, and the same area is observed as erosion along the coast due to both natural and human activities. Thiruchendur Taluk has major coastal cities, and a large number of people live around the coast. There are numerous natural resources and tourist places around the coast. Therefore, this coastal area shoreline changes studies should be examined.