Historic shoreline changes: an indicator of coastal vulnerability for human landuse and development in Kien Giang, Vietnam

Shoreline movement caused by erosion and deposition is a major concern for managing the coastal zone. Dynamic changes in shoreline location, such as those identified along the Kien Giang coast, poses considerable vulnerability for human landuse and development along the coastline. Rapid assessment techniques are required to update the shoreline maps of affected areas and monitor rates of change. Landsat Thematic Mapper imagery enables monitoring of large coastal sections of shoreline at relatively coarse spatial resolution. We compared shoreline locations of the Kien Giang coast in 1989, 1992, 2001, 2003, 2006, 2008 and 2010, measuring historical change in shoreline positions is formalised into Digital Shoreline Analysis System Application 4.1 (DSAS), an extension to ArcMap developed by the United States Geological Survey and used to interpret rates of shoreline changes. The results show the mean rates of shoreline change over selected surveyed areas vary from -9.3 m yr -1 to 12.9 m yr -1 (End Point Rate), -8.5 m yr -1 to 14.9 m yr -1 (Linear Regression Rate), and -2.2 m to 270.0 m over 1989-2010 (Net Shoreline Movement). Coastal vulnerability analysis showed 35.69% of surveyed coastlines (equivalent to 45.22 km) are ranked as very high vulnerability and high vulnerability, while 64.31 % of shorelines (equivalent to 81.48 km) is ranked as moderate, low and very low vulnerability to human landuse and development. Further aerial photos and SPOT 5 are used for more accurate shoreline assessments.