COMPARATIVE STUDY OF COASTAL CHANGE ALONG THE ANDAMAN SEA COAST AND THE GULF OF THAILAND COAST

The study areas cover the coastline of Songkhla, Nakhon Si Thammarat, and Surat Thani provinces in the Gulf of Thailand and Satun, Trang, and Krabi provinces in the Andaman Sea.  The coastal change study employs the GIS, remote sensing technique, and field investigation. The geomorphological map was created using the supervised classification method in ENVI (The Environment for Visualizing Images) program and field investigation. The geomorphological study results indicate that old tidal flat, intertidal flat, subtidal flat, old and young lagoons, marsh, and old and young sandy beaches characterize the Gulf of Thailand coast. The Andaman Sea coast is represented by rocky coast, intertidal flat, and young sandy beach. The comparison of the coastal change shows that the coastal erosion of the Gulf of Thailand is more severe than the Andaman Sea coast.  Most of the Gulf of Thailand coast is now used for aquaculture, whereas shrimp ponds sensitive to erosion have replaced the former mangrove coast. Along the Andaman Sea coast, erosion is protected by the remaining mangrove swamp, and it occurs only in the local area during seasonal storms.