Abstract:
To study the linkage between El Nino and coastline change. The coastlines of Phetchaburi and Prachuap Khiri Khan provinces were selected to be the study areas. The study focused on the areas which were directly changed by natural environment. El Nino has some effects on oceanic and atmospheric systems therefore the monthly wind, wave and rainfall data at Hua-Hin and Phetchaburi meteorological stations were analyzed to investigate the linkage of El Niño on coastline change. The study times were divided into two periods; during and after El Niño periods. The data were collected during years 1981 to 2005 (25 years) to calculate the anomaly data and to find correlation with Southern Oscillation Index (SOI). The result only showed high values of correlation (R[superscript 2]) and coefficient correlation (r) between wind anomaly and SOI at Phetchaburi meteorological station. For the anomalies of rainfall and wave, the result showed no significant relation to El Niño. This study divided coastline into three areas; Lampakbia (spit and mangrove), Puktein and RAMA 6 military area (sandy beach) to determine the percentage of changed coastlines by comparing between the two periods. The result showed that the coastlines of Lampakbia were constant in both periods and lead to a conclusion that there was no link to the El Nino effect. The percentage of changed coastlines of Puktein and RAMA 6 areas was negative anomaly which indicating an erosion state and conformed to the study hypothesis. Since the percentage of coastline change may not be directly affected by El Niño, therefore, the Land Cover Classification was used to find the impact of human activities on coastal area. Then the cumulative impacts of El Nino as well as natural and human activities were considered.