Use of high-resolution elevation data to assess the vulnerability of the Bangkok metropolitan area to sea level rise

Using high-resolution elevation data (2 m × 2 m), obtained during a 2012 aerial Lidar survey as part of the Chao Phraya River basin flood management project in Thailand, we assessed the impact of sea level rise due to climate change on the Bangkok metropolitan area. The area below the current median tide of 1.11 m was estimated to be 2,520 km2, with a vulnerable population of 3.9 million, equivalent to 23% of the total population of the Bangkok metropolitan area. In the worst-case scenario of Represen‐ tative Concentration Pathway (RCP) 8.5 (sea level rise of +1.10 m), the affected area would extend to 6,140 km2, increasing the estimated vulnerable population by 86% to 7.2 million. With a sea level rise of less than +1.10 m, the affected area would extend from the Chao Phraya River mouth to Suphan Buri, which is about 80 km inland; how‐ ever, the density of the vulnerable population would increase. The results of this study suggest that sea level rise adaptation measures, such as migration and settlement, must be developed as soon as possible.