Adaptation Strategies to Address Coastal Erosion/Flooding: A Case Study of the Communities in Bang Khun Thian District, Bangkok, Thailand

Coastal erosion is a serious problem in Thailand nowadays. The impacts of coastal erosion on the flat and low-lying Gulf area are expected to be high. The sediment supply to the coasts in the Upper Gulf of Thailand, including Bang Khun Thian district in Bangkok, has been decreasing because of dam constructions, combined with relative sealevel rise (subsidence) due to excessive ground water extraction. The loss of coastal land significantly affects the livelihood of the local people. At present, the Bangkok boundary mark at Bang Khun Thian district is already submerged. The mark was made taller by the Bangkok Metropolitan Administration afterwards. Over the past 28 years, coastal erosion has decreased the shoreline by 4-800 meters, at the rate of 20-25 meters per year. Two villages in Bang Khun Thian, whose major economic activities are shrimp and blood cockle farming, have been affected by coastal erosion. This study aims to determine households' adaptation strategies to address coastal erosion/flooding. It entailed a site visit, discussion with the local people, literature review, and a household survey. The results indicate that households have individually applied three types of autonomous adaptation strategies, which are (1) protection (e.g., stone breakwaters, bamboo revetments, and dike heightening), (2) retreat, and (3) accommodation. Of these, protection is the most popular. Each household had applied more than one adaptation option. The annual adaptation cost is approximately US$3,130 per household, which is equal to 23 percent of the average household income. The average inundated area is about 0.9 hectare per household or 8 percent of the household aquaculture area. The existing government's assistance for coastal erosion/flooding is in the form of stone breakwater, which is ineffective, and flooding compensation. This study showed that individual adaptation strategies, without any collective adaptation strategies, may not be effective solutions due to the occurrence of negative externalities if the neighbors do not apply/maintain their own protection structures. Secondly, due to low educational attainment and lack of other knowledge and skills, farmers could not shift to other occupations. This lack of livelihood choices explains why farmers are willing to pay highly to apply/maintain their protection structures. Lastly, for the protection structure to be effective in protecting the shore, it should be planned for the whole Upper Gulf of Thailand. Thus, the cooperation of the national government, local governments, and the public is necessary to address the problem of coastal erosion/flooding.