The Economic Evaluation for Solving Flood Problems due to the Expansion of Coastal Tourist City

Abstract

          Since many areas in Thailand have suffered from flooding crisis, which is becoming increasingly severe, all sectors have paid close attention to flood prevention and solution. Thus water management and flood prevention strategies are set as the national agenda.

          For the low-lying coastal city, it is easily flooded from rainwater flowing down the mountains. Additionally, flooding in coastal tourist city is an inevitable consequence of unplanned urban expansion, in which natural floodways have been blocked by man-made environment. The economic evaluation for solving flood problems due to the urban expansion of coastal tourist city is part of The surveying, designing, and master plan developing project for drainage and flood prevention systems of Pattaya City FY 2013. The project aims to 1) study flooding problems and its impacts on Pattaya City and 2) conduct the cost-benefit analysis of Pattaya City’s drainage and flood prevention systems and to evaluate and identify the optimal investment option under financial constraints. The study started from surveying the flood-affected areas in Pattaya and conducting meetings to ask flood-affected people for their opinions. Then, through flood simulations using engineering techniques, the study assessed the consequential reduced economic damage of each flood resolution option. The assessment results were then used to support the economic evaluation.

          The study results showed that the flooding in Pattaya was caused by man-made obstructions of natural floodways and the fact that the existing city-drainage systems were too small to accommodate the amount of heavy rainfall. There were 3,073 households and 483 businesses affected by flooding. The flood levels were between 0.3 and 2 meters. The flood caused 98 million baht s’ worth of damage. From the stated problems, four flood resolution options were proposed. Ranging from best to worst economic evaluation results, they were 1) the drainage network system worth 2,724 million bahts to accommodate 5-year recurrence interval of extreme rainfall; 2) the flood-mitigation reservoir worth 3,183 million bahts; 3) the drainage network system worth 3,410 million bahts to accommodate 10-year recurrence interval of extreme rainfall; and 4) the water storage tunnel under Sukhumvit Road worth 5,456 million bahts.