FLOOD IMPACT ASSESSMENT IN THE SURROUNDING AREA OF SUVARNABHUMI AIRPORT, THAILAND

Abstract

The existence of the Second Bangkok International Airport (SBIA) or the Suvarnabhumi International Airport induces more adverse effect to the flooding situation in its surrounding area. Due to limited drainage capacity, during a heavy storm, flooding in the surrounding area occurs over the area. The objective of the study is to find the most suitable flood control and drainage system that can drain floodwater from the surrounding area of 624 sq. km with minimum flood damages and impact to social and living conditions of the people in the study area. This study involves the application of MIKE FLOOD hydrodynamic model for determining the relative effects of flood control and drainage system in the surrounding area of the airport. The results of the study show that flood damages mostly occur in the central and downstream parts of the study area where drainage is insufficient. Flood depth and duration are main parameters used for the estimation of flood losses. Flood mitigation and management in the surrounding area of SBIA is planned by pumping water of 100 m3/s from Klong Samrong canal inside the study area through the proposed drainage channel to the Gulf of Thailand. The existing dikes along boundaries of the study area can protect water from the outer area to enter into the surrounding area of the airport. Flood simulation shows that a canal with capacity of 100 m 3 /s and a pumping station at the downstream end of the canal are required to cope with the drainage capacity for the flood of 100 years return period. A flood drainage channel of capacity of 100 m 3 /s is designed and will be constructed to drain flood from Klong Samrong to the sea. On the other hand, the embankment along the proposed drainage canal project improves traffic flow in the vicinity of the airport. On economic benefit, the project investment cost is Baht 8,410 million. The project benefit cost ratio is 2.12 with the economic internal rate of return of 15.61%. The construction period is 4 years. Environmental and social impacts are investigated and counter measures are proposed to reduce the impacts. The study considers compensating scheme for people who are directly affected by the flood drainage project and those who will lose their lands or their professions. Considerations are also extended to people who are indirectly affected by the project. Institutional framework is recommended to be established to manage flood control and drainage and water resources in the surrounding area of the airport.