Comparison of flood management options for the Yang River Basin, Thailand

The Yang River Basin, Thailand, has always been subjected to flooding, but due to recent developments in land use there is an increase in the vulnerability in several parts of the river basin. To mitigate impacts of flooding, both structural and non-structural measures can be taken. This paper discusses three scenario simulations focusing on flood retardation, retention, and damage mitigation measures. A main tributary was simulated by a process-based hydrological model (SWAT) and coupled to the 1D/2D SOBEK river routing model. The first scenario focused on retarding basins, the so-called natural flood storage, to reduce downstream flood flows by storing excess floodwater in low-lying areas and releasing it after the peak has passed. The second scenario concerned a green river (bypass channel) to provide storage and drainage through a large, shallow retardation basin, and an outlet for water discharge from upstream. The third scenario concerned the effect of dikes to protect areas from inundation. The results show that the green river is the most appropriate solution since it can potentially reduce a 1% to a 10% per year flood event, with a reduction of peak discharges of 14% in comparison to 9.2% reduced by natural flood storage. Copyright © 2010 John Wiley & Sons, Ltd.