Management of uncertainty flood into a large weir system in Thailand

The Upper Yom River Basin in Phrae province, Thailand with the catchment area of 5,500km2 was chosen as a flood study upstream of an existing weir using the Integrated FloodAnalysis System: IFAS. It was calibrated to the large flood in 2011, verified in 2003 and 2006using the global satellite rainfall and ground-based observation rainfall. The results ofsynthesis inflow hydrographs from IFAS showed that it was satisfied on model performancecompared to the observation data during flood period in 2011 with annual flood frequencies of59 years and fitted to the Nash and Sutcliffe Efficiency: NSE of 0.07, R2 of 0.58, RMSE of253.8 m3/s, and the observed peak flood discharge of 1,133.7 m3/s, respectively. The resultwill be benefit to flood management of the weir system in the light of climate change impacts.Keywords: Rainfall-Runoff model; Flood Frequency; IFAS; Weir Operation