Management of uncertainty flood into a large weir system in Thailand

Abstract

The Upper Yom River Basin in Phrae province, Thailand with the catchment area of 5,500
km² was chosen as a flood study upstream of an existing weir using the Integrated Flood
Analysis System: IFAS. It was calibrated to the large flood in 2011, verified in 2003 and 2006
using the global satellite rainfall and ground-based observation rainfall. The results of
synthesis inflow hydrographs from IFAS showed that it was satisfied on model performance
compared to the observation data during flood period in 2011 with annual flood frequencies of
59 years and fitted to the Nash and Sutcliffe Efficiency: NSE of 0.07, R² of 0.58, RMSE of
253.8 m³/s, and the observed peak flood discharge of 1,133.7 m³/s, respectively. The result
will 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.