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The effects of Chao Phraya dam operation on the upstream flood inundation

SUTHAM VISUTIMETEEGORN¹, KANCHIT LIKITDECHAROTE¹ & SUPHAT VONGVISESSOMJAI²

1 Department of Water Resources Engineering, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand

sutham.v@student.chula.ac.th

2 Team Consulting Engineering and Management Co., Ltd, Nuanjan, Buengkum, Bangkok 10230, Thailand

Abstract During floods, the operation of Chao Phraya dam to control downstream water discharge causes flood inundation in the upstream areas. The purposes of this research are to study the effects of Chao Phraya dam on the upstream flood, and to find new flood mitigation measures using hydrodynamic models. The results show Manning’s n-value in the Chao Phraya River and its tributaries are 0.033–0.045 in main channels and 0.050–0.070 in flood plain areas. The discharge coefficient of the gates of Chao Phraya dam is 0.6. The backwater from the operation of Chao Praya dam affects water level as far as 110 km upstream. New concepts of water diversion can mitigate the flood inundation and have no effect on the floating rice fields. The harmonious operation of Chao Phraya dam, the regulators, and the upper reservoirs will mitigate the flood inundation efficiently.

Key words backwater; Chao Phraya River; diversion dam; flood inundation; gate operation; hydraulics; hydrodynamic model