Flood Management by Real Time Flood Forecasting and Gate Operation of Ta Tapao River Basin, Thailand

要旨

The Ta Tapao River Basin, Thailand encounters frequent flooding in the lower part of the river basin. The causes of flood inundation are due to heavy rainfall, limited basin drainage and lack of storage dam. The MIKE 11 hydrodynamic model was applied, calibrated and verified with measured flood flow data in 2005 and 2006. The results show flood inundation map in good agreement with observed condition. Telemetering system was recently installed for real-time monitoring and transmission of rainfall and water level data and flow regulation in Ta Tapao River. The flow regulation delays flood flow into Chumporn City and allows storing flood water in the river basin for use after flood periods. A new contribution in flood water management is done in this study by incorporating optimal operation of flood flow regulators determined by Genetic Algorithm (GA) model with minimum flood damages in river flood flow computation using MIKE 11 hydrodynamic model. By inputting rainfall forecast determined by unit hyetograph method into MIKE 11, flood flow in the river is forecasted for every 3 hours at stations: Wang Krok, Sam Kaew Regulator and Municipal Bridge 2-Chumporn City. The results of flood forecast based GA gate operation show lagging flood levels for rising and falling limbs at Municipal Bridge 2-Chumporn City due to flood storage retention by gate regulations. Public hearing reveals that local villagers in the nearby areas of the telemetering stations wish to cooperate in taking care and maintaining the system to cope with future floods.