Effect of Stony Debris Flow on Design Discharge for Tung-Pu-Ray Creek

Abstract

The primary objective of this research is to investigate the impact of stony debris flows of Tung-Pu-Ray Creek on its design discharge by using the quasi two-dimensional cell model for inundation simulation. The research is based on the assumption that there is a linear relationship between the actual discharge hydrograph of sediment-laden flows, and the discharge hydrograph of sediment free flows. That is, the ordinates of the discharge hydrograph of sediment-laden flows are n times of water flows. Hence, using the inundation simulation by the quasi two-dimensional cell model, one can define the extent of the impact of stony debris flows of Tung-Pu-Ray Creek on its design discharge through the calibration with the actual flood inundation of the typhoon Toraji of 1990. The simulation indicates that the actual discharge of Tung-Pu-Ray Creek's sediment flows can be determined as 1.4 times of the discharge hydrograph derived from the actual precipitation data. In other words, the weighted impact of the stony debris flows on the design discharge is approximately 0.4 times in the Tung-Pu-Ray Creek case.