Author(s): Wen-Dar Guo; Tsun-Hua Yang; Ya-Chi Chang; Dong-Sin Shih; Cheng-Hsin Chen; Jui-Yi Ho; Kwan Tun Lee; Gwo-Fong Lin; Ling-Feng Hsiao; Cheng-Shang Lee
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Keywords: Scour depth; Quantitative precipitation forecast; Local scour; Hydrograph; Bridge piers
Abstract: Flood-induced scour exposes foundation and potentially causes the structure a collapse. A disaster like structure failure could result in the loss of hundreds of thousands of lives. A real time warning system, which predicts the flood stage and estimates the possible scour depth, was developed to prevent the disaster in the study. The system combines the KW-GIUH (Kinematic-Wave based Geomorphic Instantaneous Unit Hydrograph) model and the WASH123D (Watershed Systems of 1D Stream-River Network, 2D Overland Regime, and 3D Subsurface Media) model with ensemble quantitative precipitation forecast (QPF) to predict the flood stage. Based on the determination of the relationship between the water level and the scour depth, a linear scour-estimating formula is proposed. To obtain a reliable formula, many numerical experiments using SFM2D (Surface Flow Modeling 2D) were carried out to simulate general scour, contraction scour, and local scour. The system was applied in the Cho-Shui River and two typhoon events (Typhoon Kalmaegi in 2008 and Typhoon Morakot in 2009) were used for validation. The results indicate that the predicted flood stages are in a good agreement with the observed hydrographs. With the linear scour-estimating formula, the system is suitable and efficient for predicting scour depth around bridge piers.
Year: 2013