| Summary: | 碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 101 === In Taiwan, due to the special physiographic and climatic conditions, typhoon or rainstorm event occurs frequently. Besides, it usually causes disastrous inundation in the midstream and downstream floodplain, and takes losses of lives and property. The two-dimensional inundation model can simulate flood risk map in advance. It predicts the potential flood depth and velocity, enabling informed government improve emergency planning and policy to reduce the losses.
A good numerical model should give consideration to accuracy, efficiency and stability. However, it will cost large amount computational time in large fine resolution simulate areas. The multi-scale inundation simulation model using local fine grid at the dense population areas could reduce the time of calculation. The method is a feasible solution to provide a much higher resolution mesh with less computational time.
Recently, with the development of science and technology, the developments in computer hardware have greatly advanced. Computational time can be reduced by running in parallel over multiple threads. The main purpose of this research focuses on parallel the multi-scale computational method. In multi-scale inundation model, this research parallelizes global domain and all the local regions to different threads by parallel algorithm. The method makes the flood inundation model would be reduced computational time and speedup the efficiency.
The parallel method will be applied to the simulation of typhoon Morakot event of 2009 in Tseng-Wen river basin as the study case. This study compares accuracy and efficiency by the error correction and speedup ratio. The results show that it is not only improving the accuracy of simulation error to close the level of fine-grid simulation in the global area, but also raising the efficiency of computational time. The method of parallel for multi-scale inundation simulation strikes a good balance between accuracy and efficiency. The significant result of this study will greatly improve the real-time inundation early-warning system, and this high efficiency model would provide instant inundation information to authority, and it will assist the disaster reduction.
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