圖書典藏及影音數位平台

過去洪泛模擬常因計算量太大，而採用低解析度的地形資料作為計算格網的建置；然而近年來高解析度地形資料如5米以下，已經運用於3維街景地理資訊的應用。近年來電腦運算速度不斷提升及利用高效能新的演算法架構，使得洪泛模擬也能應用高解析度地形資料，則有助於往後高精度都市洪泛模擬的發展。此外高時空解析度洪泛模擬結果在3維視覺展示的應用，也需要一併進行先期研究，才能充分發揮高解析地形資料的助益，提供決策者更直接且立體的資料呈現。

This study investigates the performance of 3Di in the application for high resolution and fast computation of flood inundation. 3Di takes the advantages of quadtree technique to reduce the number of computational grids and subgrid method to compute roughness to the level of pixel grid. Several DEMs (digital elevation models) of different resolutions, including 1x1m, 5x5m, 10x10m, 20x20 m, 40x40m, are produced from the 1x1m DEM, and later used to investigate the influence of DEM resolution on the flood inundation simulation. The framework of this project includes: (1) building 3Di-2D and 3Di-1D2D models with DEMs; (2) evaluation of 3Di model performance on computational speed and computational resolution; (3) visualizing high resolution flood inundation maps on 2D maps and a 3D city model. Results show that 3Di runs 176-480 times faster than the real-time events, which means 3-8 hours of real-time situation is 1 min in 3Di simulation. Attention is also given to the resolution of DEM and its effect when 3D visualized. Based on the investigation in this project, 3Di has a great potential for fast, accurate, and visual flood inundation forecasts and may improve the way engineers communicate with stakeholders.