流域格網局部細化之淹水模擬

Abstract

近年遙測技術的迅速發展，提升了地形資料的解析度和準確性。尤其是airborne scanning laser altimetry(LiDAR)的準確度大幅改善其可用性。若使用高精度的數值地形資料(DTM)必須配合相當可觀的電腦資源以進行計算是模擬時的一項難題。大區域的模擬計算必須給予適當的邊界條件，而高精確性的資料卻可能只需應用在整體區域中有限的一小部分。若能使用不同精度的格網於不同地區(格網間互相密合)，將可減少模擬時計算資源上之浪費。 本研究主要目的在研發及建立一套淹水模式可計算不同解析度之多重格網，並進一步整合中央氣象局研發的定量降水預報系統(QPESUMS system)結合雷達觀測降雨系統之資料進行淹水模擬。 本研究模擬區域為八掌溪流域，以2005年6月12日暴雨事件，並以多重尺度格網進行淹水模擬並分析比較不同格網對模式運算時間及模擬精度的影響。結果顯示局部高解析度格網之多重格網計算方式，可在精度及效率的平衡中有更佳的表現。

The quick growing of remote sensing technology in recent years has obviously elevated the quality, in both resolution and precision respects, of topographic data. The accuracy and availability of the airborne scanning laser altimetry have been promoted and the applications are widening. The requirements of computation resources cause the difficulty for massive simulations by using the high quality digital terrain models (DTM). In most practical situations, the large area for computation is essential to having proper boundary conditions, nevertheless, the high accuracy might be needed only in limited parts of the domain. The local refinement method is a feasible solution to provide results comparable to a much higher resolution (uniformly refined) mesh with less computational expense. In this study, an efficient 2D inundation model, incorporating the QPESUMS radar precipitation and multi-scale computational method, will be established to provide accurate resolution results. The 0612 Storm event of 2005 in Bajhang River basin is adopted as the study case of the newly developing model. The accuracy and efficiency of proposed model are evaluated with different grid scale. The high performance of the multi-scale inundation model with high resolution grids in local area is obtained.