淹水細化網格邊界處理之研究

The Boundary Treatment for Local Grid Refinement of Inundation Simulations

鄒亞達(Ya-Ta Chou)

指導教授 ： 許銘熙

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.00415

摘要

台灣地區受到水文與地文條件特殊影響，每當颱風或暴雨事件發生時，中下游平原地區容易淹水造成人民生命財產損失。但應用二維淹水模式進行大區域細網格淹水模擬需要大量的計算時間，使用局部細化網格淹水模式運用不同解析度之網格進行同步模擬，將可減少模擬時之計算資源提高演算效率。
本文主要目的在處理局部細化淹水網格模式中地形解析度較高之細網格區域的邊界條件，因細網格地表高程解析度較高，粗細網格邊界上會有斷面不一致的現象，而細網格之邊界條件是將粗網格流量透過權重分配求得，分配方法為等流量法、等流速法、切西流速法與曼寧流速法。四種流量分配法之模擬精度與演算效率將會在本中作比較討論。
以八掌溪流域進行實際模擬評估誤差改善效率，使用此邊界條件處理之局部細化淹水網格模式，不僅縮短模擬時間提高演算效率，同時模擬精度能相當接近於全區細網格模擬之水準；在即時淹水預警上，其快速之演算效率能夠提供具參考性的淹水資訊，作為防災管理單位決策支援的助力。

關鍵字

淹水模式 ； 細化網格 ； 邊界處理

並列摘要

The meteorological and geographical conditions in Taiwan frequently cause inundation in the midstream and downstream floodplain when storm occurs. It usually takes losses of people’s wealth and life. Owing to the large amount computation requirements on the two-dimensional inundation simulation in large areas with fine resolution in dense population areas, the down-scale inundation simulation using local refinement grid at the dense population areas could save the time of model calculation.
The main purpose of the study is to find a reasonable boundary treatment for the local area of down-scale inundation simulation which is higher resolution in topography given by the Digital Terrain Model. Because of the higher resolution in local areas, the boundary condition between fine grids and coarse grids is not consistent. In the boundary between coarse and fine grids, the fine grids discharges are calculated by the coarse grid discharges and the allocated weighting factors. The weighting factors are equal-discharge, equal-velocity, Chezy’s formula and Manning’s formula. The simulation results and computer run time among the four weighting factors are compared in the study.
The research area is the Ba-zhang Creek Basin. The study compares boundary treatments by the error correction of simulation. The result is not only raising the efficiency of simulation, but also improving the accuracy of simulation error to close the level of fine-grid simulation in the whole area. For the real-time inundation early-warning system, the high efficiency of model could provide inundation information to assist the disaster reduction for emergency management agency.

並列關鍵字

Inundation model ； Grid refinement ； Boundary treatment

參考文獻

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