都市淹水模式中可進行不同尺度粗細網格之淹水模擬，在邊界銜接部分，採 同而使用相對應不同之演算時距，可避免因可蘭數(Courant number)選取不當而產 生計算結果逐漸發散所導致的誤差，形成數值解的不穩定性。因此在模擬過程中，
不同尺度之淹水計算網格使用不同大小之演算時距，模擬結果將更符合實際流況。
本文利用粗細網格局部細化之淹水模擬，將曾文溪北岸以不同尺度不同細化 模擬區域進行平行演算，在大尺度下以粗網格快速地進行演算模擬，對重點地區 進行局部細化之小尺度演算，已大幅提升計算效率並能維持良好之模擬精度。在 準確性(Accuracy)上，各局部細化子區域均方根誤差總平均為 0.149 公尺，顯示其 已 具 良 好 精 度 ， 與 全 區 皆 使 用 細 化 網 格 之 模 擬 結 果 相 當 一 致 。 在 效 率 性 (Efficiency)，局部細化法之演算時間，已遠遠小於全區解析度 40 公尺細網格演算 所耗時 21 小時 13 分鐘，本文經由平行演算法同步處理全區及局部模擬區域之演
水潛勢圖供給決策者使用提早防災應變。本文已建置完成之平行演算都市淹水模
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附錄 A (3-4)式推導
(1 0)
附錄 B (3-16)及(3-17)式差分式推導
12 12
4 1, ,
1 2 1
m m
i j i j
T t q q
(B-9)
附錄 C (3-24)及(3-25)式差分式推導
1 1
4 , 1 ,
1 2 1
m m
i j i j
R t q q
(C-9)
附錄 D 河系溢堤洪水演算模式
(D-1)式與(D-2)式分別表示水流之連續及動量方程式，(D-1)式係表示在一單位
依自由堰流或潛沒堰流公式計算得出。(Cunge et al., 1980; Kandaswamy and Rouse, 1957)