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題 名 | 面積門檻值對集水區地文參數與水文模擬之影響=The Influence of Threshold Area Value on Geomorphic Parameters and Hydrologic Simulation |
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作 者 | 李光敦; 江申; | 書刊名 | 中華水土保持學報 |
卷 期 | 28:1 1997.03[民86.03] |
頁 次 | 頁21-32 |
分類號 | 443.046 |
關鍵詞 | 面積門檻值; 數值高程模式; 地貌瞬時單位歷線; Threshold area; Digital elevation model; Geomorphic instantaneous unit hydrograph; |
語 文 | 中文(Chinese) |
中文摘要 | 集水區的水文反應函數可視為該地區降雨特性與地文特性所衍生之特徵函數。由於線性系統理論廣泛地為水文工作者所採用,因此區域降雨之變異特性,可經由線性疊加方式予以處理,而集水區之水文反應函數遂可視為單純由地文特性所衍生之特徵函數,因此集水區地文參數之推求結果,將直接影響地形性水文模式模擬輸出。 藉由數值高程模式之應用,可弮定集水區內各個區塊的流向。若任意指定一面積門檻值,即可進一步決定集水區之河川網路系統及其各次集水區之面積。因此,對同一集水區而言,不同的面積門檻值會擷取出相異的河川網路結構,導致推求出不同的地文因子,此將使以地形性為主之水文模擬結果有甚大差距。研究中以基隆河流域五堵以上集水區、大漢溪流域橫溪以上集水區以及新店溪流域寶橋以上集水區為驗證區域,詳細討論面積門檻值與各級序河川長度、坡度、流域面積、河川數目與荷頓比之關係。研究結果顯示,集水區各級序河川之集水面積會隨著面積門檻值而增加,而河川長度、坡度與數目則隨著面積門檻值之增加而減少,而集水區之荷頓比值亦隨面積門檻值之改變而增減。研究中並以上述數值高程模式計算所得之地文參數代入運動波一地貌瞬時單位歷線模式,發現若以不同面積門檻值所得之地文參數作水文模擬,則集水區之尖峰流量以及尖峰到達時間均有甚大差異,此一現象值得運用此類數值高程模式者參考注意。 |
英文摘要 | The hydrologic response function of a watershed can be recognized as a function resulting from the characteristics of rainfall and watershed geomorphology. Since the linear system theory is extensively employed by hydrologists, temporal variety of the rainfall in a watershed can be simulated by linear superposition. Thus, the hydrologic response function of the watershed can simply be treated as a characteristic function from the watershed geomorphology. The output from a geomorphic runoff simulation model is, therefore, influenced by the geomophic parameters of the watershed's geomorphic parameters. By applying digital elevation models (DEM��), the flow direction of each cell in a specific basin can be determined. While an arbitary threshold area value is assigned, the river network and the size of each subwatershed in the basin can be obtained. Consequently, various stream networks will be extracted by different threshold values in the same watershed. Furthermore, hydrologic simulation results would be in obvious difference owing to the geomorphic parameters deived from various stream networks. Data from three upstream watersheds. i.e.: Wu-tu, Hen-Shih, and Po-Bridge were adopted for analysis. The relationships between threshold area value and river length, slope, area, stream number and Horton's ratio are detailed discussed.The results reveal that the basin area increase with increasing the threshold area value, and the stream length, slope and stream number decrease with increasing the threshold area value.Futher investigation reveals that the Horton's ratio is also influenced by the threshold area value. Moreover, geomorphic parameters derived from various threshold area values were applied to the kinematic-wave based geomorphic instataneous unit hydrograph for runoff simulation. Simulation results indicate that the peak discharge and the time to peak discharge are highly influenced by the threshold area value used for stream network extraction. This result is significant useful for DEMs users in practical applications. |
本系統中英文摘要資訊取自各篇刊載內容。