Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/34056
標題: 南勢溪集水區颱風降雨空間分怖變異性之探討
Investigations of Typhoon rainfall spatial distribution variations in Nan Shih creek watershed of northern Taiwan
作者: 王仲豪
Wang, Jong-Hao
關鍵字: Nonparametric Statistics
無母數統計
Geostatistics
Semivariogram
Kriging
Areal Reduction Factor
地理統計
半變異函數
克利金法
面積遞減因子
出版社: 水土保持學系所
摘要: 颱風為台灣夏秋兩季常見的天氣現象,其所引發之大量降雨除了為台灣地區每年重要之水資源收獲外,亦為擾動該區水土資源空間分布之主因,同時也是此區域大規模土砂災害如山崩、土石流之啟動因子。故探討並瞭解颱風降雨之空間分布的變異性質,對於台灣水土資源之空間分配,以及土砂運動之掌握皆會有所助益。 集水區為地形劃分之單元,常被作為水文、土砂運動分析等研究之單位區域,故本研究亦以集水區為對象,進行颱風降雨空間變異特性之探討。本研究選擇位於台灣北部地區的南勢溪集水區,並依地理學第一定律,挑選鄰接本區之雨量站,以無母數統計進行檢定篩選後,計選取19個雨量站,以其所紀錄之歷年1小時最大颱風降雨量為基準,推求2、6、12、18及24小時等不同延時之最大颱風降雨量,再應用甘保氏極端值第一類分布分析重現期距為5、10、25及50年等不同頻率年之降雨量,所得結果以地理統計進行分析並建立區域型降雨面積遞減因子曲線,藉以探討集水區颱風降雨量空間分布之變異特性。 由地理統計之半變異函數分析結果顯示,南勢溪集水區颱風降雨空間分布之影響範圍為7.4公里,即各雨量站彼此間的距離如超過此範圍,其雨量資料之空間變異性不隨距離增加而變化;而在影響範圍之內,本區之颱風降雨空間分布會隨降雨延時及重現期距的增加而加大其空間變異程度。 為具體表現本區之颱風降雨空間分布之情形,遂以前項所得之半變異函數作為克利金推估之輸入函數,並應用地理資訊系統建立等雨量線分布圖。由等雨量線圖顯示,南勢溪集水區颱風降雨之分布分別由東向西以及南向北之方向遞減;颱風降雨中心多發生於福山雨量站所在之區域,降雨量則由福山雨量站向東朝下盆雨量站方向遞減;另外,位於本區北端之大桶山雨量所處之區域,則是另一處發生明顯降雨空間變化的地區,故颱風降雨在南勢溪集水區內的分布具有空間變異之特性。 有關颱風降雨量遞減程度如何隨降雨分布面積的改變而變化,遂以所得之等雨量線圖進行不同延時及重現期距之颱風降雨面積遞減因子分析,並建立其隨累積分布面積百分比而變化之降雨面積遞減因子曲線。結果顯示颱風降雨面積遞減因子會隨累積分布面積之增加,依冪定律模式呈現曲線型態之衰減。
Rainfall caused by typhoon is not only the important income of water resources, but also the key factor of disturbing the spatial distribution of soil and water resources in Taiwan. It will be help to realize the spatial distribution of soil and water resources and movement of sedimentation for our homeland by studying the spatial variations of typhoon rainfall. Watershed is a unit of topography and an elementary area that applied for the topics of spatial hydrology and sediment movement. This study first used the first law of geography and nonparametric statistics test, and then chose 19 rain gauge stations to analyze the spatial variations of typhoon rainfalls by areal reduction factor curves in the Nam Shih Creek watershed of Northern Taiwan for different durations and return periods. The results of typhoon rainfall spatial distribution from semivariograms analysis of different durations and return periods showed that the range is about 7.4km, and the spatial variation increasing by durations and return periods under the range in this site. The semivariogram models built by former analysis used as the input functions for Kriging that making isohyetal maps by integrating GIS. From the isohyetal maps, we can display the spatial distribution of rainfall caused by typhoons in Nan Shih Creek watershed. The spatial distributions of typhoon rainfall lessen gradually from east to west and south to north in this area. Such being the cases, the apparent spatial variations of typhoon rainfall is in the eastern and southern parts of this watershed. For the sake of understanding the relationship between typhoon rainfall degradation and area of distribution, this study applied the isohyetal maps that drawn in the former part to extract areal reduction factors of different durations and return periods, and forming the areal reduction factor curves. As a result of areal reduction factor curves, the areal reduction factors of typhoon rainfalls decayed with accumulative areas of spatial distribution by the power law. The areal reduction factor curves decrease mildly with the rainfall durations on increasing in the fixed return period. In the condition of fixed durations, the areal reduction factor curves also grow less mildly with the return periods extend. In previously description, it shows that the spatial variations of typhoon rainfall trend unvarying in Nan Shih Creek watershed.
URI: http://hdl.handle.net/11455/34056
Appears in Collections:水土保持學系

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