| 摘要: | 台灣為一狹長的島國。因受特殊的地形影響，造成台灣河川短促湍急與河床坡度大的特性。台灣雖處於亞熱帶地區，年平均雨量達到2,515毫米。但由於大部分降雨集中於每年五月至十月，造成降雨量的分佈不均。在台灣，因為空間與時間分配不均的情況下，使得雨量與逕流量的過度集中，因而帶來嚴重威脅。
本研究利用合理化公式探討與分析集水區流域在降雨過程中，降雨量與逕流量兩者間之相互關係。彙整自西元1991年至2002年間三峽河、橫溪、中港溪、頭前溪、後龍溪及鳳山溪等六個集水區流域十二年間每年的最大日逕流量與日降雨量資料。根據研究結果，提供相關研究者、政策決策者初期評估水文特性的影響衝擊。研究結果顯示，在直線迴歸分析與對數迴歸分析中，除橫溪流域外，其餘集水區流域所呈現之相關性均以線性迴歸較好，大部分相關係數值介於0.3~0.7，偏向於中度相關。由此可說明，在未來進行類似之研究分析時，為求有較合理之結果或數據，可依據不同流域集水區之特性選擇較適合之迴歸分析方法。而依逕流係數與逕流量呈現之關係，可將情況分為兩類；(A)逕流量增加與降雨強度增加，逕流係數變大，(B)逕流量增加與降雨強度增加，逕流係數變小。故大致可將本研究之集水區型態區分為三種類型(AA、AB、BA)。研究案例中，最大降雨事件所降下之雨量可立即反應至流量歷線圖，顯示降雨量與逕流量兩者間之相互關係明顯；相反的，在最小降雨事件中降雨並未立即反應至流量歷線圖，顯示降雨量與逕流量兩者間之相互關係並不明顯，尚有另外影響逕流產生之原因，這將是未來研究的建議方向。
Taiwan is a narrow and long island country. It is influenced by special topography, steep and short river streams. Although Taiwan locates on the subtropical area, the annual average rainfall reaches 2,515 millimeters. But because most rainfall falls during the summer time, cause the rainfall unequal distribution. Because the distribution varies in space and time in Taiwan, make both the rainfall and runoff concentrated, therefore arouse serious damages.
This study uses Rational Formula and confers the basins of water district in the course of rainfall to analyze the relationship between recorded rainfalls and runoffs. This study had collected six different river basins (San-Hsia River, Heng-Chi, Chung-Kang River, Tou-Cheng River, Hou-Lung River Feng-Shan River). The maximum daily runoff and daily rainfall data of each year from 1991 to 2002 had been gathered. Based on the findings of this study, we can provide similar studies and decision makers with adequate tools to evaluate the impact of the changes of land use over the watersheds. We have two ways to analyze the watershed, one is linear regression and other is logarithm regression. The results of the research show that it is better to use the linear regression for most watersheds except Heng-Chi Watershed. Most of the correlation coefficients values are between 0.3 and 0.7, which tend to moderate correlation. Depending on the different characteristics of the watersheds, we should choose proper regression method to achieve a better reasonable result. We may divide the relationship of rainfall and runoff into two different types. The first type is as the intensity of runoff and rainfall increases, the runoff coefficient becomes large. The other type is as the intensity of runoff and rainfall increases, the runoff coefficient decreases. Generally speaking, we may also divide the watershed into three types (AA, AB, and BA). We have also found that the interaction between the rainfall and runoff is not clear, either. There should be some other effecting factors which remain for the future study. |
