颱風與梅雨所挾帶的雨量為台灣水資源的主要來源，平均年雨量達2510毫米，但大多集中於五月至十月佔了全年雨量之78%，造成降雨量分佈不均，及受特殊地形之影響，加上河川坡陡流急，降雨後逕流入海，甚難蓄存，颱風為台灣帶來充沛的雨量，但也帶來洪水及土石流等災害。 本研究利用合理化公式探討颱風對降雨量與逕流量之間的關係，彙整自西元1995年至2004年間，橫溪、頭前溪及水里溪三個集水區流域十年間每年的最大日逕流量與日降雨量資料，根據研究結果提供後人對集水區防洪及水資源規劃上做為參考依據，並利用Arc View9.0試著計算出集水區坡度、土地利用開發之程度，藉此做為其它是否影響逕流係數之因素，結果顯示，在直線迴歸分析與對數分析中，除了水里溪外，其餘集水區之相關性，偏向於中度相關。研究中，颱風造成各流域降雨事件所降下雨量立即反應在流量歷線圖，顯示出降雨量及逕流量之間的關係，但尚有其它影響逕流產生之原因，這將是未來研究之方向。 The rainfall on typhoon and the rainy seasons are the main sources of water-resources of Taiwan. The annual average rainfall reaches 2510 millimeters in Taiwan. According to the effects of Taiwan’s topography, the rainfall are unevenly distributed. About 78％ of yearly precipitation falls between May through October. Also because the slope of rivers is steep, the surface runoff is rushed into ocean quickly with high speed and large discharges. That usually caused some disasters, such as flooding, mudslide, etc.. In this study, the rational formula was discussed to develop the relationship between rainfall and runoff during typhoon. The data of river discharge and rainfall in three different rive basins (Heng-Chi, Tou-Cheng River, Shui-Li River) were collected in order to analyzed the relation between runoff and river discharge. The Maximum daily runoff and daily rainfall data of each year from 1995 to 2004 had been gathered. Based on the results, this study, may provide the basis about the flood control and water-resource management in the watershed. Arc View 9.0 was used in order to calculate the slope of watershed and the degree of the land use. The result shows how the influence of land uses and the slope on runoff coefficient in different watersheds. The results of the analyses of linear regression and logarithm regression showed these relationships were moderate correlated, except in Shui-Li River. In the study, the rainfall caused by typhoon also showed direct responses on each river immediately which can be seen in the diagram of discharge hydrograph. From the results, it is clear that there are still some other factors which may have influence on the relationship between runoff and river discharge. And this will need further studies in the future.
