本研究利用分散式水文模式模擬颱風與梅雨降雨事件，分析這兩種不同型態的極端降雨事件之地表逕流量變化，以了解烏溪流域內因颱風和梅雨引起的地表逕流。研究中選用兩個颱風(莫拉克和柯羅莎)及 2006、2007 年的梅雨等四場總降雨量相近的颱風及梅雨事件，並藉由延時分析(標準偏差、偏度、峰度)以區別降雨型態為分散或集中型降雨，之後模擬地表逕流量進行比較，發現颱風的模擬洪峰流量結果明顯優於梅雨的模擬結果，認為未考慮基流的影響是造成模擬結果誤差之原因，進而探討基流對不同型態降雨事件之影響。由於所使用之模式為基於物理的分散式水文模式，模擬地表上各種水循環過程以推估河川逕流量，因此採用一種同為基於物理的基流分離方法 (Furey & Gupta, 2001)，其不需要率定任何參數，以討論基流對不同型態極端降雨事件模擬結果之差異，並評估加入基流分離方法對模擬結果之影響程度。結果顯示，模式加入基流分離方法對颱風事件的模擬影響較小，但對梅雨事件的模擬影響卻不容忽視。The events of the typhoon and the plum rain were analyzed with a distributed surface runoff model for the purpose to understand the characteristics of the surface runoff in Wu River watershed. Two typhoon events (Morakot and Krosa) as well as the plum rains in 2006 and 2007 were adopted because of the similar total amounts of precipitation. The types of scattering rainfall and gathering rainfall were discriminated by the magnitudes of standard deviation, skewness and kurtosis. The better agreements between the simulations and the observed peak flows were found for the typhoon events, rather than the plum rain events. It is speculated that the incapable of including the base flow of the rivers in the simulations caused the different responses between the typhoon and the plum rain events. A base flow separation method which is based on the physical concepts was included in the surface runoff model (Furey & Gupta, 2001). The results revealed the fact that the considerations of the base flow was significant for the plum rain events, but was less significant for the typhoon events.
