本研究發展一分散式集水區逕流模式，考慮了降雨、截留、漫地流、入滲與渠道流共五種水文過程。每種水文過程皆有相對應之控制方程式，此模式採有限差分法將其離散化，配合適當之輸入資料與參數，即可於計算機中模擬各種水文過程。此外，本研究以石門水庫集水區為研究區域，選用納莉颱風作為降雨事件，並使用不同計算時距和空間解析度資料驗證模式之收斂性，其次探討截留與入滲兩種水文過程在極端降雨事件中的重要性，同時分析渠道粗糙度對於洪水波之影響。最後，我們對本模式提出建議。 This study developed a distributed watershed run-off model which consider rainfall, interception, overland flow, infiltration, and channel flow. Finite difference numerical scheme was used in the model to discretize the governing equations of the hydrological processes. With appropriate data and parameters, we could use this model to simulate these hydrological processes in the computer.In this study, the watershed of Shihmen Reservoir was chosen as the research domain and typhoon Nari was chosen as the rainfall event. We validated the model with different time interval and spatial resolution ,and also discussed the importance of interception and infiltration as well as discussed the impact on flood wave with different roughness of the channel. Finally, we proposed some suggestions to the model.