本研究之目的為作河床沖淤趨勢之定性分析，主要利用一維水理模式 HEC-RAS 計算相關水理參數例如水力半徑、能量坡度等，再根據這些水理條件及泥砂條件推估溪流之推移質輸砂率。因此，配合泥砂連續方程式則可提出簡易之河床沖淤趨勢分析方法。本研究選取4個集水區並蒐集其相關河床斷面及50年重現期距之洪峰流量等資訊，利用 HEC-RAS進行水理演算以獲得更多相關水理參數，最後計算推移質輸砂率並作河床沖淤趨勢之定性分析。同時，本研究將其整個計算過程撰寫成視窗程式，以方便建立有效之簡易河床沖淤趨勢預測方法。

The purpose of this research was to study the tendency analysis of riverbed degradation and aggradation. It used the one-dimensional model HEC-RAS to calculate the hydraulic characteristics, such as hydraulic radius and energy slope etc., and to estimate the bed-load transport capacity of channel by using these hydraulic parameters and sediment conditions. Therefore, it was presented that the prediction method of tendency analysis on riverbed degradation and aggradation using the sediment continuity equation. Meanwhile, it selected four watersheds to collect the survey cross section data, and peak discharge of 50yr return period. Then it used this hydrologic information and HEC-RAS model to calculate the hydraulic parameters, and to analyze the tendency analysis of riverbed degradation and aggradation. Simultaneously, it also tried to develop a window interface program for calculating the procedures. To sum up, an efficiency tendency analysis method of riverbed degradation and aggradation could be established.