表面流速為土石流機制中一重要的物理參數，且由於監視設備提供相當廉價的資訊，故在許多河道或土石流可能發生區常架設影像監視器。本文以影像辨識法進行土石流表面流速的估算，利用質點影像量測法(Particle Image Velocimetry，PIV)與時空導數空間法(Spatio Temporal Derivative Space Method，STDSM)演算土石流表面流場並探討其差異。首先利用模擬流場與固體顆粒流實驗評估PIV與STDSM演算法之可靠度與正確性，並且由水土保持局取得土石流之現場監視影像經尺度校正與濾波處理後，利用前述影像演算法計算表面流場，以期日後能建立一土石流監視影像資訊遙測系統。

　　The surface velocity is one of the important physical parameters to study the debris flows. Owing to assure the safety of the life and wealth the monitored Video technology developed quick and more inexpensive. There are many regions have set up Video systems in river basin for monitoring the flood and debris flow. In this paper, it has been estimated by using image recognizing methods. We improve the image analysis methods, particle image velocimetry (PIV), and compare it with Spatio Temporal Derivative Space Method (STDSM). The hybrid method is tested to the experiments of the rocks floating and the simulate images. According to results, the nature debris flow images from the monitor of Soil and Water Conservation Bureau are analyzed to obtain the surface velocity by the image process. The objective is that establish the monitored Video systems using image technique to remote sensing the information of the debris flow.

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