Abstract: The Wenchuan earthquake on May 12, 2008, severely destroyed surface vegetation and caused plenty of accumulation of loose deposition, which provided abundant provenance for debris flow and increased the risk of debris flow.Previous studies revealed that the provenance of the debris flows post-earthquake was a characteristic of dynamic variation.In consideration of the blocking structures constructed in the disaster area, the risk of debris flow was generally influenced by both natural and human factors.In this study, the Qipan gully in Wenchuan County was selected as an example and field investigation, Quick-bird remote sensing and FLO-2D software were comprehensively used to analyze the dynamic variation of the provenance of debris flow and predict the risk of debris flow both without blocking structures in 2013 and with blocking structures from 2017 to 2019 under various rainfall recurrence intervals of 10 years, 20 years and 50 years.The interpretation of the remote sensing images verified the gradual variation of the main provenance of the debris flows from slope deposits (2008-2013) to gully accumulation thereafter.In addition, the estimate of accumulation depth and outrush volume proved the extreme significance of construction and timely dredging of blocking structures in the decrease of disaster risk of debris flow.The ultimate purpose of this study was to provide a theoretical basis and technical reference to prevent or mitigate disaster risk for the increasing engineering activities in high-intensity seismic areas in the future