Abstract:Landslide deposits are one of the main sources of flash flood and sediment disaster, and their spatio-temporal distribution and evolution characteristics play an important role in the early identification of flash flood and sediment disaster areas and the study of risk areas. In order to explore the spatio-temporal evolution characteristics of landslide deposits in the Wenchuan earthquake zone, this paper selected Shouxi River Basin, a typical basin in Wenchuan, as the research area, and respectively interpreted the landslide deposits based on the five stage high-resolution remote sensing images in 2007, 2009, 2012, 2015 and 2018, and established a long time series data set of “pre-earthquake and post-earthquake” landslide deposits in the research area, and combined with the key control factors such as elevation, slope, aspect, distance from channel , distance from fault and average annual precipitation, quantitatively analyzed the relationship between evolution characteristics of landslide deposits and each factor based on certainty factor model (CF), finally calculated the vegetation fraction coverage (VFC) and the vegetation coverage recovery rate (VCRR) to explore the effect of vegetation restoration on landslide deposits activities. The research results showed that the areas of landslide deposits of five stage images were 15.68×10⁴ m², 442.45×10⁴ m², 252.86×10⁴ m², 146.07×10⁴ m², 98.97×10⁴ m², and were attenuated by exponential function mode. In addition, the predicted time for the area of landslide deposits to recover to the pre-earthquake level is about 21 a. The area with the strongest activity of post-earthquake landslide deposits in the study area is 1200～2400 m in elevation, 60° in slope, SE in slope direction, less than 800 m in distance from channel , less than 1500 m in distance from fault and 830～850 mm in the average annual precipitation . The evolution trend is that the activity of the landslide deposits increases in the area with an elevation of more than 2000 m, a slope of less than 40°, a distance of more than 200 m from the channel ,a distance of more than 1500 m from the fault, the average annual precipitation is more than 840 and decrease in the aspect of E, SE and S sides. VFC increases linearly with time after the earthquake, and it is predicted that the vegetation coverage will return to the pre-earthquake level at least 14 years after the earthquake. In 2012, 2015 and 2018, the areas with moderate or above VCRR account for 37.32%, 64.24% and 70.69%, respectively. In places with high VCRR, the activity of landslide deposits is low and decreases with time, and vegetation restoration can effectively reduce the activity of landslide deposits. The above research is of great significance to enrich the theory of landslide deposits evolution and flash flood and sediment disaster risk prediction.