In order to characterize the increase of the sediment discharge caused by the Wenchuan earthquake and post-seismic heavy rainfall in the upper Min River,the SPOT images,aerial photographs and digital elevation map were interpreted,and landslides,mudslides in the area were marked.Data on sediment discharge,rainfall,landslides,and debris flows were collected for the period of 1980—2010 to describe the effects of the Wenchuan earthquake and post-earthquake heavy rainfall on the increase in sediment discharge of the area.The relationship among precipitation,sediment discharge,landslides,and debris flows before and after the Wenchuan earthquake was analyzed.The variation trends of sediment discharge in the river basin before and after the earthquake were calculated quantitatively.The research results showed that sediment discharge increased by approximately 30% due to coseismic uplift,coseismic landslides,and debris flows after the Wenchuan earthquake.The sediment discharge caused by heavy rainfall after the earthquake was 1.75 times larger than that before the earthquake.The percentage contribution of the sediment yield of debris flows induced by heavy rainfall after the earthquake to the increase in sediment discharge was 37.49%.The heavy rainfall zone basically coincided with the earthquake fault zone and the seismic landslide zone.Therefore,there was a positive-feedback relationship between the increase of sediment discharge and heavy rainfall after the Wenchuan earthquake.The loosening of surface materials and landslides driven by the Wenchuan earthquake resulted in an increase in sediment discharge into the river,bringing about a great disaster which will need to be addressed in the coming decades.
