LAUSR

Abstract On August 8, 2017, an Ms 7.0 earthquake occurred at the Jiuzhaigou World Natural and Cultural Heritage, Sichuan Province, southwestern China. Eighty-three earthquake-induced landslides that directly damaged the Jiuzhaigou heritage sites were identified via remote-sensing interpretation and field survey. The coseismic landslides were concentrated primarily within 3 km of the seismogenic fault. Large volumes of sediments were transported into catchments of the Jiuzhaigou Valley, creating a geo-environment conducive to debris flow hazards triggered by post-earthquake heavy rainfall. A methodology combining the calculation of sediment augmentation, particle model, and numerical algorithm is developed to assess the potential dangers of post-quake debris flows. Five typical catchments strongly affected by the earthquake are chosen as study cases. The simulation results at Xiajijiehai Gully show a good agreement with the actual inundation area of the debris-flow event on September 25, 2017. The comparison of pre- and post-earthquake scenarios shows that an increase in sediment supply can greatly increase the debris-flow potential dangers characterized by higher maximum flow depths and larger inundation areas.