On October 10 and November 3, 2018, at the right bank of Jinsha River in Baige village, Boluo town, Jiangda County, Tibet Autonomous Region experienced two landslides and river blocking events successively, forming a huge barrier lake. The landslide dam broke after two disposal methods of natural discharge and man-made excavation of the discharge channel. Among them, the second flooding due to the landslide dam break caused great damage to the roads, bridges, farmland and houses within the affected downstream areas of Tibet, Sichuan and Yunnan provinces. In order to deal with the unconventional and extraordinary flood threat of a similar large landslide dam break, and also for a related basic research need, our research team conducted a field investigation on the disaster situation of the flooding suffered by the Baige landslide dam break from December 21 to 29, 2018. The investigation started from the intersection of Bachu River (also known as Baqu River) and the Jinsha River in Batang County, the most severely affected area, and ended at Liyuan reservoir, where the flood threat is basically eliminated. The total length of the investigation along Jinsha River is 488.6km, and the focuses of field investigation are on the damage status of the houses, roads, bridges and water related infrastructures along the river banks The maximum inundated water level or flood level marks due to the dam-break flooding, the water level of the river during the investigation, the sediment accumulation on both sides of the Jinsha river and its particle grading, and the disaster water level of the bridge are analyzed accordingly. Some valuable disaster-related data and results are obtained, which can provide a useful data support for further related theoretical studies of dam-break flooding.
