Numerical analysis of landslide-generated debris flow on July 3, 2021 in Izu Mountain area, Shizuoka County, Japan Numerical analysis of landslide-generated debris flow on July 3, 2021 in Izu Mountain area, Shizuoka County, Japan

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Vol19 No.6: 1738-1747 

Title】Numerical analysis of landslide-generated debris flow on July 3, 2021 in Izu Mountain area, Shizuoka County, Japan

Author】SUN Tong1; SUN Dong-ya2; WANG Xie-kang1*; MA Qiang2; GOURBESVILLE Philippe3; NOHARA Daisuke

Addresses】1 State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China; 2 China Institute of Water Resources and Hydropower Research, Beijing 100038, China; 3 Université Côte d'Azur, Nice 06903, France; 4 Sustainable Society Laboratory KAJIMA Technical Research Institute, Kyoto University 6110011, Japan

Corresponding author】WANG Xie-kang

Citation】Sun T, Sun DY, Wang XK, et al. (2022)Numerical analysis of landslide-generated debris flow on July 3, 2021 in Izu Mountain area, Shizuoka County, Japan. Journal of Mountain Science 19(6).https://doi.org/10.1007/s11629-022-7309-6

DOI】https://doi.org/10.1007/s11629-022-7309-6

Abstract】With the increasing of extreme rainfall frequency, landslides accompanied by mudslides often lead to serious casualties and property damage. On 3rd July 2021, a debris flow occurred in Izu Mountain area, Shizuoka County, Japan, and then resulted in 26 deaths and 131 houses destroyed, where houses were mainly built along the banks of the creek. In order to analyse the landslide state and distribution, a two-dimensional debris flow dynamic model (Massflow)was selected to simulate the process of the landslide-generated debris flow. When the model results are considered together with remote sensing images, the volume distribution of the unstable landslide is also able to be determined. The results show that (1) the affected areas aremainly concentrated at the outfall of the gully and on both sides of the streets. (2) The pore pressure ratio is an important factor affecting the damage range of this debris flow. (3) The increase of the pore pressure ratio in the landslide makethe movement distance of debris flow increase significantly.

Keywords】Izu Mountain; Landslide; Debris flow; Numerical simulation; Pore pressure ratio