October 2019 Sediment Disaster in the Tohoku Region owing to Typhoon No. 19 (Tyhpoon Hagibis)

Irasawa, Michiya; Koi, Takashi; Tsou, Ching-Ying; Nobuaki, Kato; Matsuo, Shinjiro; Arai, Mizuho; Kaibori, Masahiro; Yamada, Takashi; Kasai, Mari; Wakahara, Taeko; Higaki, Daisuke; Ikeda, Hajime; Ishikawa, Yoshiharu; Arai, Ken‐ichi; Hirose, Shigeo; Shimoda, Tatsuya; Hideki, Kawabata; Koubu, Manabu; Satoshi, Niwa; Sugawara, Kazuhiro; Hiroyuki, Matsusaka; Tada, Norio; Kon, Toshiyuki

doi:10.13101/ijece.13.48

Cited by 15 publications

(11 citation statements)

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“…3) shows that the majority of landslides occurred on areas underlain by the granites and granodiorites along the Hatagawa Fault Zone, and are concentrated on slopes incised by major rivers. Field verification and disaster reports (Yoshikawa et al 2020); (Ochiai et al 2020); (Irasawa et al 2019) concur with this observation, citing the presence of boulder-sized weathered core-stones and decomposed granitoids together with the collapsed soil. The reports also note the reactivation of past landslide deposits due to high channel flow from increased rainfall.…”

Section: Geologic Settingmentioning

confidence: 79%

“…Most failures are characterized as shallow debris flows with average depths of 0.5 to 1 m, commonly occurring on hillsides with slopes of approximately 35° (Irasawa et al 2019). (Ochiai et al 2020) reports on the occurrence of riverbank erosion and slope base scouring due to water impact generated by the high flow velocities, explaining the mechanism by which a road embankment along Gofukuya River was washed away (Fig.…”

Section: Geologic Settingmentioning

confidence: 99%

“…4). An account by a resident within the Shinkawa River basin estimates the timing of one debris flow event between 12:00 am to 1:00 am on 13 October 2019 (Irasawa et al 2019).…”

Section: Geologic Settingmentioning

confidence: 99%

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Mapping method of rainfall-induced landslide hazards by infiltration and slope stability analysis

et al. 2021

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By utilizing the Green-Ampt infiltration equation and the infinite slope stability model, a method for analyzing shallow slope failures caused by rainfall is developed. With rainfall intensity, soil characteristics, and topography, the modified Green-Ampt infiltration equation is used to estimate the rainfall infiltration capacity and depth of infiltration in a given slope. Assigning the calculated depth of infiltration as the depth of slip surface, the factor of safety of the slope is obtained through the infinite slope stability model. A time-series visualization map of the space-time varying factor of safety is generated when the method is implemented with the aid of Geographic Information System (GIS) software. The model is applied and validated with the landslides that occurred during the October 2019 Typhoon Hagibis in Marumori, Japan. The model results show good agreement with the reported time and depths of failure, and the analysis of the spatial distribution of predicted failures yielded receiver operating characteristic-area under the curve (ROC-AUC) value of 0.90. The applicability of the model can be extended for post-analysis, real-time, or projected assessment of slope stability, depending on the nature of input rainfall data (e.g., historical, real-time, forecast, hypothetical).

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Section: Geologic Settingmentioning

confidence: 79%

Section: Geologic Settingmentioning

confidence: 99%

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Mapping method of rainfall-induced landslide hazards by infiltration and slope stability analysis

et al. 2021

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“…19 (Hagibis) in 2019, the total rainfall from October 10th to 13th was over 1000 (mm) in Hakone Town, Kanagawa Prefecture, and exceeded 500 (mm) per 24 h at 17 sites in eastern Japan, which was possibly the highest rainfall since 1982. Therefore, the typhoon caused 952 sediment disasters 5 . Furthermore, recently, in the forest areas of Japan, the decrease of understory coverage rate by overgrazing deer has become a serious problem.…”

Section: Introductionmentioning

confidence: 99%

The risk reduction effect of sediment production rate by understory coverage rate in granite area mountain forest

Mizuno

Kojima

Asano

2021

Sci Rep

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Ecosystem-based disaster risk reduction (Eco-DRR) is an important concept to the adaption of climate change for a sustainable life. In Japan, it is anticipated that damages caused by sediment production will be increased as the intensity and amount of rainfall are increased by climate change. Thus, we need to know the Eco-DRR effect of the forest for planning sustainable land use by evidence-based data. In this study, we focused on the relationship between sediment production rate and the understory coverage rate of a low mountain forest in the granite area. From the results of the field survey and statistical meta-analysis, the sediment production rate was reduced by 97% in granite area mountain forest when the understory coverage rate was 60% or more compared to when less than 30% by evidence-based data. Accordingly, we found that it will be necessary to keep forests with an understory coverage rate of 60% or more when considering the risk-reducing effect of sediment disaster in granite area mountain forests for the adaption of climate change.

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“…In October 2019, typhoon no. 19 (Hagibis), which made landfall on Japan on October 12, was reported to have generated the largest number of sediment disaster occurrences (e.g., landslides and mudflows) in Japan since 1982 [Irasawa et al, 2020], killing at least 93 people, including 31 in the Fukushima Prefecture, and leaving 2367 people homeless across Japan [Asanuma-Brice, 2019]. The heavy rainfall recorded during this event also led to the overflow of numerous rivers across Japan, including several coastal rivers draining the main radioactive plume of the Fukushima Prefecture.…”

Section: Introductionmentioning

confidence: 99%

Impact of the 2019 typhoons on sediment source contributions and radiocesium concentrations in rivers draining the Fukushima radioactive plume, Japan

Evrard¹,

Durand²,

Nakao³

et al. 2020

Comptes Rendus. Géoscience

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October 2019 Sediment Disaster in the Tohoku Region owing to Typhoon No. 19 (Tyhpoon Hagibis)

Cited by 15 publications

References 0 publications

Mapping method of rainfall-induced landslide hazards by infiltration and slope stability analysis

Mapping method of rainfall-induced landslide hazards by infiltration and slope stability analysis

The risk reduction effect of sediment production rate by understory coverage rate in granite area mountain forest

Impact of the 2019 typhoons on sediment source contributions and radiocesium concentrations in rivers draining the Fukushima radioactive plume, Japan

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