Multitemporal UAV surveys of geomorphological changes caused by postfire heavy rain in Kamaishi city, northeast Japan

Touge, Yoshiya; Hasegawa, Masashi; Minegishi, Masayoshi; Kawagoe, Seiki; Kazama, So

doi:10.1016/j.catena.2022.106702

Cited by 3 publications

(1 citation statement)

References 76 publications

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“…Recent developments in close-range photogrammetry such as SfM-MVS (Structure from Motion and Multiple-View Photogrammetry) and LiDAR (Light Detection and Ranging) has triggered an increase of topographic surface comparisons to measure erosion and deposition [1], at the coast [2], in landsliding areas [3], after post-fire geomorphological changes [4], and in volcanic areas such as Sakurajima Volcano [5]. These changes analysis are based on surface changes, and do not include variability in bulk density, which is influencing the measure and calculation of erosion and deposition.…”

Section: Conceptual Backgroundmentioning

confidence: 99%

Uncertainty in measuring the role of climate change on debris-flow triggering on volcanoes - bulk-density, temperature and moisture analysis at Unzen Volcano (Japan)

Daikai,

Gomez,

Hotta

et al. 2024

IOP Conf. Ser.: Earth Environ. Sci.

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As climate change creeps into the 21st century, the intensity of debris flows due to heavy and concentrated rainfall has increased in mountainous regions of Japan and East Asia. However, the relationship between climate change and an increase in debris flows is likely to be non-linear. Rainwater infiltrates more quickly into porous material, and the lack of vegetation cover increases evaporation and the temperature of surface sediments. In addition, periodic gully collapses bring fresh layers of porous material that increase the distance between the surface and the vadose zone. Therefore, to understand the relationship between volcanic debris flows (or lahars), parameters such as density, porosity, temperature, and moisture retention must be captured in detail in both time and space. The aim of this paper is to assess the role of loose, coarse, and porous sediments in lahar triggering. The present study was conducted at Unzen volcano in the Tansandani Guly between 31 May and 1 June 2023, 30 years after the last eruption. The dacite material is composed of a matrix of sand and coarse sand mixed with larger fractions and blocks, therefore traditional density measurement methods could not be applied, and a photogrammetric based method was used. In the field, sets of SfM-MVS photographs were taken before and after digging a hole in the sediments so that the measured mass could be compared to the volume of the hole in the sediments. After the sediments were dried, the dry and wet density, bulk density and porosity of the sample were calculated. When compared to the temperature data collected in the field, the following results were obtained: (1) The porosity of the volcanic material was highest in the lower reaches, followed by the upper reaches, and lowest in the middle reaches. This may be because fine sand washed out of the upstream area by rainfall is currently stored in the midstream area, which may facilitate debris flow generation. In addition, the downstream area has a high porosity, which may be due to the surrounding vegetation preventing the influx of new fine sand from the channel wall. (2) Because of the higher porosity and the lack of organic matter and vegetation cover, the increase in temperature acts more directly on the decrease in water content than in mountainous areas. Consequently, empirical equations for the potential for mudslides in volcanic areas with respect to surface temperature and soil moisture need to be developed for hazard and disaster risk management purposes.

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Section: Conceptual Backgroundmentioning

confidence: 99%

Uncertainty in measuring the role of climate change on debris-flow triggering on volcanoes - bulk-density, temperature and moisture analysis at Unzen Volcano (Japan)

Daikai,

Gomez,

Hotta

et al. 2024

IOP Conf. Ser.: Earth Environ. Sci.

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Spatial-temporal characteristics of more than 50,000 wildfires in Japan from 1995 to 2020

Touge,

Shi,

Nishino

et al. 2024

Fire Safety Journal

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第7回水文学フォーラム　大規模林野火災を対象とした水文学的評価開催報告

2024

J. Japan Soc. Hydrol. and Water Resour.

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Multitemporal UAV surveys of geomorphological changes caused by postfire heavy rain in Kamaishi city, northeast Japan

Cited by 3 publications

References 76 publications

Uncertainty in measuring the role of climate change on debris-flow triggering on volcanoes - bulk-density, temperature and moisture analysis at Unzen Volcano (Japan)

Uncertainty in measuring the role of climate change on debris-flow triggering on volcanoes - bulk-density, temperature and moisture analysis at Unzen Volcano (Japan)

Spatial-temporal characteristics of more than 50,000 wildfires in Japan from 1995 to 2020

第7回水文学フォーラム　大規模林野火災を対象とした水文学的評価開催報告

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Multitemporal UAV surveys of geomorphological changes caused by postfire heavy rain in Kamaishi city, northeast Japan

Cited by 3 publications

References 76 publications

Uncertainty in measuring the role of climate change on debris-flow triggering on volcanoes - bulk-density, temperature and moisture analysis at Unzen Volcano (Japan)

Uncertainty in measuring the role of climate change on debris-flow triggering on volcanoes - bulk-density, temperature and moisture analysis at Unzen Volcano (Japan)

Spatial-temporal characteristics of more than 50,000 wildfires in Japan from 1995 to 2020

第7回水文学フォーラム 大規模林野火災を対象とした水文学的評価開催報告

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Product

Resources

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第7回水文学フォーラム　大規模林野火災を対象とした水文学的評価開催報告