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農学部 森林緑地環境科学科 |
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准教授 |
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Park J.H., Shinohara Y., Gomez C., Hotta N.
Geomorphology 453 2024年5月
担当区分：責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Geomorphology
Rainfall-triggered volcanic debris flows (VDFs), or lahars, frequently occur during and/or immediately after eruptions, often because of decreases in the infiltration capacity resulting from the deposition of fine volcanic materials. Although the infiltration capacity recovers and the frequency of VDFs decreases within a decade, VDFs have continued to occur over several decades after the eruption of some volcanoes. No study has yet identified the factors controlling sediment discharge of VDFs for a specific volcano after the recovery of infiltration capacity to the pre-eruptive level. We analyzed topographic changes and sediment volumes between 2003 and 2020, using 16 digital elevation models (DEMs) and orthophotographs from aerial lidar scanning for the Tansandani and Gokurakudani gullies of Mount Unzen where the infiltration capacity has recovered after the most recent eruption in 1990–1995. We also analyzed the frequency and magnitude of VDFs in 2003–2020. Topographic changes differed before and after three large-scale VDFs in 2015 and 2016. The total volume of the three VDFs was 140 × 103 m3. Between 2003 and 2014, the width and depth of the gullies continuously increased, with the changes in the intervals of successive DEMs averaging below 5 m. Between 2017 and 2020, gully cross-sections remained U-shaped and changed little, while the channel gradient gradually decreased. U-shaped gullies promote the dispersion of VDFs and their gentle slopes reduce the velocity of VDFs. As a result, the frequency and magnitude of VDFs decreased, and deposition and erosion in the gullies were almost balanced between 2017 and 2020. Thus, we conclude that topography is the main factor that controls the occurrence and magnitude of debris flows and therefore sediment discharge after the recovery of infiltration capacity to the pre-eruptive level.
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Daikai R., Gomez C., Hotta N., Shinohara Y.
IOP Conference Series: Earth and Environmental Science 1314 ( 1 ) 2024年3月
掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IOP Conference Series: Earth and Environmental Science
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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Short communication: Concentrated impacts by tree canopy drips – hotspots of soil erosion in forests 査読あり 国際共著
Katayama A., Nanko K., Jeong S., Kume T., Shinohara Y., Seitz S.
Earth Surface Dynamics 11 ( 6 ) 1275 - 1282 2023年12月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Earth Surface Dynamics
The degradation of ground vegetation cover caused by large grazing herbivores frequently results in enhanced erosion rates in forest ecosystems. Splash erosion can be caused by drop impacts with a high throughfall kinetic energy (TKE) from the tree canopy. Notably larger canopy drips from structurally mediated woody surface points appear to induce even higher TKE and generate concentrated impact locations causing severe focus points of soil erosion. However, TKE at these locations has rarely been reported. This pilot study investigated the intensity of TKE at a concentrated impact location and compared it with general TKE locations under the canopy and freefall kinetic energy (FKE) outside the forest. We measured precipitation, TKE and FKE using splash cups at seven locations under Japanese beech trees and five locations outside the forest during the leafless and leafed seasons in 2021 in a mixed forest with evergreen coniferous trees and deciduous broadleaved trees in Japan. The TKE at the concentrated impact location was 15.2 and 49.7 times higher than that at the general locations under the beech and FKE, respectively. This study confirmed that canopy drip from woody surfaces could be a hotspot of soil erosion in temperate forest ecosystems. Throughfall precipitation at the concentrated impact location was 11.4 and 8.1 times higher than that at general locations and freefall, respectively. TKE per 1 mm precipitation (here, “unit TKE”) at the concentrated impact location (39.2 ± 23.7 J m−2 mm−1) was much higher than that at general locations (22.0 ± 12.7 J m−2 mm−1) and unit FKE (4.5 ± 3.5 J m−2 mm−1). Unit TKE in the leafless season was significantly lower than in the leafed season because of fewer redistribution of canopy drips induced only by woody tissue. Nevertheless, unit TKE at the concentrated impact location in the leafless season (36.4 J m−2 mm−1) was still higher than at general locations in the leafed season. These results show that potentially high rates of sediment detachment can be induced not only by throughfall precipitation but also by larger throughfall drop size distributions at the concentrated impact location, even in the leafless season. Further studies with more replication building on this first report are necessary to investigate how many of these concentrated impact locations may occur on average with different tree species to better assess the extent of the erosion risk under forests.
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Differences in factors determining landslide hazards among three types of landslides in Japan 査読あり
Shinohara Y., Watanabe Y.
Natural Hazards 118 ( 2 ) 1689 - 1705 2023年9月
担当区分：筆頭著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Natural Hazards
The motivation for this study was to clarify the factors that affect landslide occurrences at the national level in Japan and differences in the factors that result from landslide types. The factors that cause differences in the number of rainfall-triggered landslide disasters in 47 Japanese prefectures were examined using generalized linear models. The analysis was conducted for each of the three types (i.e., steep-slope failure, deep-seated landslide, and debris flow) of landslide disasters. For all types, the rainfall index and the number of landslide-prone areas were selected with positive coefficients while the accretionary complexes geological type was selected with negative coefficients. For steep-slope failure, forests and land for buildings were selected with negative and positive coefficients, respectively. For deep-seated landslide and debris flow, land use was seldom selected. Thus, the factors were found to have differed as a result of the landslide type. Because the number of landslides alters the fatalities and building damage in Japan, this study contributes to the prioritization of landslide countermeasures at the national level.
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Gomez C., Hotta N., Shinohara Y., Park J.H., Tsunetaka H., Zhang M., Bradak B., Sri Hadmoko D., Budi Wibowo S., Daikai R., Yoshida M.
Journal of Applied Geophysics 209 2023年2月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Applied Geophysics
Volcanic gullies develop U-shape cross-profiles due to the lahars that shape them after eruptive events. Over time, the processes of sediment-transfer change and the erosion of sub-vertical walls become a leading process. It results in debris-cones at their foot. However, the processes that generate these landforms is still unclear. Indeed, the surface is the one of a cone or a “steep debris-fan”, but are these diffusive landforms starting through progressive regressive-erosion of the wall, or do they follow an original collapse? This we do not know, and as the material is poorly-sorted with a mixture of unconsolidated fine sands to large clasts, digging a trench is not possible as it destroys the material structure. Therefore, the present contribution aims to define the development mechanisms of the side-wall debris-cones using Ground Penetrating Radar imaging, working in the Tansandani Gully at Unzen Volcano (Japan). The GPR used in the study is a Mala Ramac Pro-Ex mounted with a 500 MHz shielded antenna. The GPR signal penetrated up to 4–5 m depth and the velocity was homogeneous on average through the different material layers and at the different location, although at depth variations occurred. The structure of the units in the radargrams present units' parallel to the surface for the first 40 to 60 cm, with underneath the presence of more irregular prograding units, with eventually underneath a set of units that are structureless and often rich in blocks. The two lower structureless-units are not always present and one of the debris-cone only showed a set of rough subparallel units. This differences are the result of the debris-cones being generated by (1) at first a wall collapse or by rapid water-borne processes creating (2) bulk prograding units, which have to be put in place during a heavy-rainfall event. Finally, near the surface, the (3) thin subparallel units are most probably post-rainfall deposition, resulting from gravity process in dry-material. This can be inferred because there is no evidence of erosion or remobilization in layers and the process has been observed in the field. For the observed debris-cones, their formation is dominated by a wall collapse, which is then recovered by finer-grained units deposited sub-horizontally to the surface.
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森林水文学入門
篠原慶規（ 担当： 分担執筆 , 範囲: 蒸発散）
朝倉書店 2022年9月
記述言語：日本語 著書種別：教科書・概説・概論
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森林学の百科事典
篠原 慶規（ 担当： 共著）
丸善出版 2021年1月
総ページ数：694 担当ページ：災害防止と保安林（第13章 森林と災害） 記述言語：日本語 著書種別：事典・辞書
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The necessity of sensor calibration for the precise measurement of water fluxes in forest ecosystems. IN Forest-Water Interactions
Shin'ichi Iida, Takanori Shimizu, Yoshinori Shinohara, Shin'ichi Takeuchi, Tomo'omi Kumagai（ 担当： 共著）
Springer Nature 2020年2月
総ページ数：643 担当ページ：519-536 記述言語：英語 著書種別：学術書
MISC 【 表示 ／ 非表示 】
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はげ山的水源涵養機能からの脱却
篠原 慶規
森林科学 98 ( 0 ) 41 - 41 2023年6月
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The July 2020 Rainfall-Induced Sediment Disasters in Kumamoto Prefecture, Japan
JITOUSONO Takashi, SHINOHARA Yoshinori, SHIMIZU Osamu, TAGATA Satoshi, TERAMOTO Yukiyoshi, TORITA Eiji, NAGATANI Naomasa, NAKANO Koji, NISHIWAKI Ayato, HIRAKAWA Yasuyuki, FUKUZUKA Kozaburou, IGURA Mari, MIZUNO Hideaki, UE Hirotaka, OHISHI Hiroyuki, KAKIMOTO Tsuyoshi, KITOU Ken-ichi, KOGA Syozo, SAKAI Yusuke, SAKASHIMA Toshihiko
砂防学会英文誌 13 ( 4 ) 93 - 100 2021年4月
記述言語：英語 掲載種別：記事・総説・解説・論説等（学術雑誌） 出版者・発行元：公益社団法人 砂防学会
On July 4, 2020, heavy rainfall was observed in the southern part of Kumamoto Prefecture and the northern part of Kagoshima Prefecture. Due to heavy rainfall, floods and sediment disasters such as collapses and debris flows occurred predominantly in the Kuma River basin of Kumamoto Prefecture. We conducted field investigations at four sites in Ashikita Town and Tsunagi Town, Kumamoto Prefecture, where collapses and debris flows caused deaths. We also conducted field investigations in the Kawauchi River branch of the Kuma River, where vast amounts of sediment discharge caused damage to houses. The objectives of these investigations were to clarify the situation and mechanism of the disasters and to propose procedures to recover from the disasters. This report briefly summarizes the results of these investigations.
DOI： 10.13101/ijece.13.93
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地頭薗 隆, 篠原 慶規, 清水 収, 田方 智, 寺本 行芳, 鳥田 英司, 永谷 直昌, 中濃 耕司, 西脇 彩人, 平川 泰之, 福塚 康三郎, 伊倉 万理, 水野 秀明, 植 弘隆, 大石 博之, 垣本 毅, 木藤 賢一, 古賀 省三, 坂井 佑介, 坂島 俊彦
砂防学会誌 73 ( 4 ) 41 - 50 2020年
記述言語：日本語 掲載種別：速報，短報，研究ノート等（学術雑誌） 出版者・発行元：公益社団法人 砂防学会
On July 4, 2020, heavy rainfall was observed in the southern part of Kumamoto prefecture and the northern part of Kagoshima prefecture. Due to the heavy rainfall, floods and sediment disasters such as landslides and debris flows were occurred especially in the Kuma River basin of Kumamoto prefecture. We conducted field investigations at four sites in Ashikita-town and Tsunagi-town, Kumamoto prefecture, where landslides and/or debris flows caused deaths. We also conducted field investigations in the Kawauchi River branch of the Kuma River where huge amounts of sediment discharge caused damage to houses. The objectives of these investigations were to clarify the situation and mechanism of the disasters and to propose procedures to recover from the disasters. This report briefly summarizes the results in these investigations.
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大規模土砂移動に伴う災害の特徴整理と影響範囲の予測および対策に向けた課題 査読あり
今泉 文寿，堤 大三，中谷 加奈，権田 豊，逢坂 興宏，福山 泰治郎，宮田 秀介，篠原 慶規，水野 秀明，原田 紹臣，水野 正樹
砂防学会誌 70 ( 1 ) 20 - 30 2017年5月
記述言語：日本語 掲載種別：記事・総説・解説・論説等（学術雑誌）
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篠原 慶規
水文・水資源学会誌 30 ( 2 ) 126 - 126 2017年
記述言語：日本語 掲載種別：記事・総説・解説・論説等（学術雑誌） 出版者・発行元：水文・水資源学会
 本書は，小川滋先生が九州大学を2005年に退職された際，企画された2冊のうちの1冊である．「環境と生物」を基本テーマに，森林と水との関わり，森林の環境保全機能について網羅的に解説している。本書が取り扱うトピックスに興味を持った学生や，周辺分野の研究者が，基本的な知識，考え方を得るためにうってつけの書である．
講演・口頭発表等 【 表示 ／ 非表示 】
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森林の成熟が土砂災害発生に与える影響の全国的評価
篠原慶規，Novia Lusiana，今泉文寿
日本森林学会大会 2024年3月8日
開催年月日： 2024年3月8日 - 2024年3月11日
記述言語：日本語 会議種別：口頭発表（一般）
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高密度のマダケ林における樹冠遮断の特徴
木村健人，篠原慶規
日本森林学会大会 2024年3月8日
開催年月日： 2024年3月8日 - 2024年3月11日
記述言語：日本語 会議種別：ポスター発表
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宮崎大学田野フィールドの常緑広葉樹林におけ る樹冠遮断量の計測
阿部悠南，後藤君龍，高木正博，篠原慶規
日本森林学会大会 2024年3月8日
開催年月日： 2024年3月8日 - 2024年3月11日
記述言語：日本語 会議種別：ポスター発表
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様々な表層崩壊跡地における土層厚の回復
松永美月，竹内万結，佐藤忠道，執印康裕，久米朋宣，篠原慶規
日本森林学会大会 2024年3月8日
開催年月日： 2024年3月8日 - 2024年3月11日
記述言語：日本語 会議種別：ポスター発表
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降雨による土砂災害の死者数の長期変動は何によって決まっているのか？
篠原 慶規, 久米 朋宣
水文・水資源学会研究発表会 2023年9月6日 水文・水資源学会
開催年月日： 2023年9月3日 - 2023年9月6日
記述言語：日本語 会議種別：口頭発表（一般）
日本の降雨による土砂災害の死者数は，戦後，2000年頃まで一貫して減少してきた。1945年～2019年の降雨による土砂災害の死者数及び死者数に関わる様々な自然的・社会的要因の変動を比較・分析することで，自然的側面（降雨，森林）及び社会的側面（土木構造物の設置，危険性が高い場所の世帯数，１世帯あたりの人数，住宅構造，避難したかどうか）の両面から，この要因解明を試みた。2000年頃まで見られた死者数の減少は，住宅構造の変化（平屋の減少）に加え，前期は避難した人の増加が，中期は森林の成熟が，後期は土木構造物の設置が寄与した可能性が高いことがわかった。このように土砂災害の死者数減少をもたらす要因は，社会の成熟度と呼応し，時代と共に変化することがわかった。
受賞 【 表示 ／ 非表示 】
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若手農林水産研究者表彰（農林水産技術会議会長賞）
2023年11月 農林水産省 森林および竹林の水土保全機能に関する研究
篠原慶規
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日本森林学会奨励賞
2017年3月 日本森林学会
篠原 慶規
受賞区分：国内学会・会議・シンポジウム等の賞 受賞国：日本国
科研費（文科省・学振・厚労省）獲得実績 【 表示 ／ 非表示 】
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降雨は火山災害を激化させるのか：時系列データの統合・再構築に基づく山体変形解析
研究課題/領域番号：23K17801 2023年04月 - 2025年03月
独立行政法人日本学術振興会 科学研究費補助金 基盤研究（C）
担当区分：研究分担者
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土砂災害による死者数の時空間変動要因の解明
研究課題/領域番号：21K04590 2021年04月 - 2024年03月
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(C)
担当区分：研究代表者
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森林から河川へ流出する炭素量は吸収量に対してどの程度の割合なのか？
研究課題/領域番号：21H02238 2021年04月 - 2024年03月
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(B)
高木 正博、
担当区分：研究分担者
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地上計測とドローンを用いた高時空間分解能の森林蒸散量の推定
研究課題/領域番号：18K14492 2018年 - 2021年03月
科学研究費補助金 若手研究(B)
担当区分：研究代表者
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表層崩壊の危険性を評価する上で土壌水分の空間的不均一性は考慮する必要があるのか？
研究課題/領域番号：25850109 2013年04月 - 2016年03月
科学研究費補助金 若手研究(B)
その他競争的資金獲得実績 【 表示 ／ 非表示 】
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斜⾯崩壊後の経過年数や植⽣回復が⼟層厚に与える影響評価
2023年04月 - 2024年03月
砂防・地すべり技術センター 研究開発助成
担当区分：研究代表者 資金種別：競争的資金
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熱赤外カメラを用いた斜面崩壊時の湧水発生状況の把握
2018年04月 - 2019年03月
砂防学会 若手助成
担当区分：研究代表者 資金種別：競争的資金
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令和４年度火山噴火後の土砂流出継続期間の検討
2022年05月 - 2023年03月
国土交通省 九州地方整備局 一般受託研究
担当区分：研究代表者 受託研究区分：一般受託研究
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土石流発生域の地形的特徴を考慮した土砂生産モデルの構築
2020年05月 - 2021年03月
国土交通省九州地方整備局 一般受託研究
担当区分：研究代表者 受託研究区分：一般受託研究
共同研究実施実績 【 表示 ／ 非表示 】
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GCOM-C 陸圏プロダクトとしての全球蒸発散指数推定アルゴリズムの開発
2021年06月 - 2022年03月
国立研究開発法人宇宙航空研究開発機構 学内共同研究
担当区分：研究分担者 共同研究区分：国内共同研究