2022/09/29 更新

写真a

ニシイ リヨウコ
西井 稜子
NISHII Ryoko
所属
災害・復興科学研究所 准教授
職名
准教授
外部リンク

学位

  • 博士(理学) ( 2010年3月   筑波大学 )

研究キーワード

  • 地形学

研究分野

  • 人文・社会 / 地理学

経歴

  • 新潟大学   災害・復興科学研究所   准教授

    2020年4月 - 現在

  • 新潟大学   研究推進機構 超域学術院   助教

    2019年4月 - 2020年3月

  • 新潟大学   研究推進機構 超域学術院   特任助教

    2017年2月 - 2019年3月

所属学協会

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論文

  • 平成16年新潟県中越地震後に発生した地すべりの分布特性について 査読

    後根裕樹, 西井稜子, 石井靖雄, 櫻本智美, 藤平大

    日本地すべり学会誌   57 ( 2 )   4 - 13   2020年3月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

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  • 複数時期の航空レーザ測量データを用いた変動斜面末端部とすべり面発達の推定 査読

    西井稜子, 石井靖雄, 佐藤匠, 本間信一

    日本地すべり学会誌   56 ( 2 )   31 - 38   2019年3月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

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  • Forest harvesting impacts on microclimate conditions and sediment transport activities in a humid periglacial environment 査読

    Imaizumi F, Nishii R, Ueno K, Kurobe K

    Hydrology and Earth System Sciences   23   155 - 170   2019年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Continuous and large sediment supply in a steep landslide scar, Southern Japanese Alps 査読

    Ryoko Nishii, Fumitoshi Imaizumi, Hiromu Daimaru, Wataru Murakami

    Geomorphology   312   51 - 59   2018年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier B.V.  

    Continuous sediment supply in the Aka-kuzure landslide scar, in the tectonically active alpine Southern Japanese Alps, was investigated using airborne light detection and ranging data in 2000, 2003, 2007 and 2012. In addition, we focused on the spatial variability of denudation patterns based on topographical analyses using DEMs. Denudation volume for the past 12 years reached about 106 m3 and mean annual denudation rate ranged from 0.25 to 0.31 m/yr. Topographical analyses revealed that sediment supply in the scar consists of a combination of two denudation types, sporadic-deep and wide-thin. These denudation types have different roles in the topographical development of the landslide scar. Sporadic-deep type supplies less volume than wide-thin type but still contributes to channel development, as it mainly occurs on lower-order streams and tends to change the convex slope into a concave slope. In contrast, although denudation depth of the wide-thin type is thin, the area affected by this type extends to the whole landslide scar. Consequently, the wide-thin type accounts for most of the total volume lost, for which detachment by frost shattering is suggested as an important role.

    DOI: 10.1016/j.geomorph.2018.04.002

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  • 地すべりのひずみ及びひずみ速度の経時変化による崩壊の切迫性評価 査読

    杉井良平, 西井稜子, 石井靖雄

    日本地すべり学会誌   54 ( 6 )   259 - 268   2017年11月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3313/jls.54.259

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  • 地すべりキーワード101(ワン・オー・ワン)-18-

    西井 稜子

    日本地すべり学会誌   53 ( 3 )   109 - 111   2016年

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    記述言語:日本語   出版者・発行元:公益社団法人 日本地すべり学会  

    DOI: 10.3313/jls.53.109

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  • Effects of deforestation and weather on diurnal frost heave processes on the steep mountain slopes in south central Japan 査読

    Kenichi Ueno, Kousei Kurobe, Fumitoshi Imaizumi, Ryoko Nishii

    EARTH SURFACE PROCESSES AND LANDFORMS   40 ( 15 )   2013 - 2025   2015年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    Freezing and thawing processes play an important role for the gravitational transport of surface materials on steep mountain slopes in Japan. The effects of deforestation on frost heave activity were observed through the 2012/2013 winter season in Ikawa University Forest, a southern mountainous area in central Japan (1180-1310 m above sea level). During periods without snow cover, needle ice development prevailed at a clear-cut site, and the downslope sediment movement of upper soil was 10 to 15 cm through the winter season. At a non-cut site, rise and fall in the ground surface level prevailed on a weekly scale, with no evident downslope movements at the surface; ice lens formation in the soil layer is assumed. Abrupt changes in the radiation budget, such as the strengthening of nighttime radiative cooling and increases in daytime direct insolation, induced frequent development/deformation of needle ice at the clear-cut site. In snow-free periods, the day-to-day variability in needle ice growth length and in nighttime averaged net radiation showed significant correlations; cloudy weather with warmer and moist air intrusion associated with synoptic disturbances prevented the occurrence of needle ice. Namely, day-to-day weather changes directly affected the mass movement of the upper soil after deforestation. Shallow snow cover occurred discontinuously through the winter and is likely an important factor in keeping the soil moisture sufficiently high in the upper soil layer for initiating needle ice during snow-free periods. We also discuss contributions of coastal extratropical cyclone activities providing both snow cover and cloudy weather in the southern mountain areas of central Japan to the intra-seasonal variability in frost heave and its indirect effect on soil creep and landslides on the deforested steep slopes. Copyright (c) 2015 John Wiley & Sons, Ltd.

    DOI: 10.1002/esp.3776

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  • Parallel retreat of rock slopes underlain by alternation of strata 査読

    Fumitoshi Imaizumi, Ryoko Nishii, Wataru Murakami, Hiromu Daimaru

    GEOMORPHOLOGY   238   27 - 36   2015年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Characteristic landscapes (e.g., cuesta, cliff and overhang of caprock, or stepped terrain) formed by differential erosion can be found in areas composed of variable geology exhibiting different resistances to weathering. Parallel retreat of slopes, defined as recession of slopes without changes in their topography, is sometimes observed on slopes composed of multiple strata. However, the conditions needed for such parallel retreat have not yet been sufficiently clarified. In this study, we elucidated the conditions for parallel retreat of rock slopes composed of alternating layers using a geometric method. In addition, to evaluate whether various rock slopes fulfilled the conditions for parallel retreat, we analyzed topographic data obtained from periodic measurement of rock slopes in the Aka-kuzure landslide, central Japan. Our geometric analysis of the two-dimensional slopes indicates that dip angle, slope gradient, and erosion rate are the factors that determine parallel retreat conditions. However, dip angle does not significantly affect parallel retreat conditions in the case of steep back slopes (slope gradient > 40 degrees). In contrast, dip angle is an important factor when we consider the parallel retreat conditions in dip slopes and gentler back slopes (slope gradient < 40 degrees). Geology in the Aka-kuzure landslide is complex because of faulting, folding, and toppling, but spatial distribution of the erosion rate measured by airborne LiDAR scanning and terrestrial laser scanning (TLS) roughly fulfills parallel retreat conditions. The Aka-kuzure landslide is characterized by repetition of steep sandstone cliffs and gentle shale slopes that form a stepped topography. The inherent resistance of sandstone to weathering is greater than that of shale. However, the vertical erosion rate within the sandstone was higher than that within the shale, due to direct relationship between slope gradient and vertical erosion rate in the Aka-kuzure landslide. (C) 2015 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.geomorph.2015.02.030

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  • 二次元電気探査による重力性変形地形浅層部の可視化の試み 査読

    西井稜子, 池田 敦

    地学雑誌   122 ( 4 )   755 - 767   2013年8月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Tokyo Geographical Society  

    Sackung features (scarps) have developed extensively in the Japanese Alps as a result of gravitational deformation. Electrical resistivity tomography was applied to evaluate the internal structure below eight scarps located above 2600 m a.s.l. The range of resistivity values differed significantly between the scarps and is mainly controlled by the moisture content of the ground. High- and low-resistivity areas were distinctly separated below some scarps. Areas of relatively low resistivity are considered as slightly fractured bedrock. In contrast, areas of high resistivity are likely to indicate highly fractured bedrock and/or talus without matrix. Such boundaries between high- and low-resistivity areas seem to correspond to fracture planes estimated from topography.

    DOI: 10.5026/jgeography.122.755

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    その他リンク: https://jlc.jst.go.jp/DN/JALC/10023208833?from=CiNii

  • 南アルプスにおける地形変動と土砂収支最近の研究動向と展望 査読

    松岡憲知, 今泉文寿, 西井稜子

    地学雑誌   122 ( 4 )   591 - 614   2013年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Tokyo Geographical Society  

    This review paper synthesizes geomorphic dynamics, sediment transport and resulting natural hazards in mountains of the southern Japanese Alps and their drainage basins, where climatic and geological situations produce highly active landform dynamics. In alpine areas above the timber line, shallow diurnal freeze-thaw action operating in the thin topsoil produces small-scale periglacial forms, and gravitational spreading leads to numerous sackung features where snow-melt and heavy rain in places promote rockslides. In subalpine and montane areas, deep-seated landslides originate from fractured sedimentary rocks, deep V-shaped valleys, and heavy rain, while shallow landslides continue with historical forest clearance. Continuous slope failures prevent vegetation recovery and maintain debris input to valleys. Steep valleys contribute to high-density debris flows. Frequent or repetitive occurrences of these mass movements promote continuous denudation of slopes, rockfall accidents along hiking trails, and sedimentation at artificial dams. They occasionally cause significant hazards to villages further downstream. Predicting and mitigating slope hazards require distinguishing among annual, low-magnitude processes, episodic high-magnitude processes and geomorphic changes associated with long-term climate change.

    DOI: 10.5026/jgeography.122.591

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    その他リンク: https://jlc.jst.go.jp/DN/JALC/10023208710?from=CiNii

  • Precursors and triggers of an alpine rockslide in Japan: the 2004 partial collapse during a snow-melting period 査読

    Ryoko Nishii, Norikazu Matsuoka, Hiromu Daimaru, Masatsugu Yasuda

    LANDSLIDES   10 ( 1 )   75 - 82   2013年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    The Aresawa rockslide in the Japanese Alps encountered a deep, partial collapse during an early snow-melting period in May 2004, followed by further progressive movement of the headscarp area. This paper reconstructs the pre-failure topography of the Aresawa rockslide based on the analysis of aerial photographs taken in multiple periods, and analyzes the factors controlling the threshold for the 2004 collapse. At least seven months before the collapse, new tension cracks emerged about 25 m behind the headscarp as a result of downslope movement of an unstable rock slab 5-10 x 10(5) m(3) in volume, accompanied by the development of a slip plane below a pre-existing shallow trough (sackung feature). The collapse finally occurred when progressive weakening of the rock mass was combined with water infiltration into the ground during rapid snow melting.

    DOI: 10.1007/s10346-012-0353-5

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  • Kinematics of an alpine retrogressive rockslide in the Japanese Alps 査読

    Ryoko Nishii, Norikazu Matsuoka

    EARTH SURFACE PROCESSES AND LANDFORMS   37 ( 15 )   1641 - 1650   2012年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY  

    The Aresawa rockslide in the Japanese Alps experienced a partial collapse (510 x 105?m3) in 2004, followed by an accelerated downward movement of the head area rather than stabilization. This paper discusses the kinematics of a retrogressive rockslide area and factors promoting slope instability subsequent to the 2004 collapse, on the basis of geodetic surveys and meteorological observations from 2006 to 2010. The unstable area covers at least 2.3 x 104?m2 and consists of five active blocks. The main blocks are separated from the stable rock slope by pre-existing sackung features that follow the strike of the bedding plane. Shear zones below these sackung features have developed into slip planes potentially causing the next collapse. In particular, the propagation of a slip plane causing movement at 70?cm?yr-1 in the head area is promoted by bidirectional movement. It consists of slow dip-slip movement in snow-accumulating periods and rapid side-slip movement in snow-melting and snow-free periods, both of which occur on the same slip plane. This bidirectional movement appears to result from the combination of a loss of lateral support by the 2004 event and the immature state of the slip plane. The primary trigger of the acceleration in the unstable area is the stress release by the 2004 collapse. In addition, the presence of a potential slip plane below the sackung features also promotes slope instability, suggesting that sackung features behind a rockslide area may predefine the new head scarp of a forthcoming collapse. Copyright (C) 2012 John Wiley & Sons, Ltd.

    DOI: 10.1002/esp.3298

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  • 赤石山脈三峰岳周辺の岩石氷河の14C年代 査読

    池田 敦, 西井稜子

    第四紀研究   50   309 - 317   2011年

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  • Monitoring rapid head scarp movement in an alpine rockslide 査読

    R. Nishii, N. Matsuoka

    ENGINEERING GEOLOGY   115 ( 1-2 )   49 - 57   2010年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The Aresawa rockslide in the Japanese Alps, which partially collapsed in May 2004, produced a number of new tension cracks in the head area. This paper discusses the dynamics of the rock slope and controls on the surface velocity, based on the results of on-site monitoring of the surface movement and meteorological parameters (air and ground surface temperatures, precipitation and snow depth). The rock mass deformation progressed at ca. 60 cm yr(-1) mainly along a slip plane dipping downslope at ca. 50 degrees. The surface velocity of the slipping rock mass showed a significant seasonal variation in response to the water infiltration. The velocity was small (<= 1 mm day(-1)) in winter. Subzero air temperatures and a heat-insulating snow cover, and resulting growth of seasonal frost, prevent water infiltration into the bedrock and contribute to the rock slope stability. Most of the movement in this period is attributed to gravitational deformation originating from the overburden pressure. In contrast, the surface velocity increased (up to 10 mm day(-1)) during snow-melting and snow-free periods. Snowmelt and rainfalls promote water infiltration into the bedrock, destabilizing the rock slope and accelerating the rock slip. Such a rapid movement is attributed to water-induced sliding superimposed on gravitational deformation. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.enggeo.2010.06.014

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  • 飛弾山脈の花崗岩山域における斜面崩壊が線状凹地の分布に及ぼす影響 査読

    西井稜子

    地学雑誌   118 ( 2 )   233 - 244   2009年

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    記述言語:日本語   出版者・発行元:Tokyo Geographical Society  

    Linear depressions and associated uphill-facing scarps, which result from the gravitational deformation of rock slopes, have widely developed along the main ridge in the Mt. Eboshi area, northern Japanese Alps. The role of landslides in the development of linear depressions in granitic rocks is evaluated from the distribution of linear depressions, characteristics of landslides (form, magnitude and frequency) and characteristics of bedrock (geology, discontinuity, degree of weathering and rock mass strength). The morphology of landslides and changes in the areas of landslides from 1958 to 2004 are compared to the development of linear depressions. Most linear depressions lie parallel to the main ridge and the strike of major rock joints, although their distribution differs between the northern and southern areas. In the northern study area, linear depressions are concentrated on the gentle upper slopes and landslides have intensively occurred on the lower slopes. In contrast, the southern area shows sporadic occurrences of linear depressions on the middle to upper slopes and has experienced only minor landslides. The intensive occurrences of landslides and linear depressions in the northern area are considered to result basically from debuttress and stress-release caused by the landslide activity. In addition, the lower rock mass strength in the northern study area also promotes the development of linear depressions.

    DOI: 10.5026/jgeography.118.233

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    その他リンク: https://jlc.jst.go.jp/DN/JALC/00330973494?from=CiNii

  • 飛騨山脈・野口五郎岳周辺における花崗岩類の風化特性と地形 査読

    西井稜子

    地形   28 ( 3 )   239 - 256   2007年7月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:日本地形学連合  

    Weathering characteristics of two kinds of granites and their influences on landforms are compared along the main ridge of the Mt. Noguchi-goro area, the northern Japanese Alps. The two lithologies (granites A and B) contrast in the Schmidt rock hammer rebound, P-wave velocity, weathering index and physical rock properties. The granite A has lower rock strength and produces finer rock debris composed mainly of pebbles and finer materials than the granite B, reflecting the difference in the mineral composition. The granite A is subject to granular disintegration resulting from the high content of plagioclase that is sensitive to weathering. In contrast, the granite B produces a wide range of rock debris sizes from pebbles to boulders, reflecting the high content of K-feldspar that is less susceptible to granular disintegration and the predominance of macrogelivation along joints. The weathering characteristics of the two lithologies affect the types and morphology of the alpine landforms in the area, including patterned grounds, tors and mass movement features. For instance, the fine and homogeneous sizes of debris lead to the predominance of sorted stripes on slopes in the granite A area, while the wide range of debris sizes is responsible for turf-banked terraces in the granite B area. The contrasting weathering features indicate that chemical weathering plays an important role in the grain size distribution of surface materials as well as frost shattering.

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    その他リンク: http://dl.ndl.go.jp/info:ndljp/pid/10807706

  • Rockfall hazard in the Daisekkei Valley, the northern Japanese Alps, on 11 august 2005 査読

    Yoshihiko Kariya, Go Sato, Kuniyasu Mokudai, Jiro Komori, Masaki Ishii, Ryoko Nishii, Yosuke Miyazawa, Noriko Tsumura

    LANDSLIDES   4 ( 1 )   91 - 94   2007年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    This paper describes a rockfall event in the Daisekkei Valley of Mount Shirouma-dake (2,932 m), the northern Japanese Alps. The rockfall occurred on a steep cliff comprising well-jointed felsites and produced debris of >= 8,000 m(3). Most debris was deposited on an elongated snowpatch located immediately beneath the cliff, and it caused casualties among people who were trekking along a trail on the snowpatch. Additionally, a large rock block slipped 1 km on the snowpatch. The rockfall could have been due to the differential retreat of the rockwall, which contains areas of high- and low-density joints. Seasonal and diurnal freeze-thaw activities and snow avalanches and wash appear to be important factors responsible for the retreat. Although some rock blocks that can collapse further remain on the rockwall, the position of the mountain trail in the Daisekkei Valley is fixed. Fundamental reform of tourism systems for climbers, including education on natural hazards, is required.

    DOI: 10.1007/s10346-006-0067-7

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受賞

  • 日本地形学連合2018年秋季大会ベストポスター賞

    2018年11月   日本地形学連合  

    西井稜子

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  • 2014年度信州フィールド科学賞

    2014年12月   信州大学 理学部 信州山の環境研究センター  

    西井稜子

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  • 日本地すべり学会第53回研究発表会若手ポスター賞

    2014年8月   日本地すべり学会  

    西井稜子

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担当経験のある授業科目

  • 環境保全学特論

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  • 斜面災害論

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  • 斜面災害特論Ⅰ

    2020年
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  • 環境保全学特論

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