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柏谷, 健二 ; Kashiwaya, Kenji
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金沢大学環日本海域環境研究センター
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柏谷, 健二 ; Kashiwaya, Kenji
概要:
金沢大学環日本海域環境研究センター
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柏谷, 健二 ; Kashiwaya, Kenji
概要:
金沢大学環日本海域環境研究センター
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| 4.
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柏谷, 健二 ; Kashiwaya, Kenji
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金沢大学環日本海域環境研究センター<br />Landform changes in lake-catchment systems may give a great insight into clarifying the relations
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hip between geomorphic processes and geomorphic histories. Tracers and dating tools for mass movement (physical properties, Cs-137 and Pb-210_<exe>) are inevitable in these studies ; changes in physical properties and Pb-210_<exe> concentration of sediments are closely related to geomorphic changes, Cs-137 concentration in surface layers is connected to surface erosional processes and Pb-210_<exe> and Cs-137 of lake sediments are available for sediment dating. Short-term observation and analyses in the systems reveal some relationship between the processes and sediment information, suggesting clues to find long-term causal relations in landform evolutions.
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嶌田, 敏行 ; 柏谷, 健二 ; 兵頭, 政幸 ; 増澤, 敏行 ; Shimada, Toshiyuki ; Kashiwaya, Kenji ; Hyodo, Masayuki ; Masuzawa, Toshiyuki
概要:
金沢大学環日本海域環境研究センター<br />Hydro-environmental fluctuations in the central Japan during the Late Holocene have been imprinte
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d in the sediment cores from Lake Yogo, where hydrological conditions changed at c.700 AD; from low water regime to high water regime. An abrupt change in ^<210>Pb concentration of the cores shows that rapid increase in the sedimentation rate may have been connected to artificial channel construction in 1960. Temporal fluctuation in mineral particle size of sediment corresponds to yearly averaged precipitation observed near the lake before the construction (1896-1960), leading to that an annual precipitation around Lake Yogo in the Little Ice Age may be estimated about 2,200 mm and in the late part of Medieval Warm Episode about 2,500 mm, larger than during the past 30 years (about 2,000 mm).
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柏谷, 健二 ; 大井子, 宏和 ; 川谷, 健 ; 沖村, 孝 ; Kashiwaya, Kenji ; Taishi, Hirokazu ; Kawatani, Takeshi ; Okimura, Takashi
概要:
金沢大学環日本海域環境研究センター
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| 7.
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柏谷, 健二 ; Kashiwaya, Kenji
概要:
金沢大学環日本海域環境研究センター<br />リルの発生・発達過程を解明するために,実際の裸地斜面に試験地を設け,種々の観測と試験を行なった.その結果,ここの斜面では,リル侵蝕の発生には10分間当たり1mm以上の降水量が必要であり,斜面下流
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端での流出土砂量は表面流出量の自乗に比例することがわかった.また斜面の侵蝕されやすさの目やすである受蝕係数は時間の経過とともに指数関数的に減少することが示された.さらに,実斜面と模型斜面の対応は流路面積数とホートン数を通して可能であることがわかり,また模型斜面で有効であった確率過程に基礎を置いた理論式を用いてリル数を計算してみたところ,その値は実測値と比較的良い一致を示し,理論式の有効性がこの斜面でも認められた.
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| 8.
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論文
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柏谷, 健二 ; Kashiwaya, Kenji
概要:
金沢大学環日本海域環境研究センター<br />リルの発達過程を定量的に表現するための基礎として,一つのモデルに対する確率微分方程式を導入した.これは,「合流確率は流路数に比例し,分流確率は流路幅/水深に比例する」という仮説から導かれたもので
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ある.実験的に検討した結果,前記の二つの仮説は妥当なものと認められた.さらに上記の方程式の定常解から,最も出現確率の高い流路本数が導かれることが示され,それは実験結果とかなり良好な一致を示した.
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| 9.
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柏谷, 健二 ; Kashiwaya, Kenji
概要:
金沢大学環日本海域環境研究センター<br />For an appropriate explanation of geomorphological features, it is necessary to study both the ch
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aracters of materials which constitute the features and the transformation of the features.Model experiments dealt in this paper offer one effective method to analyze the latter i. e., to examine the laws on the transformation of the features and their fundamental equations.If the experiment is to be considered from the point of view of investigating the fundamen-tal equations, numerical experiments operated by computor today have the similar meaning with model experiments.In either case the features in the prototype should be reproduced in the experiment. Numerical experiments are often useful when proper controlling factors and the laws of their working mechanism are well known. On the other hand, model experiments are sometimes operated in cases where their laws are not well known, because they can be operated with some knowledge on controlling factors in the trial and error steps.As to geomorphological phenomena, generally it is difficult to obtain proper equations for them, and then model experiments may be used to estimate the basic relations among them.The first problem in carrying out the model experiments on geomorphological pheno-mena is that the appropriate dynamic similarity conditions should be observed.The fundamental conditions for satisfying the similarity laws areP1/m1=P2/m2=……=Pn/mn (1)orPi/Pj=mi/mj (i, j=1, 2, …, n) (2)Setting Pi/Pj=πp, mi/mj=πmwe obtain πp=πm (3)where p is a physical factor in the prototype, and m that in the model.Eq. (3) indicates that pr-numbers in the prototype must be equal to those in the model for the phenomenon to reappear in the model.But it is seldom possible that all π-numbers in the model are in conformity with those in the prototype. This is the limitation of the model experiment. In some cases, however, it is possible to operate the experiment by easing the similarity law i. e., dividing a pheno-menon into some local regions in space and time.In the model experiment on gully morphology, the eroding force by surface runoff was assumed to be a dominant factor. The fundamental equation of surface erosion is given by Horton (1945), which may be written as followsdmp/dtp=kepApτep (4)with m: eroded mass, t: time, ke: erosion proportionality factor, A:area, τe: eroding force per unit area, and suffix p: prototype.The scaling relations are developed simply by postulating that the fundamental equation be valid in the prototype as well as in the model.Hence Eq. (4) becomesdmm/dtm=kemAmτem (5)in the model. Here the suffix m indicates the model.As the physical factors in the model and those corresponding in the prototype are related by scaling ratios, the ratio of Eq. (4) to Eq. (5) may be written as followsdmp/dmm dtm/dtp=kep/kem Ap/Am τep/τem (6)Using m ∝ ρ8l3, A ∝ l2 and τe ∝ ρwV2, Eq. (6)become sρwp/ρsp kevp=ρwm/ρsm kemVm (7)with ρs: the density of soil, l: length, ρw: the density of water, and v: velocity. Here, all variables are expressed by representative quantity.
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| 10.
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柏谷, 健二 ; 横山, 康二 ; 奥田, 節夫 ; Kashiwaya, Kenji ; Yokoyama, Koji ; Okuda, Setsuo
概要:
金沢大学環日本海域環境研究センター<br />ガリーの発達過程を幾何学的形態の変化として把握することを目的として,本稿においてはガリーの有する幅,間隔,あるいはその数の統計的法則性とその水理学的発生条件を検討した.その結果ガリーは各々の斜面
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において特有な幅,あるいは特定の間隔に集中することが解った.また,これらのことからガリーの本数も,一つの斜面においてその幅に比例する傾向があることが解った.次に,ガリーの水理学的発生条件として新たに導入したSoil Factor (ƒ1/3/Kただしƒ;表面流出率, K; 固結度)なる物理定数が対象とする斜面の侵食性を示すものとして有効であることが解った.
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