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J. Jpn. Soc. Soil Phys.
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   *Application of Soil Physics to Rainwater Dynamics at Forested Hillslopes
Ken’ichirou KOSUGI** Graduate School of Agriculture, Kyoto University, Kyoto 0*0῍2/*,, Japan
Abstract
Rainwater dynamics at forested hillslopes are one of the most important themes in foresthydrology, because they have large e#ects on storm and base ﬂow hydrographs, occurrences ofslope failures, material transports in forest ecosystem, and stream water chemistry.

Rainwater

inﬁltration and discharge processes at forested hillslopes can be e#ectively studied by using
methodologies developed in soil physical studies, which includes methods for determining
saturated-unsaturated soil hydraulic properties, equipments for measuring matric potential andwater content in ﬁeld soils, and numerical simulation techniques for saturated-unsaturated soil
water ﬂow.

This paper introduces several previous and new studies which applied themethodologies of soil physics to the analyses of rainwater dynamics at forested hillslopes.
Topics includes characteristics of forest soil hydraulic properties in comparison with disturbed
sandy and loamy soils, e#ects of pore structure of forest soil on rainwater inﬁltration, indices ofwater holding capacity of forest soils, e#ects of soil water-repellency on heterogeneous inﬁltrationand occurrence of surface runo#, experiments and modeling of soil-pipe ﬂow, as well as rainwaterinﬁltration in weathered bedrock.
Key words : forest hydrology, forest soil, water retention characteristic, hydraulic conductivity,
pipe ﬂow

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rado State Univ., Ft. Collins.

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bution model for soil water retention. Water

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unsaturated soil hydraulic properties. Water1 652  Q8

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retention characteristics of forest soils based onF_`T 74 -??

soil pore radius distribution. J. For. Res., , : +῍2.

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Kosugi, K. (+331 b) : New diagrams to evaluate soil KOV Z +** ¼ ,**/

26+/῍,- IJKL (Mpore radius distribution and saturated hydraulicconductivity of forest soil. J. For. Res., , : 3/῍+*+.

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Kosugi, K., Mori, K. and Yasuda, H. (,**+) : An inverse
modeling approach for the characterization of
unsaturated water ﬂow in an organic forest ﬂoor.
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Kosugi, K., Uchida, T. and Mizuyama, T. (,**.) : Numerical calculation of soil pipe ﬂow and its e#ect
on water dynamics in a slope. Hydrol. Process.,+2 : 111῍123.

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Uchida, T., Kosugi, K. and Mizuyama, T. (+333) :Runo# characteristics of pipeﬂow and e#ects ofKutílek, M. and Nielsen, D.R. (+33.) : Soil hydrology.
p. /-, Catena Verlag, Cremlingen, Germany.
Noguchi, S., Tsuboyama, Y., Sidle, R. C. and Hosoda, I.

pipeﬂow on rainfall-runo# phenomena in a
mountainous watershed. J. Hydrol., ,,, : +2῍-0.

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pathways in a forested slope segment. Soil Sci.
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