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Fingered flow occurred in the unsaturated soil

Research Project

Project/Area Number 09660263
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Irrigation, drainage and rural engineering/Rural planning
Research InstitutionSaga University

Principal Investigator

CHO Hiroyuki  Department of Agricultural Sciences, Saga University, Assistant Professor, 農学部, 助手 (90136599)

Co-Investigator(Kenkyū-buntansha) INOUE Mitsuhiro  Tottori Univ., Arid Land Research Center, Associate Professor, 乾燥地研究センター, 助教授 (90032309)
TORIDE Nobuo  Department of Agricultural Sciences, Saga University, Associate Professor, 農学部, 助教授 (70212074)
Project Period (FY) 1997 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,300,000 (Direct Cost: ¥2,300,000)
Keywordsunsaturated soil / preferential flow / wetting front / fingered flow / glass beads / water retention curve / water movement / solute transportation / プリファレンシャル フロー / 不飽和土 / フィガリング / 不飽和透水係数 / フィンガリング現象 / 2成層土 / 水分特性
Research Abstract

When fingered flow occurs during ponding infiltration in a fine-coarse-textured profile, a thin wet zone forms directly below the textural interface (induction zone). During the onset of wetting front instability, a thin induction zone develops from which many small fingers grow initially. Subsequently, a few of these fingers become dominant; they continue to grow at the expense of the remaining fingers which stagnate. Two possible mechanisms govern this process: (1) the pressure head gradient required to laterally transport water from any location at the soil surface to the nearest finger is such that the water entry value of the dry soil is exceeded at some distance from a finger, thus causing another finger to fully develop at that point, and (2) the flux density strongly amplified wavelength of perturbations of the wetting front or the pressure head. Finger spacing in the former case is determined by the properties of the induction zone, and in the latter case by the flux conducted by an individual finger as well as the water supply rate.
In order to investigate flow in the induction zone, and nature and extent of the interaction between the induction zone and the fingers, we performed two-dimensional experiments using a glass-bead porous medium. Pressure heads in the induction zone and the fingers were monitored by microtensiometers. We made small disturbances (notches) at various intervals in the textural interface to trigger finger formation and change the number of fingers occurring at first.

Report

(4 results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report
  • 1997 Annual Research Report
  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] Gerrit H. deRooij and Hiroyuki Cho: "Modeling colute leaching during fingered flow by integratig and expanding various theoretical and empirical concepts"Hydrological Sciences Journal. 44(3). 447-465 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Hiroyuki Cho and Gerrit H. deRooij: "Fingered floe I the role of the induction zone below the soil surface and the capillary fringe"Proceedings of the International Workshop on Characterization and measurement of the Hydraulic Properties of unsaturated Porus Media. Part 1. 423-432 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] De Rooij, G.H. and H.Cho: "Modeling solute leaching during fingered flow by integrating and expanding various theoretical and empirical concepts"Hydrological Sciences. 44(3). 447-465 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Cho.H, and G.H.de Rooij: "Fingered flow: the role of the induction zone below the soil surface and the capillary fringe"Proceedings of the International Workshop on Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media, Riverside, California, October 22-24, 1997, edited by M.Th.Van Genucheten, F.J.Leij and L.Wu., Published by the University of California, Riverside. Part 1. 423-432 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Gerrit H.de Rooij and Hiroyuki Cho: "Modelling solute leaching during fingered flow by integrating and expanding various theoretical and empirical concepts"Hydrological Sciences Journal. 44(3). 447-465 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] Hiroyuki Cho and Gerrit H.de Rooij: "Fingered Flow:The Role of the Induction Zone Below the Soil Surface and the Capillary Fringe"Proceedings of the International Workshop on Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media. Part1. 423-432 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] Gerrit H,De Rooij and Hiroyuki Cho: "Modeling solute leaching during fingered flow by integrating and expanding various theoretical and empirical concepts" Hydrological Sciences Journal. (未定). (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] H.Cho and G.H.DeRooij: "Fingered Flow:the Role of the Induction Zone Below the Soil Surface and the Capillary Fringe" Praceedings of International Workshop:Characterization and Neasuremens of the Hydrau1ic Properties of Unsaturated Porous Media. (未定). (1999)

    • Related Report
      1998 Annual Research Report

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Published: 1997-04-01   Modified: 2016-04-21  

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