| Project/Area Number |
17380141
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | Niigata University |
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Principal Investigator |
MORII Toshihiro Niigata University, Institute of Science and Technology, Professor (30231640)
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| Co-Investigator(Kenkyū-buntansha) |
TAKESHITA Yuji Okayama University, Graduate School of Environmental SriPnce, Associate Professor (90188178)
SHIMADA Kiyoshi Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Professor (20123234)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥13,620,000 (Direct Cost: ¥13,200,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2005: ¥9,800,000 (Direct Cost: ¥9,800,000)
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| Keywords | Soil hydraulics / Site characterization / Radar investigation / Inverse estimation of soil hydraulics / Soil permeability / Water retention of soil / Effect of plant cover on soil hydraulics / ボアホール・レーダー / ボアホール透水計 |
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| Research Abstract |
(1)Object
It is well known that a precise and rapid estimation of soil hydraulics (that is, water permeability and water retention characteristics of soil) is really required when we are trying to solve soil disasters triggered by heavy rainfall or soil seepage, or soil pollution problems. To estimate precisely and rapidly the soil hydraulics in-situ, a Site Characterization System (SCS) which is a assembly combined technically a in-plane measuring equipment/ tool with a vertically-directed measuring one should be constructed effectively. In the research project, the in-situ permeability test procedures were well combined with borehole radar as well as borehole permeameter to construct the SCS. The research project successfully proceeded during three academic years.
(2)Important results
An integrated procedure, the SCS, to determine the hydraulic conductivity of the sand sediment soil that is characterized by an inclusion of the large gravel particles and cobbles in the sand was investiga
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ted. Firstly the Guelph pressure infiltrometer (GPI) method was employed to measure the field-hydraulic conductivity of the sand, and extended so that it can determine the unsaturated moisture properties of the soil. Secondly the descriptive cylindrical soil model representing sand, gravel and voids was assumed to derive the functional relationship of the hydraulic conductivity of the sand sediment soil with the hydraulic conductivity of the sand measured by the GPI and the gravel content of the soil. The functional relationship derived was successfully examined by the laboratory permeability test. Because the mass content of gravel and cobbles are dominant factor which affect the functional relationship derived, it was tried to introduce borehole radar into the integrated procedure, the SCS, to effectively estimate the gravel content. Numerical examinations were also challenged to show the practical influence of the gravel content on the prediction of storm runoff in the sand sediment soil. The followings were remarked:
a) The GPI method was effectively applied to the sand sediment soil to determine the field-saturated hydraulic conductivity of soil. It was found that the procedure to determine the field-saturated hydraulic conductivity of soil is consistently and is not time-consuming. It may be practically important to show that the permeability of soil could be statistically evaluated owing to simplicity and rapidness of measurement of the GPI method.
b) The GPI was extended to measure the volumetric moisture content near soil surface during the constant-head infiltration. Both the infiltration rate and the volumetric moisture content measured with time were successfully analyzed by the GA+FEM to estimate the soil parameters that describe the unsaturated moisture properties of soil.
c) The hydraulic conductivity of the unified soil mass, which represents the permeability of the sand sediment soil, was theoretically derived by applying the continuity law of flow to the descriptive cylindrical soil model, and effectively examined by the laboratory permeability test. The key parameter that characterizes the hydraulic conductivity of the sand sediment soil is the gravel content by mass. The numerical prediction of the storm runoff in the sand sediment soil showed the practical influence of the gravel content. Less
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