1997 Fiscal Year Final Research Report Summary
Control of mass flow systems for the harmonious balance of intensive utilization and environmental protection of a peatland
| Project/Area Number |
07556052
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NAKANO Masashi The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 教授 (00011908)
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| Co-Investigator(Kenkyū-buntansha) |
SHIOZAWA Shou Tsukuba University, Agricultural and Forestry Sciences, Associate Professor, 農林光学系, 助教授 (80134154)
KASUBUCHI Tastuaki Yamagata University, Faculty of Agriculture, Professor, 農学部, 教授 (00250960)
UMEDA Yasuharu Hokkaido University, Faculty of Agriculture, Honorary Professor, 農学部, 名誉教授 (90001411)
NISHIMURA Taku Tokyo University of Agriculture and Engineering, Faculty of Agriculture, Lecture, 農学部, 講師 (40237730)
MIYAZAKI Tsuyoshi The University of Tokyo, Graduate School of Agricultural and Life Sciences, Asso, 大学院・農学生命科学研究科, 助教授 (00209892)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Peat / Mass flow / Hydraulic conductivity / Transmissivity / Groundwater / Shrinkage / N_2O gas / Thermal conductivity |
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| Research Abstract |
The purpose of this study was to construct an appropriate mass-flow-managing-system which is suitable to harmonize technologies that is required to reclaim the agricultural lands for the improvements of food productions and technologies that is required to sustain and conserve the environmental and biological resources in peatlands. Bibai peatland, Hokkaido, was selected as a test field, where the mass flow patterns both within the natural bog peat area of about 50 ha and in the cultivated agricultural lands surrounding the bog peat area were measured and analyzed to find the appropriate mass-flow-managing-system.
In the natural bog peat area, the elevation of the land surface decreased at most 20cm under the accumulated snow in winter season and restored with the melt of snow. The thermal conductivity of bog was so small that the snow may not melt easily at the interface between the bog and snow, resulting in the shortage of water supply to the groundwater. The natural bog peat area wa
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s covered with mainly two kinds of plants, the bog itself where the ground water level was relatively high and the low bamboo where the ground water level was relatively low. The transmissivities of this bog area, defined by the integration of the hydraulic conductivity from the land surface down to the depth given (we chose 180 cm here), were almost equal under both covering plants. In the transient peat area, we found remarkable anisotropy of hydraulic conductivity and irreversible shrinkage behavior of them. In the fen area, the peat was more or less mixed with clay soils and the anisotropy of hydraulic conductivity was not so large.
N_2O gas fluxes from the soils into atmosphere were proportional to the gradient of gas concentrations within the soil. The fluxes were estimated to be 8 to 14 ng/m^2s in the upland fields, 2 to 10 ng/m^2s in the temporary uncultivated rice fields, and 0 to 1 ng/m^2s in the bog area.
The thermal feature of Bibai peatland was mainly attributed to the high dependence of their thermal conductivity on water content and to the very small values of them comparing with those of usual soils. Less
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