2000 Fiscal Year Final Research Report Summary
Basic study on pollutant movement in an unsaturated zone considering stagnant.
| Project/Area Number |
11660241
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | University of Tsukuba |
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Principal Investigator |
YASUDA Hiroshi University of Tsukuba, Institute of Agricultural and Forest Engineering, Associate Professor, 農林工学系, 助教授 (60136538)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Porous flow / Stagnant / Convection dispersion / Unsaturated zone / Heterogeneity |
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| Research Abstract |
To evaluate pollutant movement in an unsaturated zone, tracer tests were carried out for various soils. This research emphasizes the existence of stagnant region in porous zone due to heterogeneity of soils.
Results show that there is effect of stagnant region in porous zones on pollutant movement. Ratio of the mobile region to the stagnant region was estimated as magnitude 10^<-1> for saturated condition, while that was from 10^<-3> to 10^<-2> for the unsaturated condition. Since solute movement in unsaturated zone was well fitted by the numerical simulation using tlte analytical solution, the four parameter model due to the concept of stagnant region is enough reasonable.
The heterogeneity was also considered for the experimental results. Even for the spatial scale of the experiments, 10^<-2> to l0^<-1> m, the heterogeneity was recognized. Heterogeneity of undisturbed soil was larger than that of disturbed one.
The conclusion is :
1. We should consider the existence of stagnant region for evaluation of pollutant movement in unsaturated zone.
2. The Convection Dispersion Equation considering stagnant effect works well for the evaluation of pollutants movement in unsaturated zone.
3. Since heterogeneity was recognized for laboratory experimental scale, the model considering heterogeneity in addition to stagnant effect is necessary for analyses in the future.
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