1998 Fiscal Year Final Research Report Summary
Water Environment around Subsurface Drainage in a Tea Field
| Project/Area Number |
08660290
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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 | Mie University |
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Principal Investigator |
KAJISA Takamitsu Faculty of Bioresources, Mie University, , Associate Professor, 生物資源学部, 助教授 (60177376)
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| Project Period (FY) |
1996 – 1998
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| Keywords | drainage / subsurface druinage / Manning's law / hydro-graph / simulation / tea field |
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| Research Abstract |
1) The runoff especially from the under-drain was found to be dominant over that from the terrace. There was no time for the water table on the downside bank area to reach the soil surface. For this terrace, it was found that Manning's law is applicable for most cases including small floods. Therefore, an example that Manning's law is effective in analyzing the subsurface flow could be presented. Since Manning's law was originallyapplicable to surface flow , this law may provide a useful approximation without having to take into consideration the actual path of the water flow.
2) In the results obtained from the numerical simulation of subsurface flow in soil of uniform water permeability it should be noted that the area at the lower end of a terracehad no under drainage. Thus it was ascertained that the value of p is in the range of0.0-1.0. This index p corresponding to Manning's law is 0.6 : By discussing some of the results from the simulation, the expectation is that Manning's law is applicable forgetting a hydro-graph using rainfall data. In this case the value of p is a little smaller than 0.6 at the boundary
3) A three-dimensional infiltration model was made to simulate the flow in complicated conditions (for example, artificially cut unpermeable layers, under-drain pipes, cracks, sloping soil surface, or other conditions). For such a complicated area, the answers obtained using the model are likely to diverge. A new type of idea for making the answers more accurate was suggested and applied to this model.
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