| Project/Area Number |
62480075
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
農業土木
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| Research Institution | EHIME University |
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Principal Investigator |
SATO Koichi EHIME University, Dep.of Agriculture, Professor, 農学部, 教授 (70033149)
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| Co-Investigator(Kenkyū-buntansha) |
TAKASE Keiji EHIME University, Dep.of Agriculture, Associate Professor, 農学部, 助教授 (90133165)
SAKURAI Yuji EHIME University, Dep.of Agriculture, Associate Professor, 農学部, 助教授 (00036427)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1988: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1987: ¥4,500,000 (Direct Cost: ¥4,500,000)
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| Keywords | Land Development / Hydrologic Cycle / Runoff / Evapotranspiration / Groundwater / Excess Moisture injury / Rill / Soil Erosion / 農地造成 / 地水循環 / 流出特性 / 農地保全 / 土壌水分消費量 / 改良山成畑 / 草地造成 / 高水流出 / 低水流出 / リル侵食 / 限界掃流力 |
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| Research Abstract |
In this research, soil and hydrologic factors have been investigated in some catchments, which include a lot of small farm lands reclaimed from forest, to evaluate the influences of reclamation and consider the conservation of catchments. The results are. summarized as follows.
1. The characteristics of soil are directly changed by the reclamation. In particular, the increase in dry density of surface soil layer reduces the infiltration capacity and water retention capacity of soils, which control hydrologic cycle in a catchment. As a result, the *peak.discharge from farm land may increase tree times and direct runoff may increase twice as much as that from forest. And the evapotranspiration from land may decrease in some degree, compared with that from forest. However, the long-term runoff characteristics may be influenced little or not influenced.
2. The changes of subsoil soil and hydrologic factors in the reclaimed farm land, may aggravate the conditions for the growth of crops. Compaction of subsurface layer by machines will cause a perched groundwater in subsurface layer. And the decrease in permeability of soil and the decrease of slope may interrupt the drainage of rainfall and cause damage to crops.
3. The soil erosion by rills is serious problem in reclaimed farm lands. The Horton's law is applicable to the rill network in fields and it is possible to simulate it using a probability model. The critical flows for rill initiation were measured or estimated with experiments in a laboratory or investigations in fields to clarify the mechanism of rill initiation.
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