| Project/Area Number |
59480062
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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 |
林学
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| Research Institution | Kyushu University |
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Principal Investigator |
TAKESHITA Keiji Kyushu Univ. Fac. of Agr., Professor, 農学部, 教授 (20117154)
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| Co-Investigator(Kenkyū-buntansha) |
SETSU Takao Kyushu Univ. Fac. of Agr., Associate Professor, 農学部, 助教授 (70117141)
MARUTANI Tomomi Kyushu Univ. Fac. of Agr., Asistant Professor, 農学部, 助手 (40112320)
MIZOTA Chitoshi Kyushu Univ. Fac. of Agr., Asistant Professor, 農学部, 助手 (10089930)
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| Project Period (FY) |
1984 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 1986: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1985: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1984: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Pyroclastic flow / Loss of forest / Infiltration capacity / Surface flow; Gully erosion / Land slide / Fine soil / 地形変化 / 細土生成 |
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| Research Abstract |
We have assumed following problem of pedological and topographical phenomena. and obtained corroboration concerning about formative process of soil and topography.
Soil and topography were deformed accidentary by volcanic action. mainly pyroclastic flow and volcanic ash in 7.5x <10^4> years and 2.2x <10^4> years ago.
・ Large zone of Kyushu disrict was coated with high temperature deposits of large-scale pyroclastic flows (about diminished 200-300 <km^2> individually), and simultaneously most of forest were destroied and plant were lost, caused by high temperature.
・ Infiltration capacity was extreamly decreased caused by the loss of plant.
・ Gully erosion was acceleted violently with surface flow caused by the decrease in infiltration capacity.
・ Channels with gully erosion were dissected in the slope and bearing point of slope body took away caused by stream flow in channels.
・ Large-scale and great many landslides occured in moutain slope caused by loss of bearing point. ・ All of soil was carried away and all of slope was bared.
After the accident. forest would be recovered quitely and it would accompanied with increase of infiltration capacity and decrease of landslides. gully erosion as following process.
・ Soil was formated with depositional agent of plant registance.
・ Infiltration capacity increse. -> Surface flow decrease. -> Gully erosion decrease. -> Land slides decrease.
Physical weathering supplied with debris from bed rock, and volcanic eruptions supplied with fine soil from ash Recent erosion : Soil erosion caused by accidental heavy rain. Recent landslide : Destruction of soil structure caused by subsurface flow and groud water.
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