2020 Fiscal Year Final Research Report
Effective of deforestation in Sumatra island in Indonesia on hydrologic cycle at the river basin scale including downstream wetland
| Project/Area Number |
17H04586
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Hydraulic engineering
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
小杉 賢一朗 京都大学, 農学研究科, 教授 (30263130)
寶 馨 京都大学, 総合生存学館, 教授 (80144327)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Keywords | 森林伐採 / 流出・氾濫 / RRIモデル / パーム椰子 / 土壌水分 / 地下水 / スマトラ島 / バタンハリ川流域 |
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| Outline of Final Research Achievements |
Groundwater levels were observed on the slopes of natural forests and plantations in Sumatra, Indonesia. The groundwater level was relatively shallow (0-4 m) on the slope of the natural forest, and the level fluctuated rapidly to storms especially at the foot of the slope. On the other hand, on the slope with palm forest, the groundwater level was deeper (6 to 8 m) and the response speed to rainfall was slower near the ridge. In both cases, most of the rainwater penetrated underground and subsurface flow dominate storm runoff.
The above findings were reflected to the hydrologic modeling. The model simulation suggested that the impact of land use changes on flood runoff is comparatively smaller. On the other hand, the impact of future climate change will be larger, and the frequency and severity of flood inundation will increase in peatland area in the downstream.
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| Free Research Field |
水文学
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| Academic Significance and Societal Importance of the Research Achievements |
スマトラ島における顕著な土地利用の変化は、流域水循環に大きな影響を与えるものと仮説を立てて研究を開始したが、斜面観測の結果に基づいて構築した流域スケールの水文モデリングの結果によれば、その下流域における洪水への影響は限定的であることが明らかになった。その理由は、天然林、アブラヤシ林斜面のいずれも、降雨の多くが表層土壌に浸透をして、厚い土層を流れる側方流が流出の主要な成分であることに起因している。なお、土地利用に比べて、将来の気候変動の影響が大きく、当該流域では、下流泥炭湿地に広がる洪水氾濫の頻度が高まる、より深刻化することが懸念された。
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