| Project/Area Number |
17H02980
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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 | 一般 |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Shimane University |
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Principal Investigator |
Saito Yoshiki 島根大学, 学術研究院環境システム科学系, 教授 (00357071)
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| Co-Investigator(Kenkyū-buntansha) |
香月 興太 島根大学, 学術研究院環境システム科学系, 講師 (20423270)
瀬戸 浩二 島根大学, 学術研究院環境システム科学系, 准教授 (60252897)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥17,680,000 (Direct Cost: ¥13,600,000、Indirect Cost: ¥4,080,000)
Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2019: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2018: ¥5,720,000 (Direct Cost: ¥4,400,000、Indirect Cost: ¥1,320,000)
Fiscal Year 2017: ¥9,230,000 (Direct Cost: ¥7,100,000、Indirect Cost: ¥2,130,000)
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| Keywords | デルタ / エスチュアリー / 潮汐卓越 / 堆積相モデル / メコン河 / 放棄河道 / 大河川 / 潮汐 / 潮汐卓越型デルタ / 完新世 / 人新世 / 堆積 / 河口域 / メガデルタ / 潮汐卓越型 / アジア / 河川海洋漸移帯 / メコン / 堆積作用 / 河川海洋遷移帯 / 地質学 / 層位・古生物学 / 海洋科学 |
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| Outline of Final Research Achievements |
The tide-dominated estuary model was revisited based on the study of modern tide-dominated large river systems, with a focus on the fluvial to marine transition zone in a tide-dominated setting. A tide-dominated river deltas show characteristic upstream to downstream trends in channel width, sinuosity, and depth, and in sediment facies distributions. There are two distinct tracts separated by areas of morphological changes and sediment facies changes. The upstream tracts are characterized by constant width, relatively high sinuosity, seaward-increasing depth in morphology, and relatively coarse-grained sediment, and are mainly controlled by the fluvial dynamics. The downstream tracts are characterized by seaward-increasing width, relatively low sinuosity, seaward-decreasing depth in morphology, and sand-mud alternations in sediment, and are mainly controlled by the tidal dynamics. These delineations are crucial to understanding the processes of deltas and estuaries.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究の成果は，潮汐が卓越する大河川の堆積作用の理解を深めるとともに，大河川の維持管理に貢献する．現在多くの大河川で砂利採取が行われており，河岸侵食や河道水深の増加による塩水侵入などの環境劣化が問題となっている．本研究は潮汐が影響する河川下流域における堆積作用や物質収支の理解を深め，大河川の維持管理や人間活動の影響評価に貢献する．また今回提示したモデルは地質時代の地層の解釈に新しい見方を提示するもので，特に石油貯留岩の堆積環境の理解や層相分布の解釈に貢献する．
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