| Project/Area Number |
19580283
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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 | Kagoshima University |
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Principal Investigator |
MOMII Kazuro Kagoshima University, 農学部, 教授 (40136536)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAGAWA Kei 鹿児島大学, 農学部, 准教授 (90315135)
神野 健二 九州大学, 大学院・工学研究院, 教授 (80038025)
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| Project Period (FY) |
2007 – 2009
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| Project Status |
Completed (Fiscal Year 2009)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2009: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2008: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2007: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 海水侵入 / 地下水 / 地下ダム / 人工涵養 / 室内実験 / 数値計算 / 水資源 / 海岸帯水層 / 止水壁 / 注水井戸 / 密度効果 / 数値解析 / 移流分散 / 密度流 / 数値モデル / 浸透池 / 水資源開発 |
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| Research Abstract |
Seawater intrusion is often a major constraint to optimal use of fresh groundwater from coastal aquifers. Excessive groundwater extraction to meet growing demands from an increasing coastal population and the expected rise in mean sea level from global warming will cause seawater to encroach farther inland and threaten the available groundwater supply. In this study, laboratory experiments and numerical analysis were performed to determine the effectiveness of physical barriers and artificial recharge methods to control the seawater intrusion in coastal aquifers. The physical barriers examined were subsurface dams and partially penetrating flow barriers, while the artificial recharge methods included recharge ponds and recharge wells. In the study of subsurface dams, experimental and numerical results show that the residual saltwater trapped in storage areas by cutoff walls is completely flushed out by the freshwater flow from inland.
In the study of subsurface flow barriers, we found that saltwater repulsion was linearly related to horizontal barrier location and a third-order polynomial function of penetration depth. For a particular freshwater discharge, this relationship can be used to determine the theoretical saltwater repulsion achieved by subsurface flow barriers of specific depth and location relative to the toe of the intruding saltwater wedge.
In the artificial recharge studies, results show that more effective saltwater repulsion can be achieved when recharge is applied near the saltwater toe. Recharge becomes less effective when applied farther and higher from the toe. These findings imply that, for the same recharge rate, recharge wells are more effective than recharge ponds in repulsing saltwater intrusion.
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