2022 Fiscal Year Final Research Report
Examination of evaluation methods of the physical impact of freshwater inflow associated with the heavy rainfall on hypoxia in coastal seas
Project/Area Number |
19K12415
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 64040:Social-ecological systems-related
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Research Institution | Kyoto University |
Principal Investigator |
Kobayashi Shiho 京都大学, フィールド科学教育研究センター, 助教 (60432340)
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Project Period (FY) |
2019-04-01 – 2023-03-31
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Keywords | 集中豪雨 / 貧酸素化 / 沿岸海域 |
Outline of Final Research Achievements |
In this study, we estimated freshwater inflow to the small inlet during heavy rainfall by combining a river model and an ocean model, and divided the influence of freshwater inflow on hypoxia into biochemical and physical processes, in order to quantify the physical impacts of changes in flow structure caused by heavy rainfall on hypoxia in coastal seas. In this study area, seawater exchange is enhanced during river runoff due to heavy rainfall, but after the runoff, strong salinity stratification suppresses seawater exchange and the associated oxygen supply. The results of the field observations and the model simulations suggest that shallow enclosed seas with high benthic productivity of the bottom layer, rich in organic matter, and high oxygen consumption in summer may be susceptible to temporary strong hypoxia due to increased heavy rainfall.
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Free Research Field |
海洋環境学
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Academic Significance and Societal Importance of the Research Achievements |
本研究では河川モデルと海洋モデルを結合し,これにより任意の海域において,集中豪雨時の淡水流入量を迅速に評価できるようにした.また,淡水流入が貧酸素化に及ぼす影響を生物化学過程と物理過程に分け,これまで不明な点の多かった集中豪雨による流動構造の変化が貧酸素化に及ぼす物理的影響を示した.これにより流量データのない二級河川のみが流入する半閉鎖性海域においても,豪雨時に海域に流入する淡水量を降雨量から推定し,豪雨による海洋構造の変化を把握することができる.また急な低塩分化による養殖貝類のストレス評価,気候変動により増加する集中豪雨が海洋の貧酸素化に及ぼす影響の予測等,社会的な課題の解決にも応用できる.
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