2019 Fiscal Year Final Research Report
High-precision evaluation of mountainous catchment water balance by combined use of isotopic tracers and numerical models
| Project/Area Number |
15H02957
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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 |
Geography
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| Research Institution | University of Tsukuba |
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Principal Investigator |
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| Project Period (FY) |
2015-04-01 – 2020-03-31
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| Keywords | 流域水収支 / 山岳 / 同位体トレーサー / 数値モデル |
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| Outline of Final Research Achievements |
Stable isotopic monitoring for precipitation and river water was made over mountainous region mainly in the central Japan, with regional survey for soil water, lake water, cold and hot springs. Based on these data set and meteorological/horological data, each term of catchment water and isotope budgets were estimated by spatiotemporal averaging using various types of numerical models. As a result, estimated precipitation was in good agreement with Radar-AMEDAS data, although Climate Mesh data were underestimated. In common catchments, groundwater flow across the divide accounts for 2.2-5.5% of precipitation and tends to be greater in large catchments with lower mean elevation.
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| Free Research Field |
水文科学
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| Academic Significance and Societal Importance of the Research Achievements |
我が国をはじめとして、山岳地域に主たる水源を求める国は多い。しかしながら、山岳域では降水量観測地点が疎であることにより水収支評価の精度が低く、流域界を横切る地下水流の存在や程度についても十分な検討がなされてこなかった。そこで本研究では、同位体トレーサーと数値モデルを融合させたアルゴリズムを開発し、降水量と越境地下水流量の定量的評価を可能とした。結果として、越境地下水流量は他の水収支項と比較して軽微であったが、未知の物理量を科学的根拠をもって示せたことには価値があり、山岳降水量観測値の信頼性評価がなされたことも重要である。また、新たに構築された方法論は今後の水循環トレーシングの基盤となり得る。
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