Groundwater quality modeling toward sustainable use of subsurface dams in coastal areas

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06309
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41030:Rural environmental engineering and planning-related
• Research Institution: National Agriculture and Food Research Organization
• Principal Investigator: Yoshimoto Shuhei 国立研究開発法人農業・食品産業技術総合研究機構, 農村工学研究部門, 上級研究員 (10435935)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 水資源 / 南西諸島 / 涵養年代推 / カルスト水文学 / 水文地球化学

Outline of Final Research Achievements

This study revealed the groundwater flow situations in areas where subsurface dams are situated. Water quality indicators for groundwater dating and calcite saturation were found to be applicable to illustrating rapid groundwater flow through conduit networks in aquifers of the Ryukyu limestone and its influencing extents. Based on the findings above, a water budget model considering rapid groundwater flow through the conduit networks was developed to evaluate an impact of concentration of rainfall under the ongoing climate change on water resources of a subsurface dam; upon an assumption of concentrated rainfall, simulation results indicated possible decrease in amount of water recharging the dam.

Free Research Field

農業農村工学

Academic Significance and Societal Importance of the Research Achievements

本研究で得られた地下ダム貯留域の地下水流動状況に関する知見は、地下ダム水資源の水質保全、とりわけ沿岸部に設置された地下ダムの残留塩水の挙動や地下水中の硝酸性窒素の消長に関する理解に資するものであり、地下ダム水資源の保全施策に貢献することが期待される。また、地下ダム水資源への気候変動の影響評価によって、農業用水資源への気候変動影響の全国評価への貢献とともに、今後の地下ダムの水資源管理手法の検討にも役立てられると期待される。