Visualization of present state and countermeasure effects of local groundwater pollution(Fostering Joint International Research)

2019 Fiscal Year Final Research Report

• Project/Area Number: 16KK0014
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)
• Allocation Type: Multi-year Fund
• Research Field: Geotechnical engineering
• Research Institution: Nagasaki University
• Principal Investigator: NAKAGAWA Kei 長崎大学, 水産・環境科学総合研究科(環境), 教授 (90315135)
• Project Period (FY): 2017 – 2019
• Keywords: 硝酸性窒素 / 地下水汚染 / 数値シミュレーション

Outline of Final Research Achievements

Nitrate pollution in groundwater is a serious environmental problem in the Shimabara Peninsula, Nagasaki Prefecture, Japan. For efficient countermeasures and remediation of the groundwater, numerical simulation may constitute a powerful tool. Along this line, we developed a numerical model to improve the understanding of transport processes in the nitrate pollution and we evaluated the effects of remediation countermeasures by using the FREEWAT software including MODFLOW as numerical engine. The steady state results of groundwater flow simulations reproduced observed hydraulic head data. According to the numerical transport simulation results (performed using MT3DMS), the general trend of concentration changes well agreed with observation during the past 44 years. Remediation simulations indicate that it will take about 18 years for groundwater concentrations to fall below Japanese drinking water standards. The pre-requisite is a 40% reduction in nitrate load of the source zone.

Free Research Field

環境地下水学

Academic Significance and Societal Importance of the Research Achievements

本研究成果は，環境省の「地下水保全のための硝酸性窒素等地域総合対策検討会」および長崎県の「島原半島窒素負荷低減対策会議」において公表していくことを考えており，対策効果の見える化を行い，実質的な地域における水環境改善に役立てることができる点に意義があると考える．また本国際共同研究の活動を通じ，ルンド大学のポスドクや博士課程学生らと協働で，国際的な地下水汚染問題に関するプロジェクトに取り組むことなど，国際的な研究ネットワークの構築も進めることができた．