Development of evaluation techniques for heterogeneity of carbonate aquifers where freshwater lenses occur

2014 Fiscal Year Final Research Report

• Project/Area Number: 24780238
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Irrigation, drainage and rural engineering/Rural planning
• Research Institution: National Agriculture and Food Research Organization
• Principal Investigator: YOSHIMOTO Shuhei 独立行政法人農業・食品産業技術総合研究機構, 農村工学研究所資源循環工学研究領域, 主任研究員 (10435935)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 地下水 / 小島嶼 / 気候変動 / 環境同位体 / 硝酸性窒素 / 炭酸塩岩帯水層 / 六フッ化硫黄 / 涵養年代推定

Outline of Final Research Achievements

Geochemical indicators such as major ions, sulfur hexafluoride, chlorofluorocarbons, nitrogen/oxygen isotopes in nitrate, and radon were applied to understand situation of groundwater flow and solute movement in heterogeneous carbonate aquifers which have freshwater lenses.
In the Ryukyu Limestone aquifer of Tarama Island, Okinawa, the groundwater was thought to be composed of mixed water which had been recharged in multiple (or continuous) ages, although the shallow groundwater in the coastal areas would have been recharged in relatively recent time.
On the other hand, in Laura Island of Majuro Atoll, the recharged water was estimated to flow in the surface of the freshwater lens, without mixing with the deeper groundwater.

Free Research Field

地下水学