2023-07-06 ニューサウスウェールズ大学(UNSW)
◆鍾乳石を使用して行われた研究では、過去の酸素同位体の変化を分析することで、降雨の減少が地下水補給に与える影響を明らかにしました。この減少は過去800年間で前例のないものであり、地域の水供給や生態系にとって重要な問題です。今後はさらに過去のデータを分析し、地下水の補給の限界と持続可能性についての理解を深める予定です。
＜関連情報＞
- https://newsroom.unsw.edu.au/news/science-tech/decades-less-rainfall-have-cut-replenishing-groundwater-800-year-low-wa
- https://www.nature.com/articles/s43247-023-00858-7
オーストラリア南西部の地下水涵養量の減少を洞窟が実証、過去800年間で前例なし Caves demonstrate decrease in rainfall recharge of southwest Australian groundwater is unprecedented for the last 800 years
Stacey C. Priestley,Pauline C. Treble,Alan D. Griffiths,Andy Baker,Nerilie J. Abram & Karina T. Meredith
Communications Earth & Environment Published:09 June 2023
DOI:https://doi.org/10.1038/s43247-023-00858-7
Abstract
Billions of people worldwide rely on groundwater. As rainfall in many regions in the future is projected to decrease, it is critical to understand the impacts of climate change on groundwater recharge. The groundwater recharge response to a sustained decrease in rainfall across southwest Australia that began in the late 1960s was examined in seven modern speleothems and drip waters from four caves. These show a pronounced increase or uptick in regional drip water and speleothem oxygen isotopic composition (δ18O) that is not driven by a change in rainfall δ18O values, but is in response to the shallow karst aquifers becoming disconnected from rainfall recharge due to regional drying. Our findings imply that rainfall recharge to groundwater may no longer be reliably occurring in this region, which is highly dependent on groundwater resources. Examination of the longer speleothem record shows that this situation is unprecedented over the last 800 years.
