Evalute of the climate change and full-thickness circulation on lake thermal environment

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K12972
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Geography
• Research Institution: Nanzan University (2019); Nihon University (2017-2018)
• Principal Investigator: OYAGI Hideo 南山大学, 総合政策学部, 准教授 (50453866)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 湖水循環 / 大深度湖沼 / 溶存酸素 / 倶多楽湖 / 摩周湖 / 自然地理学

Outline of Final Research Achievements

This study focused on the changes in the vertical flow of the lake water circulation, the water temperature stratification and freezing phenomenon. Especially in Lake Kuttara, it was researched the relationship between the vertical flow and the dissolved oxygen on the lake bottom area. It was clarified seasonal change in the behavior of the dissolved oxygen and the vertical flow direction and velocity. In Lake Mashu, water quality analysis was conducted on the residence time of lake water and spring water around the lake. It was examined to clarify the interrelationship between lake leaked water and groundwater.

Free Research Field

総合領域

Academic Significance and Societal Importance of the Research Achievements

本研究は，湖水循環速度・微細鉛直流の解明や温暖化があたえる深水層水温への影響を評価することを目的としており，特に，湖水循環の速度を考察することにより，鉛直対流による溶存酸素の鉛直輸送の実態を把握することができた。大深度湖沼における湖底直上の微細な鉛直流速実測例は世界的にも少なく，微細な鉛直流速の季節的変化について示し，湖水全循環混合機構を解明するための実測例を蓄積できたことは，将来の日本の湖沼環境に対する方策を判断する不可欠な科学的根拠となる。