Ōno’s 50-Year Journey to Protect Its Water Cycle

Episode 4 – Science Reveals the Invisible River

How Isotope Research Helped Visualize Ono’s Water Cycle

In 2012, the City of Ono had an opportunity to hear a lecture by Professor Nakano of the Research Institute for Humanity and Nature (RIHN), titled “Collecting a Thousand Waters: What We Learned from Sampling a Thousand Points.”
Inspired by this work, the city requested that a similar investigation be conducted in Ono.

A collaborative research initiative was launched involving RIHN, Kagawa University, Doshisha University, and local elementary schools in Ono.
Using data collected from approximately 8,000 wells across the city, a comprehensive groundwater temperature survey was carried out.The purpose of this survey was to determine whether rising air temperatures due to recent global warming have affected the temperature of Ono’s groundwater.

Students in the 4th to 6th grades of local elementary schools participated by simultaneously measuring the temperature of groundwater used in their households on designated survey days.
This approach not only enabled continuous monitoring of groundwater temperature changes across the city, but also fostered environmental awareness among children from an early age.

In addition to RIHN, Ono has collaborated with other academic and research institutions.
Since 2013, the University of Tsukuba has been conducting water cycle analysis in the Ono Basin using stable isotope techniques.

Furthermore, the National Institute for Land and Infrastructure Management under the Ministry of Land, Infrastructure, Transport and Tourism analyzed the groundwater flow of the Ono Basin over a two-year period (2013–2014) using a hydrological circulation model.

Through these collaborative scientific efforts, Ono has increasingly attracted attention in recent years as a valuable research field for understanding groundwater-based water circulation systems.