Just two ingredients are required to make the traditional Japanese rice wine, Saké: rice and water. So, it’s no surprise that Nada — the biggest Saké-producing area in Japan — is home to the high-quality groundwater used in the brewing process that yields the first-rate Saké for which the area is known.
What makes this groundwater so special is the area where it’s located, with the Rokko Mountains in the north and Osaka Bay to the south. Created by river overflow, the geologic layer that lies beneath Nada is a complicated mix of aquifer (which is permeable) and aquiclude (which is porous, but not permeable). Formed inside this complicated geologic layer is 水みち(Mizumichi), a unique and unusual soil type through which the groundwater flows.
With Nada located between the cities of Kobe and Osaka, urban development in the area, which includes numerous major highways and railways, poses a potential threat to the prized water that resides below ground. Consequently, the Sumikawa Hydrogeological Institute, located in Nishinomiya City, currently works to preserve and protect the high-quality groundwater in the region, and has been doing
so since 1954.
In order to understand how construction and other urban development activities might be affecting the groundwater, researchers from the Institute collect and analyze data pertaining to water temperature, water quality, and water level.
In the past, the researchers used float type gauges and chart recorders to measure and record water levels. Although the chart recorders provided values in real time, clarity of the ink could be negatively affected by moisture and heat. And not only did the recording paper deteriorate easily, but it was also often stained by slugs who had crept along chewing the paper and leaving trails that obscured the data. Sumikawa staff also found that other, more self-contained data logging devices had their own set of drawbacks, such as their susceptibility to become damaged on rainy days, and the need to bring a computer to the monitoring site in order to download data.
Today, Institute staff rely on water level and water temperature data from research-grade HOBO U20 data loggers deployed at depths of 3m to 45m inside approximately 400 groundwater observation wells throughout the Saké brewing area. They also use HOBO U24 loggers to measure salinity. These rugged, compact HOBO loggers can be
easily downloaded using a waterproof data shuttle, eliminating the inconvenience and risk of bringing a laptop computer into the field to collect data.
Depending on the exact deployment location and situation, the loggers are set to record data at 1-minute to 1-hour intervals, with the data being downloaded and analyzed once a week or once month. At the same time, the researchers collect water samples for laboratory analysis.
The Sumikawa Institute reports that the advantages of using the HOBO loggers include their low cost, their convenient compact size, their extensive battery life for long-term monitoring, their rugged construction, and the user’s ability to set logger start times, configure logging intervals, and review time-sequenced data in relation to nearby construction activities that have the potential to threaten the groundwater. For example, in one case researchers were able to use logger data to identify the cause of a consistent drop in water level at a particular location, which turned out to be due to unreported water pumping by a construction company doing work in the area.
Having recently expanded its toolbox to include HOBO MX2501 pH and temperature data loggers, which use Bluetooth Low Energy (BLE) technology for wireless communications, as well HOBO U26 loggers to monitor dissolved oxygen levels, it appears that the Sumikawa Hydrogeological Institute’s understanding of the water resources in the Nada region can only increase. And with that increased understanding comes better water preservation, and perhaps even better water, and better Saké!