Note: Names of organizations, offices, departments, etc. in the article are as of when the article was first published.
Located in the center of Nagano Prefecture, Lake Suwa is the largest lake in the prefecture with an area of approximately 13 square kilometers (5 square miles). It is an important water body that is used in many ways for industry, tourism, and agriculture in the surrounding area, and local residents are highly concerned about the quality of the water.
In the middle of Lake Suwa, there are T&D loggers that log data for the monitoring of water quality.
Curious about the conditions under which the measurements are being made, we requested an interview with the project team that is conducting the water quality survey of Lake Suwa.
| Date | December 19, 2023 |
|---|---|
| Place | Suwa City, Nagano Prefecture |
| Models in Use | RTR500BM, RTR505BL |
| Purpose | To monitor environmental conditions of Lake Suwa |
The “Lake Suwa Water Quality Observation Project” is an industry-academia-government collaboration to contribute to environmental conservation by observing the water quality of Lake Suwa in real time. The project aims to visualize the water quality of Lake Suwa using IoT, and to predict the future environment through continuous data collection and analysis.
In the project, two water quality monitoring devices installed in Lake Suwa are continuing fixed-point observations, and our RTR500B series loggers are being used for logging the observation data.
When we requested an interview about the status of the installation, we were granted an opportunity to do so in conjunction with the retrieval of the monitoring devices in preparation for the freezing of the lake surface during the winter season.
Early in the morning on a clear December day, all the people involved in the project gathered on the shore of Lake Suwa, and boats were sent out one at a time to retrieve the monitoring devices installed at the two locations on the lake.
We were allowed to board one of the boats and spoke with Hisaomi Masuzawa of MOLE’S ACT Corporation, who manufactured the equipment, and the project representative, Professor Yuichi Miyabara of the Suwa-Rinko Research Station, Lake and Highland E&R Center, Faculty of Science, Shinshu University.
Q: When and why did you start monitoring the water quality of Lake Suwa?
Mr. Masuzawa: The monitoring itself started in 2018.
The project started in 2017, but the year before that there was a massive death of wakasagi (smelt) in Lake Suwa. There was a belief that the cause of this was the lake water’s anoxic condition. When we heard that, we thought about what we could do to contribute to the local community using IoT, which we at MOLE’S ACT have been doing for a long time. We brought the idea of “real-time observation of Lake Suwa” to the city of Suwa, where we were introduced to Prof. Miyabara of Shinshu University, and the project began.
――So you already had the idea for real-time monitoring in mind when you approached the city.
Mr. Masuzawa: These days our company’s main business is molds, but originally we also ran a botanical plant business. We needed to monitor temperature, humidity, CO2, and images remotely, but it would have cost several million yen upfront to install a system that covered all of these.
We looked around and found a variety of inexpensive digital sensors, but they all had different specifications, and it was difficult to manage the data. We wondered if we could mesh them all together by ourselves, so we set up monitoring systems using microcomputer boards such as Raspberry Pi or Arduino. So we had some experience in IoT.
Then, we asked ourselves, “What can we do with our IoT technology, even though we don’t know anything about the water in Lake Suwa?”
At first, we didn’t know much about how to proceed, so we built this first unit (Unit 1) through a process of trial and error. The structure of the floating body was made from cooler boxes, plastic pallets, and other materials that could be procured at the local DIY store.
We arrived at the installation site of Unit 1. We asked about the equipment as we proceeded to remove the anchor and buoy that hold the measuring device in place and tow Unit 1 to the lake shore.
――Is this how you recover the equipment every year?
Professor Miyabara: Yes, every year, we collect the anchors before the cold weather sets in, and when it warms up, we install them again. We install them in the middle of March.
If there is no ice, we can leave them alone, but when the lake freezes over, there is a risk of them being swept away or overturned by various forces, so we remove and collect them.
Q: What is being measured in Unit 1?
Mr. Masuzawa: Dissolved oxygen, water temperature, and turbidity. It is also equipped with a camera to take images.
The water temperature in Unit 1 is measured by a thermocouple type sensor. It was difficult to find a good waterproof sensor, so we made our own.
It also has a sensor to measure airflow, which is used by house builders to see the flow of air indoors. But unlike wind speed and direction, the sensor can show the wind flow in color which means that the wind can be visualized; so we put it on to monitor the airflow.
――Is there a relationship between wind and water quality?
Professor Miyabara: Yes, they are related. From which direction the wind blows and how strong the wind blows are both important factors.
With the current sensor, we cannot tell the direction of the wind, but we can tell if it blows strongly or not. Water movement and wind are related. When the wind is strong, the water mixes well within the waves. Conversely, if the wind is weak, the water at the top can be warm and the water at the bottom can be cold. When the difference in water temperature between the upper and lower parts of the water becomes large, wind is an important identifier in analyzing what caused the change.
Incidentally, the water depth here (where Unit 1 is installed) is about 5.5 meters, the deepest point in Lake Suwa. Even so, when strong winds blow, the water temperature even in the deeper part of the lake changes.
They are measuring water temperature and dissolved oxygen at depths of 0.5 m, 3.0 m, and 5.0 m below the water surface.
――The parameters you are measuring are water temperature, turbidity, wind, and dissolved oxygen? What is dissolved oxygen?
Professor Miyabara: It is the amount of oxygen contained in water. Dissolved oxygen is in itself a very important element for living things. It is thought to be linked to the mass deaths of wakasagi (smelt) that occurred in the past and the recent decrease in catches. Oxygen tends to be low, especially in the deeper parts of the lake, so when considering the conditions of living things it is important to monitor this situation and check when and where low oxygen conditions are resolved.
――What is turbidity? Is it different from water clarity?
Professor Miyabara: Transparency can only be measured by putting a disc in the water and looking at it with the human eye, so one would have to go to the site to measure it. If we use turbidity, which indicates the degree of turbidity of the water, as an alternative indicator, we can use sensors to measure it and continuously see how it is changing.
We also send a boat out every two weeks to take actual measurements, but even if we get data for that day, of course we don’t know what happens on the other 13 days.
Considering the living creatures, every two weeks is too long, and we need to look at a shorter span of time to follow what is happening. If you don’t watch continuously, you will miss, for example, whether plankton is increasing or decreasing. By looking at the data in units of one hour instead of every day, you can see the difference between day and night. Continuous data is fascinating in the sense that it can reveal a variety of things when it is connected.
Q: How has the water quality of Lake Suwa been changing?
Professor Miyabara: The biggest change in water quality is due to the construction of a sewage treatment plant, which has prevented wastewater from homes and businesses from flowing directly into the lake.
The first sewage system was built in 1979. It was not until around 2000 that it became widespread and almost all of the town was connected. The water quality gradually improved, and it is said that the water in Lake Suwa became visibly cleaner around the year 2000.
I came to Shinshu University in 2001, so I have not actually seen the “not-so-good” water quality before that, but there have even been changes since then.
What is different since I first started coming to the lake is that water weeds called ‘hishi’ (trapa japonica) have started to grow thickly along the water’s edge. In 2001, there was very little of it, but now it covers about 10% of the area of the lake, so that is a very visible difference.
In terms of the relationship between creatures, some creatures are more likely to inhabit areas where water weeds grow, so I think that the lake has become an environment where a diverse range of creatures can now live.
On the other hand, there is talk that recently the wakasagi (smelt) population is declining, and I would like to know the cause of this situation.
Returning to the shore, we handed over Unit 1 to the waiting students and then we headed out by boat to get Unit 2.
Unit 2 is equipped with several RTR505BL data loggers that measure voltage signals from various sensors and an RTR500BM mobile base station (data collector) that transmits data via a cellular phone connection to T&D WebStorage Service, a cloud service provided by T&D.
Q: What was the reason for placing loggers and a collector in the second unit?
Mr. Masuzawa: In the box of Unit 1, there is one 20-amp battery that can be charged by a solar panel. We designed the device based on the specifications of that battery, but since there are many items to measure, we wanted to find a way to reduce current consumption.
So we decided to build a second unit (Unit 2) using T&D data loggers, which operate on batteries and can measure voltage analog signals from a sensor.
When we consulted with Mr. Morimura at the Kankyo Gijyutsu Center Co., Ltd. about how to operate the T&D loggers outdoors, he provided us with a variety of information about environmental measurement and voltage signal logging, which was very helpful in the production of Unit 2.
(For more information on the relationship between T&D loggers and Mr. Morimura of the Kankyo Gijyutsu Center Co., Ltd. please refer to the article in the following link.)
T&D LOGGERS: More than just for TEMPERATURE! (Episode 1)
――By using our loggers were you able to solve some of the issues you faced with Unit 1?
Mr. Masuzawa: Yes, the box in Unit 1 is full of microcomputer boards, with one board per sensor. For example, if a sensor malfunctions and one system goes bad, it will need to be replaced. However, it is difficult to obtain the same parts because new sensors and microcomputer boards are constantly being introduced and changed. If the specifications of the components change, the programs that run them also must be changed, making the time and effort required for development impractical.
So, we decided to use commercially available products that were as inexpensive and easy to use as possible, instead of building everything ourselves from scratch, and that’s how we decided to use T&D loggers.
The social infrastructure systems division of MCC (Mitsui Consultants Co., Ltd.) operated the cloud to consolidate the project monitoring data, and we used to send the data from Unit 1 to them by ourselves using microcomputer boards such as RasPi.
However, by using T&D loggers, we can make use of T&D WebStorage Service which is provided free-of-charge, and data can easily be sent there.
And by using an API, we can get the data from that free cloud service to our own cloud server. Battery life of the T&D loggers is quite long, and we can also easily check the battery life of each logger by simply looking on WebStorage.
We also want to reduce the overall power consumption, and we are able to do so by making effective use of the pre-heat function (a function that reduces battery and power consumption by turning on the power to the sensor only when measuring) in T&D’s voltage loggers.
Also, as I mentioned earlier, we made the water temperature sensor for Unit 1 ourselves, but it was difficult to ensure reliability with our own self-made sensor.
We were verifying it by comparing the data with that from a sensor that Prof. Miyabara had, but then we decided to try a Pt100 (platinum resistance thermometer) sensor from T&D, which had a waterproof processing option and could be connected to the RTR505BL, and even though it was expensive it was worth it (laughs)!
That was one of the reasons we decided to use T&D loggers.
While we built Unit 1 ourselves, Unit 2 was built with funds raised by Shinshu University through crowdfunding. Thanks to Prof. Miyabara and his team, we were able to reach our goal and create a system using T&D loggers and Pt sensors.
We arrived at the installation site of Unit 2, and started collecting the devices.
――Is the data being measured at Unit 2 the same as that of Unit 1 as you described earlier?
Professor Miyabara: Unit 2 takes measurements at the center of the lake and also has a different sensor than Unit 1. In order to check the amount of plankton, we have attached a chlorophyll sensor to a T&D voltage logger and measure it that way.
The amount of chlorophyll can tell us whether the amount of plankton has increased or decreased.
Moreover, I think it is better to see what kind of plankton has increased by looking at the images. When you look at the images with the human eye, you can tell whether something is floating or not, and whether that something is smooth or long and thin; by doing this you can tell the difference between the organisms. So I wanted to take pictures of the surface of the lake, not a really wide area, but enough to recognize things floating on the surface of the water.
Therefore, I attached a camera to the device so that I could get the images, but unfortunately, a bird got on it or something happened and the camera slipped to facing down. I placed it back in position, but once again it immediately slipped and faced down again (laughs).
Mr. Masuzawa: Despite the stories, there truly is a tremendous amount of information that can be gathered from the image data.
When experts look at the images of the water surface, they can tell whether blue-green algae is likely to increase or decrease in the future.
We would like to accumulate this data and compare it with other items we are measuring.
In the future, we hope to use the collected data with AI to predict the occurrence of blue-green algae and other types of algae, and furthermore, to forecast the water quality and environment of the lake.
Q: You mentioned crowdfunding for the production of Unit 2. Was this Professor Miyabara’s idea?
Professor Miyabara: When the idea of crowdfunding came up in the science department, I thought it was the only way we could get it done. We had also been talking about building a new observation device, so I said, “Let’s do it”.
However, we had a goal, so in order to exceed it, we kept sending out information to various media, including on the Internet and social media. I even went on the radio. Thanks to everyone’s efforts, we were able to achieve our goal!
Mr. Masuzawa: We even named it “SUWAKO WATCH”.
A nameplate with “Suwako Watch” written on it is affixed to Unit 2.
Professor Miyabara: We thought it would be a good idea to have one of the crowdfunders to give us a fun nickname rather than some serious sounding name; so we decided to ask for people to submit a nickname as well.
As a part of crowdfunding, of course we sent out reports and returns to the people who contributed…The most difficult part was that we had planned to give back the gift of seeing the Suwa fireworks display at the Suwa-Rinko Research Station there (pointing to a building by the lake), but the fireworks display was canceled due to Covid-19 for a few years… This year the fireworks display was held, so we were finally able to give the gift to our supporters.
The Lake Suwa Fireworks have been a yearly summer tradition in Suwa since 1949. Held annually on August 15, it is one of the largest fireworks displays in Japan, attracting about 500,000 spectators.
The Suwa-Rinko Research Station is located close to the fireworks display site. It must be a spectacular sight to see the tens of thousands of fireworks going off from there.
Q: Were there any problems during the monitoring?
Mr. Masuzawa: Unit 1 has a high center of gravity and has a shape that is susceptible to water resistance, so it once tipped over while being pulled and carried by a boat. Fortunately, there was no problem with the equipment inside. For Unit 2, the Suwako Watch, we lowered the center of gravity of the floating device and changed the shape of the lower part of the device to make it easier for water to flow with less resistance.
As for logger related troubles, the Pt sensor was once disconnected and had to be replaced. The cause is a little unknown, but since we are dealing with the natural environment, many things can happen… Driftwood can come in from typhoons, and there are carp over one meter in size in the lake, so anything can happen.
The most frightening of all is lightning. Our observation equipment is like a lightning rod in the middle of the lake. I think lightning probably strikes it sometimes, but so far it’s been working fine.
Q: After actually operating the system through monitoring, do you have any requests for us to help improve the system?
Mr. Masuzawa: The RTR500B series is very convenient for us as there is an app that allows various settings to be made directly from a smartphone.
However, with the Windows-based system, it is possible to view data remotely, but it is not possible to communicate and operate or change settings. It would be very nice to be able to do that.
The reason for this is that if you are measuring all the time, the time stamp of the data sent from the loggers gets out of sync. When data from T&D WebStorage Service is imported to the public cloud via API, it is linked by time, but if the time is off, the data is sometimes skipped. There are ways to compensate for this in the program on the import side, but right now we are adjusting the logger recording time to prevent data from being duplicated or skipped. I am doing this from my smartphone on behalf of the project team, including setting the recording and transmission intervals, but I think it would be more convenient if, for example, Shinshu University members could set up the logger from a Windows PC instead of an app.
――We are aware of the convenience of being able to set up the RTR500B series remotely, and we are currently working on a way to allow users to change various settings of the RTR500B series from a browser screen logged into T&D WebStorage Service.
Mr. Masuzawa: Also, I like T&D’s voltage logger, which is easy to use in combination with various sensors and very easy to install and add on to, but it would be nice if the system could send images as well, such as for monitoring images of the water surface, which was mentioned earlier.
Right now we are using a single RasPi to process the image data, but we also use a gateway to transmit the data, which also eats power. Anyway, I wanted to make the device compact… as the number of systems handling data increases, so does the size, weight, and power consumption, so I want to unify them as much as possible.
The images don’t have to be that beautiful, so it would be great to be able to send them easily from a mobile base station using a SIM card.
――I think that data aggregation is an important theme for the IoT and the role it plays in our lives. We need to think about this in new and various ways.
Q: What role will IoT play in the future of the Lake Suwa Water Quality Observation Project?
Mr. Masuzawa: Lake Suwa is a natural habitat for people in the Suwa area, but we would like to build on these activities to attract the interest of the younger generation, especially students, in ways that are related to sustainability issues.
I believe that the IoT will become both more and more necessary and common in the future. In this context, we will continue to observe Lake Suwa together with our team of professors. We are currently taking data at two locations, but in the future we would like to collect more data so that we can forecast the environment, including the weather, at the lake. In order to do that, we need to compare the current conditions.
At the moment, the data collected must be analyzed by humans, but this analysis will lead to forecasts and other future applications. The part of the process which is to source the data, collect it and automatically store it is where IoT can be used to great advantage.
If we do what others are already doing, there will be no development as a business, so we are also talking about how to solidify areas that no one else is doing. In our main business of molds, we are working on molds that other companies cannot do and solid metal bonding technology that no one else is doing.
In this context, our work here at Lake Suwa is quite unique. I believe that if it can be done successfully in the middle of Lake Suwa, it can be used anywhere (laughs).
We hope that people will see our achievements and want to make use of our monitoring and IoT technologies.
――Thank you so much for taking time from your busy schedule to talk with us.
Mr. Masuzawa: Thanks for coming out here, I thought it was interesting as a human being to do an interview in a place like this once in a while. It is fun to meet people like this!
T&D loggers are used in harsh environments.
Battery operation, free cloud computing, and API integration all seem to be very important for such applications. The ease of installation and expansion, the convenience of the app… All of these factors brought up in the interview gave me a stronger sense than ever of the reasons why people use T&D products.
We are honored that our equipment, manufactured here in Nagano Prefecture, can contribute to the goal of environmental conservation at Lake Suwa.
We would like to express our deepest gratitude to Professor Yuichi Miyabara, Hisaomi Masuzawa, and the staff of Shinshu University for their cooperation in this interview. We will continue to support their research activities with T&D loggers!
