Artificial system

Tokyo aims to make practical use of artificial rain technology

As the world faces the prospect of more extreme weather events, including droughts, Japan is one of many countries working to advance artificial rain technology to help alleviate water shortages. water when rainfall is scarce.

In Tokyo, metropolitan authorities set up artificial rainmakers on the eve of the Tokyo Olympics and Paralympics last year in a bid to increase the amount of water stored in dams during periods of drought.

Photo taken on August 1, 2022 shows Tokyo’s artificial rain device, dubbed “Ogouchi Smoke Station”, next to the Ogouchi Dam in Okutama, western Tokyo. (Kyodo)

One is erected inside a newly constructed shed near the Ogouchi Dam, upstream of the Tama River system in Okutama, western Tokyo. The pipes extend around a silver-colored tank connected to a retractable roof of the facility, dubbed the “Ogouchi Smoke Station.”

“The material that will become the seeds of the raindrops is blown into the sky from here,” said Tetsuo Nakamura, head of the Ogouchi Reservoir Management Office, located some 65 kilometers west of the Japanese capital.

In the “seeding” process, the smoke generated by the combustion of liquid silver iodide mixed with acetone is emitted from the plant, with the silver iodide becoming the core around which the water condenses to form a raindrop.

It is a weather modification method that experts say has limited effectiveness and almost no practical application today. Nevertheless, the metropolitan government has three other generators at sites on the west side of the dam in Yamanashi Prefecture.

According to the Tokyo government, silver iodide is a difficult substance for the body to absorb, and there have been no reports of harmful effects of artificial rain on the human body or the environment.

Tokyo introduced artificial rain generators in 1965. But due to aging, it jointly developed new models with the Meteorological Research Institute of the Japan Meteorological Agency, after replacing two old generators at a cost of 80 million yen ($570,000) since 2020.

Through the use of foreign know-how, the city was able to improve the method of combustion and the concentration of the solution, allowing more efficient dispersal of raindrop nuclei than usual, said a metropolitan government official. .

However, only 5 percent of precipitation can be expected to be increased by using the rain generator, and only if certain weather conditions, such as wind direction, are met.

Although the rain generators were made available to deal with a possible water shortage during the Olympic and Paralympic Games, there was no possibility of operating them.

Photo taken on August 1, 2022 shows the interior of the “Ogouchi Smoke Station” used as an artificial rain device. A liquid placed inside a tank (L) is vaporized and smoke emitted into the sky from the Okutama facility, west of Tokyo. (Kyodo)

Since 1965, the devices have been in operation for about 800 days and have not been put into practice since 2001. Although there were droughts in 2013 and 2016, the machines have only been used as a test, partly because of water development. sources other than the Tama River system.

“Artificial rain generators alone cannot solve water shortages,” the metropolitan government official said. “But the simple act of operating them implicitly conveys the seriousness of a situation to citizens and is a way of asking for their cooperation in limiting their water consumption.”

The artificial rain technology has been adopted by 50 countries around the world, including Thailand, which experiences severe water shortages during its dry season.

In Japan, weather modification research began in the 1950s. Masataka Murakami, a specially appointed professor at Nagoya University who helped develop rainmakers for the Tokyo government, said their effects on increased rain and snow have been “scientifically proven” in recent years.

To increase rainfall more reliably, the Tokyo government had considered using airplanes to seed clouds directly with the basic substance of raindrops, but abandoned the plan due to high maintenance costs.

Speaking of the potential benefits of new research on artificial rain production, Murakami said, “In addition to artificial precipitation, if it becomes possible to artificially adjust the amount and location of rain and snow at the future, this could be used to reduce torrential rains. and other disasters.”