The blog post dated September 24, 2026, titled “Nagoya Torrential Rain” discusses “stormwater retention” technology as a flood control measure for urban areas; in this post, I’ll introduce a related topic.
The City of Nagoya has been implementing a measure that involves constructing massive underground stormwater retention basins to temporarily store rainwater, then pumping it out once the rain subsides to discharge it into rivers, canals, and the ocean. The Nagoya Central Stormwater Retention Basin, which runs beneath Nagoya Station, consists of a tunnel with an inner diameter of approximately 6 meters and a length of approximately 5 kilometers, capable of storing up to about 100,000 cubic meters of rainwater. The stormwater stored in the Nagoya Central Stormwater Retention Basin is sent to the Hirokawa Pumping Station via the Sannōbashi Stormwater Trunk Line (currently under construction). At the Hirokawa Pumping Station, located at the end of the line, the plan is to discharge the stormwater into the Nakagawa Canal using pumps situated 65 meters below ground.
It has also been reported that in July 2025, six large-capacity drainage pumps manufactured by Ebara Corporation were delivered to the Hirokawa Pumping Station. While it is unclear whether the technology used in these pumps is the same as that described here, Ebara Corporation has filed and obtained numerous patents related to high-capacity, durable pump systems. I believe that this accumulation of technological advancements underpins the flood control measures that protect the city from heavy rain. (Conan)
(Reference)
1. Nagoya City Water and Sewerage Bureau (Japanese only)
https://www.water.city.nagoya.jp/category/hirokawa/162929.html
2. CBC TV, September 11, 2025 (Japanese only)
https://newsdig.tbs.co.jp/articles/-/2160069?page=3
3. Kikai News (Japanese only)
Ebara Delivers Six Large Drainage Pumps to Nagoya City’s Hirokawa Pumping Station, Contributing to Enhanced Flood Control Measures | kikai-news.net