We Went Inside Japan’s Epic Storm Simulator

TL;DR

Japan's NIED facility near Tokyo can simulate up to 300mm of rainfall per hour to research landslides and flood-proof housing that protect millions of lives.

Key Points

• 1.The Large Scale Rainfall Simulator in Tsukuba, 75km northeast of Tokyo, is a 75×15m hangar with 2,176 nozzles suspended 16m high, allowing droplets to reach terminal velocity before hitting the ground.
• 2.It can reproduce rainfall from 50mm to 300mm per hour — 300mm nearly matching the strongest rainfall ever recorded (1947), and far exceeding the 200mm Hurricane Ida dropped in an entire day in 2021.
• 3.The entire building moves on rails powered by electric motors, traveling at ~1m per minute, allowing researchers to position the rainfall over different permanent test setups on the site.
• 4.Dr. Sakai's team uses the facility to develop sensors that detect dangerous soil conditions before landslides strike — critical because landslides cause roughly half of all natural disaster fatalities in Japan.
• 5.Researchers also used the simulator to develop the world's first flood-proof house, sealing entry points with hollow window gaskets, float-valve air vents, and backflow prevention valves on utility pipes.