Catalyst: Tokyo Flood Prevention - Exploring the Japanese capital's vast labyrinth of underground flood defences Subscribe to Journeyman for daily uploads: http://www.youtube.com/journeymanpictures Go to the Journeyman Science playlist: https://www.youtube.com/playlist?list=PLlGSlkijht5iXbPX7d_oTP47c9C3kArQ0 Fifty metres beneath the world’s largest metropolis – the Japanese capital, Tokyo – is an amazing underworld river system. 6.4km of tunnels, colossal water tanks, massive pillars and giant pumps are part of an immense coordinated effort to pump floodwaters out into Tokyo Bay, and protect the city’s 35 millions inhabitants from devastating floods. But with year-round heavy rains seeming increasingly frequent, Tokyo’s flood management – already the most advanced in the world – is being pushed to even greater lengths to protect the population. Mark Horstman goes underground to explore the gargantuan underground world of Tokyo’s flood defence systems. ABC Australia - Ref 6284 Journeyman Pictures brings you highlights from the cutting-edge science series, ‘Catalyst’, produced by our long-term content partners at ABC Australia. Every day we’ll upload a new episode that takes you to the heart of the most intriguing and relevant science-related stories of the day, transforming your perspective of the issues shaping our world.