J-STORIES – The Tokyo metropolitan space goals to be disaster-resilient and to guard its residents from pure disasters. With many rivers flowing via the world, authorities do their utmost to mitigate injury from flooding. The Metropolitan Outer Space Underground Discharge Channel is a novel feat of engineering constructed to maintain properties and companies protected and dry. Its dramatic pressure-adjusting water tank, often called the “underground shrine,” can be fashionable with each home and worldwide guests.
A One-of-a-kind Flood Management Facility Upstream from Tokyo
The Metropolitan Outer Space Underground Discharge Channel is among the world’s largest items of flood management infrastructure. Its pressure-adjusting water tank, situated in Kasukabe Metropolis, Saitama Prefecture, is open to guests and is definitely accessible by prepare from central Tokyo.
The channel is managed by the Ministry of Land, Infrastructure, Transport and Tourism’s (MLIT) Edogawa River Workplace, which oversees flood management infrastructure and associated initiatives for the Nakagawa/Ayase River basin within the northern Tokyo metropolitan space. The metropolitan space encompasses Tokyo and elements of six neighboring prefectures.
The low-lying watershed is gradual to empty and due to this fact susceptible to flooding throughout heavy rains, a phenomenon compounded by the world’s fast growth over the previous 70 years, a change spurred by its quick access to central Tokyo. Though solely 5% of the basin was thought of “city” — dominated by asphalt and buildings — in 1955, by 2015 city land had expanded to 53%. As water-retaining rice paddies and fields had been misplaced, the rivers turned faster to overflow.
The underground discharge channel was constructed to handle this concern. Accomplished in 2006 following 13 years of development, the channel redirects overflow from the watershed’s small and mid-sized rivers. Put merely, water collected by overflow levees throughout heavy rains flows into underground shafts — every giant sufficient to suit the Statue of Liberty — and is carried by tunnel to the pressure-adjusting water tank, a surprisingly photogenic area often called the “underground shrine.” The water is then pumped through turbine at a charge of 200 cubic meters per second to the Edogawa River, which flows into Tokyo Bay.
MLIT estimates that the channel, used a median of seven instances per 12 months, has diminished the financial results of flood injury by roughly 148.4 billion yen throughout its first 18 years of operation. Situated upstream of the metropolis, the channel capabilities as one of many most important pillars of flood-resistant city growth measures that shield Tokyo from injury attributable to heavy rains.
Descending to the Underground Shrine
4 totally different excursions of the discharge channel can be found by reservation; we took the “Underground Shrine Course,” which lasts 55 minutes and prices 1,000 yen per individual. The tour started with a proof of the discharge channel within the RyuQkan exhibit corridor foyer. Then, we descended on foot into the pressure-adjusting water tank.
A flight or two down the roughly seven flights of stairs, the temperature dropped perceptibly and the air turned even moister than the humid summer time outdoors. The descent was shorter than anticipated, which is nice as there are not any elevators or escalators.
Contained in the water tank, rows of hulking pillars pale barely into the grey mist towards the far aspect of the cavernous area. Nearer our tour group, daylight filtered in via the spherical shaft from the place, when the channel is in use, water flows into the tank. The ground was dotted with swimming pools of water a centimeter or so deep, reflecting the lights and making waterproof sneakers a should. Often, drops of condensation fell from the ceiling far above.
The massive, empty corridor wearing uniform concrete is hanging, an unlimited feat of engineering at a scale essential to tame rivers.
After additional clarification by the guides in regards to the dimension of the ability and the amount of water it could actually deal with — solely in Japanese, however with worldwide visitors following alongside through the multilingual audio information app — we got 20 minutes of free time to take images and wander round a cordoned-off part of the huge corridor.
The tour had quite a lot of members, all benefiting from the other-worldly surroundings in their very own method. A younger couple dressed all in black took atmospheric images, holding their telephones at low angles to seize dramatic pictures. Different guests posed with a smile and peace signal, dwarfed by an enormous pillar. A doting grandfather snapped pictures of his full of life grandkids.
Spreading Consciousness of Catastrophe Prevention
After the tour, we spoke with Sugama Daijiro, a specialist for development work with MLIT’s Edogawa River Workplace, to study extra in regards to the discharge channel.
“We imagine it’s important for individuals to grasp this facility’s function, so we collaborated with contractors from the development stage to have the ability to supply excursions,” Sugama says. “It’s also a authorities coverage to advertise flood management infrastructure as a tourism useful resource.”
Sugama estimates that roughly 10% of discharge channel guests are worldwide. The workplace additionally offers examine excursions for officers from different nations.
Along with managing the discharge channel, the workplace works to forestall flooding in its jurisdiction via infrastructure tasks similar to levee enhancements. It additionally implements varied initiatives on catastrophe threat discount, the native surroundings, and associated training for youngsters.
“Our workplace manages flood prevention throughout the watershed, not simply in Tokyo or Saitama Prefecture,” Sugama explains. “We work to scale back strain on the watershed as a complete via drainage.”
Regardless of the discharge channel’s efficacy and big scale, Sugama cautions that it could actually’t mitigate flood threat fully. “We’re all the time bettering our infrastructure and considering of flood countermeasures,” he says.
Sugama emphasizes that everybody in the neighborhood, not simply the related authorities, can do their half: Households can set up rainwater assortment tanks and chorus, as a lot as attainable, from draining baths throughout a flood alert. Residents ought to perceive evacuation procedures, in addition to analysis hazard maps when selecting a spot to reside, he provides.
Visiting the Underground Discharge Channel shouldn’t be solely an opportunity to marvel on the scale and potentialities of engineering, but in addition a chance to mirror on catastrophe preparedness and our place within the dynamic pure surroundings round us — even on the earth’s largest metropolitan space.
Interview and written by Annelise Giseburt
The Metropolitan Outer Space Underground Discharge Channel
Ministry of Land, Infrastructure, Transport and Tourism Edogawa River Workplace
