일 도쿄 지하철역 완전차단 침수방지시스템 등장 Tokyo Tackles Flood Control as Typhoons Swamp

해외 침수방지 차단벽 시스템 사례(참고자료)

 

작년에 일본 도쿄에 설치된 침수방지 차단벽 시스템 사례

 

Removable flood prevention system installed in one of New York

City's largest office buildings 최근 뉴욕 대형빌딩에 설치된 제거 가능한

침수방지시스템 사례

 

일본 도쿄(東京)에 출구를 완전히 봉쇄해 침수를 방지할 수 있는 지하철역이 등장했다. NHK는 24일 도쿄 지하철 9개 노선을 운영하는 도쿄메트로가 대규모 수해가 발생했을 때 지하가 침수되는 피해를 방지할 수 있는 완전 밀폐 출구를 처음으로 완공했다고 보도했다. 도쿄메트로는 주오(中央)구 가야바초(茅場町)역의 침수 예상 출구에 여닫을 수 있는 철제문을 설치하고 측면과 천장을 두께 2.4㎝의 강화유리로 덮어 빗물 유입을 차단할 수 있도록 했다. 도쿄메트로는 현재 중앙·지방정부의 침수 예측 자료를 바탕으로 1.5m 이상의 침수가 예상되는 도쿄 전역 32개역, 114개 출구에 밀폐 시스템을 설치하는 공사를 진행하고 있다. 완공되는 2022년에는 도쿄 도심 지하철역의 침수 피해를 방지할 수 있을 것으로 기대되고 있다. 일본 정부는 집중호우로 도쿄를 관통하는 아라카와(荒川)강의 제방이 무너지면 100개가 넘는 지하철이 침수될 것으로 관측하고 있다. 이에 따라 전문가들은 종래에 설치했던 높이 70㎝ 수준의 지하철역 출구 지수판이 효과를 발휘할 수 없을 것이라고 지적해왔다. 도쿄메트로 측은 “빗물은 낮은 지대로 흘러들어오기 때문에 (지하철역은)호우 대책을 마련해야 할 필요성이 특히 크다”면서 “승객의 안전을 확보하고 교통 마비를 방지할 수 있는 대책을 추진할 것”이라고 강조했다. 문화일보 김하나 기자 hana@munhwa.com

 

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Tokyo Tackles Flood Control as Typhoons Swamp

Subways

 

Photographer: Noriyuki Aida/Bloomberg
The underground regulating reservoir tunnel under

construction in Tokyo.

 

By Jacob Adelman Below the condos and boutiques of Tokyo’s upscale Minato ward -- which includes Roppongi Hills, home to Goldman Sachs Group’s Japan headquarters -- a boring machine has carved out the city’s newest defense against floods.   “There are many buildings, there’s a freeway,” said Satoshi Yamamoto, who’s directing the Tokyo government’s 24.5 billion yen ($240 million) project to build a giant subterranean reservoir -- the city’s second of three -- to handle flood waters from the Furukawa river that winds through the area. “We decided the best approach was to go underground.”   When it’s completed in 2016, the 3.3-kilometer (2-mile) reservoir will be able to handle 135,000 cubic meters of water, enough to fill 54 Olympic-sized swimming pools. Tokyo is becoming increasingly reliant on this solution as more typhoons hit the country each year, a trend that Yamamoto said may be linked to global warming. The flooding is exacerbated by the city’s sprawling concrete footprint that keeps rainwater from seeping safely into the ground.   Tokai Downpour “Japan has no choice,” Marcelo H. Garcia, director of the Ven Te Chow Hydrosystems Laboratory at the University of Illinois at Urbana-Champaign, said in a phone interview. “With the lack of space they have, they have to come up with some ingenious way of doing this.”   The area is especially flood-prone because of the proximity of buildings and roads to the river, which runs above-ground from near the busy Shibuya subway and train station to Tokyo Bay, according to the Tokyo government’s construction office.   A storm equivalent to the so-called Tokai Downpour in 2000, when hourly rainfall exceeding 11 centimeters burst levees in the central Japan city of Nagoya, would cause floods over two meters (6.6 feet) deep in some areas of Minato, according to the area’s disaster planning map. The underground reservoir project was approved in 2008 after a series of devastating storms, including a 2004 typhoon that flooded the nearby Azabu-Juban subway station, Yamamoto said. Residents asked for anti-flood measures after suffering widespread damage to their properties, he said.   Metal Skeleton During heavy rain, water will flow into an intake channel on the Furukawa’s southern bank when it gets too high, much like the overflow hole in a bathroom sink. It will descend 52 meters -- about 16 stories -- down a drop-shaft into a tunnel that follows the river’s curves, at one point passing beneath the tracks of Tokyo’s Namboku subway line. Once the storm subsides, the water is returned to the surface about 2 kilometers downstream.   “It’s pumped back up to the river,” Yamamoto said.   On a recent afternoon, the tunnel’s oxidized metal skeleton was still visible near the bottom of the drop shaft, where its ceiling had not yet been covered over with cement. Workers in light blue coveralls and white hardhats drove forklifts along the floor of the tunnel, cut by contractor Tobishima Corp. (1805) using a cylindrical boring machine working at a rate of 14 meters a day. Flood Control Together with a separate 3.2-kilometer reservoir under construction in the northwest of the city, the Furukawa project represents a tripling down on a method that’s been stemming floods since initial construction on the city’s first such tunnel was completed in 1997.   The approach derives from the standard flood-control method used in other cities, where water is pumped to above-ground reservoirs during storms. Chicago, for example, stores water and sewage in a nearby quarry during heavy rains.   “What makes this system particularly noteworthy is ju   st its scale, because it’s underneath one of the largest cities in the world,” said Patrick Lynett, a civil engineering professor who studies cities’ water-management tactics at the University of Southern California in Los Angeles. “It allows them to have this flood control out of sight.”   Tokyo’s size and density leave it no space for a typical above-ground solution. The Tokyo-Yokohama metropolis is the world’s second-biggest by land area after the New York City area, with more than double New York’s density, according to data compiled by the London-based City Mayors Foundation.   Flooded Homes It’s also facing more occurrences of flooding as the frequency of storms increases. The city’s first underground reservoir, which is even larger than the Furukawa project, was called into action five times last year, compared with a usual rate of once or twice per year, according to Yoshiaki Takahashi, who oversees the facility in western Tokyo. It was used most recently on Aug. 10, when Typhoon Halong, the 11th of the season, poured 17 millimeters of rain in an hour on the Japanese capital.   That reservoir absorbs overflow from three rivers and was built after a typhoon in 1993 flooded more than 3,000 homes, causing 15.6 billion yen in damages, according to Takahashi.   Tokyo’s Yamamoto said global warming appears to be making storms and typhoons occur more frequently, which would increase usage of the city’s underground reservoirs. Japan saw an average of 13 typhoons during the first three years of the current decade, compared with an average of about 11 over the six previous decades, Japan Meteorological Agency data show. “It’s exactly the kind of thing you expect with the warming,” said Bradley Opdyke, a climate scientist at Australian National University in Canberra.   Other cities may try to replicate Tokyo’s system as the need for flood-control measures grows. Hong Kong and Singapore - - which experience rainfall from the same East Asian monsoon as Tokyo and are similarly densely populated -- are obvious candidates, according to the University of Illinois’s Garcia.   “It may come in as a useful method to basically deal with flooding,” he said. “It’s like a gigantic rain barrel.” bloomberg

 

 

 

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