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The new norm: Japanese experts warn of more rain, raging rivers and submerged homes

  • October 23, 2019
  • , The Japan Times
  • English Press



With torrential rain, raging rivers and submerged homes, the havoc wrought by Typhoon Hagibis was a grim reminder that extreme weather may now be the new norm in this disaster-prone nation.


It was only last month that compact Typhoon Faxai nailed the Kanto region, blowing off roofs and triggering massive blackouts in Chiba Prefecture. But the damage from giant Hagibis — which had morphed into the equivalent of a Category 5 hurricane before weakening upon approach — was a double whammy for areas struggling to get back on their feet and a wake-up call on how centralized disaster planning seems to be failing Japan.


As of Tuesday, the government confirmed that the record-breaking rainfall Hagibis brought caused levees to collapse at a whopping 135 spots in 71 rivers, including the Chikuma and the Abukuma, which inundated communities in Nagano, Fukushima and Miyagi prefectures.


The storm left at least 84 people dead and nine missing, according to NHK. Nearly 68,600 homes were flooded, with around 5,800 destroyed or heavily damaged. Nearly 4,000 people remain in evacuation centers.


“We should expect the frequency of powerful typhoons and heavy rains to grow with global warming,” said Kazuhisa Tsuboki, a professor at the Institute for Space-Earth Environmental Research at Nagoya University.


Warm ocean temperatures increase the amount of moisture in the air that feeds typhoons, Tsuboki said, and research has shown the strongest ones have only grown stronger in East and Southeast Asia.


“Typhoon risks for midlatitude countries such as Japan are definitely escalating,” he said, adding that Faxai and Hagibis, the 15th and 19th named storms of the season, respectively, were among the strongest to make landfall in the Kanto and Tokai regions since the Meteorological Agency began keeping records in 1951.


Accurate forecasts of intensity and moisture are vital to prepare for incoming typhoons, but Tsuboki said the methods employed by the Meteorological Agency using satellite images are inadequate. “Ideally, we should be flying weather observation aircraft, but that’s still at an experimental stage.”


Japan hasn’t been complacent in the face of the growing danger. Historically prone to typhoons, large cities such as Tokyo have built dikes and floodgates along rivers and coastlines, and retention basins are being built to manage storm runoff to prevent the flooding.


One such facility, the ¥230 billion Metropolitan Area Outer Underground Discharge Channel in Kasukabe, Saitama Prefecture, is the world’s largest. It is credited with easing the flood risks in rivers to the east of Saitama during Hagibis.


As the storm approached, the government was quick to raise the alarm, issuing a special heavy rain warning for Tokyo. East Japan Railway Co. suspended many train runs in the capital ahead of the typhoon, and Central Japan Railway Co. and West Japan Railway Co. canceled or suspended shinkansen services as many supermarkets and department stores in Kanto and Tokai closed for the entire day.


“The suspension of railway services was a good call, and people seem to be more understanding of its necessity in these situations,” said Hitoshi Tsunashima, a Nihon University professor who is an expert on railway engineering. “More of an issue is restoring services after disaster strikes, as the impact of typhoons on transportation systems cannot be foreseen.”


In the aftermath of Typhoon Faxai, millions of passengers were affected when trains were canceled or delayed at the start of the workweek.


“Corporations need to be more flexible, closing offices or allowing employees to telecommute in these instances,” Tsunashima said. “In the meantime, cities need to devise measures to boost the resilience of critical transportation infrastructure while reviewing and improving transport policy,” he said, suggesting the wider implementation of so-called bus rapid transit systems.


When sections of the Kesennuma Line in Miyagi Prefecture were destroyed by the 2011 Great East Japan Earthquake and tsunami, JR East converted the line into a dedicated BRT route that is still used to this day.


Hagibis also exposed weak points in the nation’s transportation infrastructure. One-third of the trains used for the Hokuriku Shinkansen line were damaged when the overflowing Chikuma River inundated their depot in Nagano. While the damage to each of the 10 trains and 120 carriages has not yet been specified, Tsunashima said they may need to be scrapped, estimating the cost of replacement at ¥30 billion to ¥40 billion.


“The rail yard was on elevated land, but that wasn’t enough to prevent floodwater from submerging the trains. While the extent of the deluge may have come as a surprise, new measures need to be hashed out to protect rail yards when massive flooding is expected.”


If there’s one lesson to be learned from Hagibis, Tsunashima said, it is that conventional wisdom is no longer relevant in the face of modern typhoons.


The Chikuma River, for example, runs through Nagano, a land-locked prefecture in the center of Honshu with the lowest annual rainfall of all 47 prefectures.


But torrential rain soaked the prefecture during Hagibis, breaking records in several locations and causing parts of the riverbank to fail.


“People need to understand that levees aren’t impenetrable and could break if enough pressure is applied,” said Norio Maki, a professor at Kyoto University’s Disaster Prevention Research Institute. “We need to be prepared for the worst and devise evacuation plans and insure our homes in the event that disaster strikes.”


And with rural depopulation accelerating, Maki said it would be desirable if residents in the countryside consider moving to safer areas to mitigate the risks rather than relying on man-made infrastructure for protection.


He raised the example of Totsukawa, a mountainous village in Nara Prefecture hit by heavy rain and landslides in 2011 that killed six and left seven residents missing.


Following the tragedy, the graying village — Japan’s largest in terms of area — decided to designate seven areas as spots to build community centers with disaster-resistant public housing for the elderly, plus walkways, cafes and rest stops, to encourage residents scattered among its 54 hamlets to converge on areas with better transportation access.


“We chose areas that are relatively disaster-resilient, and have so far completed work in two districts,” said Hiroyuki Tamaki, a village official. “Our aim is to provide the public infrastructure necessary to prevent our residents from moving out of the village.”


Totsukawa, with a population of around 3,400, has reason for concern: In 1889, major flooding triggered hundreds of landslides, killing 168 and displacing thousands. The destruction was so brutal that nearly 2,500 residents, or more than a fifth of the population, decided to relocate to Hokkaido, naming the new village Shintotsukawa (New Totsukawa).


In the meantime, urban centers are facing higher environmental risks due to their dense populations and complicated lifeline and infrastructure networks.


“Major disasters take place in cities, and cities are also the source of major disasters,” Maki of Kyoto University said.


On the eastern edge of Tokyo, for example, most areas in the so-called five wards of Koto — Adachi, Edogawa, Katsushika, Koto and Sumida — are projected to be submerged in a worst-case storm surge scenario that could affect 2.5 million people, or over 90 percent of their combined population.


While the Arakawa and Edogawa rivers, which run through the five wards, managed to spare the capital from flooding during Hagibis, reports said many retention reservoirs were close to capacity.


“I think we need to accept that no matter what we do, disasters strike,” Maki said.


“Looking ahead, perhaps we should be focusing on having each region establish its own, autonomous infrastructure systems rather than relying on a centralized system.”

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