Environment

Explaining Japan's Worst Weather Disaster in Decades

The recent rainfall was unprecedented and disaster experts said that torrential rains are becoming more frequent, possibly due to global warming.

Tokyo: Torrential rains unleashed floods and set off landslides in western Japan last week, killing at least 176 people, forcing millions to evacuate and leaving dozens missing in the country’s worst weather disaster in 36 years.

Below are some reasons for the high death toll.

Extreme weather

Remnants of typhoon Prapiroon fed into a seasonal rainy weather front fuelled by warm air from the Pacific ocean, a pattern similar to one that caused flooding in southwestern Japan exactly one year ago that killed dozens of people.

The recent rainfall was unprecedented and disaster experts said that torrential rains are becoming more frequent, possibly due to global warming.

“The government is just starting to realise that it needs to take steps to mitigate the impact of global warming,” said Takashi Okuma, an emeritus professor at Niigata University who studies disasters.

Submerged houses are seen in a flooded area in Mabi town in Kurashiki, Okayama Prefecture, Japan, July 8, 2018. Credit: Reuters/Issei Kato

Submerged houses are seen in a flooded area in Mabi town in Kurashiki, Okayama Prefecture, Japan, July 8, 2018. Credit: Reuters/Issei Kato

Risk awareness

Municipalities in Japan have been required since 2001 to create and publicise “hazard maps” showing risks of flooding and landslides. By 2013, 95% of municipalities had produced flood hazard maps and 81% had produced maps for landslides, according to the land ministry.

However, experts say many homes in Japan were built in risky areas before the 2001 requirement to distribute hazard maps.

Kurashiki city in Okayama prefecture, where the Mabi district was especially hard hit by this week’s floods, distributed a hazard map in 2016, said the Yomiuri newspaper.

Despite orders and advisories to evacuate, which may have been issued too late, some residents appear to have ignored the warnings because they did not know where to go or how to get to safety.

Asked if he knew he lived in a designated risk area, Kenji Ishii, a 57-year-old resident of Mabi district, said, “I’m afraid I did not know that very well”.

A satellite image of an overview north of Kurashiki, Japan "after the floods" captured July 10, 2018. Credit: Satellite image ©2018 DigitalGlobe, a Maxar company/Handout via Reuters

A satellite image of an overview north of Kurashiki, Japan “after the floods” captured July 10, 2018. Credit: Satellite image ©2018 DigitalGlobe, a Maxar company/Handout via Reuters

Quakes not floods

Japan, one of the most seismically-active places in the world, has stressed earthquake preparedness and regulations to make buildings quake-proof, but it has done less about potential flood disasters, said Okuma from Niigata University.

After several smaller disasters in recent years, the Ministry of Land, Infrastructure, Transport and Tourism has drafted plans to improve flood control and evacuation planning.

Land use

The government monitors weather conditions and issues early warnings, but the nation remains vulnerable to disasters because most of the country outside major cities is mountainous and construction takes place on virtually every bit of usable land.

Reforestation policies after World War II saw many mountains logged and replanted with trees having roots that are less able to retain water. This has contributed to the danger of landslides, which accounted for a large number of the deaths in this latest disaster.

(Reuters)

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