Why torrential rain killed so many

Residents look over the flooded town by heavy rain in Kurashiki, Okayama Prefecture, western Japan, on July 7, 2018.
Residents look over the flooded town by heavy rain in Kurashiki, Okayama Prefecture, western Japan, on July 7, 2018. PHOTO: EPA-EFE

TOKYO • Disaster-prone Japan, often hit by earthquakes and typhoons, is known for its emergency preparedness.

Yet the record rainfall which battered swathes of western Japan last week has left more than 100 dead. The Straits Times looks at factors that have led to the heavy toll.


While the torrential rainfall last week began with a typhoon front that hits Japan annually, it was a deluge never seen before. Records were broken at at least 93 weather point locations, with rainfall in some areas as much as three times that of the previous high.


Weather patterns have been closely tracked by meteorological agency officials and the national government, which has sought to build dams for flood control. But 73 per cent of Japan's terrain is mountainous - which means many areas are either built on, or hemmed in by, steep slopes, putting homes in the path of potential landslides.

There are also many rivers coursing through the country, and while efforts have been made to reinforce their embankments, this has not been sufficient to cope with a deluge like last week's.


Japan comprises 47 prefectures - some of them as large as, or even bigger than, Singapore. The bustling cities of Tokyo, Yokohama and Osaka will evoke images of a concrete high-rise jungle, but the picture cannot be more different in the rural areas.


The sheer size of the prefectures means development within each prefecture is not uniform. In Hiroshima prefecture, for example - which saw at least 44 deaths - the majority of the victims hailed from the more mountainous regions in the east. Comparatively, southern Hiroshima, which is flatter and more developed, has been spared the brunt of the damage.

Many of the traditional-style houses in rural Japan are also built of wood, which means their foundations are more suited to withstand earthquakes than the crushing impact of a torrent of flood water.


At one point, evacuation warnings or orders covered 19 prefectures, with a total population of up to 5.9 million people, Kyodo News reported.

But these were neither mandatory, nor widely heeded, as many people might have been lulled into a false sense of security, having survived years and decades of heavy rain.

"Human beings have a so-called normalcy bias, meaning people try not to evacuate, ignoring negative information," said Dr Hirotada Hirose, a disaster management expert.

"This human nature means people can't react to disasters like landslides and flash floods, which occur suddenly."

Japan's warning system has also been criticised, as much of it is left to the discretion of local or municipal governments without disaster management experience.

Walter Sim

•Additional information from Agence France-Presse

A version of this article appeared in the print edition of The Straits Times on July 10, 2018, with the headline 'Why torrential rain killed so many'. Print Edition | Subscribe