豪雨被害 的確な情報で早めの避難を

The Yomiuri Shimbun (Jul. 18, 2010)
In 'guerrilla rain' fight, the key weapon is data
豪雨被害 的確な情報で早めの避難を(7月17日付・読売社説)

Torrential rains caused by a seasonal rain front have brought death and destruction to the nation, mainly in western Japan.

A number of people have been killed or are missing. The victims were crushed in their homes by mudslides or swept away by rain-swollen rivers.

In the past month, there have been over 350 reported landslides. In Matsue, a mudslide on the slope behind a private house caused two huge rocks, each measuring four meters in diameter, to strike the building, killing two residents. In Yaotsucho, Gifu Prefecture, a mudslide crushed a private house, killing three residents.



Landslides must be studied

In recent years, experts have attributed large-scale mudslides to the so-called deep-seated landslide mechanism. Heavy rain soaks into cracks in the bedrock, which has been weakened over time, and when the bedrock collapses downhill, it takes a large volume of upper soil with it.

Unlike shallow landslides, which can be prevented to a certain degree through good forestry practices, there are no known measures to prevent the occurrence of deep-seated landslides. We consider it necessary to urgently study what steps could be taken.

Meanwhile, the phenomenon of so-called guerrilla rain--sudden downpours into relatively narrow zones, mainly in urban areas--has attracted attention in recent years. Such rain is caused mainly by cumulonimbus clouds that form in a clash of warm and cold air. But some experts think the urban heat island phenomenon and global warming trends have a causal relationship to the sudden downpours.

Guerrilla rain is frightening in that it is difficult to predict and the damage it causes occurs all at once.

In the summer of 2008, five workers died in Tokyo after being washed away by a surge in sewer water while working underground. Also that summer, a swollen river killed five people, including primary school children, in Kobe.

On July 5 this year, an intense rainfall of 107 millimeters per hour was recorded in Tokyo's Itabashi Ward.

To prevent damage from heavy rain, it is essential to have highly accurate weather forecasts and to issue appropriate warnings. Such information must be adequately conveyed by local governments to residents in affected areas. It is imperative that those residents be advised to evacuate if necessary as soon as possible.

The Land, Infrastructure, Transport and Tourism Ministry has started introducing advanced radar systems capable of accurately measuring the strength of precipitation mainly in major cities. Such radar can also be used to predict situations in wide areas affected by heavy rain. There also are private-sector services offering guerrilla rain forecasts on mobile phone sites.

Since late May, the Meteorological Agency has issued warnings and advisories on heavy rain and floods in a much more detailed manner as it increased the number of forecasting areas from 375 to 1,777 to correspond to each municipality.


Stay alert to stay safe

We urge each municipal government to effectively use such information to issue advisories and instructions for evacuations of local residents. It also is important that local governments regularly conduct disaster drills and establish systems to provide local residents with necessary information via community wireless services and other means in the event of an emergency.

As the rainy season winds down across the nation, summer vacations will soon start for schoolchildren. We are entering a holiday season during which people flock to beaches, mountains and rivers. People must not forget to take precautions against rain and flood disasters wherever they go.

(From The Yomiuri Shimbun, July 17, 2010)
(2010年7月17日01時49分 読売新聞)

by kiyoshimat | 2010-07-18 06:24 | 英字新聞

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