What was seen from the deaths of 83 people was September 28, 21:23.
"Evacuating to the second floor does not help ..."
This is a reality that was confronted by looking closely at the "disaster areas" and "history" of the victims of the heavy rain disaster in July.
There may be no guarantee of life in vertical evacuation.
It's a big lesson that we need to keep in mind.
* Analysis is as of September 25.
(July Heavy Rain Coverage Group / Social Affairs Department Reporter Shinya Fujishima Keijiro Saito, Director of Network News Department Motoki Tanaka)
I can't help even on the second floor
The lives of 83 people lost in the heavy rain disaster in July.
Couldn't the damage be reduced even a little?
In order to derive issues and lessons, we (Fujishima, Saito) decided to gather information through reporters in each region and take a closer look at the "location" and "situation" of the damage.
By location of the damage, the most common were those who died "indoors".
In fact, there were 58 people (70%), which is 70%.
It is probable that this disaster was caused by the fact that it occurred during the hours when people were often at home from dawn to morning.
To my surprise, at least seven of them were "not helping even if they were upstairs".
As a person in charge of disaster reporting, I (Fujishima) sometimes call on TV to "ensure safety on the second floor" when the situation is imminent.
Of course, I knew that there were people who couldn't guarantee their lives, but I was shocked to find out that fact.
<< Area of flooding such as collapsed houses >>
All seven people were affected by the disaster at their homes along the Kuma River, a first-class river that flows through Kumamoto Prefecture.
By municipality, there are 5 people in 3 households in Kuma Village and 2 people in 1 household in Hitoyoshi City.
Of these, three people from one household in Kuma Village and two people from one household in Hitoyoshi City were washed away and killed.
Looking closely at the location of the site, they had something in common.
That is, all the houses were in the area called "Flood area such as collapsed houses" set by the government.
As many people may not be familiar with, the "presumed flooding area such as collapsed houses" indicates the place where the building is washed away by the force of the flooded water and there is a risk of collapse.
This area is often designated as a place near a river or a place with deep inundation.
At that time, Mr. Kaho Ichihana, who lives in the Watari district of Kuma village, was taking a picture of the "flooding area such as collapsed houses" in the Watari district from a hill with a smartphone.
The picture was taken around 9:30 am on July 4th.
The area where houses are lined up along the river is like a river with a large amount of water overflowing from the Kuma River.
The muddy brown water reaches up to the second floor, and the house can only see the roof.
According to the analysis of the experts who saw the video, it was found that the speed was about 3 meters per second, which was very fast for flooded water.
When I entered the area after the water had drained, there were houses with only foundations left.
It seems that it has flowed out due to the momentum of water.
Very dangerous "flooding area such as collapsed houses".
So how many homes are there in this area?
We used the building data of Zenrin, the largest map company in Japan, to find out how many houses are in the "presumed flooding area such as collapsed houses" along the Kuma River.
Below is the result.
Along the Kuma River, there were a total of 5,000 buildings from upstream to downstream.
Especially in Kuma Village and Hitoyoshi City.
(Data for each municipality is at the end of the article)
Whether or not it actually collapses depends on the structure of the building, but there is no doubt that many homes are at risk.
And it is not only the Kuma River that has such risks.
"Flood areas such as collapsed houses" are located in rivers around the world.
For example, there are also "Arakawa" and "Tama River" that flow through Tokyo.
<< Deep inundation assumption >>
"It doesn't help even if I'm on the second floor."
Of the seven, the other two were on the second floor and were affected, although their homes were not washed away.
Both were from the Watari area of Kuma, a man in his 60s and a woman in his 70s.
Looking at the inundation assumptions of the country, the place where the two people were home was supposed to be inundated by about 14 meters in the worst case.
The height is comparable to the 4th floor and above of the building, and even the 2nd floor is completely submerged.
If the depth of inundation exceeds 5 meters, the second floor will also be submerged.
Some people have gone up to the roof to save their lives, but it's not easy for the elderly and people with disabilities.
<< Common necessity of "horizontal evacuation" >>
"Flood area such as collapsed houses" and "Deep inundation area".
I think there is only one action to protect yourself that is common to these two.
It is a "horizontal evacuation" to evacuate to a safe place before the river floods and begins to inundate.
Even if you can't go far, you may not be able to help unless you move to the upper floors of a sturdy reinforced concrete building.
90% of dead people Disaster area
Of the 83 victims, 78 were found to have been affected by the disaster.
I also investigated whether these people were in places where risks were expected in advance.
We obtained data on "inundation area," "sediment disaster warning area," and "sediment disaster risk area" from the national and prefectural governments and superimposed them on the map.
The majority of 66 people (85%) were then affected in areas where the risk of disaster was indicated.
When a similar survey was conducted on Typhoon No. 19 in 2019, about 70% of the dead were affected in places where risks were indicated in advance, but this time it exceeded that.
<< Looking at the hazard map Issues for the government >>
"Look at the hazard map!".
I'm sure everyone is tired of hearing this call.
I, the caller, also feel that I'm persistent.
However, looking at these results, I feel regretful that I couldn't make the most of it.
At the same time, I would like the government to promote the creation of an environment where hazard maps can be viewed more easily.
There are issues such as being published only on paper and not being posted on the "Overlapping Hazard Map" site of the Ministry of Land, Infrastructure, Transport and Tourism.
We need a mechanism that allows anyone to easily know the risks without omission.
Hazard map "Undeveloped" locations
On the other hand, 11 people were killed in places where risks were not shown in advance, so-called "unexpected" places.
Looking at the breakdown, 8 people were flooded and 3 people were landslide disasters.
Looking closely at the eight people who died in the flood, six were along small and medium-sized rivers with no hazard maps.
Delays in the development of hazard maps in small and medium-sized rivers have long been an issue.
However, there are about 20,000 rivers flowing in Japan, and it is difficult to prepare a detailed hazard map for all of them overnight.
What should I do?
Professor Motoyuki Ushiyama of Shizuoka University, who conducted the analysis together, taught me as follows.
"Don't worry just because the hazard map doesn't show any danger. It's important to stay away from the river and not on the roads beside the river during heavy rains. It is important to keep away from land lower than the surrounding area, such as flat land along the river, considering that there is a risk of inundation. "
On the other hand, it is the site of a sediment-related disaster that occurred in an unexpected area.
Three family members died in a house in Tsunagi Town, Kumamoto Prefecture.
It is certainly located outside the "earth and sand disaster warning area".
We also asked Professor Ushiyama about these cases.
Professor Ushiyama, Shizuoka University
"It is certainly outside the place where there is a risk, but it is a very close place. Even in the past disasters, there are casualties just outside the place where there is a risk. Even outside the sediment-related disaster warning area, if you are only a few tens of meters away, consider that there is a risk. "
To prevent repeated sacrifices
Looking at the deaths of 83 people highlighted the importance of "knowing the risks in advance" and "evacuating horizontally early".
Some people may think, "I know that ..." because it has been repeatedly pointed out before.
However, it is a very heavy reality that many victims have been killed in places where risks have been indicated in advance.
The same thing is repeated in every disaster.
Please check the risk of your place of residence once again and evacuate as soon as possible when a disaster is imminent.
I think that the government that issues information and us news media have a responsibility not only to disseminate risk information, but also to think more seriously about "how to use the information" and "how to evacuate".
Disaster type
Disaster area
Relationship with risk areas
It may have been saved if I was on the second floor
Damaged by car
Expected flood area such as collapsed houses x building data
Reporter of the Social Affairs Department Shinya Fujishima
Social Affairs Department Reporter Keijiro Saito
Motoki Tanaka, Director, Network News Department