Approaching typhoon and hazard map from scratch | NHK News

Approaching Typhoon and Hazard Map to Know from 1 October 20:10

Following typhoon No. 19, which caused great damage, the next typhoon and the next typhoon are also approaching Japan. "Where" and "what" is the information to protect yourself. I gathered useful information immediately after knowing the hazard map. (Network Press Dept. Ken Meida, Shinsuke Sugoi)

After the typhoon ...

There was a tweet that became a hot topic after the typhoon.

"The place name conveys the memory of the disaster."

There was a case that the place name showed that there was a disaster in the past, and it was the content that it became reference.

On the other hand, there is a growing tweet that says “Some place names have changed due to mergers, etc. It is better not to link to disasters”, and the typhoon No. 19 has increased interest in the dangers of the land. I heard.

The following tweets also appeared.

On the country site

Hazard maps show dangerous areas in disasters, and are published in various government agencies. So I decided to see what kind of information is available. First is the Ministry of Land, Infrastructure, Transport and Tourism.

There is a site called “Ministry of Land, Infrastructure, Transport and Tourism Hazard Map Portal Site”
▽ There were two, "Hazard map to overlap" and ▽ "My town hazard map".
(URL) http://disaportal.gsi.go.jp/

Hazard map to overlap

Of these, "Overlapping hazard maps" will show the surrounding map when you enter your address.

And you can see four types of disaster information: flood, sediment disaster, tsunami, road disaster prevention information.

When I entered Tokyo / Edogawa Ward and clicked on the flood information, the whole area became beige and pink, mainly near the river.

This color shows the largest flood inundation expected area due to typhoons, etc. It is explained that the place where it became beige is 0.5 to 3 meters, and the pink is 3 to 5 meters. It was.

According to the Ministry of Land, Infrastructure, Transport and Tourism, this information was created based on information assumed by the state and local governments for 445 rivers managed by the country and 107 rivers managed by prefectures.

My town hazard map

Next, I tried using another “my town hazard map”. Also enter the state and city where you live.

Then, what kind of hazard map the local government is making will come out.

When I entered Adachi-ku, Tokyo, I found that there was a “flood” hazard map and a “storm surge” hazard map (in areas with many ponds, there is also a “pond” hazard map).

If you click, it will fly to the local government website, and it seems that you can easily find hazard maps not only in the area where you live, but also in the area where relatives living away from you live.

However ...

However, the information that appears here, not necessarily reflecting the latest information assumed by the local government, may not be updated. After referring to it, it would be better to check in each municipality.

There was also a flooded navigation

In addition, there were also what were called “location-based flood simulation search system” and “flood navigation”.
(URL) http://suiboumap.gsi.go.jp/

If you entered the name of the river, you could see which area was flooded in how long when the embankment broke down.

When I entered Tama River, a lot of blue dots came out. Each blue dot indicates where the embankment broke down. Clicking on one point and playing the “animation display” at the top left shows the passage of time, such as 10 minutes, 20 minutes, 12 hours, 24 hours, etc. I could see visually that the inundation spreads.

Note! Nationwide rivers are not covered

However, there are only about 300 rivers, about 70% managed by the country, and about 100 rivers managed by prefectures.

“Prefecturally managed rivers are created based on information created by the prefecture. Some of the information arrived here, but it has not been created yet, or simulation information has not yet arrived.” ( Person in charge)

Hazard maps, what you can see

So what kind of information is on the flood hazard map made by the municipalities that are important, flooding around the Tama River created by Setagaya Ward in Tokyo where the Tama River was flooded due to the impact of this typhoon No. 19 I looked at the hazard map.

Inundation depth

The assumption is that a two-day total rainfall in the Tama River basin has been recorded for about 590 mm.

First, the depth of flooding is color-coded with vermilion shades. You can see that the deeper the color, the deeper the flooding occurs when flooding occurs.

There is also an image diagram using a house as a measure of the depth of inundation. For example, it can be seen that 3 meters of water floods the first floor of the house and 5 meters of water floods the second floor of the house.

House collapse

You can also see the danger of a house collapse due to a flood. The part surrounded by light gray spots is called the “expected area of ​​inundation such as collapse of houses”, and earlier evacuation is required.

How to evacuate

And for evacuation, there are two patterns of “horizontal evacuation” and “vertical evacuation”.

“Horizontal evacuation” is intended for people living in “expected flood areas such as collapsed houses” by moving to evacuation shelters, safe places, and nearby high places.

On the other hand, “vertical evacuation” refers to an evacuation method that moves to higher places such as the second floor of the building, where floods and heavy rains become intense and it is more dangerous to go outdoors for evacuation.

Run away here, run away

The location and name of the evacuation center are indicated by a red circle, and the evacuation direction as a guide is indicated by an arrow. Hazard map had the image of showing only dangerous areas, but also I felt that `` a map that summarizes various information necessary when heavy rain damage is likely to occur '' .

Don't overtrust the map

However, the flood hazard map is only a simulation based on the assumed rainfall. Even if it does not reach the expected rainfall, there is a possibility of local inundation occurring in a short time due to heavy rain, etc. In the issue, victims are present even in places that are not included in the inundation area.

Knowing the dangers assumed by the hazard map, such preparations to prepare more in the vicinity of low land and rivers are likely to be necessary for future typhoons.