In this heavy rain, I think there are more opportunities to hear the word "evacuate from dangerous places" in evacuation information and news from local governments.
So what exactly is a "dangerous place"?
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Where there is a risk of flooding
"River flooding" can cause great damage due to heavy rain.
Be careful mainly near the river and in the so-called "lowlands" that are lower than the surroundings.
Specifically, in the immediate vicinity of the river embankment or in the area designated as the "presumed flooding area such as collapsed houses", there is a possibility that the entire house will be washed away when the river overflows.
In Mabi-cho, Okayama Prefecture, where the embankments broke one after another due to the "heavy rains in western Japan" in 2018, flooding of up to 5 meters or more occurred in the area along the Oda River, causing great damage such as the death of 51 people.
In addition, at least five people were killed in the flood damage that occurred in the Kuma River, which flows through Kumamoto Prefecture, in July last year, when the houses in the "presumed flooding area such as collapsed houses" were washed away.
In each area, the risk was almost the same as the range that was assumed in advance in the "hazard map" published by local governments.
It is important to check your home risks in advance and know if you are in a “dangerous place”.
Be careful of "lowlands" even outside the risk zone
In addition to places where the risk of inundation is assumed, "lowlands" where the altitude is lower than the surroundings and where water tends to collect are also high risk places.
In Typhoon No. 19 in 2019, many people disappeared in the "lowlands" other than the places where inundation was expected.
Check the positional relationship between your home and the embankments and bridges on the river.
If they are at the same height, there is a risk of flooding.
Be careful of the "merging part" of the river!
In addition, it is necessary to be careful because water easily collects at the "confluence" where rivers meet.
Especially in the case of the main stream and the "confluence" of the tributaries that flow into it, when the main stream rises, the water of the tributaries cannot be discharged, and the "backwater phenomenon" in which the water level rises may occur and flood.
At the "confluence", once a flood occurs, there is no escape for water and there are many places where the water level rises sharply, so people living nearby need to be careful.
"Sediment disaster caution area" is dangerous
Places where debris flows and landslides are expected to cause sediment-related disasters are also "dangerous places" that can cause great damage.
Prefectural governments have designated areas that require evacuation and other measures as "earth and sand disaster warning areas."
Even with this rain, sediment-related disasters occurred in Unzen City, Nagasaki Prefecture and Okaya City, Nagano Prefecture, causing casualties, but all sites were designated as "sediment-related disaster warning areas."
In addition, places where there is a risk of sediment-related disasters are indicated by prefectures as "debris flow dangerous mountain streams," "landslide risk points," and "steep slope collapse risk points."
It is extremely difficult to evacuate after a landslide disaster occurs.
It is important to understand the risks of the place where you live in advance and to ensure early safety by evacuating to a safe place before a disaster is imminent.
Check the risk with "Hazard Map"
You can check whether your home is in a "dangerous place" by checking the "hazard map" distributed by local governments.
However, disasters can occur even in places where risks are not displayed on the hazard map.
If your area is "near a river," "land lower than the surrounding area," or "near a cliff, slope, or mountain stream," consider the risk of a disaster and consider evacuating early.