「洪水」はfloodと言います。
例文
A flood caused the destruction of many houses in Hiroshima.
洪水が広島の多くの家を[破壊](https://eikaiwa.dmm.com/uknow/questions/34492/)しました。
The flood ruined all our furniture.
洪水で[家具](https://eikaiwa.dmm.com/uknow/questions/31992/)が全部駄目になりました。
The flood caused a lot of damage.
その洪水はたくさんの被害を出しました。
他の表現
debris flood: 土石流
flash flood: 鉄砲水
参考になれば幸いです。
Generally, when water pours through the streets or fills buildings, leaving cars and fields submerged, it is known as an 'inundation' or 'flood' or 'flooding'.
"There is severe flooding predicted tonight."
水が道路にあふれたり、建物に入り込んで、車や田畑が浸水することは、一般的に「inundation（洪水）」「flood（洪水）」「flooding（洪水）」と言います。
【例文】
"There is severe flooding predicted tonight."
（今夜はひどい洪水が予想されています）
When normally dry land becomes submerged with water, we call this a "flood".
A "floodplain" is a low plain near a river that often floods. It is not a good idea to build on floodplains.
When the water levels of a river are too high and they overflow, you can say that the river has "burst its banks". Dams and dykes are man-made structures that are built to hold water in a reservoir. When these overflow, we can also say that they have "burst".
一般的に乾いた土地が、水で浸水することを "flood"（洪水）と言います。
"floodplain"とは、よく洪水が起こる川に近い低い平野のことを言います。floodplains（氾濫原）に何かを建てるのはよくありません。
川の水位が高くなりすぎて、あふれると、 "burst its banks"（堤防が決壊する）と言うことができます。
Dams（ダム）やdykes（堤防）は、貯水池に水をためておく人口の建造物です。 これらの水があふれると、"burst"（決壊する）と言います。
A flood is a natural disaster where water overflows from a body of water to dry land. This is the same term all over the world.
Flooding is when the event itself is happening. For example, you can say "The river is flooding right now."
I hope this helps :)
floodは、乾いた土地に、水域から水が溢れ出す自然災害です。これは、世界中で共通の言葉です。
Floodingとは、洪水が起こっているときです。
例：
"The river is flooding right now."
川が今氾濫している。
The natural disaster where there is a large amount of water that overflows, usually due to heavy rainfall or storm, is called "a flood". For example, you may say:
-There was a flood in my city and a lot of people's homes were damaged.
-There has been a lot of flooding in recent years in many places around the world because of climate change.
"a flood"（洪水）は、普通大雨によって大量の水があふれ出る自然災害を言います。
例えば、次のように言うことが出来ます。
【例文】
-There was a flood in my city and a lot of people's homes were damaged.
（私の街で洪水があって、多くの人の家が被害を受けました）
-There has been a lot of flooding in recent years in many places around the world because of climate change.
（近年、気候変動の影響で、世界中の多くの地域で洪水が起きています）
A great flow of water, usually from a downpour of rain, is called a flood. If this happens sudden, it is called a flash flood. Other words used to describe a flood include: deluge ad inundation. However, these words are not as common. Rainfall that makes rivers overflow and flows onto usually dry land can be very dangerous. The communities in danger usually receive flood warnings.
When there is a large amount of water that overflows from the ocean or maybe even in dryer areas where there is typically less rainfall or water flow, it is called a, "flood," or, "flash flood." Usually there are other types of natural disasters that can help cause this but sometimes it can come simply from rainfall.
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