Translation guide
The English word 'inundation' can refer to literal flooding or to being overwhelmed by a large amount of something. Japanese has distinct words for these senses, and the most natural choice depends on context.
To describe an area being covered with water, such as from a river overflowing or heavy rain.
The most common word for a flood, typically from rivers or heavy rain. Used in news and everyday speech.
To express being flooded or swamped with a large quantity of something, such as work, emails, or requests.
A metaphorical use of 洪水 (flood) to mean a deluge of something. Commonly used with words like 情報 (information) or メール (emails).
洪水 is the general term for flood. 浸水 focuses on water entering buildings or land. 氾濫 specifically means a river overflowing. In news, you'll often hear 河川の氾濫 (river flooding) and 浸水被害 (flood damage).
A flood warning has been issued.
The city suffered severe inundation after the dam broke.
大雨で川が氾濫し、町が洪水になった。
The river overflowed due to heavy rain, and the town was flooded.
Refers to water entering buildings or land, often from heavy rain or storm surges. Focuses on the result of being submerged.
My house was flooded due to the typhoon.
Specifically refers to rivers overflowing their banks. Often used in compound phrases like 河川の氾濫 (river flooding).
Please be careful of river flooding.
Used when roads or fields are completely covered with water, often in news reports. More technical than 浸水.
The road was flooded and closed to traffic.
I feel like I'm drowning in a flood of information.
Means a rush or flood of people, inquiries, orders, etc. Emphasizes the sudden, overwhelming arrival.
We are being inundated with inquiries.
Literally 'like a mountain', used to describe a huge pile or overwhelming amount of something, similar to 'a mountain of work'.
I have a mountain of things to do.
Means to surge or rush in, like waves or a crowd. Can be used metaphorically for a flood of emotions or people.
A flood of spectators surged in.
Beware of above-floor flooding.
While ～の洪水 is a common metaphor, it can sound dramatic. For everyday situations like 'flooded with emails', 殺到 is often more natural. Use 洪水 metaphorically for an uncontrollable, massive amount.
I'm flooded with emails. (natural)
It's a flood of emails. (dramatic, but possible)
苦情が殺到した。
We received an inundation of complaints.