A flash flood.
That would be called a flash flood.
A flash flood
18 hours of heavy rain
It is called a flash flood. They normally happen when heavy amounts of rain fall up stream from were it actually happens.
heavy rain
because of heavy rain
Streams and rivers can usually cope with excess rain. However, after a prolonged period of heavy rain, rivers sometimes burst their banks and flooding occurs.
heavy rain caused it
After a heavy rain, or in the spring when the snow melts.
heavy rain falls
tewksbury last flooded in 2007 due to heavy rain.
the uk floods were caused by heavy rain and the river banks burst and the pakistan floods were caused by monsoon rain