The family huddled on the platforms, silent and fretful. The water was six inches deep in the car before the flood spread evenly over the embankment and moved into the cotton field on the other side.
– John Steinbeck
The Grapes of Wrath, Chapter 30. This is an example of situational irony, where the outcome is the opposite of what is expected. The Joads left Oklahoma for a better life because a disastrous drought there resulted in the Dust Bowl. Now in California they find themselves victims of a flood.