It is true that the word only appears in that story. That doesn't mean it was a tsunami.
So you claim- but you have no evidence for it. The text does not say that at all. How did the ark survive all those waves?
The ark was built to withstand the rain and the tsunamis created by the asteroid shower.
The story of the dove and the olive branch doesn't work with a tsunami either.
The dove and olive branch was a year after the asteroid shower.
Your idea that all on the above are related to the flood is pure speculation. Geologists date these to way before the flood.
That is proof that the asteroid impacts are related to the flood.
Since the earth is only 6,000 years old, the geologists are off in the dates (they claim millions of years).
If the asteroids hit prior to the flood, the evidence would have been washed away by the flood.
If the asteroids hit after the flood, then the evidence would have been declared to be recent instead of millions of years old.
Since the geologists have dated the asteroid impacts to the dates of the dinosaur fossils that were buried in the flood, then the asteroids hit the earth at the same time as the dinosaurs were buried in the flood and became fossils.
It is quite simple when you look at it with the correct paradigm (young earth and global flood instead of millions of years of evolution).