There is one in particular that is close to what Bible chronology places the flood.
Since the Bible chronology itself is made up, I don't see the significance. Major floods occur frequently -- what is called "a hundred year flood" occurs, roughly, every one hundred years. A "two hundred year flood" occurs every two hundred years. That a major flood occurred within a couple of hundred years of Ussher's date really isn't amazing. No matter what the date is given for the flood, there would have been a major flood at that time, give or take a hundred years or so.
Spare a thought for the stay-at-home voter;
His empty eyes gaze at strange beauty shows
And a parade of the gray suited grafters:
A choice of cancer or polio. -- The Rolling Stones