A major flood leaves distinctive features, including:
a wide, relatively shallow bed, not a deep sinuous river channel.
anastamosing channels (i.e., a braided river system), not a single, well-developed channel.
coarse-grained poorly sorted sediments, including boulders and gravel, on the floor of the canyon.
giant ripple marks.
streamlined relict islands.
Such features are observed on a local scale in the Channeled Scablands (McMullen 1998; Parfit 1995) and on Mars (NASA Quest n.d.). They are far from global, though.
Almost all features of the earth can be explained by conventional geology, including processes such as plate tectonics and glaciation. There are exceptions, but such exceptions can be explained by both natural and catastrophic events.