Well, I don't know about Ken Ham, but according to the evidence in the Greenland GISP2 ice core, the Noahic flood was not worldwide.
http://www.asa3.org/ASA/PSCF/2003/PSCF12-03Seely.pdf
I know that YECs like to claim that the Grand Canyon was a result of the Noahic flood, but it could easily be explained by major LOCAL floods, as could all major canyons in the US, like Pecos, Black, and Santa Elena canyons.
BTW, these evidences do not in any way hinder my faith in Christ. I think Ham's statement is extremely exaggerated.
TD