I would certainly want to find out more about past floods (historian and archaeologist speaking, so you might expect that). That knowledge will be very useful in developing your plans. But history is not an infallible guide to the future. What is the size and extent of your watershed? What development has occurred within that watershed and how might it affect future flooding? I would certainly agree that " Lots of people have died trying to drive through moving water that seemed shallow enough to ford" - that was a frequent occurrence in SAR operations in Southern Arizona. Typically victims drove around plainly marked barricades. The more I have seen of flooding, the more respect I have.