I am praying for you guys. My BIL and SIL went down to Houston today to bury her dad , I don't think they'll make it out of there for at least a week, as it's probably all going to get closed down. I think if you get the total rain fall predicted that you better find high ground. Don't worry about your tools, just get to a safe location. I can't imagine that much water coming down and not being a disaster.
Good luck, disconnect your electrical cords, at least you would have a fighting chance at a rebuild. I realize you can't move the big machines easily, but you can take other valuables and get them as high as possible.
If you could get a tarp under your equip, you could seal it up from water by getting it under and bringing it up to the top of the machine.. then tie it off, it may keep the water out if you are careful enough not to rip the tarp.