Most people don't live in flood areas, nobody has suggested storing food on the bottom shelves (pictures are just that, pictures, not suggestions), if you do live in a flood area don't store food that can be damaged by water low down, tins won't be damaged by water (a bit of rust on the outside of a tin never harmed anyone that I'm aware of) and it's easy to store food in an airtight (and waterproof) box.
All I see is people picking holes in perfectly good advice,
I don't have room to store food... Then make room. Put it in a box inthe attic, under a bed, clear out some junk in a cupboard, put it behind the sofa.
I can't afford it... Yes you can. Nobody is so poor that they can't afford an extra tin of something everytime they do the shopping.
Nobody told me what I should stock up on... Use common sense, it's not rocket science.
It's really not a, difficult thing to do, I've always had a bit of extra food because my mum always did and drilled it into me that there will always be a time that you need it, she got that attitude from my grandma who lived through the war. If my grandma could feed a family of 7 during the war then there's no excuse for saying we can't do it now.