The problem with flat-land is that the lower lying spots can fill up with water VERY fast.
/johnny
My first experience with that about 4 yrs ago in Pryor OK visiting my aunt. On the way intro town there is a sign....TURN AROUND DON’T DROWN.....I said huh? Had to ask WTH? Cousin said it is a flash flood area or the creek runs over there or something like that, anyway water real fast and they have had people try to drive through it and drown. Saw some pretty funny road signs in that area.