If everyone in the flood are lived on a barge, or some sort of well adapted floating house, and the warning comes there would be nothing to do but make sure the kids and livestock are on board, check the anchor chain to make sure it will run free, and raise the gang plank.

When the water recedes you re-level the house and get to farming. In Egypt the Nile would flood every year. And every year the farmers would move short term to higher ground or onto boats. When the Nile returned to its banks rich silt, the source of agricultural richness, was left behind.

One of the reasons Egyptians got good at math and geometry was because the boundaries of the fields had to be surveyed and reestablished every year based on landmarks miles away.