how to tell if a remote lot ever floods?
You could make indicators, e.g. stakes with a water-soluble dye (food coloring? water-color marker?) at various levels, covered by a plastic tube, and with a cone over the top, leaving some air-space between cone and tube. Direct rain should not be able to hit the stake, but standing water would rise in the tube, blurring the dye marks.

These indicators would be very inexpensive and easy to make, so set out a fair number in different locations.