Rule 8:
Beware of manholes and ditches in flooded areas.

Of the seven people killed by a torrential storm in Kochi in September 1998, two stepped into manholes that had been uncovered by water pressure.
In 2004, a man drowned in an irrigation ditch during torrential rains in Fukui.
When the ground is hidden by floodwaters, it is not safe for walking. If you must walk, use a stick as a probe.