Means in the UNLIKELY EVENT of >>
Consider changing your route before setting out on a trip involving river crossings where there has been heavy rain in catchment areas. Check with local authorities if there is a possibility that bridges may have been damaged by flood waters.
Be prepared to spend time and energy looking for a safe crossing place. Be aware of possible dangers downstream if someone were swept away whilst crossing. Be prepared to wait for a swollen river to subside, or more realistically, use an alternative route.
DO NOT attempt to cross a dangerous river.