Raised air intakes were not intended for wading. They were originally designed for use in dusty/Sandy environments where their function was to separate at least some of the dust from the air, before it reached the filter, thus prolonging the service life of said filter.
It was noticeable that military Land Rovers sprouted RAI during the gulf wars, before that the only military Land Rovers fitted with RAI were those used by the Royal Marines for beach landings and the like