When I go through Venice inspired streets, I first try to observe the other cars that are passing through it by looking at the waterline in relation to the height of their vehicles as a gauge

I also take note of the fording depth for most vehicles which is 1/2 of a vehicle's tires. Except of course for those who lower their cars since the car floor is definitely closer to the ground. Most people worry about water going in their exhaust pipes which is not really a problem if you just keep moving forward, try not to stop until you reach higher ground.