"can the north be flooded and the south does not.."

Yes, it depends on if the north is a lowland or a highland.

North is not always up and south is not always down in a 3 dimensional world.

Point of reference is very important.

Because of gravity, water flows from high to low.

But if there is a wave of water large enough, it will cover the high and low places.

There will be no where to run...

There are already mountains under water as InI type.

Peace