Water as a landing surface for a jet airliner with engines mounted under the wings is a very risky choice.
However in the case of the crew on the airbus they chose the best option available and fortunately all survived.
I was asked what I though about why only one engine separated the from the wings by someone on Avcanada.
I will copy my reply here to give my thoughts on what happened and how difficult it is to know how the landing will turn out.
O.K. as long as everyone here understands that I am only posing a possibility based on what I have observed airplanes to do when landing on the water.
Here is one possibility that seems to me could have caused the left engine to separate and the right one to stay on.
When you look at the engine nacelles from the sides they have a smooth curve upward to the intake lip.
At water contact if the left wing was just a fraction lower that the right wing and the water entered the intake a fraction of a second before the right engine there would be an immediate yaw to the left with the result being a further lowering of that wing.
The right engine nacelle could then momentarily have " skied " just long enough for the deceleration forces to have reduced just enough to not meet the shear point of the bolts as the engine submersed .
There seems to have been a yaw to the left just as it slowed down which could be the result of the left wing having been lower in the water which was first started by the momentary skiing of the right engine nacelle...once the right engine entered the water it would have helped counter the dragging left wing with no engine attached.
There I probably should not have posted that but based on my experience flying sea planes that could be what happened.....
For sure he had the touch down attitude correct because the airplane did not self destruct.
Hopefully you all will take into consideration that is only my take on what could have happened based on my back ground flying and training on large sea planes.