I have an experiment for anyone who didn't think the plane will take off

depends more on air speed, if the wind is pushing down river, and the plane is pointing up river, it will actually assist the plane in takeoff. It will reduce its actual speed, but the total airspeed over the wings of the plane is increased.

Assuming that the thrust of the engines are capable of overcoming any negative “ground (water) speed” caused by the force of water flowing in the opposite direction of the movement of the plane. I feel that any modern age airplane engine will be able to take off.