The turbine blades should cause the water to rebound.
Work Step by Step
The change in momentum of the water is greater when it rebounds than if the water is simply brought to a dead stop. The water is not only brought to rest, but the force is great enough to reverse its momentum and send it backwards. Because the water has a greater change in its momentum, the turbine blades have a greater change in their momentum, i.e., they spin faster.