Complex sentence: As the water depth increases over the shallows of the point bar, the vortex flow can extend closer toward the convex bank and the water speed at any point can increase dramatically in response to only a small increase in water depth.
Split into simpler sentences: As the water depth increases over the shallows of the point bar, the vortex flow extends closer toward the convex bank. The water speed at any point can increase dramatically in response to only a small increase in water depth.