Answer:
The overall velocity of the water when it hits the bottom is:

Explanation:
Use the law of conservation of energy.
Call it instant [1] to the moment when the water is just before reaching the falls.
At this moment its height h is 206 meters and its velocity horizontally
is
m/s.
At the instant [1] the water has gravitational power energy 

The water also has kinetic energy Ek.

Then the Total E1 energy is:

In the instant [2] the water is within an instant of touching the ground. At this point it only has kinetic energy, since the height h = 0. However at time [2] the water has maximum final velocity 
So:

As the energy is conserved then 

Now we solve for
.
