I believe the answer is
POTENTIAL ENERGY. The water at the top of the waterfall has Potential Energy.
Potential Energy is defined as the energy that is stored when an object is at
rest. At the top of the waterfall, water will have maximum potential energy. When
the water falls down, it is will already have kinetic energy which is energy
that is produced through continuous motion. When it is finally in the bottom,
water will have maximum kinetic energy.
