with a ram the energy from a larger amount of falling water produces the energy to raise a smaller amount of water much higher than the source of this water. The ram will let much of the water fall through it but use the energy to move some of it.
I am sorry i thought you wanted to use the same water to move it back to the top and start again.
I am not particularly sure what your question is. I think i answered it though.
I just found this wonderful websight...
http://www.clemson.edu/irrig/equip/ram4.htm
It says 8 gallons of water fall to pump one gallon, i had no idea it was that efficient ...i think that is really dependant on how fast the water is moving and how high you are pumping the water.
This sight has diagram on how to build one.