OK if by "highly geographically dependent" you mean "not highly geographically dependent".

You need a hill, but there are a very, very large number of hills. Most usually you need to build an earthen dike around the top of the hill, although often a natural feature allows it to be shorter.

The reservoir does not need to be deep because the "head" is from it to the bottom of the hill, or even to the water table well below that.

The reservoir or reservoirs are good places to float solar farms.