Pool for Gathering Rain Water
This is another green idea. A lot of people would say "Well there are cliffs everywhere why don't I just drop things from that?" Realistically, this is the only drawing that would work with that idea. Surveyors could best map out plans for cities to build such a system using the topography maps and they could record which street drains should be blocked to fill the pool and which should be left open to prevent flooding. The pool is then used with a conveyor type device to make usable energy.