The graph below demonstrates the cyclic process of electricity generation in hydroelectric power station.
Overall, there are two main steps consisted of pumping water and generating it to electricity. Moreover, it is clear that the flow of water goes forward and returns constantly.
At the beginning, the river flows down to the high level reservoir, which is mostly blocked by huge dam, and there is solely channel on the bottom intake water during the daylight hours. From the intake hole, water continues migrate to the generator located in the power station, where reversible turbines are operated. At this stage, two processes occur at the same time: while water goes to low-level reservoir, the electricity moves from the generator up to power lines and then to national grid.
The operation does not stop and on-going at night. The amount of water returns from the low point to the generator section, where it pumps by turbines into high-level reservoir and remain there, because intake section normally closed at night.