The diagram below shows how electricity is generated in a hydroelectric power station. Summarize the information by selecting and reporting the main features and make comparisons where relevant.

The picture illustrates the process of electricity generation in a hydroelectric power station. Overall, the process is divided into two stages, day and night. It starts with water from the river flowing into the high-level cistern and ends with electricity being generated and sent to the national grid in the day. At night, the water from the lower reservoir flows back to the original cistern.

At the first stage of the generation process, in the daytime, the water flows from the river into the high- level reservoir, before being held back by a dam. Under the dam, there's an intake that opens during the day and closes at night, water flows through it and down to the power station. In the power station, the electricity is produced via reversible turbines and is passed to the national grid through power lines. Mean while, the excess water runs to low- level reservoirs.

The process continues with the stored water in the low- level reservoir is reverted to the reversible turbines during the nightstep. Consequently, the turbines pump it back into the high- level reservoir. The stored water and the river water continue to flow down, the production of electricity begins again in the daytime.