To begin
, the electricity is made by hydroelectric power station and the process Linking Words
started
 from 
the river. The river's Wrong verb form
starts
water
 goes to a huge Use synonyms
reservoir
 which has a massive dam. At the dam back there is Use synonyms
water
 intake which at the day time is open and at night time closed. 
Following, electricity generated by the Use synonyms
water
 flow during the day, Use synonyms
however
, the Linking Words
water
 Use synonyms
pumpped
 back to the high-level Correct your spelling
pumped
reservoir
 through the dam at night. For the previous Use synonyms
process
 reversible turbines are used for Add a comma
process,
water
 flow. Use synonyms
While
 the sun is up, a low-level Linking Words
reservoir
 is reached by Use synonyms
river’s
 Correct article usage
the river’s
water
. In the night hours, the Use synonyms
water
 returned Use synonyms
into
 a high-level Change preposition
to
reservoir
.  
Use synonyms
Also
 in the process, the national grid was achieved by power lines because of the generator.  The reversible turbine and the generator created the power station which helped the Linking Words
water
 flow forward and backwardUse synonyms