You must be able to understand from a clear perspective how some basic principles of physics work before getting to know the real process of coming up with hydropower. That notwithstanding, it is very simple to grasp the basics because hydropower processing occurs in two main levels.
The water cycle
The first one is the water cycle which revolves around the formation of clouds by water that is evaporated from large water masses like rivers, seas and oceans. When this water falls down as rain, there is some that will get back to the water bodies where it originated from while other waters will fall on higher elevations than that of the seas, rivers and oceans. Due to hydroelectric power, this increase in the elevation occurs, which means production of hydroelectric power through this level is wholly dependent on water evaporating from the water bodies and then losing its original elevation when falling down.
Hydropower processing level
Secondly, there is the hydropower processing level that largely involves the earth's gravitational force to work. This relies on the fact that particles fall from above in elevation owing to the force of gravity which also applies to a human being when he jumps up and falls to the ground. In the same way, water drops from very high in the skies fall to a lowered elevation than it originally was due to this gravity.
When this water is used in dams to produce electricity, the same principle is applied as there is the need to reduce some gravitational force of the water to ensure that energy that is produced can be easily transferred from the dam to its consumers. Therefore, turbines that are used in generating power at a hydroelectric dam are the ones that make good use of the water's gravitational pull to rotate the generators for the production of electricity.
Twin reservoir method
There is also another process used to generate hydroelectric power through the use of twin reservoirs. This basically means that when water that is taken in by a plant to generate power is released, it is stored in a second reservoir instead of being released freely back to the river. While there, it can be re-used for the same purpose or for a different one. One of the reservoirs is usually located at a higher ground than the other and this method is more economical. All said and done, there are three main types of hydropower plants which are very crucial in the processing of hydroelectric power by any dam.
Impoundment is the most common and is usually large to enable it store large amounts of dam water. In this one, water flows from the reservoirs through the turbines and as they are rotated electricity is produced as it initiates several other steps. Then there is the diversion plants which directs some sections of water from rivers through canals and may not necessarily require a dam to function as required. Pumped storage plants on the other hand stores some energy when there is low demand for power as well as some waters that are released for power generation when demand goes high.