The higher the dam, the farther the water falls and the more power it has. In other words, water falling twice as far has twice as much energy. Amount of Water Falling. More water falling through the turbine will produce more power. The amount of water available depends on the amount of water flowing down the river.
Bigger rivers have more flowing water and can produce more energy.
A river with twice the amount of flowing water as another river can produce twice as much energy. It's not that hard. Let's say that there is a small dam in your area that is not used to produce electricity. Maybe the dam is used to provide water to irrigate farmlands or maybe it was built to make a lake for recreation. From talking to the person who operates the dam, we learn that the dam is 10 feet high, so the water falls 10 feet.