<span>Hydroelectric power is produced as water passes through a dam, and into a river below. The more water that passes through a dam, the more energy is produced. Once a dam is built, an artificial man-made lake is created behind the dam. Electricity is produced by a device called a turbine.
The inventions of automobiles has cause ground transportation to grow over the 20th century. This makes the roads vulnerable to an eruption. Hope this helps :)
