Hydro. What is it, Advantages and Disadvantages. Example

-From Falling Water OR Trapped by Dam which is Allowed to fall through Tunnels that spin Turbines --> Electricity A: Flexible and Efficient - They can be Adjusted to suit the Energy Demand at the Moment D: Habitats and Communities Threatened from Flooding - Reservoir. Expensive to Make E: China has the Three Gorges Dam [Largest in World] and makes more than USA & Canada Combined