Overall, installation of hydropower facilities has required the flooding of nearly 22 000 ha, or about 1.9 ha per GWh of electricity generated (in a year of average hydropower productivity), although with great variability among plants. This is in addition to noise, potential landscape disruption and disturbance of bird species. However, unlike large hydropower plants, the land occupied by wind farms can be used for other purposes and their environmental impacts are more easily reversible.