What effects does water energy have on the environment?

Question by elizabeth m: What effects does water energy have on the environment?
please have LEGIT information information because this is for a class and i really need this grade

Best answer:

Answer by Nigel P
By “Water Energy” I have to presume you mean Hydro-Electric power (the days of direct water power by using water mills is long gone, though the industrial archaeology of it is fascinating)
here is a rework of an earlier answer:

Hydro power is simply generating electricity from water flowing through turbines. While you can use the natural flow of a river in small scale schemes more usually it is associated with damming a gorge to get a large head of water then running large scale turbines off the flow from the base of the dam.

Advantages. If you have the right geography, like Iceland or parts of Scotland then you can generate a lot of power at low cost (once the dam is buildt you just have maintainance and the interest on the capital for the building costs, the “fuel” is free.) Hydro power does not produce pollution in the same way as fossil fuel or nuclear plants do, so this is a considerable benifit to the environment but see the disadvantages below.

Disadvantages – you need the right geography, a flat, arid land is not good for hydropower, or even a flat, wet land. You need somewhere with reasonable hills or mountains, with damable valleys.
In some places the damming and flooding of the valley has little or no detrimental human or environmental impact but schemes like the 5 Gorges project in China (Worth googling to get more details of this project) have both dramatic environmental impact, both from flooding of land and upsetting the flow of water, and of silt downstream as well as making many thousands of people homeless.
Badly sited and designed dams can also be a huge safety hazard if they break, fortunately they tend to be reasonably well designed and planned nowadays.

Disrupting the water flow can have advantages, such as flood control and water storage in areas with rainy and drough seasons but it can also deprive the river and people downstream of the water they need.
Silt settling out in the impounded lake can clog up the lake and removing the silt can make the river erode more rapidly downstream.

The impounded lake can have some advantages, while it is a different ecosystem to the flowing river this is not always bad, the flooded valley may become a tourist attraction, both for lakeside views, boating, fishing etc and this needs to be balanced with the loss of habitat and resources from the original valley

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