TWO DISADVANTAGES of hyrdroelectric power?!?

Question

i'm doing a biology assignment that needs two addvantages & disadvantages of hydroelectric energy. i have the advantages but i need the disadvantages. HELP PLEASE?

Answer 1

The fact that you're on a biology assignment gives us the clue as to what disadvantages you are looking for. Obviously, there's a lot of ecosystem in a free-running river, such as salmon runs, which are seriously disrupted or even stopped by dams. But here's two of for you, evils of hydroelectric dams:

1) Disrupts natural flow of sedimentation, which provide for silty river banks and habitat. For example, for thousands of years man has depended on regular flooding of the Nile to keep its banks fertile, but now with the Aswan Dam, this isn't happening so much any more.

2) Loss of river life. For example, the San Joaquin River in central California used to be the home of giant Chinook Salmon and migratory birds. Today, with the Friant Dam in place, almost all of that is gone. See wiki link.

I will throw in a freebie 3)

3) Can ruin a scenic wilderness, as what happened in Hetch Hetchy Valley, part of the Grand Canyon of theTuolumne, formerly called "the Sister of Yosemite". Would any sane person today suggest damming Yosemite? No. But that's what people did with the O'Shaughnessy Dam.

Answer 2

I agree with Agent 47: Dams disrupt fish migration.

Also:
1. Dams cause the area behind the dam to flood, changing the ecosystem from a flowing stream and streamside land into standing water.
2. Dams cause temperature changes in the stream below the dam. When they let the water go through faster, the water temperature is lower than when the water goes through more slowly.
3. Sediments accumulate in the reservoir behind the dam instead of being deposited downstream. This has been a big problem in countries such as Egypt where agriculture depends upon the annual floods and deposition of sediment.
4. Dams can fail (break) and cause disastrous floods.
5. Dams can cause arguments between neighboring countries or states because they interrupt the water supply downriver.

Answer 3

As the previous answer says, building dams can have a negative impact on the environment. This includes impacts on fish life, but perhaps more importantly, the downstream flows contain less silt, which can degrade the downstream farmlands.

The other main problem with hydroelectricity is that most cities are built on flat land, near the coast and far from places where it makes sense to generate hydroelectricity.

Answer 4

I'll give you one:

Threatens the environment with human interference. Think about it... you're putting a concrete wall in the middle of fish runs. That's just one example.