Can someone please state two possible environmental problems caused by using hydroelectric power?

Can someone please answer this question for my physics homework.|||Damage caused by flooding valley.





Danger to lands below dam if it fails.|||"To obtain conventional hydroelectric power, the dam is installed across a river as opposed to a tidal estuary. The stored water then covers previously usable land whether or not there was a lake there before. For large scale hydro, with an output of up to 100MW, (about the largest in the UK), a dam tens of metres high may create a reservoir covering several square kilometres. For small-scale hydro, up to 5MW, the dam is likely to be less than ten metres high and the reservoir only a few hundred square metres.





All hydroelectric power stations are installed on natural water courses and they frequently disrupt these considerably. The reservoir created by the dam may silt up due to sediment deposition from the incoming rivers and, depending on the design and operation of the power station, water flow downstream may be considerably reduced at times. This may have beneficial effects in that flooding can be limited, but that depends very much on the location.





The greatest environmental problems arising from hydroelectric schemes are visual impact and the potential effect of a dam burst. Almost without exception, suitable sites for hydroelectric schemes are found in areas of great natural beauty. The dam, power station, pipelines and electrical connections frequently have an adverse impact, although the power station itself can be buried or at least harmonised with its surroundings. To these, however, must be added the variation in the water level of the reservoirs which may expose unsightly silt margins, and the removal of water from the watercourse between intake and power station which may have included waterfalls or other scenic attractions.





The possibility of a dam burst is probably the most significant safety problem facing hydroelectric schemes and there have been several tragedies in various parts of the world.





The most obvious hazard to wildlife posed by hydroelectricity is the interference with the natural habitat of flora and fauna particularly migratory fish, although this can be reduced by the provision of fish passes and a statutory minimum water flow. On the other hand, the formation of a large reservoir might actually encourage other species.





Finally, the provision of extra water sports facilities by the creation of a lake and the reduction in the 鈥榳ilderness鈥?of the area in which the scheme is located are conflicting aspects of all hydroelectric schemes. The attitude taken towards them therefore depends very much on the individual鈥檚 preference."





From: The Institution of Engineering and Technology|||The previous answers are correct.


Just to expand a little,although whether this is physics is questionable.


Displacement of the population and wildlife and vegetation,above the dam wall, would be a major cause of concern.


I'm sorry I'm sure there are others but my wife is calling me.|||Flooding and also changing the temperature of the surrounding waters, which would impact plants and animals.|||Flooding land and diverting natural river courses.