Do hydroelectric dams cause environmental harm?



  1. 0 Votes

    Hydroelectric dams are a touchy issue in many environmental circles.  While hydropower can potentially produce large amounts of electricity while contributing little if at all to global warming, there are other negative environmental impacts associated with dams – some of them very serious.  Large dams in the western United States represent the most important threat to endangered salmon runs; salmon that once migrated freely up and down major each year now find their way blocked by giant dam projects.  In the developing world, dams have flooded large areas of rain forests and other valuable ecosystems, and displaced human communities that previously lined the edges of many rivers.  On the other hand, smaller-scale dams can be built with much less environmental damage, but of course produce less electricity as well.  In the end, it seems that hydroelectric projects almost certainly have some role to play in providing society with low-carbon energy.  Whether the benefits of a particular hydroelectric project outweigh the costs, however, will depend on the details of the project in question.

  2. 0 Votes

    Environmental problems associated with dams also includes changes to the hydrology of the river where the dam is located. Dams can halt the the sediment flow of rivers, altering the natural state of the ecosystem. Apart from changing the river’s natural state, dams can even stop functioning if too much sediment and silt build up behind the dam in a process known as siltation. Another problem with dams is the amount of water loss to evaporation. Although dams, in many cases, are designed to create more available water for agriculture, the still water in the reservoir is more susceptible to evaporation than the water flowing in a river. One more problem with damming rivers is that the riparian (along a river) ecosystem is adversely effected. Dams stop seasonal floods that many native plants have adapted and evolved to flourish in. When these processes are altered, it creates a new niche for invasive species to inhabit. For example, many of the dammed rivers in the South West United States are experiencing tamarisk (a plant originally found in the arid climates of the Middle East) invasions, resulting in further competition among native species such as cottonwoods and willows. 

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