When standing lakes, springs, or aquifers are not available, people must look for other options to get their water. Rivers are supplies of freshwater, but they are fast moving and do not contain enough water in a single location to draw for the most part. The get freshwater, places around rivers will often times build dams in order to create man-made reservoirs, sometimes big enough to be lakes. So how does a dam work? This video gives a great illustration how dams work to create not only the source of freshwater, but flood control and hydroelectric power as well. It also goes over the use of levees for flood control that were introduced in 3.1.3. Along with the great benefits, there are some major environmental drawbacks to using a dam as well, such as silt building up behind the dam (silting), destruction of the habitats of animals/people in the reservoir area, and more. Pay attention to both the advantages and disadvantages in the video.
Here's a diagram of a dam with labels.
Here's a summary of the advantages and disadvantages of large-scale water storage:
ENOUGH WITH ALL THESE DAM CASE STUDIES!
Haha. I made a funny meme thing.com. Anyway, it is important to look as specific cases of dam/river diversion implementation to see examples of both the positive and negative impacts. We will look at 2 from different economic regions: Colorado River Basin (MEDC - USA) and The Three Gorges Dam (LEDC/Transitional - China). These and others should also be covered in the case study project in class.
Read about the 2 cases and take notes from the followings sites:
Because of the disruption of the hydrologic cycle, dams have contributed to the following rivers running dry at different parts of the year:
- Colorado and Rio Grande, U.S.
- Yangtze and Yellow, China
- Indus, India
- Danube, Europe
- Nile River-Lake Victoria, Egypt
Also, like the Aral Sea you watched a video on earlier dealing with water diversion, Lake Chad in Africa is disappearing due to dam construction. Many of those cases will be covered in detail in the project as well.
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