Iguazu falls at the intersection of 3 countries: Brazil, Argentina, and Paraguay. I've already described our brief trip to Argentina. For the second day, we took a brief trip into Paraguay to check it out.
The main attraction to Paraguay is the Itaipu Dam. This is the second largest hydroelectric dam, in size, in the world, second only to the Three Gorges Dam in China. However, the annual energy output of Itaipu is the largest. In 2008, the produced a record 94.7 terrawatt-hours which is comparable to the amount of electricity the entire planet uses in two days.
|The Itaipu Dam in Paraguay|
|A broader view of the Itaipu Dam. The foreground shows the discharge channels, which open (but don't generate electricity) if the water level is too high.|
Paraguay used to own the territory of Parana, where the Iguazu Falls are located. However, they were landlocked and, according to our tour guide, wanted access to the sea. In 1864, war broke out as Paraguay invaded Brazil and Argentina in order to reach Uruguay. Uruguay was a small nation, easily conquered and with access to the ocean. However, the three nations formed a Triple Alliance and soundly beat Paraguay. Paraguay now no longer controls the falls and lost a lot of territory as a result of the war.
|A satellite view (from Google Earth) of Itaipu Dam. The discharge channels are partially open. Up to 40 times the Iguazu Falls rate can pass through these channels.|
|These 10-meter diameter tubes channel the water to turbines about 50-meters below that generate electricity|
We can calculate the velocity water, or anything really, would reach given an initial height of about 100-m with:
mgh = 1/2 mv^2
The mass cancels, and we can ignore the factor of 2. Between friends, g is 10 m/s^2, so we have v^2~1000 or v~30m/s.
The rate of water is just the velocity times the cross-sectional area. We were told the diameter of the tubes were 10-m (internal) so we have a rate of (3*25)*30 ~ 2200 cubic meters/second. This is likely to be off by a factor of a few, but certainly accurate within a factor of 10. In comparison, Iguazu Falls has an average flow rate of about 1800 cubic meters/second so a statement like "the amount of water in the Iguazu Falls falls through two of these tubes each second" is a perfectly believable statement. Considering there are 20 tubes, we can see that the Rio Paraná has 10 times the flow of the Rio Iguazu.
After the brief excursion to the dam, we went shopping. None of us really were up for it, but apparently the rest of the tour group would die if they couldn't shop. At least we got a look at the city, but we were not impressed:
|The streets of Ciudad del Este, in Paraguay|
Here's a brief video of the Itaipu Dam. Not as impressive as my Iguazu Falls video, but here you go: