I decided to write the title of this post in Portunhol because the confluence desribed below is of rivers that are shared by speakers of both Portuguese and Spanish. (Caution: very nerdy linguistic details ahead) I considered using CONFLENCIA instead, since typing in all capital letters is a way to avoid accent marks, and the spelling in the two languages differs by a single diactrical mark. This is why most shirts and bags I order from LL Bean are embroidered with GEOGRAFIA. In doing two minutes of research on the subject I found one article supporting the all-caps convention and another article condemning it.
Now back to the geography. A confluence is simply the place where two rivers meet. I have been writing about specific confluences for some while, and this new post will serve as a confluence of those confluence posts -- hence "Confluence of Confluences" in the title. I was brought to the subject by this image, from the Facebook group Fatos y coriosidades (Facts and curiosities).
The caption translates to:
There exists an extremely symbolic point in South America where three nations are found in just one place: Brazil, Argentina, and Paraguay. It is the famous Triple Frontier, marked by the confluence of the Iguaçu and Paraná Rivers. On one side is Iguaçu Falls (Brazil), on the other Port Iguazú (Argentina) and, to the west, City of the East (Paraguay). This place is impressive not only for its geography, but also for the intence cultural and commercial integration among the three countries.
And here is an intriguing curiosity: in each country there is an obelisk painted with the colors of the national flag, positioned in a way that each can be seen from the other two -- a true triangle of frontiers visible to the naked eye.
In addition to the curiosities mentioned in the original post, I noticed that the confluence at the Triple Frontier exhibits a characteristic that is fairly uncommon among the millions of riparian conflences in the world: the two rivers retain distinct coloration because of different sediment loads and relatively slow mixing currents.
The most significant example of a non-mixing confluence is known (sometimes) as the Wedding of the Waters, also in Brazil. In this case, the waters of several countries come together, but no national boundaries are to be found for hundreds of miles up any of the hundreds of streams represented by the confluence of the Rio Negro and the Rio Solimões at Manaus. For this geography nerd, the Amazon begins at this confluence, though an increasing number of maps apply the word "Amazon" to the lower portion as well as the entire length of the Solimões.
In this video posted in 2011, Florida Aquariam educator Allan Marshall goes all in with an explanation of what makes this confluence so special.
Prior to seeing this video, I had no idea that the river was so deep. I knew about the temperature difference between the two rivers, but I did not fully understand the reasons. The waters are flowing from regions with very different climates, so they begin with very different temperatures. It so happens that the waters that start of cooler also have the higher reflectivity, helping them to remain cooler all the way to the center of the Amazon Basin.
And Now for Those Confluences
As I suggest above, confluences have had my attention for some while. In order to finish this post in a relatively timely fashion, I will just point to some of the other material I have posted on the topic. Some of these posts include links to still other posts. So if you get lost on the morass, I apologize ...
Wedding of the Watersis a 2015 post I created for the blog that I was maintaining back then as part of our Project EarthView outreach program. It includes a link to the video above and a bit of context about the entire basin.
Confluences is a 2015 post on this blog (Environmental Geography) that I created after I was delighted to find an article about ten visually interesting confluences around the world. My post includes a link to that original article as well as my own contribution: a Google map showing all of those intersections in one view. I have now amended that map to include the Triple Frontier.
Down the Creek is a 2023 post about the Rio Madeira, the longest of the Amazon's 1,300+ tributaries. Madeira Playlists points readers to photos and videos from my 2023 voyage from Porto Velho to Manaus, ending with my own closeup views of the Wedding of the Waters.
And finally, my six-part course Amazônia: Fables to Forests includes a slide set entitled Tributaries and Confluences. These are the maps and illustrations I use for an entire lecture on the hydrography of the Amazon Basin itself.
Lagniappe
This bonus bit is for students in my environmental classes who just happen to like the sound of a phrase, that is a speciality of both geology and geography and that was a big part of my master's thesis and that has kept me interested in the form and function of rivers for many years. This is for them, if they happen to be reading this:
Geography asks three questions:
