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Monday, April 8, 2013

The Rio de la Plata!

The Rio de la Plata between Uruguay and Argentina.

In our blog, Wally and I often mentioned the water view that we can see from our terrace. While it looks like the ocean to us, it is really considered a view of the Rio de la Plata (a river).
We often get asked about this river so using a recent comment as a jumping off point, I thought I'd post about the Rio de la Plata.

Anonymous said...
Hello Denise,  What do you see from your window, the ocean or the “Rio de la Plata”?
I just wonder if the “Rio de la Plata” is really a river or rather a gulf. I guess it is a mixture of saltwater and freshwater otherwise it would not be considered a river, but for me it is hard to understand how the freshwater can prevent saltwater penetration... it is more than 200 km wide at its mouth!

Best regards,Geraldo
Well Geraldo, people say, we see a river from our house. The Rio de la Plata (River of Silver/money) is considered the widest river in the worldThe Nile river is the longest in the world although the Amazon river is also contending with that spot. The Rio de la Plata is not very deep though. It averages 5 meters deep unless you factor in the artificial channels dredged into it then it's around a 10 meter depth average. If you click on the Wikipedia link above you can see a Google satellite photo of the true river. The river (proper) lies between the banks of 2 countries, Argentina and Uruguay.

Overnight ferry, crossing the Rio de la Plata from Uruguay to Argentina.
 Geraldo mentions an interesting point,  "I just wonder if the “Rio de la Plata” is really a river or rather a gulf. I guess it is a mixture of saltwater and freshwater otherwise it would not be considered a river, but for me it is hard to understand how the freshwater can prevent saltwater penetration..."   
The America Heritage dictionary says that the word Gulf means "a large area of a sea or ocean partially enclosed by land."  The Rio de la Plata has a large estuary system (wide mouth). This estuary is why some people consider the Rio de la Plata not a river since salt water does mix with fresh there.   While the mouth of the river (that meets at the Atlantic ocean) does lies in a gulf-like estuary system the reason it is also considered a river is because it also has an inner section with upper and middle reaches that are shallow and devoid of salt water intrusion. In other words the ocean is not the only water present.

The Rio de la Plata river is fed by two main rivers, the Paraná river and the Uruguay river which contribute 97% of the freshwater to the Rio de la Plata. There are also many smaller rivers and more than a hundred streams that flow into the Rio de la Plata. The river is funnel shaped with the beginning at it's source, being only 2 km wide (1.2 miles) its mouth widens to 220 km (140 miles), where it then flows into the Atlantic Ocean. It is 290 km (180 miles) long. With a surface area of some 35,000km (14,000 square miles).

 The wikipedia states that A submerged shoal, the Barra del Indio, acts as a barrier, dividing the Río de la Plata into an inner freshwater riverine area and an outer brackish estuarine area.[6] The shoal is located approximately between Montevideo and Punta Piedras (the northwest end of Samborombón Bay). It is the freshwater of the inner area that causes many to describe the Río de la Plata as a river.[4]

An interesting characteristic that results from all of those fresh water sources flowing into the Rio de la Plata is sediment. About 57,000 cubits meters worth of sediment enters the river each year. If you look at the google photo (on the wiki site) you can see how muddy the river looks and is. The Rio de la Plata although meaning silver or money (plata) has earned the nickname "The lion colored river" because of its brown colored waters. The brown color is attributed to the 90% suspended clay particles and the other 10% to sand and silt. Because of the large amount of sediment, the river would not be navigable except for the dredging projects that keep the main channel clear, allowing ships to pass. Generally, the river is quite calm except when the gales of the Southeast blow. As mentioned in my Alpha zone post, people say that because of the buildup of sediment in this river there are parts of it that some people claim, one can walk upon. 

About once or twice a year the winds or tides or something other will unbalance the freshwater mix and cause a backlash of extra salt content, then all along the coast the result is lots of dead fish.

Now the problem about whether "I" have a view of the river or of the ocean from my house on the coast comes about in regards to the river's length. The maritime maps show the river as not only between the banks of Argentina and Uruguay (it's width) but also spilling out into the Atlantic Ocean, forming a Y(or T) shape. Once the river leaves it's mouth between the banks of the countries of Uruguay and Argentina it meets the Atlantic Ocean but it then travels or flows both up to the left and down to the right, along this stretch of Atlantic coastal line for a while, after leaving the mouth, as clearly seen by the physical brown colored water. So the answer or key in understanding this question about the river and my terrace view of it, comes in the form of the range and extension assigned to this river by observation, laws and legislation, once it spills into the Atlantic Ocean. 

My view of the "river" and the Atlantic Ocean far beyond it.
FREPLATA, is an agency that was assigned a project study of the Rio de la Plata river and its maritime front. One objective was to collect and disseminate data about this river and its surrounding area and maritime use.
They have on their website outlined the legal treaty for the river's use.
Chapter 1 discusses the jurisdiction of the river and article #1 explains its agreed upon area definition.

ARTICLE 1. The Rio de la Plata extends from Punta Gorda parallel to the imaginary straight line that joins Punta del Este (Eastern Republic of Uruguay) and Punta Rasa del Cabo San Antonio (Argentina), in accordance with the provisions of the Treaty of Uruguay River Limits of April 7, 1961 and the Joint Declaration on the Outer Limit of the Rio de la Plata from January 30, 1961.

ARTICLE 2. Establishing a range of exclusive jurisdiction adjacent to the coast of each Party on the River. This coastal strip has a width of seven nautical miles from the outer edge of the River and the straight line linking Cologne (Eastern Republic of Uruguay) and Punta Lara (Argentina) and from this last line to the parallel of Punta Gorda width of two nautical miles. However, its outer limits will be inflected as necessary to avoid exceeding the edges of channels in the shared waters and remaining channels including access to ports. Such limits shall not be approximated within five hundred meters from the edges of channels located in the shared waters and will turn away more than five hundred meters to the edges and the mouth of the access channels to ports.

Did you notice in Article 1, the use of the word imaginary line. This imaginary line joins Punta del Este, Uruguay the river's designated coastal end (or limit assigned to it) to Punta Rasa del CaboArgentina ending the other direction that the river flows to along the coast. Those are the agreed upon left and right outer coastal limits of this river. So by law and maritime charts, I have an outer coastal limit river view. The land mass of Uruguay curves at this point so I have a diagonal view of the river not the traditional view of its width between the 2 countries ( from one of its banks). I look at the brown water spillage into the Atlantic, I look diagonally across this (legal entity) towards the bluer Atlantic Ocean in the distance.

Montevideo, the Capital of Uruguay sitting on the Rio de la Plata

Notice how brown the waters are in this photo! This is a photo of the capital city of Montevideo that actually does sit on the bank of the Rio de la Plata it sits at the mouth of it, towards the Atlantic Ocean. Still, that brown water clearly marks this as belonging to the river.

I have a confession to make, most of the photos that I take of the water view from my deck are done on what I call blue water days! The water in front of my house although facing what seems to be the Atlantic Ocean definitely is still influenced by the Rio de la Plata. The only thing that keeps our retirement area from being a true beach paradise is the brown water, instead of having pretty blue water as shown in typical idyllic post card beach scenes.

The brown water from the Rio de la Plata running along the coastline.
In this photo of a fishing boat, taken from my terrace, you can see a very brown line of water in a sea of more brown water. The coastline of Uruguay has many bay-like indentations that result in calmer waters along its coast. This water, right off the coast from my house, is not too deep due to a lot of sediment deposited on its bottom. The water here is very calm with little wave action (it does have some strong undertow in places).  Everyone agrees however, that starting at around Punta del Este in the northeast, the true Atlantic Ocean, free from the influence of the muddy waters of the Rio de la Plata begins. The water at Punta del Este is much bluer and the surfers are out in force riding the Atlantic waves.

So Geraldo, the water view from my terrace is the "brown water" belonging to the Rio de la Plata but if I look past this brown ribbon I see the Atlantic Ocean in the distance. Either way, I enjoy my view immensely!


Anonymous said...

Hi Denise and Wally,

Have been reading and loving your blog for some time. I wondered if I might ask you some detailed questions. I know some time ago Wally had suggested this might be possible for another reader. I'm going to leave an email address and hope to hear from you. Thanks, Fizzer

Anonymous said...

But depending on curents and tydes, even on Montevideo I have experienced blue water days. And its funny because somedays the beach water taste "sweet" and others very salty, depending on currents.

But in the area were you guys live blue waters are more frecuent than in montevideo.

Victor said...

This is cool!