Wednesday, July 11, 2012

A Subfluvial Tunnel through a Landscape of Local Politics

[for the next month or so, all blogging will be done via tablet from South America; expect experiments in formatting as I get accustomed to using something called an 'app' with its relatively limited text and image-sizing options; however the images appear on the screen, they should link to larger, nicer images if you click on them]

[At the head of the great delta of the Rio Parana, the twin Argentine cities of Parana (right) and Santa Fe (left) form one of the country's major metropolitan areas and are connected by a 1960's-era tunnel; the tunnel runs under the narrow point in the river just north of the city of Parana and connects to Santa Fe via a highway that is visible slicing through the floodplain]

This past weekend we had the chance to spend some time in the mesopotamia region of Argentina, so called because of its locations between the Parana and Uruguay Rivers. The Parana in particular has long been an object of fascination for us because of the massive amounts of water and sediment it slurries creating a fecund geomorphology of incredible scale, beauty and danger, and because its deepwater channel has historically been a primary channel of South American industry. The distributed system of ports, urban centers, infrastructures, military installations, and agricultural lands that stretch from Buenos Aires in the south to Puerto Iguazu and the Triple Frontera region and on to Sao Paulo in the north offer an incredible example for urban and landscape studies with eerily similar parallels to the Mississippi River.

[A shot from inside the nerve center of the Parana Subfluvial Tunnel; all manner of 1970's era diodes and monitors feed information about carbon monoxide levels and automobile weight and speed to a small team of technicians; periodic surveying of river conditions is also done to monitor the speed of currents and sediment deposition patterns]
Beginning in the 16th century the city of Sante Fe was an important stop for people moving west from La Plata up in to Paraguay or overland to Alto Peru. The city of Parana was birthed from its frequently flooded twin when a few inhabitants made their way across the river to the higher ground offered by the hills on the eastern side of the river. The city briefly served as the capital of the Argentine Confederacy after the fall of Juan Manuel de Rosas' provincial dictatorship and the temporary split of the province of Buenos Aires from Argentina in 1853.

What is really strange and interesting is why a tunnel was used here instead of a bridge. There are no high-masted ships this far up the Parana River and though the spans are huge here it would still seem easier to build above the water as was done further downstream at Rosario and Buenos Aires. By my recollection most crossings of the Mississippi, Hudson, and East River are by bridge, boat, or air tram. By putting the inhabitable transit route underwater it seems you invite a host of maintenance and monitoring issues including ensuring that carbon dioxide levels aren't too high there is sufficient coverage of the tubes by sediment and armored mats. Why invite that if it is not necessitated by commercial vessels?

The answer, according to the historian we spoke with at the infrastructure exhibit on site, is one of local politics. The federal government, which the city of Parana has had a complex relationship with since 1853, owns the water and air rights along the Parana River and any bridges, ports, and other infrastructures in or over the water are the jurisdiction of Buenos Aires. Like in many countries they tend to move slowly and be somewhat disinterested in spending federal dollars for local improvements. Land rights are another matter however, even if that land is covered by a river.

The governors of the neighbor states of Santa Fe and Entre Rios, where the cities of Santa Fe and Parana are located respectively, signed a declaration in 1960 to construct the long awaited connection between the two provinces that literally and figuratively subverted federal control of the river and connected the twin cities.
[the Parana Subfluvial Tunnel is 2,907 meters long, with a diameter of 14 meters, and a maximum depth of 32 meters below the mean river elevation. The tunnel consists of 37 tubes of the type shown above and is covered with a geotextile, 3 meters of sand, and a heavily armored articulated concrete mat laid over top]

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