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Earth Matters

October Puzzler Answer: Lluta River

November 1st, 2013 by Adam Voiland


Congratulations to Jaimen W. for solving the October Puzzler the fastest.  The answer is Chile’s Lluta River. See the Image of the Day that we published on November 1, 2013, for details about the area. Phil Echelman was right on Jaimen’s heels, responding with the correct answer just two minutes after Jaimen. Congratulations also to Javier Canete, Alan W, and Juan Pablo Joui for offering interesting information about the area.

The unique perspectiveand beautyof satellite imagery never ceases to fascinate me. In this case, the satellite perspective of Lluta River does a remarkable job of illustrating how constricted and precious water and farmland is in this extremely arid region. But distance also blurs detail. I was curious about what this river valley looked like from the ground, so I did some searching on Panoramio and Flickr.  I’ve included two of the many shots I came across at the top and bottom of this post. The panorama at the top was taken by Gustavo Canales;  Julie Laurent took the photograph at the bottom.


While researching the Lluta, I  ended up in touch with Pablo Pastén González, an engineer at Northwestern University and the Pontifical Catholic University of Chile. His group has been studying the Lluta since 2007.  Via email, he shared some thoughts about what he finds most notable about the river.

“The interplay between the Atacama aridity, the presence of ancestral communities, high arsenic and boron concentrations in the fluvial network deriving from the complex interaction of hydrodynamic and biogeochemical factors, with natural (geothermal) and anthropogenic (legacy mining) sources upstream from the place of your picture makes it a prime spot for research in the geosciences.  At the same time, the presence of ancestral cultures, the proximity of the border with Perú, and the push from the Chilean government to increase economic activity (mining, agriculture, tourism) makes it a fascinating place where science meets economic development and policy.

For example, not far upstream from the place of your picture, the Chilean government is planning to build the Chironta dam, a reservoir that seeks water storage for irrigation and flood control during the “Bolivian winter,” the wet season between December and March.  What’s puzzling is that the Lluta brings high concentrations of arsenic-loaded particles that will probably make the sediments of this dam into an arsenic reservoir. We expect that the dam will work as a giant settling basin that will decrease the concentration of total arsenic flowing downstream (i.e. less arsenic will flow through the reach in your picture), but an arsenic time bomb that could be set off by the wrong biogeochemical/hydraulic conditions in the dam.”


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