SI Research Notes: Where does the Amazon Really Begin?

The mighty Amazon River runs over 4,000 miles from the Peruvian Andes through Brazil to the Atlantic Ocean. A historical definition of the “source” of a river is the point at which water must flow the greatest distance to flow into the river. However, finding the ultimate “source” of a great river can be problematic.

The most distant sources of the River lie in southern Peru. The Rio Lloqueta, a small river in the Andes Mountains, is located about 130 kilometers north of the city of Arequipa in southern Peru. The five main tributaries of the Lloqueta—named Carhuasanta, Sillanque, Apacheta, Calomarco, and Ccaccansa—reach almost to the summits of the continental divide. The peaks include Nevado Mismi Mountain. Land use in the Rio Lloqueta basin is seasonal and limited to grazing alpacas and llamas.

In 2000, research teams coordinated by Andrew Johnston of the Center for Earth and Planetary Studies (CEPS) at the Smithsonian Institution’s National Air and Space Museum (NASM) surveyed the area of the Lloqueta River.

During the 2000 field work, more than 20 researchers were equipped with high-precision Global Positioning System (GPS) equipment. Separate teams mapped all five main tributaries of the Lloqueta by recording locations as GPS receivers were taken along the path of each stream. An overview of the entire southern part of the Lloqueta drainage basin was also created.

Of the five Amazon River tributaries, Carhuasanta had the greatest length with consistent water flow. The Apacheta is capable of having longer surface flow, but this stream has been observed to become dramatically shorter in dry years. The results of the NASM Center for Earth and Planetary Studies field work confirmed that the most distant sources of the Amazon River, a subject of interest for centuries, lie on the ice-covered slopes of Nevado Mismi, an 18,360 ft high mountain about 80 miles north of the city of Arequipa, Peru.

For more information visit
www.nasm.si.edu/ceps/research/johnston/amazon/