19 July 2009

Preparations 3 - The Pongo and the "soliton"

With the help of the detailed (military) map of Ecuador and the map of the Maranon corrected by La Condamine himself (see post of 11th July 2009), most of the places on the route between Loja and Borja could be traced.
However, the question remained where Chuchunga was located, the port where La Condamine started his descent of the Rio Maranon.

A Google-search for Chuchunga brought me in contact with "Zitoune", who crossed the Pongo de Manseriche several times in both directions, who has lived in Las Chachapoyas, who knows this region of Peru very well, and who signs his messages with the poetic words:
"Es un hombre que se va, la lagrima se queda. El Chachapoyano".
("A man is going, the tears are staying"; "Un homme passe, les larmes restent"; traduit par Catherine Marchand).

Zitoune allowed me to present one of his photographs of the entrance of the Pongo:

Entrance of the Pongo de Manseriche.
Photograph taken by "Zitoune" in August-September 2007.

We hope to come to the Pongo de Manseriche in February next year. Zitoune writes me that at this time, during the wet season, the water level can be very high. If it is above 21 feet (or "pieds", indicated on a scale probably in Borja) the passage is not dangerous. At lower levels, between 16 and 21 feet, however, a wave of 2 to 3 m can go back and forth through the Pongo, making the passage impressive but also dangerous.

La Condamine writes in his "Voyage sur l'Amazone" that the water level in the Pongo decreased rapidly ("a vue d'oeil") from a height of 21 pieds! He was there on 10 July 1743. I wonder whether the scale he used is the same as the one mentioned by Zitoune.

When I asked Zitoune about the wave he confirmed that this was a single wave! According to a colleague, the physicist Theo Odijk, such a wave could perhaps represent a so-called "soliton" or solitary wave, first observed and described by Scott Russell in 1834 in a canal in England. This represents a non-linear phenomenon that could be compared with a tsunami and has been described in a book by Ablowitz and Clarkson (1992).

In his last letter, Zitoune also helped me to find Chuchunga, the village or canon (spanish "quebrada") mentioned several times by La Condamine. Google located the "Rio Chiriaco Chuchunga" at S 5° 24' W 78° 6'.

According to S.S. Renner (Smithonian Contributions to Botany no. 82: "A History of Botanical Exploration in Amazonian Ecuador, 1739-1988") the port Chuchunga is near the present-day town of Nazaret.
La Condamine writes that since his departure from Jaen he had to cross the Chuchunga torrent 21 times. Before reaching the village he had his 4th accident in which all his instruments, books and papers became wet. Did he carry a microscope with him? I wonder how we will reach Nazaret and whether we will be able to see "the wave" in the Pongo.

Chuchunga, near Nazaret, where La Condamine started his descent of the Maranon.