Arch. Myriam B. Mahiques Curriculum Vitae

Tuesday, October 20, 2009

Proposed Fractal Urban Analysis for Uros' Islands

Basic urban morphology analysis is commonly applied to aerial pictures of cities or settlements anywhere on urban or suburban areas; for rural areas, the focus is on land use. But, little attention is paid to the analysis of settlements as part of islands. Apart from the well known methodology to measure an island’s coastline with the application of fractals theory, islands represent a difficulty at the time of measuring certain parameters accurately. The Uros’ islands, in Peru, are an example of this issue, given that an urban analysis based on Euclidian geometry would be unappropriate.

The Uros Indians of Peru and Bolivia are actually a mix of Uros, Ayamaras and Incas. They live in the Andes region on more than forty floating islands on Lake Titicaca. It is during the rainy season, from November to February, when the islands float on the surface of the lake.

Totora plant.

A totora sculpture and houses.
These islands have the particularity of being made of totora (Schoenoplectus californicus) reeds which grow naturally on the banks of the lake. The reeds are used to make the dwellings, boats, furniture, containers, clothing, strings, and the islands themselves; reeds are matted as a fabric-ground and added to approximately every three months as they disintegrate at the bottom. The dense roots that the plants develop and interweave from a natural layer called Khili (about one to two meters thick) support the islands. They are anchored with ropes attached to sticks sunken into the bottom of the lake. Each step on an island sinks about 2-4” depending on the density of the ground below. As the reeds dry, they break up more and more as people walk on them. In consequence, moisture gets to them, they rot and a new layer has to be added to the “ground”. (Adaptation from
Totora reed has played a cultural role. It has also been noted that it has been used as both food for humans and livestock. The value of totora to local residents justified the efforts spent in maintaining adequate supplies of this plant. Increases in population, politics, and yearly variation in climate patterns have created a reduction in available totora and contributed to an increase in management practices. (Banack, Sandra A., Rondon Xanic J., Diaz Huamanchumo, Wilfredo. 2004)

Because of their own materiality, when using a satellite photograph for fractal analysis, we are tempted to “read” the islands with the dwellings as clusters; but the filled areas are not easy to separate from the landscape. These islands boundaries are interpreted by ambiguous pixels, not only for the reed that is an amalgam with the water, besides, the islands change in size and more are created as needed; they also have movements, what in concept generates a dynamic edge with infinite shapes. In case we decide to find out the fractal dimension of the edge, it will be only valid for the specific instant when the aerial picture was taken.
Since these islands are an agglomerate, the “buildings” cannot be separated in parts, not even from the island that gives them support, because everything is part of the same totora fabric. That is, these islands cannot be considered as flat projections, they have a 3 Dimension that includes the dwellings and public construction (school).

Binary file of a sector of Uros' island. Personal archives.

Rugosity fractal analysis. Personal archives.

Plot of sector of island's elevation. Personal archives.
Then, a more complete fractal urban analysis cannot be met only by measuring the area of the fractal dimension of edges; the topography, becomes so important that the texture (rugosity), the elevations, and of course the island in itself, have to be included in the study. The following pictures are part of a more extensive study on the Uros’ islands. The selected .jpg file had to be transformed into a binary file in order to use the corresponding softwares of images analysis.

Banack, Sandra Anne; Rondon Xanic J. and Diaz Huamanchumo Wilfredo. Indigenous Cultivation and Conservation of Totora (Schoenoplectus Californicus) in Peru. In Economic Botany 58(1) pp.11-20. The New York Botanical Garden Press. 2004

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