Benvenuti in queste pagine dedicate a scienza ed arte. Amelia Carolina Sparavigna

Tuesday, December 11, 2012

Chimu Surveying

An Ancient Surveying Equipment of Chimu
The Chimu lives in the pre-Columbian Peru, struggling to survive in one of the world's driest desert.
They were therefore "hydraulic engineers". Some of their knowledge about the management of water came from their predecessors, the Mochica, who lived in the Peru's Moche Valley during the 1st millennium AD. Mochica built a network of canals to irrigate their fields. 

 Adapted from http://www.specialtyinterests.net/eop.html

This is a Chimu surveying instrument shows how calculate the slope of the land. "The device consisted of a ceramic bowl pierced by a hollow sighting tube passing through a calibrated, cross-shaped opening (inset). And artificial horizon was established by aligning water with the three dots in the bowl, which was leveled in a larger, sand-filled vessel atop a tripod (far left); when the sighting tube was in the center of the cross-shaped opening it was parallel to the artificial horizon. Chimu surveyors marked a rod at the height of the level sighting tube, then moved the rod a known distance along uneven ground and sighted the mark. The ground slope corresponded to the tube angle indicated by the calibrations inside the bowl." From

Feats and wisdom of the ancients

Front Cover
Time-Life BooksAug 1, 1990 - History - 143 pages

Surveying and Hydraulic Engineering of the Pre-Columbian Chimú State: ad 900–1450, Charles R. Ortloff, Cambridge Archaeological Journal, Volume 5 / Issue 01 / April 1995, pp 55-74
Abstract The Chimú state of northern coastal Peru (ad 900–1480) developed massive irrigation-based agricultural systems supplied by intricate networks of canals drawing water from river sources in coastal valleys under their political control. Further intervalley canal systems, some up to 50 miles in length, were constructed to shunt water between river valleys to augment intravalley supplies. A high degree of civil engineering skill was necessary to construct and maintain such complex systems; knowledge of surveying and of open channel flow hydraulics was paramount. Some of the technology used by the Chimú has been investigated: surveying instruments and calculating tools have been unearthed and analyzed to provide some understanding of the technical base used for canal design. Details of the hydraulics knowledge-base have been extracted from computer simulation of the functioning of ancient Chimú canal designs. This article assembles known pieces of information related to Chimú civil engineering practice and attempts to provide a plausible methodology that could have been implemented by the Chimú to survey the precise canal bed slopes necessary for proper hydraulic functioning of large canal systems through rugged Andean foothill and mountain areas.