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.
Feats and wisdom of the ancients
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.