Irrigation canals from the Calchaqui valley (province of Salta, Argentina)

Abstract

The archaeological site of Las Pailas, located in the north of the Calchaquí valley (province of Salta, Argentina), is one of the largest agricultural areas developed in the region during the Late Period (900–1430 CE) and the Inca Period (1430–1530 CE). The site consists of a residential area and an extensive area of cultivated land crisscrossed by a dense network of canals, both with and without stone lining, used for irrigation of the fields. This paper presents the results of the topographic contour and architectural mapping of the lined canals, located in a sector of the archaeological site. The canals have stone lining on their walls and ceilings, and most of them are below ground surface, covered by a layer of sediment. Larger and smaller canals distributed water from river intakes to cultivated fields. This required the development of a technical knowledge that included the control of slopes, the management of water flow velocities and discharge values, and the covering of pipes to avoid sediment accumulation and clogging. The analysis of the density of the canals suggests that the irrigation of the fields was a task of great importance for pre-Hispanic peasants.