The origins of Andean irrigation

An integrated floodwater and canal irrigation system in Tarata village in the Bolivian Andes was in use in AD 719 and apparently existed for thousands of years. An analysis of the sedimentology and geomorphology in the area indicates that a hybrid-style irrigation system is responsible for the layer of silt on the Tarata fan. Long term irrigation restricts the deposition of the coarse sediments to the canalized main channel but the fine sediment is dispersed to other parts of the fan surface.