Transformation of maritime desert to an agricultural center: Holocene environmental change and landscape engineering in Chicama River valley, northern Peru coast

Abstract

Some of the earliest Andean populations settled in the region's arid coastal river valleys, supported by abundant marine life despite having domesticated plant cultigens as early as ∼10 ka. In the Chicama River valley, this maritime economy dominated at the Preceramic site, Huaca Prieta, until ∼6 ka, after which agricultural production began to increase significantly. This agricultural expansion was motivated in part by the development of arable fine-grained soils along the coast as the result of slowing sea-level rise, enhanced river floods, and unique basin lithology. Local populations made use of the stabilized floodplain and wetland settings to conduct raised-terrace farming. By ∼3.5 ka, growth in agriculture and the new fine-grained sediment resources led to several major cultural developments, including the production of fired-ceramic pottery and adobe-brick monument construction associated with the Cupisnique culture. Populations thereafter expanded into the middle valley, where the Salinar and Gallinazo cultures used small water-control structures to farm local ravines. These cultural and technological developments all parallel natural environmental changes driven by increasing ENSO-related water and sediment discharge. By ∼1.8 ka, though, further expansion of agriculture –and arable land– was driven primarily by direct human manipulation of the environment. The construction of an ever-expanding network of irrigation canals diverted increasing volumes of water and sediment to distal reaches of the Chicama valley, supporting the great Moche and Chimu civilizations, and persisting through the Inka and Colonial periods. This history of Chicama valley traces strongly coupled interactions between the human and natural environments, supporting significant socio-cultural, economic, demographic, and technological advances.