Threats to archaeological heritage in coastal Peru: Agricultural expansion

Until a few decades ago, agriculture in coastal Peru was largely confined to the valleys of rivers which have their origins in the Andes. Some desert areas outside of the river valleys had been under irrigation already in prehispanic times and had – as a consequence of the early colonial population collapse – been abandoned for centuries. Since the mid twentieth century, there have been many larger and smaller projects to expand irrigation agriculture beyond the confines of the river valleys, in particular in northern Peru (e.g. in the Piura and Lambayeque regions).

But also in other river valleys, many large and small attempts have been made to expand irrigation agriculture, leading to a doubling of the irrigable area in the coastal lowlands from 1964 to 2000. Irrigation systems were expanded along the margins of the river valleys, which had been the primary areas for settlement and burial during prehispanic times. The construction of irrigation canals as well as the levelling and ploughing of fields have destroyed and still threaten large numbers of archaeological sites.

Many prehispanic archaeological sites are located in the valley of the Rio Ingenio, a tributary to the Rio Grande de Nazca. In high-resolution satellite images and on the surface, remnants of buildings and settlement terraces can be identified, pockmarked and surrounded by thousands of looting pits.

At one site near the confluence of Rio Ingenio and Rio Grande, two irrigation canal segments and large scale bulldozing traces document an attempt to turn the area into irrigated fields. As at least one of the canals is already visible in a 1966 Corona spy satellite image, this may relate to the mid-twentieth century National Plan for Improving Irrigation. The canals were never finished, but the damage to the archaeological site is irreversible.

Unfinished irrigation canals cutting through a prehispanic archaeoogical site. Satellite image (c) Google Earth.

Unfinished irrigation canals cutting through a prehispanic archaeoogical site. Satellite image (c) Google Earth.

A bulldozed prehispanic archaeological site, likely in an attempt to create irrigable fields. Satellite image (c) Google Earth.

A bulldozed prehispanic archaeological site, likely in an attempt to create irrigable fields. Satellite image (c) Google Earth.

In 2006, inspection of some looting pits closer to the Rio Ingenio had revealed well-preserved, mummified human remains dating to the Late Intermediate Period. Preservation was excellent due to the extremely dry climate of the Peruvian coastal desert. By late 2012, the area had been converted to an irrigated field. As a consequence of this conversion, human remains still remaining under the surface are now subject to rapid destruction by moisture and tillage.

GoogleEarth image of 25 March 2005 showing a looted archaeological site near the Rio Ingenio.

Satellite image of 25 March 2005 showing a looted archaeological site near the Rio Ingenio. Satellite image (c) Google Earth.

Orthophoto of the same site (based on terrestrial Structrure-from-Motion), showing that the site had been converted to a field by 11 December 2012.

Orthophoto of the same site (based on terrestrial Structrure-from-Motion), showing that the site had been converted to a field by 11 December 2012.