Peru: using past technologies to solve future problems

Climate change and water shortages threaten the survival of rural communities in the Peruvian Andes. Robert Early explains how ancient Inca know-how is relevant today.


Those living in the Andean highlands today face huge challenges, as did their pre-Inca and Inca ancestors. The tropical Andes host 99% of the world’s tropical glaciers, most of them in Peru. The last few decades have seen a 30% reduction in the surface of these glaciers, and an increase in extreme climate events. The knock-on effects on both the water-cycle and agricultural production are becoming ever more problematic for these mountain communities, and we need to find a way to mitigate significant water shortages. In Peru, they are looking to the past for a solution, with the re-introduction of Inca terraces and ancient irrigation systems, but on a massive scale.

The terraced landscape of the Peruvian Andes allows the most efficient use of land in a region afflicted by water shortages and the adverse effects of climate change.

Since 1977, the Cusichaca Trust has combined detailed archaeological and environmental investigations in Peru, focusing on the agricultural infrastructure of the Incas and their predecessors. Initial research was carried out in the Cusichaca side-valley of the Urubamba Valley, Cusco, and over the last 25 years the archaeological data collected has been applied to rural development programmes in the Cusco, Apurímac, and Ayacucho regions. These programmes have been incredibly successful: it is estimated that 30km of canals and 600ha of terracing have been restored to full productivity.

Tourists visiting the Sacred Valley of the Incas and the World Heritage Site of Machu Picchu will be familiar with the impressive staircases of terraces throughout the valley and beyond. These Inca and pre-Inca agricultural systems are a common feature of the Andean landscape, which was much more intensively farmed in the past than it is today. Most were constructed to prevent soil erosion and to extend the area of land available for cultivation.

Inca terraces under restoration, and one of the cultivated terraces in bloom.

The abandonment of many terrace systems in the Andes after AD 1534 was due to social and political changes following the arrival of the Spanish, rather than to a lack of sustainability. Populations were decimated, and an emphasis was placed on mining rather than agriculture, resulting in an estimated 500,000ha of a possible terracing being abandoned or lost through erosion. Inevitably, traditional agricultural practices declined, and the associated techniques for construction, maintenance, and management were lost.

In the 1960s and 1970s, the Peruvian government implemented a series of agrarian reforms, and large tracts of land were returned from hacienda estates. As a result, indigenous communities began to take an interest in their Andean past. In the Cusichaca valley, initial attempts by local communities to re-use Inca irrigation systems relied on modern materials (such as cement that was both unsuitable and costly) and systems of farming using modern techniques and machinery that were inefficient and unsustainable within such extreme environments. It was clear to the Cusichaca Trust that there was a need to understand more fully the agricultural processes and techniques of the Inca.

Renovation work to bring the irrigation canals to life.

Archaeological survey, excavation, and environmental research by the trust’s founding member and current director Ann Kendall has identified a remarkable concentration of different types of terrace system, modified and adapted over some 11,000 years in response to past climate changes. Studies provide evidence that these carefully engineered terrace systems were linked to vast and complex irrigation systems. They were fed from high-altitude lakes or purposely constructed reservoirs (cochas). Rain and glacial meltwater were sometimes diverted into natural underground caverns (almunas), from where they emerged once more along Andean hillsides as springs that were used to provide water for irrigation. By the Inca period, terrace systems were often sophisticated, with double-faced stone walls and stone fill for drainage. Furthermore, their engineering paid particular attention to the need to retain water, enabling microbiological activity that in turn increased the nutrients in the soil, promoting continuous cultivation. Terrace systems also controlled or at least slowed down the movement of water, which raised the temperature of the terrace soils, and thus reduced climatic risk. The success of these agricultural systems enabled a healthy surplus for the Inca, and estimations suggest that about 95% of agricultural production could have been exported from the Cusichaca valley, compared to next-to-no surplus produced in the 1970s.

One of the Inca irrigation canals now back in use.

The Cusichaca Trust’s rural development programmes have combined archaeological and environmental research with ethnographic, anthropological, and historical evidence to understand the different past and current occupation practices of farmers within their study areas. The restoration programmes have resulted in a significant increase in the percentage of production of, for example, maize, potatoes, quinoa, and broad beans, all of which can be sold at local markets.

Building on the past

Adopting methodologies from the past can only be useful if they are relevant to current social, economic, and environmental conditions, and contribute to the sustainability of future populations. It was perhaps easier working with poverty-stricken communities in the 1970s and 1980s than in today’s Peru, an emerging South American economy, where rural communities have rising aspirations and a desire for modernity. The Trust has worked closely with local partners, devising appropriate projects that reduce poverty and increase self-sufficiency among rural communities that are often isolated. Extensive field survey, rehabilitation programmes, and capacity-building workshops undertaken by an independent Peruvian NGO (Asociación Andina Cusichaca) set up by the Cusichaca Trust aim to enable local communities to share the knowledge of their ancestors and, when relevant, use it together with modern practices to improve local agricultural production.

Cultivated terraces on the Peruvian Andes.

Peru is the only South American nation predicted to experience permanent water stress by 2025. The ongoing shrinkage of Andean glaciers has acted as an impetus for a national goal to design rural policies that will benefit thousands of disadvantaged rural residents, while at the same time safeguarding one of the nation’s most valuable resources: water. The Peruvian government recently announced a US$35 million project to rehabilitate 300,000ha of pre-Hispanic terracing with the support of the Inter-American Bank. To ensure the success of such an ambitious scheme, we need to draw on the good-practice guidelines set out by the Cusichaca Trust and similarly focused NGOs. However, these innovative solutions that reference the Peruvian past will need to be developed alongside modern scientific initiatives if they are to combat the very real threat of climate change and water shortages.

Highland agricultural terrace and irrigation systems have been developed by past civilisations in often inhospitable environments across all the continents of the world. However, modern farming and changes in commercial demand have led to their abandonment and the subsequent loss of ancient technological knowledge. The research in applied archaeological techniques conducted by the Cusichaca Trust over nearly four decades has been a success, and can be shared and replicated to offer creative and sustainable models for rural development in other parts of the world. The second World Conference on Nature and Cultures of Terraced Landscapes will be held on 19-22 May 2014 in Cusco, and will provide an important forum for future collaboration.

Rob Early is a trustee of the Cusichaca Trust and Head of International Business, Oxford Archaeology.