Understanding landscape evolution in studies of terraced agriculture

Posted on 23 March 2017

New research carried out at the Konso Cultural Landscape highlights past complex landscape management

A York archaeologist has carried out research studying the evolution of an agricultural terraced landscape in Ethiopia.

The Konso Cultural Landscape consists of 200 km2 of stone walled terraces and fortified settlements. Designated as an UNESCO world heritage site in 2011, it provides a 600 year-old example of how human beings adapted to a dry and unforgiving environment.

It was thought that the terraces constructed on the hillside were created to retain soil for agriculture, but new research by Dr Cruz Ferro Vazquez, at the University of York’s Department of Archaeology, now suggests that they were built to protect the land below from slope erosion. 

Demonstrating sophisticated knowledge of engineering and dynamics of the landscape, the Konso agricultural system provides an insight into the functions of terrace systems and how their practices can still be relevant to cultivating this harsh landscape today.

The research combined stratigraphy, geochemistry, micromorphology and pyrolysis GC/MS to analyse the evolution of the landscape through time. Understanding this evolution is essential for successful long-term management.

Dr Ferro says: “The impressive terraced landscape in Konso includes some 40 historic walled towns surrounded by a system of dry-stone agricultural terracing, complemented with a complex array of other soil and water conservation techniques such as water and soil harvesting; inter-cropping; agroforestry; livestock; and beekeeping activities. As a result, the stony hillsides of Konso are turned into protected fertile agricultural landscapes.

Yelas are a key feature of the Konso terraced landscape. This particular type of field is built by placing a few courses of stones transversally to the river, where fine sediments entrained within running water are deposited, permitting more drystone courses to be added and further alluvial sediments to be captured. Terraces were then constructed for protecting this crucial agricultural resource from stoney material eroded down hillslopes.

“Careful construction of artificial offtakes and channels ensured that flow rates to yelas were kept low and produced an efficient particle size selection, allowing for the capture of fine sediments.

“Although erosion has been and still is a pressing concern for land degradation in the Ethiopian highlands, it has also been the foundation of the Konso system’s productivity, and this fact needs to be taken into account when planning management and developmental interventions.”

To read the full article in the Journal of Environmental Management, visit http://dx.doi.org/10.1016/j.jenvman.2017.01.036