Agricultural infrastructure as cultural geomorphosites: case studies in Switzerland and Tunisia

Cultural geomorphosites are places where geomorphological features interact with cultural elements (historical or archaeological vestiges, religious monuments, etc.). Over time, agricultural practices have adapted to local conditions (climate, morphology) and have often modified landforms and hydrological conditions. New landscapes, combining the local hydro-geomorphological context and the needs of agriculture, have thus been created: e.g., terraced landscapes, drainage and irrigation systems, and clogging facilities in alluvial plains. In this communication, we compare three agricultural systems in three different geomorphological and climatic contexts.

The Upper Rhone valley (Canton of Valais, Switzerland) is characterised by relatively dry climatic conditions explaining the presence of an important network (about 800 km) of irrigation channels, called Bisses, dating back to the Middle Ages. In the last decades, this network has been recognised as a cultural heritage and the agricultural infrastructure has sparked a renewed interest for tourist and cultural reasons. Indeed, the paths along the channels are used as tourist trails and several abandoned channels have been renovated for tourist use.

The Matmata-Dahar plateau, in Southeast Tunisia, is an arid area (annual rainfall < 150 mm) resulting in a negative climatic water balance very constraining for rain-fed agriculture. It explains the development of water-harvesting techniques called Jessour, which form a hydraulic unit made of three main components: (1) a dam across the thalweg; (2) a terrace which includes the cropping area and (3) an impluvium, which is the runoff sub-catchment area. The Jessour have not yet been recognised as (geo)cultural heritage.

Lavaux is a vineyard region located on the northern shore of Lake Geneva, Switzerland. Named a UNESCO World Heritage site as a cultural landscape in 2007, it testifies to centuries of wine growing and adaptation by man to manage hydrological processes and sediment fluxes. Structural geomorphology and differential erosion resulted in a steep stair-like slope where the vineyard terraces were created. Because the natural processes have been significantly modified by man, Lavaux can be considered as a cultural geomorphosite.

The communication has three objectives: (1) to analyse the geomorphological context (morphometric analysis, structural geomorphology, main processes) of the three cases and to show the impact of the geomorphological context on the building techniques; (2) to identify active processes and their impact on the infrastructure’s maintenance; (3) to evidence features that allow us to speak of cultural geomorphosites.