Sustainability of modern land terracing for vineyard plantation in a Mediterranean mountain environment – The case of the Priorat region (NE Spain)

Vineyard restructuring in the Priorat region of NE Spain has transformed both traditional vineyards and abandoned cultivated hillslopes into mechanized vineyards. These new terraced vineyards do not look sustainable under existing environmental conditions. A survey assessing the terrace design of the new mechanized vineyards was initiated a few months after crop establishment. Using a Geodimeter total station, vertical and horizontal intervals between the terraces and the slope of the terrace risers were measured. The results were then compared to accepted terrace design criteria. Additionally, the magnitudes and locations of soil movement that occurred on the risers after vineyard establishment were surveyed. Vineyard infrastructure and vines affected by mass movements as well as rainfall characteristics were also evaluated. The results indicate that the modern terraces are unstable and may lead to a degraded environmental situation. The only factor considered by farmers at the time of the terrace construction is trafficability, i.e., the width suitable for machinery movement. Therefore, the terraces have riser heights (4.8 ± 3.0 m) and widths (6.2 ± 3.5 m) greater than accepted design criteria for the steep conditions in the study area. Indeed, one extreme rainfall event shortly after the terrace construction induced landslides which affected 4950 m2. About 75% of the area affected by the mass movements occur in the lower third of the slopes, where 6.9% of the plants, irrigation and training systems were damaged.