Soil losses in rainfed Mediterranean vineyards under climate change scenarios. The effects of drainage terraces.

Most vines in the Mediterranean are cultivated on bare soils, due to the scarcity of water. In addition, most traditional soil conservation measures have been eliminated to facilitate the movement of machinery in the fields. In such conditions, high erosion rates are recorded. Given the predicted changes in precipitation and an increasing number of extreme events, an increase in erosion processes is expected. In this study, erosion processes under different climate change scenarios were evaluated as well as the effects of implementing drainage terraces in vineyards. Soil losses were simulated using the WEPP model. The results confirmed the relevance of extreme events on annual soil losses. The WEPP model gave satisfactory results in predicting runoff and soil losses, although the soil losses recorded after some extreme events were under-predicted. The model responded to changes in precipitation and because of that a decrease in precipitation gave rise to a decrease in soil losses. For the scenario in 2050, runoff volumes decreased between 19.1 and 50.1%, while erosion rates decreased between 34 and 56%. However, the expected increase in rainfall intensity may contribute to higher erosion rates than at present. The construction of drainage terraces, perpendicular to the maximum slope, 3 m wide and 30 m between terraces, may lead to an average decrease in soil losses of about 45%.