Gullies and Debris Flows analysis: a case study in Sardinia and a rheological modelling approach.

Soil erosion is one of the main causes of desertification in the Mediterranean basin. Recently, the role of channelled erosion in sediment delivery has been underlined by several studies. Rheological studies of Debris Flows, which provide information on the properties of the mixture, are essential for improving prediction and designing mitigation for potential hazard areas. The paper has two aims: describing a simplified experimental methodology, settled up for studying the relationships between Gully erosion and land use, applied to an experimental hilly site threatened by desertification in Central Eastern Sardinia (Italy); showing a Debris Flow model, based on a dimensional analysis and calibrated with experimental data, to identify the causes for momentum transport in the process. The results show a very significant impact of agricultural activities on Gully activity and density, while the Debris Flow model proves to be capable of satisfactory predictions of actual events.