Evaluation of the effect of land vegetation cover on water and energy balance of an unsaturated pyroclastic cover

Abstract

Abstract. Land cover features can strongly affect the actual soil wetting state; for example, the presence of a vegetated cover can induce relevant variations in the main components of soil-atmosphere water balance: interception and evapotranspiration. For these reasons, its proper characterization represents a crucial point in typical geotechnical issues as, for example, the assessment of slope stability conditions. To this aim, in the work, in two different hydrological year albeit characterized by comparable weather patterns, the variations induced by varying land cover have been investigated for water and heat balance of a soil volume constituted by pyroclastic soil. These soils, mantling a large part of slopes in Campania Region, are particularly interesting since they have been often affected, in last years, by landslide phenomena causing huge damages and victims. Observations are retrieved by a physical model constituted by a soil layer exposed to weather forcing and instrumented to record weather variables, component of soil surface heat balance and soil state properties within the layer. The two antipodal considered land cover conditions are bare soil and full natural vegetation (mixing of Lolium perenne, Festuca rubra and Poa pratensis); on Campania slopes, the first condition can be retrieved on slopes in man-modified areas (road cuts, quarries) while the second ones are plant species commonly found on Mediterranean slopes. The analysis focused on Summer season where in clearer way, different behaviour can be detected stressing the variations induced by the vegetation cover not only on the potential evaporative demand but also on the actual values.