Effects of the Vegetation on the Hydrological Behavior of a Loose Pyroclastic Deposit
Procedia Environmental Sciences
The effects of the vegetation cover are introduced into a simplified hydrological model of a slope covered with pyroclastic materials, located in Cervinara, in the Apennines of Campania (southern Italy). The vegetation consists of deciduous chestnut trees (Castanea sativa) with a dense seasonal understory, mainly constituted by ferns (Pteridium aquilinum) and other shrubs. The brushwood grows during late spring and summer, while it is nearly absent during the rest of the year. Approximately in
... he same period, from May to September, the chestnut trees have deep foliage, while in October the leaves dry and fall. Such seasonal vegetation cover affects rainfall infiltration, as indicated by soil water potential data collected by a hydrological monitoring station operating since 2010 at the slope. The effects of the vegetation are introduced in the hydrological model in two ways: interception of the precipitation, and a root water uptake model which distributes the total evapotranspiration flux over the root depth, according to the local value of soil water potential. The presented results show that the introduction of seasonally variable values of leaf area index and interception capacity ensures good performance of the hydrological model. The results also show that, through rainfall interception and root water uptake, the vegetation cover has positive effects on slope equilibrium, by keeping soil suction high enough to prevent the establishment of the conditions which lead to slope failure.