Physical modeling of rainfall infiltration processes in stratified pyroclastic soils
Abstract
Every year landslides cause many damage to people, structures and infrastructure. The prediction of these natural processes is of great important in order to reduce the risks for all the people. Also for this reason, many researches have been developed over the years to understand the underlying processes trigger landslides, with particular attention to the rainfall infiltration processes, runoff generation, groundwater recharge and the effects in terms of stability and soil resistance. The processes in layered slopes, in particular, can be strongly affected by the different hydraulic properties of the soils constituting the layers, with potential downslope flow diversion. In this work, the results of a transient infiltration test carried out in a densely instrumented physical model of a layered volcanoclastic sloping cover, are presented. The model consists of two connected channels (trigger and propagation fig.1) of 1 meter wide and 3 meters in length each. It is equipped with tensiometers for measuring the suction inside the slope, pressure transducers at the bottom of the flume to measure positive water pressures, TDR system for measuring volumetric water content and laser-displacement transducers for measuring surface displacements in the orthogonal direction to the sliding plane. The soil cover was constituted by a layer of gravelly pumices interbedded between two layers of finer ashes (sandy loams), from Sarno area (Southern Italy - near the volcano Vesuvio), affected by landslide events on 5 May 1998. Even with such an extreme contrast in texture, capable of significantly delaying the advancement of infiltration through the layer of pumices, flow diversion occurred only temporarily at the interface between the upper layer of ashes and the pumices. Although a long-lasting intense rainfall was applied the accumulation of water above the upper edge of the pumices soon led to the establishment of high water potential gradient, which redirected the infiltrating flow through the pumices and stopped the downslope flow diversion.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H31O1974O
- Keywords:
-
- 1804 Catchment;
- HYDROLOGY;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1839 Hydrologic scaling;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY