Teresa Salvatici

Debris flow hazard assessment by means of numerical simulations: implications for the Rotolon creek valley (Northern Italy)

On 4th November 2010, a debris flow detached from a large debris cover accumulated above the lowermost portion of the Rotolon landslide (Vicentine Pre-Alps, NE Italy) and channelized in the valley below within the Rotolon Creek riverbed. Such event evolved into a highly mobile and sudden debris flow, damaging some hydraulic works and putting at high risk four villages located along the creek banks. A monitoring campaign was carried out by means of a ground based radar interferometer (GB-InSAR) to evaluate any residual displacement risk in the affected area and in the undisturbed neighbouring materials. Moreover, starting from the current slope condition, a landslide runout numerical modelling was performed by means of DAN-3D code to assess the impacted areas, flow velocity, and deposit distribution of the simulated events. The rheological parameters necessary for an accurate modelling were obtained through the back analysis of the 2010 debris flow event. Back analysis was calibrated with all of the available terrain data coming from field surveys and ancillary documents, such as topographic, geomorphological and geological maps, with pre- and post-event LiDAR derived DTMs, and with orthophotos. Finally, to identify new possible future debris flow source areas as input data for the new modelling, all the obtained terrain data were reanalysed and integrated with the GB-InSAR displacement maps; consequently, new simulations were made to forecast future events. The results show that the integration of the selected modelling technique with ancillary data and radar displacement maps can be a very useful tool for managing problems related to debris flow events in the examined area.

Runout modelling of gravity-induced pyroclastic density currents at Stromboli volcano (Italy)

Gravity-induced pyroclastic density currents (PDCs) at Stromboli volcano were investigated by means numerical and empirical modelling. With the aim of testing the suitability of landslide numerical model DAN-3D and empirical models are used related to gravity-induced PDCs, in particular this work presents the results of the back analysis of three events occurred on 1906, 1930 and 1944 at Stromboli volcano. These two methods were able to reproduce the extension and the order of magnitude of the thickness of the PDCs reported in the literature. The best results of DAN-3D models were obtained using a Voellmy model with frictional coefficient of f = 0.19 and a turbulence parameter ξ = 1000 m/s. The mobility terms, find with the numerical model, are compared with empirical data of literature of the similar events.

Optical design of a hyperspectral drone advanced camera for soil monitoring using an electro-optical liquid crystal technology

In the context of environmental monitoring, it is very important to improve systems for the identification, assessment and management of environmental risks through the use and integration of analytical techniques combined with hyperspectral airborne sensing technologies. Remote-sensing applications are varied, but nevertheless an accurate mapping of the soil required the use of complex scientific instruments installed on airplanes or helicopters. The high integration of electronics, combined with the computing power of modern processors, allows the development of integrated and compact hyperspectral systems installed on drones.1 The drone era poses new challenges to optical devices design: they shall be light, compact and robust, easy to assemble and to control. This work explains the optical system design of HYDRACAM (HYperspectral DRone Advanced CAMera), an instrument devoted to hyperspectral imaging by using an electro-optical liquid crystal tunable filter combined with a commercial camera. The commercial ray tracing software Zemax/OpticStudio2 was used to perform the optical design. The main challenge was to manufacture a low cost optical device, containing the mass and the total length to suit a drone payload. A huge effort was made in order to combine strict constraints (such as the filter narrow entrance aperture and its acceptance angle) with ambitious optical performance requirements (high spatial resolution, large field of view). First, a description of the work done to find a trade-off between cost and opto-mechanical constraints is provided: the choice of the commercial objective, the choice of the custom lenses materials and shapes and some optical design original solutions are addressed. Then, the details of the optical performance analysis are discussed.

Integration of ground-based interferometry and terrestrial laser scanning for rockslide and rockfall monitoring

A rockslide in Central Italy has been monitored by means of a ground-based interferometric radar and a terrestrial laser scanner in order to monitor its displacements and to provide both an early warning system and a feedback for the restoration works. The radar furnished near real time displacement maps that were integrated with 3D models of the slope reconstructed through the laser scanner. The integration between the two techniques permitted to reconstruct a high resolution 3D displacement maps of the rockslide also in the areas where profiling works created disturbance to radar data. As a support to the safety of workers and the durability of structural interventions, several detachment areas of rockfalls were also identified and the volume of the blocks calculated.