Luca Falconi

The RUSLE erosion index as a proxy indicator for debris flow susceptibility

Debris flows represent dangerous occurrences in many parts of the world. Several disasters are documented due to this type of fast-moving landslides; therefore, natural-hazard assessment of debris flows is crucial for safety of life and property. To this aim, much current work is being directed toward developing geotechnical-hydraulic models for the evaluation of debris flow susceptibility. A common base for such current models is parameterization of background predisposing and triggering factors such as inherent characteristics of geo-materials, topography, landscape and vegetation cover, rainfall regime, human activities, etc. which influence the occurrence of these processes on slopes. The same factors are also taken into account in soil erosion prediction models. Consequently, it seems worth investigating the effectiveness of the soil erosion index as debris flows susceptibility indicator. To this aim, a logistic regression analysis was carried out between the erosion index assessed by means of the Revised Universal Soil Loss Equation (RUSLE) model and the inventory of debris flows that have occurred in an area in Sicily (Southern Italy). Model assumptions were verified and validated by means of a series of statistical tools. Different possible scenarios were also evaluated by considering hypothetical changes in soil erosion rate under different rain erosivity conditions. Notwithstanding the rough approximations in model data collection, the outcomes appear encouraging.

Monitoring, Geomorphological Evolution and Slope Stability of Inca Citadel of Machu Picchu: Results from Italian INTERFRASI project

The Geology of Machu Picchu area is characterised by granitoid bodies that had been emplaced in the axial zones of the main rift system. Deformation of the granite, caused by cooling and tectonic phases, originated 4 main joint sets, regularly spaced (few decimetres to metres). Several slope instability phenomena have been identified and classified according to mechanism, material involved and state of activity. They are mainly related to rock falls, debris flows, rock slides and debris slides. Origin of phenomena is kinematically controlled by the structural setting and relationship with slope face (rock falls, rock slide and debris slides); the accumulated materials is the source for debris flow. Geomorphological evidences of deeper deformations are currently under investigation.

Geomorphology Hazard Assessment of Giampilieri and Briga River Basins After the Rainfall Event on the October 1, 2009 (Sicily, Italy)

Mud and debris flows constitute a serious threat for several Italian regions as attested by recent several disasters attributable to such phenomena. The adoption of effective mitigation measures is complicated by the difficulty in predicting spatial and intensity features of future events.

Multi-Temporal and Quantitative Geomorphological Analysis on the Large Landslide of Craco Village (M118)

The village of Craco (Basilicata, Italy), is being affected by severe landslide phenomena mainly due to the geological and geomorphological setting of the area. The village has been interested by a progressive abandon of the population after the occurrence in the time of landslides and earthquakes that caused the disruption of large portions of the urban settlement. Several landslide typologies can be recognized in the area: rock-falls in the upper part of the hill, rotational and translational earth slides, earth-flows, rock lateral spreading. The main purpose of the paper is to reconstruct the evolution of the geological and morphological dynamics acting on the southern slope of Craco, where the largest landslides occurred in the past.

Heuristic Method for Landslide Susceptibility Assessment in the Messina Municipality

October 1st 2009 a heavy rainfall caused more than one thousand debris flows in two small basins south of Messina town (North–East Sicily, Italy). After the disaster Messina Municipality entrusted the risk assessment of its whole territory to a geomorphology and GIS team, led by ENEA, that applied and improved a heuristic method aimed at the identification of the areas prone to landslide triggering, based on the recognition of physical and dynamical characteristics of phenomena. This landslide susceptibility method is a GIS based process that consists in four steps: Field Survey, Site Analysis, Macro-Area Analysis and Susceptibility Analysis. Through the Field Survey of natural and anthropic conditions of past and recent phenomena a landslide inventory is generated, and each thematic map is stored in a GIS database. In the Site Analysis a univariate statistical analysis of the inventory leads to classify each causative factor as a discriminating parameter (condition necessary for slope instability) or as a predisposing factor (condition that works together in worsening slope stability). In the Macro-Area Analysis the GIS overlay of all thematic maps is performed to recognize, in surrounding areas, features similar to those of past events. Finally a susceptibility function runs the weighted sum of Predisposing Factors in zones where all Discriminating Parameters are present, deriving the Susceptibility Map. The here discussed heuristic GIS method allows the integration of multidisciplinary knowledge, both quantitative and qualitative, thus exploiting field experience.

Debris Flow Risk Assessment in the Aguas Calientes Village (Cusco, Perù)

In this paper a landslide risk assessment in the area of Aguas Calientes village (Machu Picchu, Cusco, Peru) is applied. A study carried out into a capacity building project (FORGEO) was focused on localising source areas and runout of debris flows triggered by heavy rainfall in the Alcamayo catchment and on assessing debris flow intensity. Starting from an inventory of several previous debris flows occurred in the area, an evaluation of the local predisposing parameters to these events was used as input for susceptibility and hazard GIS based analysis. Empirical formulas reported in the literature were adapted to the research area context to estimate the runout of potential events. An analysis of exposure of structures and infrastructures was also performed during the project and high residual risk conditions were found for the Aguas Calientes village. These results may aid local authorities involved in land use planning, management policies and landslide risk reduction.

Landslide Hazard Assessment Project in the Messina Municipality Area (Sicily, Italy)

In the last 4 years Messina Municipality has been hit by rainfall events that triggered a great number of debris flows. Due to 2009 event ENEA started landslide hazard researches in the south of the Municipality. Messina territory (210km2) is located at the NE culmination of Peloritani Range, formed by seven metamorphic Units covered by late orogenic terrigenous formations and by Plio-Pleistocene deposits. Steep slopes lead to high erosion rates, that increased in last years because of intense rainfall. The first step of the hazard assessment method is an inventory of landslides, followed by the detection of landslide parameters. Through GIS analysis of this parameters landslide susceptibility is assessed. Geomorphological analysis allows evaluating the runout and energy of the future events. Rainfalls data analysis allows definition of triggering threshold for the area. These parameters will be tested in a test site field for the measurement of soil saturation.

Rockfalls Monitoring Along Eastern Coastal Cliffs of the Favignana Island (Egadi, Sicily): Preliminary Remarks

Favignana island (Sicily, Italy) is a historical and environmental attraction site frequented by tourists during the long warm season of the year. For several centuries the calcareous sandstone outcropping in the east side of the island has been extracted and used as building stone. Actually the quarries and the caves are undergoing to erosional and gravitational processes that are influencing the touristic use. As well as putting at risk the safety of people attending the area, the diffused rock falls are likely to jeopardize sites of great anthropological value that, once destroyed, can no longer be reconstructed. An integrated monitoring project of the cliffs is aimed to identify the most active areas and to provide support to the local government’s policies in the implementation of mitigation measures. If adequate measures will be taken in the future, operators and users of the tourist circuit will have the opportunity to enjoy these amazing areas with lower level of landslide risk.

The Role of FPGA-Based Architectures in the Control Room Modernization Process: Preliminary Results of a Case-Study

In the context of a plant modernization, developing digital I&C technology is a crucial challenge to improve nuclear plants safety and reliability. Digital technology is usually oriented to achieve functions such as plant control, monitoring, simulation and protection in a user-friendly way. On the other hand, the analogue instrumentation implemented in the so-called “old generation consoles” is often essential and not immediately or completely replaceable. As a consequence, the interaction between the analogue and digital data seems to be a necessary step before starting the digital I&C licensing process. The fundamental difference between analogue and digital technologies relies on the fact that digital logic is based on processors, hence it can be customized by programming its software. However, introducing new code can result in a new set of potential failure modes to be accounted for. As a consequence, original analogue systems mostly assure a higher level of protection with respect to digital systems. In this scenario, a benefit could arise from the use of Field-Programmable Gate Arrays (FPGAs), based on a hardware architecture whose routing is made via software, thus resulting in a variety of possible tasks. FPGAs’ employment ranges from automotive and industrial applications, ASIC prototyping, software defined radios, radar, image and DSP. In this work a critical analysis of FPGA fundamental features and potentialities in nuclear plant I&C design is achieved in conjunction with some practical applications. Troubles arising from coping with processor-based system are presented and compared to benefits and potentialities offered by FPGA real-time architectures: indeed, FPGAs comprise a higher number of logic blocks and functions able to manage parallel processes with self triggering, and provided into a “non-frozen” structure but easily reconfigurable. This characteristics of being in-system programmable (ISP), i.e. a device capable of being programmed while remaining resident in a high-level system, can be considered as the main advantage of using FPGA. The employment on a large scale is also justified by its high determinism and testability, leading to high performance in terms of reliability. As a case-study, we propose a supervisory full-digital system that has been designed, realized, tested and validated implementing a FPGA architecture to be used in parallel to the TRIGA nuclear reactor RC-1 analogue console at the ENEA Casaccia Research Centre in Rome. We report on the design choices, and on pros and cons of using FPGA instead of the classical processor-based architectures. This preliminary apparatus has been developed using the LABVIEW environment and FPGA-based technology, an appropriate tool to get across simulation to Hardware-in-the-Loop (HIL) technique allowing to move on production from prototyping.Copyright

Susceptibility to Sea Cliff Failures at Cala Rossa Bay in Favignana Island (Italy)

Since the Roman Age and until the last century, an intense quarry activity took place at Favignana Island (Sicily, Italy) that significantly changed the morphology of the eastern part of the Island that is characterized by sea cliffs. This mining activity produced an extensive network of open air quarries, underground quarries and tunnels, locally named “Pirrere”, that are hosted into Pleistocene calcarenites. The sea cliffs of the eastern coast of Favignana Island were also influenced by the past mining activity and they are currently affected by diffused instabilities as proved by the wide block-size talus distributed all along the coast. A more detailed slope stability analysis was performed on a sea cliff located in the western sector of Cala Rossa Bay. To constrain such an analysis, engineering-geological field and remote surveys were carried out to reconstruct the geological setting as well as to characterize the mechanical properties of the rock mass. Finally a 3D model of the joints net was obtained. Based on geometrical and geomechanical joints features, a kinematic-compatibility analysis for rock landslide mechanisms (i.e. planar sliding, wedge sliding and toppling) allowed to identify 78 rock blocks particularly prone to failure. Considering hydrostatic pressure related to joints saturation condition as well as pseudostatic forces due to earthquake, 12 hazard scenarios were considered as reliable for the sea cliff area. The obtained results demonstrate that: (i) planar and wedge sliding are more suitable landslide mechanisms respect to toppling; (ii) the SE part shows higher susceptibility to failures; (iii) water pressures within joints play a more destabilizing action respect to earthquakes. Such an analysis represents a preliminary contribution to manage protection strategies for reducing the landslide risk in the touristic site of Cala Rossa bay and to preserve the unique heritage of the “Pirrere” quarries.