Gianluca Marcato

IRTROCK: A MATLAB toolbox for contactless recognition of surface and shallow weakness of a rock cliff by infrared thermography

Infrared thermography (IRT) can be used in remote recognition of potential weakening features of a rock cliff like shallow holes, high fracturing, moisture or material inhomogeneities, providing useful information for the corresponding rock mass geo-engineering characterization. A method aimed at such a recognition is proposed here together with its MATLAB implementation (IRTROCK package). It is based on the acquisition of a series of IRT images during the night-time cooling of a rock mass and on the search for possible anomalous thermal transients. The IRT alone is unable to completely characterize a rock mass; a meaningful interpretation of the results requires a geological on-contact survey or other on-contact or contactless techniques. Nevertheless, the results obtained in a portion of the cliff, where a detailed study with other techniques has been carried out, can be advantageously extended to the whole cliff. Moreover, the IRT measurements can be easily and safety repeated over time to evaluate possible changes that affect the studied rock mass. The effectiveness of the proposed approach has been verified in two test sites.

A web-based platform for automatic and continuous landslide monitoring: The Rotolon (Eastern Italian Alps) case study

In the Small Dolomites group (Eastern Italian Alps), the Rotolon catchment is affected by a landslide that historically threatened the nearby village of Recoaro Terme. After the last re-activation on November 2010, the need to deploy devices to monitor deformations on the unstable slope became of paramount importance. This paper deals with the methodology, the techniques and the integrated services adopted for the design and the realization of a web-based platform for automatic and continuous monitoring of the Rotolon landslide. The choice of a web environment simplifies data collection, while a remote control permits technical maintenance and calibration on instruments and sensors in the field. Data management is straightforward on a single server, with the dataset being continuously updated. There is a user-friendly web interface which allows a practical up-to-date solution for decision-makers. This web-based monitoring platform represents the first step in the implementation of a complete early warning system. We design a multi-source and web-based platform for automatic and continuous monitoring.A user-friendly web interface allows a practical up-to-date solution for decision-makers.A better knowledge of the processes improves the quality of research.The framework is open and supported for custom requests.

Integration of laser scanning and thermal imaging in monitoring optimization and assessment of rockfall hazard: a case history in the Carnic Alps (Northeastern Italy)

Rock cliff monitoring to evaluate related rockfall hazard requires a deep knowledge of the geometry and kinematics of the rock mass and a real-time survey of some key features. If a sedimentary rock system has sloping discontinuity planes, an open joint could become a potential sliding surface and its conditions must be monitored. It is the case of the Passo della Morte landslide (Carnic Alps, Northeastern Italy), where sub-vertical joints exist. Remote sensing techniques such as terrestrial laser scanning (TLS) and infrared thermography (IRT) allow a fast and efficient contactless geometrical and geomechanical examination of a rock mass. Therefore, they can be used to recognize those joints that require monitoring with on-site instrumentation such as extensometers and/or inclinometers, or also acoustic emission sensors, aiding the arrangement of monitoring systems which are generally quite expensive to install. Repeated IRT surveys would provide useful information about the evolution of unstable slopes, thus suggesting how the on-site monitoring system could be improved. Moreover, data gathered by TLS and IRT can be directly used in landslide hazard assessment. In the test site, an open joint was recognized together with a fair joint that could change in the next future. The results were validated by means of extensometer data.

Assessing the Effect of Mitigation Measures on Landslide Hazard Using 2D Numerical Runout Modelling

Landslide mitigation measures are used to reduce the risk affecting mountain communities. The quantitative estimation of the change or reduction in risk, after implementing mitigation measures, requires modeling of past events and the forward prediction of possible future occurences. However, the forward-prediction of landslide hazard is subjected to uncertainties due to the lack of knowledge on some key aspects like the possible source volume that can be triggered and model parameters that determine the landslide runout. In this study, a back-analysis of a debris flow event was carried out using MassMov2D to create a set of parameter ranges for forward-predicting runouts with mitigation measures. We approached the issue of uncertainty by systematically sampling parameters from wide ranges and running hundreds of different runout scenarios. Simulations from back-analysis were compared with the forward-predicted models to determine changes in the spread and intensity of debris flows affecting elements at risk (e.g. houses and roads). This study is a first step towards a quantitative risk assessment (QRA) being carried out within the EC FP-7 funded CHANGES network (Grant Agreement No. 263953).

Appraise the structural mitigation of landslide risk via numerical modelling: a case study from the northern Apennines (Italy)

The Ca’ Lita landslide is a large and deep-seated mass movement located in the northern Apennines, about 70 km west of Bologna (Northern Italy). It consists of a composite landslide that affects Cretaceous to Eocene flysch rock masses and chaotic complexes. Many of the sectors making up the landslide have resumed activity between 2002 and 2006, threatening some villages and an important road connecting several key industrial facilities located in the upper watershed. This paper presents the management of the emergency, dealing with the investigation campaigns (geological, geomorphological and LiDAR surveys, borehole drillings, seismic surveys), with the monitoring (in situ instrumentation) and with the design and construction of mitigation measures. The whole process, from landslide reactivation to date, has been modelled on a numerical basis with the finite difference code FLAC 2D, to assess the efficiency of the mitigation system and to propose further countermeasure works in different scenarios.

Isotopic features of precipitation and groundwater from the Eastern Alps of Italy: results from the Mt. Tinisa hydrogeological system

Abstract This study analyses water stable isotopes data collected from precipitation (one rain gauge) and groundwater outlets (seven occurrences and two springs) at Mt. Tinisa, in the Eastern Alps of Italy. Limestones and dolostones outcrop in the mountain relief, making up a single aquifer which feeds the monitored outlets with almost steady discharges. Lack of runoff in the streambeds throughout the whole year means that all meteoric water can be considered as recharging the aquifer. Sampling was undertaken during the periods 2005–2010 (precipitation) and 2014–2015 (groundwater) via monthly and two/three-monthly field-activities, respectively, which allowed a total of 138 water samples to be gathered and analysed. Results highlighted the presence of apparent isotopic anomalies in groundwater in comparison with meteoric water. The study demonstrates that the assessment of groundwater residence time and estimates of the mean monthly isotopic content in rainwater have been necessary to correctly compare the two isotopic datasets and relate the anomaly to the recharge time-window, occurring in the late autumn.

A new data assimilation procedure to develop a debris flow run-out model

Parameter calibration is one of the most problematic phases of numerical modeling since the choice of parameters affects the model’s reliability as far as the physical problems being studied are concerned. In some cases, laboratory tests or physical models evaluating model parameters cannot be completed and other strategies must be adopted; numerical models reproducing debris flow propagation are one of these. Since scale problems affect the reproduction of real debris flows in the laboratory or specific tests used to determine rheological parameters, calibration is usually carried out by comparing in a subjective way only a few parameters, such as the heights of soil deposits calculated for some sections of the debris flows or the distance traveled by the debris flows using the values detected in situ after an event has occurred. Since no automatic or objective procedure has as yet been produced, this paper presents a numerical procedure based on the application of a statistical algorithm, which makes it possible to define, without ambiguities, the best parameter set. The procedure has been applied to a study case for which digital elevation models of both before and after an important event exist, implicating that a good database for applying the method was available. Its application has uncovered insights to better understand debris flows and related phenomena.

Microseismicity and Acoustic Emission for Landslide Monitoring (North-East Italy)

In the North-East Italy, along the left side of the Tagliamento River, the area around an old road tunnel, named Passo della Morte, is involved in a Deep Seated Gravitational Slope Deformation. The most active blocks move up to 5 cm/year. The western part is moreover characterized by sub-vertical limestone layers and a dense system of discontinuities and fractures which create ideal conditions for rapid rock slope failure. High risk is represented by the interference with a national road and the Tagliamento River. A microseismicity and acoustic emission monitoring system was designed to monitor signals generated by rock slope deformation, in order to obtain informations about the rock slide mechanism, to recognize precursory phenomena or to provide precursory patterns. It is composed by a seismometer and a piezoelectric transducer. The amount of microseisms and acoustic emission detected by these instruments was analyzed and a close relation between them was found. The influence of precipitations in the rock mass deformation was evaluated and an evident correlation between precipitation and microseisms/acoustic emission was found.

The Rotolon Catchment Early-Warning System

Severe instability processes have affected the Rotolon catchment (Eastern Italian Alps) for long time. The first written proof of a landslide occurrence dates back to 1798. The last re-activation occurred in November 2010 when, after a cumulative rainfall of 637 mm in 12 days, a mass of approximately 320,000 m3 detached from the unstable slope and evolved into a debris flow that ran for about 4 km along the channel, threatening the villages along the stream. Since then, the design and the implementation of an early-warning system was considered of primary importance, in order to mitigate the risk for the valley inhabitants. A monitoring network consisting of 42 topographic benchmarks and 6 wire extensometers was installed and a warning system was deployed along four sections of the channel. The latter consists of 3 pendulum sections and a trip-wire section. Alarm sirens installed near the settlements are activated when the warning system is triggered by a debris-flow event, guaranteeing some minutes lead time to the local population. In this way the inhabitants could evacuate in time and reach safe areas thus reducing the risk. A Decision Support System (DSS) is also integrated with the deployed sensors, therefore technicians may support crisis response with a user-friendly instrument.

Applicability of Two Propagation Models to Simulate the Rotolon Earth-Flow Occurred in November 2010

Since 1920, recurrent collapses and earth-flows have interested the Rotolon torrent. The last one occurred in November 2010 when about 320,000 m3 detached in the triggering zone and flowed for more than 4 km. This paper deals with the calibration of two numerical models developed for the analysis of flow-like landslide propagation, both using SPH as computational method. For describing the flowing mass behavior it was adopted the Voellmy rheological model calibrated on the base of two LiDAR surveys captured just before and after the event.