Matteo Del Soldato

Badland susceptibility assessment in Volterra municipality (Tuscany, Italy) by means of GIS and statistical analysis

Badlands can be defined as complex and peculiar types of erosional formations that develop in clayey environments and are mainly favoured by lithological and topographic features, as well as by markedly seasonal climate. This work aims at assessing badland susceptibility in Volterra municipality located in Tuscany region (Italy) by means of bivariate statistical analysis implemented in a geographic information system. The Volterra municipality is affected by intense soil erosion processes, including rill and gully erosion usually turned out as badland forms, mostly occurring on Pliocene–Pleistocene clayey sediments. Firstly, an inventory of 234 badland areas was produced on the basis of an available pre-existing database, integrated with the interpretation of aerial photographs and supported by a field survey. Badlands were distinguished in type A and type B, according to different evolutional stage, vegetation presence and consequently different landforms. Then, nine geoenvironmental factors supposed to be predisposing for badland occurrence were chosen and combined with the spatial frequency of badland areas derived from the inventory, through Information Value Statistic approach. The result was a badland susceptibility map that highlights a strong control of lithology, slope gradient and land use in conditioning badland development in the investigated area. The effectiveness of the performed model was demonstrated by a validation test computed through a receiver operating characteristics analysis. The outcomes of this work provide an updated badland database that is useful for soil erosion management and further land-use planning within the Volterra municipality.

Continuous, semi-automatic monitoring of ground deformation using Sentinel-1 satellites

We present the continuous monitoring of ground deformation at regional scale using ESA (European Space Agency) Sentinel-1constellation of satellites. We discuss this operational monitoring service through the case study of the Tuscany Region (Central Italy), selected due to its peculiar geological setting prone to ground instability phenomena. We set up a systematic processing chain of Sentinel-1 acquisitions to create continuously updated ground deformation data to mark the transition from static satellite analysis, based on the analysis of archive images, to dynamic monitoring of ground displacement. Displacement time series, systematically updated with the most recent available Sentinel-1 acquisition, are analysed to identify anomalous points (i.e., points where a change in the dynamic of motion is occurring). The presence of a cluster of persistent anomalies affecting elements at risk determines a significant level of risk, with the necessity of further analysis. Here, we show that the Sentinel-1 constellation can be used for continuous and systematic tracking of ground deformation phenomena at the regional scale. Our results demonstrate how satellite data, acquired with short revisiting times and promptly processed, can contribute to the detection of changes in ground deformation patterns and can act as a key information layer for risk mitigation.

A new approach for landslide-induced damage assessment

ABSTRACT The accurate evaluation of landslide-induced damage is a necessity for planning of proper and effective mitigation measures. It requires the implementation of field investigations to identify structural failures to more effectively trace landslide boundaries. Many methods have been proposed to classify landslide-induced damage of buildings. The existing methods demonstrate several advantages and drawbacks depending on the parameters considered, as lack of some important features and difficulties in applicability. A new classification approach of landslide-induced damage of facilities is proposed, which specifically focuses on assessing of damage degree and its relationship to the ground motion intensity and impact severity. The new approach is designed in two steps: a chart utilized during surveys to quantify cracks on structures and ground surface; an a posteriori ranking of structures performed using a cell-grid matrix. Furthermore, a damage recording scheme useful for field surveying is proposed. This approach considers several parameters derived from different existing methodologies by smoothing out drawbacks and homogenizing the considered features. The resulting approach provides a new procedure of landslide-induced damage assessment adoptable in case of private dwellings, as it does not require internal accessibility, and it is exploitable for different landslide events and for different kinds of structures and facilities.

A multi-sensor approach for monitoring a road bridge in the Valencia harbor (SE Spain) by SAR Interferometry (InSAR)

This project was developed in the framework of the DORIS project (ground deformation risk scenarios: an advanced assessment service) funded by the EC-GMES-FP7 initiative (grant agreement 423 no. 242212) and by the Spanish Ministry of Economy and Competitiveness (MINECO) and EU FEDER, under project TIN2014-55413- C2-2-P. ALOS PALSAR images were provided by the project JAXA- 1209. The authors thank the University of Florence for founding Matteo Del Soldato for the PhD abroad period of research to the Department of Civil Engineering of the University of Alicante and the Autoridad Portuaria de Valencia for its kindly support.

Assessment of landslide-induced damage to structures: the Agnone landslide case study (southern Italy)

Landslides are among the most important and frequent natural calamities that cause severe socio-economic and human losses. After earthquakes, landslides are responsible for the greatest number of casualties and the largest amount of damage to man-made structures. On average, southern Italy is affected by a high spatial density of landslides due to its complex geological setting, which often predisposes it to slope instability phenomena under both natural and anthropogenic influences. Structurally complex formations are widespread in the southern Apennines and are characterized by high heterogeneity and very poor mechanical properties. Thus, these formations represent one of the main factors contributing to the predisposition of slopes to landsliding. In this paper, landslide-induced damage was investigated and analyzed in an area within the municipality of Agnone (Molise region), which is affected by a complex landslide that involves a structurally complex formation. The approaches used were based on six different methods that have previously been described in the literature, and a comparison of the results was made. Data regarding the damage, which consists largely of cracks observed in buildings and at the ground, were compiled through field surveys. The results were critically analyzed to note the advantages and constraints of each classification scheme. The aim of the work was to apply and compare different approaches in order to test the best and most accurate procedures for assessing damage due to landslides at the scale of individual buildings as well as to provide an objective assessment of the degree of landslide damage to structures and facilities.

Evaluation of Building Damages Induced by Landslides in Volterra Area (Italy) Through Remote Sensing Techniques

This paper aims to detecting terrain movements in landslide-affected and landslide-prone zones and their damaging effects on the urban fabric. The case study is the Volterra area in Tuscany region (Italy), covers about 20 km2 and is extensively affected by diffuse slope instability. Firstly, the spatial distribution and types of the landslides were studied on the basis of the geological and geomorphological setting coupled with a geotechnical monitoring. Secondly, satellite SAR (Synthetic Aperture Radar) images acquired by ENVISAT and COSMO-SkyMed sensors respectively in 2003–2009 and 2010–2015 and processed with Persistent Scatterer Interferometry (PSI) techniques, were exploited. In particular, these satellite radar data combined with thematic data and in situ field surveys allowed the improvement of the geometric and kinematic characterization of landslides, as well as allowing a deformation and damage assessment to be undertaken on built-up zones. The classification of damage degree and building deformation velocity maps of the study area were also evaluated through PSI displacement rates. Furthermore, as a single building-scale analysis, maximum differential settlement parameters of some sample buildings were derived from radar measurements, and then cross-compared with constructive features, geomorphological conditions and with field evidences of known landslide areas. This work allowed the correlation of landslide movements and their effects on the urban fabric and provided a useful stability analysis within future risk mitigation strategies.

Subsidence Evolution of the Firenze–Prato–Pistoia Plain (Central Italy) Combining PSI and GNSS Data

Subsidence phenomena, as well as landslides and floods, are one of the main geohazards affecting the Tuscany region (central Italy). The monitoring of related ground deformations plays a key role in their management to avoid problems for buildings and infrastructure. In this scenario, Earth observation offers a better solution in terms of costs and benefits than traditional techniques (e.g., GNSS (Global Navigation Satellite System) or levelling networks), especially for wide area applications. In this work, the subsidence-related ground motions in the Firenze–Prato–Pistoia plain were back-investigated to track the evolution of displacement from 2003 to 2017 by means of multi-interferometric analysis of ENVISAT and Sentinel-1 imagery combined with GNSS data. The resulting vertical deformation velocities are aligned to the European Terrestrial Reference System 89 (ETRS89) datum and can be considered real velocity of displacement. The vertical ground deformation maps derived by ENVISAT and Sentinel-1 data, corrected with the GNSS, show how the area affected by subsidence for the period 2003–2010 and the period 2014–2017 evolved. The differences between the two datasets in terms of the extension and velocity values were analysed and then associated with the geological setting of the basin and external factors, e.g., new greenhouses and nurseries. This analysis allowed for reconstructing the evolution of the subsidence for the area of interest showing an increment of ground deformation in the historic centre of Pistoia Town, a decrement of subsidence in the nursery area between Pistoia and Prato cities, and changes in the industrial sector close to Prato.

From ERS 1/2 to Sentinel-1: Subsidence Monitoring in Italy in the Last Two Decades

The use of InSAR (Interferometric Synthetic Aperture Radar) products has greatly increased in the last years because of the technological advances in terms of both acquisition sensors and processing algorithms. The development of multi-interferogram techniques and the availability of free SAR analysis tools has significantly increased the number of worldwide applications of satellite measurements for mapping and monitoring geohazards. InSAR techniques excel in determining ground deformation in urban areas, where the coherence of the radar images is high, and the obtainable results are particularly reliable. Thus, measuring urban subsidence has always been one of the main targets of the InSAR analysis. In this paper, we present a brief review on the applications, in the last decades, of both single and multi-interferogram techniques to monitor ground lowering in urban areas along the Italian Peninsula. Because of its geological context, Italy is prone to slow natural subsidence phenomena sometimes aggravated and accelerated, especially along the coasts and in urbanized areas, by anthropogenic factors (i.e. groundwater overexploitation, consolidation in recent urban expansion, geothermal activities). The review will show how the interferometric data allowed the scientific community to increase the knowledge of the phenomena, map their spatial distribution and reconstruct their temporal evolution. The final goal of the review is to demonstrate the added value of InSAR data in supporting groundwater management and urban development in Italy.

Comparison of different approaches for landslide-induced damage assessment: the case study of Agnone (southern Italy)

Landslides constitute one of the most important geo-hazards affecting southern Italy. Particularly, in this area slope movements have over time caused relevant socio-economic losses and, in some cases, also casualties. Prevention, prediction and monitoring of landslide phenomena play a key-role to avoid or minimize their effects. In this work, damage suffered by facilities located within and surrounding a deep-seated landslide were classified through three different approaches. The investigated area is located in the municipality of Agnone (Molise region, central-south Italy), which is strongly affected by landslide processes. A main landslide event that occurred in 2003 is still active, exhibiting slow and intermittent movements. In this contribution, three different approaches for landslide-induced damage assessment are compared and their discrepancy discussed, highlighting the benefits and drawbacks of the different approaches. Finally, the future development of a new methodology and classification for infrastructures damage assessment is evaluated, merging the procedures used in this work.