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The study aims to evaluate ground deformations in a vast area characterized by the coexistence of intense anthropic activities and offshore natural gas production. Onshore subsidence can be studied by GNSS, InSAR, high precision leveling and extensometers that provide broad datasets for a fully integrated description of the phenomenon. At present, seafloor subsidence monitoring cannot be carried out by high precision leveling, and GNSS is the only reliable method, implemented by means of permanent stations installed on offshore hydrocarbon production facilities. In the Northern/Central Adriatic Sea gas production platforms, GNSS data are recorded since more than 15 years, allowing to estimate not only the average subsidence of the platform/seafloor, but also possible velocity variations due to underground fluids withdrawal. This study shows the comparison of 22 offshore GNSS permanent stations located in the study area. Raw data have been processed with two different software packages (GIPSY-OASIS and GAMIT-GLOBK) based on different approaches and considering different boundary conditions of geodetic and/or modeling nature. Main results point out the high accuracy of the GNSS technology considering also the impact of data processing. Finally, at selected permanent stations we also performed a comparison of results obtained by GNSS, InSAR and high precision leveling.

GNSS technology has become widely used for monitoring purposes. The high precisions nowadays available have made the technique suitable also for the monitoring of structures that are usually affected by very small displacements. In this work we investigate the issue concerning the monitoring of a tall structure such as the Garisenda tower, which lay in the Bologna city centre, by using GNSS data gathered by a permanent station placed on its top. We consider the need to investigate the variations in the leaning of the structure, therefore also the position of the ground at the bottom of the structure should be known. Unfortunately it is not possible to place a GNSS receiver under a tall structure in urban context because of the too poor sky visibility. A solution would be to choose another permanent station located as close as possible assuming its behaviour coherent with the ground under the monitored structure. This hypothesis has proven not to be verified in the analysed case, where four permanent stations located within few kilometres far from the Garisenda tower were available. Therefore a strategy to combine data from the five permanent stations using a uniform strain model was developed in order to define a reference to which compare the positions given by the GNSS sensor placed on the top of the tower. The impact of such strategy will be shown and discussed in terms of mean variation of the leaning of the tower over a period of about four years.

Il litorale emiliano-romagnolo costituisce un'importante ricchezza naturalistica e socio-economica a livello nazionale, per questo motivo la difesa della costa è tra i temi d’interesse dell’azione di governo della Regione Emilia-Romagna e di diversi Enti locali. La conoscenza dello stato attuale della costa e della sua evoluzione nel tempo sono tra i requisiti fondamentali per una corretta definizione delle politiche di salvaguardia del patrimonio paesaggistico – ambientale e di tutela del quadro economico della fascia costiera. Per questo motivo da diversi decenni l’Agenzia regionale per la prevenzione, l’ambiente e l’energia dell’Emilia-Romagna (Arpae), su incarico della Regione, svolge attività di monitoraggio per l’individuazione delle dinamiche costiere ed il riconoscimento dei vari fattori incidenti sulla dinamica litoranea e le criticità presenti. In questo ambito si inseriscono le periodiche campagne di rilievo topografico e/o batimetrico della spiaggia emersa e dei fondali antistanti. Queste misure sono indispensabili per monitorare la continua evoluzione del litorale dovuto al fenomeno dell’erosione costiera e decidere quali politiche adottare per la sua conservazione nel tempo. Una delle tecniche di conservazione è il ripascimento, tecnica che prevede l’apporto di sabbia proveniente da accumuli litoranei e giacimenti sottomarini nelle zone più colpite dall’erosione. Per svolgere adeguatamente questa attività è fondamentale conoscere la quantità di materiale eroso dal mare e questo valore viene solitamente stimato confrontando tra loro i rilievi topografici e/o batimetrici eseguite nella medesima area in tempi diversi. Al fine di poter correttamente confrontare rilievi eseguiti in periodi diversi, e anche da ditte differenti, è necessario definire in modo univoco un sistema di riferimento a cui riferire tutti i rilievi. Tale sistema di riferimento è bene che sia adeguato per precisione e materializzazione alle tecniche di rilievo che si intendono utilizzare. Per questo motivo l’Unità Mare Costa di Arpae, per conto della Regione Emilia-Romagna, ha riscontrato la necessità di costruire una struttura geodetica di riferimento per le future attività di monitoraggio lungo il litorale emiliano–romagnolo. In questo lavoro vengono descritte le varie fasi che hanno condotto alla creazione di questa struttura di riferimento denominata Rete Geodetica Costiera (RGC), realizzata dall’Unità Mare Costa di Arpae in collaborazione con il Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali (DiCAM) dell’Università di Bologna.

In the last decade, a number of correction services for global navigation satellite systems (GNSS) precise positioning have been developed, mainly for offshore applications, based on a precise point positioning (PPP) real-time processing. These allow receiving corrections without the need for an internet connection or reference benchmarks around the survey area. In the paper, we tested the Atlas correction service implemented in a Stonex S900A machine (Monza, Italy), with the purpose to verify its performances under optimal operational conditions and in the practical case of a land survey on several benchmarks along the Adriatic coast. The data analysis focused on: accuracy with respect to the reference frame, repeatability of the coordinates considering short and long acquisition periods, time to initialize the survey, and reliability of the formal errors provided by the instrument. The system confirmed the declared performances in most cases and is shown to be a viable alternative to other GNSS techniques also for land surveys where no obstacles affect the sky visibility.

Until a few years ago, a precise survey was only possible using global positioning system (GPS) and Global'naja Navigacionnaja Sputnikovaja Sistema (GLONASS) constellations, but the result was not guaranteed under conditions of poor sky visibility, as in urban canyons. Currently, the number of Global Navigation Satellite System (GNSS) satellites in orbit has strongly increased thanks to the great evolution of the Galileo and the Beidou constellations. In this paper, we investigate the impact of using different constellations and their combinations, in static positioning with the classical differencing approach. For this purpose, two distinct baselines of different lengths (10 and 60 km) were processed using commercial software over a period of one year (2018.24-2019.24). Data were acquired by permanent stations belonging to the European Permanent Network (EPN) network providing 24-h observing sessions. Two datasets were tested, one consisting of 24-h Receiver Independent Exchange Format (RINEX) files and the other considering only 2-h sessions of data acquisition. In both cases, a one-year-long time span has been considered. The baselines were processed considering each of the four GNSS constellations and a series of combinations, for a total of eight solutions. Results have been evaluated looking at the accuracy and repeatability of the coordinates, together with the main constellation parameters. During the analyzed period the number of contemporary visible satellites of the BeiDou constellation was still too poor over the considered area, and therefore this constellation did not provide comparable precisions in respect to the others. Positioning precision provided by the Galileo constellation has shown to be very close to those given by GPS or GLONASS, with a significant difference only on the height component, especially in the case of processing 2-h data. As for 24-h observing sessions, the use of multiconstellation observables actually leads to small improvements in precision with respect to the use of GPS data only, mainly appreciable considering the vertical component. The GPS-Galileo combination gives quite the same performances of the GPS-GLONASS one, but it can potentially take advantage of the integrity message provided by the European constellation.

GNSS real-time techniques and UAV photogrammetry can be alternative methods for the monitoring of sand beaches. This activity is particularly important in environments such as the Emilia-Romagna coastline. In this paper, two couples of surveys (year 2019 and 2020) performed using GNSS or a low-cost UAV equipment over a common area were compared in order to analyse: point-wise height differences, profile shapes along defined sections, and volumes variations over time. Both surveys were aligned to the same reference benchmark through GNSS measurements. The highest discrepancies between the two surveying methods (tens of cm) were found in vegetated areas and along the shoreline, otherwise, the height differences are mainly within the 10 cm level. In terms of volumes, excluding the most critical areas, differences close to zero can be found. Obtained results show that GNSS and UAV photogrammetry provides similar results, at least for quite flat terrains and when decimetre-level accuracy is required.

The relatively poor spatial resolution of thermal images is a limitation for many thermal remote sensing applications. A possible solution to mitigate this problem is super-resolution, which should preserve the radiometric content of the original data and should be applied to both the cases where a single image or multiple images of the target surface are available. In this perspective, we propose a new super-resolution algorithm, which can handle either single or multiple images. It is based on a total variation regularization approach and implements a fully automated choice of all the parameters, without any training dataset nor a priori information. Through simulations, the accuracy of the generated super-resolution images was assessed, in terms of both global statistical indicators and analysis of temperature errors at hot and cold spots. The algorithm was tested and applied to aerial and terrestrial thermal images. Results and comparisons with state-of-the-art methods confirmed an excellent compromise between the quality of the high-resolution images obtained and the required computational time.

We provide a dataset of 3D coordinate time series of 37 continuous GNSS stations installed for stability monitoring purposes on onshore and offshore industrial settlements along a NW-SE-oriented and ~100-km-wide belt encompassing the eastern Italian coast and the Adriatic Sea. The dataset results from the analysis performed by using different geodetic software (Bernese, GAMIT/GLOBK and GIPSY) and consists of six raw position time series solutions, referred to IGb08 and IGS14 reference frames. Time series analyses and comparisons evidence that the different solutions are consistent between them, despite the use of different software, models, strategy processing and frame realizations. We observe that the offshore stations are subject to significant seasonal oscillations probably due to seasonal environmental loads, seasonal temperature-induced platform deformation and hydrostatic pressure variations. Many stations are characterized by non-linear time series, suggesting a complex interplay between regional (long-term tectonic stress) and local sources of deformation (e.g. reservoirs depletion, sediment compaction). Computed raw time series, logs files, phasor diagrams and time series comparison plots are distributed via PANGAEA (https://www.pangaea.de)., Measurement(s) ground deformation process Technology Type(s) GPS navigation system Factor Type(s) GNSS station • temporal interval Sample Characteristic - Location Adriatic Sea Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.13034372

Emilia-Romagna coast consists of 110km of low and sandy beaches, which are particularly exposed to coastal erosion. Among different defence projects, the current trend is going towards soft interventions, such as beach nourishment. In 2016, the third intervention of “Security projects through submarine sand nourishment for critical areas of the regional coastline” was completed. This paper concerns the analysis of the eight coastal stretches involved by this project. A Monitoring Plan for the years 2017 and 2018 has been arranged to evaluate the evolution of each beach and the intervention effectiveness. Morphological variations in terms of shoreline, height, beach profiles and accumulated or eroded volumes have been evaluated by comparing surveys performed on each beach at different times. In the specific case of this project, the presence of a new geodetic infrastructure along Emilia-Romagna coast, the Coastal Geodetic Network (RGC), ensured advantages to surveys’ realization. All the observed results show good evolutions from a general point of view, even if it is difficult to deduce a single trend for the eight beaches. On the other hand, the increasing availability and spatial coverage of data from monitoring surveys could provide powerful instruments for coastal studies. This paper confirms monitoring activities as an efficient way to evaluate beaches’ morphological changes and coastal defence intervention effectiveness.

The Garisenda tower in Bologna is a symbol of the city and one of the most valuable heritages of the medieval age. The tower is leaning markedly since the XIV century because of a foundation failure and its stability is nowadays under constant monitoring through many sensors. In 2013 a GNSS permanent station was installed on the top of the tower with the aim to test the satellite technology for this particular kind of structural monitoring. Being the leaning of the Garisenda the subject of the investigation and being the sensor placed on its top, one fundamental hypothesis is the stationarity of the ground under the tower with respect to the reference system used for the GNSS measures. This hypothesis has demonstrated to be unreliable considered the high precision of the survey and the Earth crust dynamics, therefore opening interesting issues concerning the reference to be used in such kind of monitoring. The proposed solution rely on a strain model of the area surrounding the Garisenda tower, estimated using data from four other GNSS permanent stations already present in Bologna. The method is described and results are shown in terms of trend over time of the Garisenda's leaning. Nevertheless, the methodology can be generalized for every kind of structural monitoring based on GNSS data for which millimetre level of precision is needed.

The present Italian kinematic field has been estimated by a network of about 780 GNSS permanent stations. The daily observations acquired with a sampling rate of 30 seconds from January 01, 2001 to December, 31, 2015 have been analysed through the GAMIT/GLOBK software, adopting a distributed procedure. The position component time series (North, East and Vertical) are analysed in order to obtain a reliable estimation of: average velocity, amplitude and periods of seasonal signals, dimension of instrumental and/or seismic steps and noise. These characteristics have been studied in order to verify possible correlations with some characteristics of GNSS installation and/or natural and anthropogenic phenomena present in some areas. The average velocity of the 414 sites characterized by a time span greater than 2.5 years and an efficiency greater than 50% have been used in order to estimate the present kinematic pattern in the Italian peninsula and surrounding areas. The horizontal velocity field is characterized by some interesting features that are compatible with the long term deformation pattern deduced from geological observations. The vertical velocity field is characterized to an heterogeneous distribution probably due to the strong influence that anthropogenic activities have on this component .

GNSS technology is still not considered as a suitable method for structural monitoring because of its relatively low precision, despite the increase in acquisition frequencies. This paper aims to evaluate a strategy for filtering a daily kinematic GNSS solution using a movement smoothing model based on the observations of previous days, so as to obtain a less scattered solution. A test was conducted with a permanent GNSS station located on top of the medieval Garisenda tower in Bologna (Italy), as it is an important part of the city’s cultural heritage and a reliable test site. Because of the presence of the adjacent Asinelli tower, which is taller than the Garisenda, sky visibility is not optimal here, and for this reason a particular sequential filtering can be adopted in order to obtain more accurate solutions. The test was performed using RTKLIB software to calculate 1 Hz baselines between the test station and a master one located on a stable area about one kilometer away from the tower. In order to obtain reliable results, several variables were considered both in the data processing phase and in defining the filter. All results are reported and discussed in detail in the paper. The test results reveal a reduction in scatter of about 20% in the filtered kinematic time series, especially in weaker geodetic components.

GNSS is one of the most used technique to monitor Reference Frame, Plate motion, Landslides, Structures, etc... Data acquired by GNSS satellites have to be processed considering models, approaches and strategies which are influencing the final results and, if wrongly done, may introduce biases. In this work the Precise Point Positioning (PPP) approach for GNSS data processing has been considered and investigated. As well-known PPP is faster and more flexible compared to the carrier phase differenced approach. On the other hand the differenced approach has been generally characterized by a better repeatability, especially for quite small baselines. Until few years ago one of the major limits of PPP was the impossibility to resolve the ambiguity as integer but nowadays some methods are available to resolve this aspect expecting an increasing of the precision. Starting from two subsets of the IGS Tracking network (one located in Europe and composed by 16 stations around Italy and another one, composed by 9 stations and located in Antarctica) processed respectively for 11 and 3 years, the impact of some data processing strategies has been considered. For both the networks different kind of solutions has been obtained, each one using more refined strategies, considering the ambiguity phase resolution, the possibility to frame the solution using global transformation parameters (provided by JPL), or framing the solution using regional transformation parameters. Furthermore, with the aim to evaluate in polar regions the impact of different tropospheric models in GNSS solutions the Antarctica network has been processed also considering the Vienna Mapping function instead of the Niell MF. The results will be synthetized by two parameters which are accuracy and precision: accuracy has been obtained comparing each solution with the reference ITRF2008 solution (ITRF2008-TRF-IGS.SNX.gz) and precision has been estimated considering the scattering of the solutions (time series) around a straight line obtained by a least square approach.

This study was carried out by the SEADOG Research Center at Politecnico di Torino (Italy). The pur- pose of this work was to evaluate which complexity degree would be required to reliably approach a subsidence study for different scenarios. The study was based on sensitivity analyses which were performed using a series of 3D synthetic numerical models of which the structural characteristics and geological and mechanical properties were based on available public data of onshore and offshore hydrocarbon fields in Italy. An array of simulations, both one-way and two-way coupled, were carried out to assess the magnitude and extension of subsidence potentially induced by hydro- carbon production. The results allowed the calculation of subsidence indices defined as the rate of compaction propagation (i.e., the ratio between the maximum surface displacement and the maximum reservoir compaction) and as the rate of volume loss (i.e. the ratio between the volume of the subsidence bowl or cone and the volume variation of the reservoir). These indices together with the degree of the underground systems’ heterogeneity led to the definition of the Intact Rock Qualitative Subsidence Index (IRQSI), upon which the needed complexity degree of a subsidence study can be discerned.