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Speleothems show an array of shapes. Flowstones are commonly tabular sheet-like deposits, which cover cave floors and walls. They can procure detailed information about past hydrogeological conditions through their morphology, geochemical composition and stratigraphic properties, which in turn are related to the climate conditions at the surface. This is possible if the climate and environmental factors controlling the formation of these deposits are well understood. In Bossea Cave (north-east Italy), we have investigated highly symmetrical wavy flowstones that have never been described in detail before. These deposits show a cyclical repetition of sloped and sub-vertical layers, with knickpoints migrating downslope. This paper investigates the origin of these peculiar carbonate deposits, using: i) terrestrial laser scanning surveys; ii) petrographic observations; iii) oxygen and carbon stable isotope analyses; iv) hydrochemical monitoring data of feeding waters. According to these analyses, we have generated a genetic model that demonstrates: 1) laminar flow of CaCO3–rich water prevails during the deposition of the flowstone; in accordance, the final flowstone architecture does not appear to be influenced by random irregularities of the underlying bedrock substrate. 2) The peculiar morphology is inherited by ripples occurring in the flowing water films during carbonate deposition, which trigger the precipitation of regularly spaced CaCO3 deposits along the bedrock slopes. Because of these ripple-induced initial deposits, calcite then deposits as sloped and sub-vertical layers, giving rise to a wavy-like morphology. 3) Wavy calcite layers are only deposited after heavy rainfall events occurred within two to four consecutive rainy days (10 to 20 mm/hour during rainfall peaks; average rates between 3.5 and 7.0 mm/hour); in contrast, calcite deposition cannot occur during low rainfall events (less than 5 mm/hour during rainfall peaks, average rates around 0.8 mm/hour). We therefore propose that the studied wavy flowstones are hydroclimatic indicators, testifying the occurrence of flashy type recharge related to heavy rainfall events. Similar deposits could record these same hydro-climatic conditions in other karst areas. In recent decades, storms have caused more frequent flooding in highly populated Mediterranean areas, especially in Italy. Wavy flowstones may offer a new archive to gain a better understanding of the long-term dynamics of intense precipitation events and, thus, help to improve future climate scenarios.

This study explores the spatial relationship between the number of recorded events of the Safe Delivery App, which is a mobile learning tool to train midwives in developing countries, during three months, and several independent variables, including the number of health facilities, pregnancies, number of women of childbearing age, number of infants aged 0–1 years, mobile network coverage data and total population density. The study aims to identify and analyse the reach of the Safe Delivery App at the district level in Ghana country, considering the correlation between dependent and independent variables. The geospatial analysis of App usage events layered with several related explanatory variables is based on Geographically Weighted Regression. The explanatory variables were able to predict and explain the number of events with of accuracy score of 90 % at the district level. The results have provided valuable insights into the further roll-out of the App and helped to highlight the districts that need further support to roll out the Safe Delivery App considering the analysed independent variables.

In the past few years, the rapid evolution of multi-constellation navigation satellite systems boosted the development of many scientific and engineering applications. More than 100 satellites will be available in a few years, when all the four global constellations (GPS, GLONASS, Galileo, and Beidou) will be fully deployed. This high number of visible satellites has improved the performance of precise point positioning (PPP) techniques both in terms of accuracy and of session length, especially easing the modeling of ionospheric biases. However, in the presence of severe environmental and atmospheric conditions, the performance of PPP considerably deteriorates. It is the case of high-latitude scenarios, where the satellites coverage is limited, the satellites geometry is poor and ionospheric scintillation are frequent. This paper analyzes the quality of PPP solutions in terms of accuracy and convergence time, for a GNSS station in Antarctica. Single and multi-constellation results are compared, proving the benefits of the availability of a higher number of satellites as well as the improved robustness to the presence of moderate and strong phase scintillations. The use of PPP multi-constellation at high latitudes is indeed essential to guarantee high accuracy, and to obtain a low convergence time, of the order of tens of minutes.

The possibility to access undifferenced and uncombined Global Navigation Satellite System (GNSS) measurements on smart devices with an Android operating system allows us to manage pseudorange and carrier-phase measurements to increase the accuracy of real-time positioning. The goal is to perform real-time kinematic network positioning with smartphones, evaluating the positioning accuracy regarding an external mass-market device. The positioning of Samsung Galaxy S8+ and Huawei P10 plus smartphones was performed using a dedicated tool developed by the authors, considering a continuous operating reference station (CORS) network with a mean inter-station distance of about 50 km. The same positioning technique was also applied to an external GNSS low-cost single-frequency receiver (u-blox EVK-M8T) to compare performance between the receiver and antenna embedded in the previous smartphones and this low-cost receiver coupled with a mass-market antenna (Garmin GA38). Attention was also focused on the phase ambiguity resolution, that it is still a challenging aspect for mass-market devices: even if the two smartphones provide slightly different results, the accuracy obtainable today is greater than 60 cm with a precision of few centimetres in real-time, if a CORS network is available. For real-time applications using portable devices, decimetre-level accuracy is sufficient for many applications, such as rapid mapping and search and rescue activities: these results will open new frontiers in terms of real-time positioning with portable low-cost devices.

Bees provide essential pollination services to natural ecosystems and agricultural crops. However, managed and wild (unmanaged) bee populations are in decline worldwide. In order to better manage and restore bee populations, long-term monitoring programs are required. Direct bee monitoring is costly, labor intensive, and requires high expertise. Therefore, cost-effective indicators for bee diversity and community composition are essential.Here we propose to test the cost-efficacy of novel aerial techniques along with classical ground methods to collect biotic and a-biotic indicators of bee diversity and community composition. We will couple classical ecological monitoring approach with advanced photogrammetric tools, in order to develop a multi-scale and multi-temporal platform for monitoring bees. To this end, we formed a complementary, interdisciplinary research group of a pollination ecologist, soil chemists, environmental engineer, geomatics engineer, and topography surveyot. The study will include field work in two complimentary study systems in central Israel, light sandy vs heavy vertisol soils. In each study system we will concurrently conduct bee, flower, bee nesting substrates and soil surveys using classical tools/approaches, as well as apply advanced photogrammetric tools, based on RGB images, with thermal, multispectral data. The indicative ability for bee diversity and community composition of the different biotic and a-biotic measures collected, will be tested using advances statistical tools. Our findings may be instructive to other insects and plant groups, thus provide a novel generic approach towards the ecological monitoring of terrestrial systems.

Passageways cut through rock might be subjected to rockfalls. If a falling rock reaches the road area, the consequences can be disastrous. The traditional rockfall risk assessment method and risk mitigation are based on on-site investigations performed by a geologist or a rock engineer. The parameters resulting from the investigation, such as discontinuities, orientations and spacings, potential rockfall initiation locations, slope geometry, and ditch profile, are either measured or estimated. We propose a photogrammetry-based method for estimating the probability of failure for rockfall. Several photographs of the rock-cut are taken, and a 3D geometry is computed using photogrammetry. This model already allows remote visual inspection of the site. The information about joint planes can be discovered semiautomatically from the point cloud. Next, the probability of rockfall reaching the road area is computed using probabilistic kinematic analysis on the geometry extracted using photogrammetry. The results can be used to define the rockfall probability for each rock-cut. Furthermore, the results can be used to determine the appropriate rockfall risk mitigation actions for each rock-cut.

This work presents an Ultra-wideband-based (UWB) approach to seamless positioning and navigation applied in a real test-bed. It deploys two different solutions for positioning estimation in function of the operational environment. Outdoors, a classical hybridization between Global Navigation Satellite System (GNSS) and Inertial Measurement Unit (IMU) is applied while indoors, an UWB/INS integration is performed relying on a low-cost commercial platform which integrates both UWB unit and IMU. The implementation of this procedure will be presented with more details in the paper. The aim of the work is to validate the performances in term of accuracy, precision and seamlessness behavior of the low-cost UWB technology available today. The results shown an overall accuracy of about 60 cm considering the entire path walked, both outdoor and indoors.

The use of GNSS for landslide monitoring is not a novelty. In most cases, the GNSS receivers and antennas are only a subset of instruments usually considered and used in a complex monitoring network, where more often a continuous monitoring is required. In the present work, the proposed GNSS solution is composed by a dual frequency (L1 + L2) receiver, with a solar power and with a radio connection to a ground station, where the rover’s measurements are collected and processed. The most critical aspect is the management of the collected data because the approach, which is normally used, assumes a fixed position of the GNSS antenna during the acquisition time window. Methodology for data acquisition and positioning (real-time or post-processing) and its duration, type of receivers, and antenna used (single or multi-constellation, single or dual frequency, mass-market or geodetic), data processing strategies (i.e., single epoch, static, kinematic), and GNSS network services are fundamental factors, which may favor one or another solution, according to time, economy, and infrastructure readiness in the field. Starting from the previous experience of the research group, this work investigates the possibility of employment of GNSS mass-market receivers and antenna for Network Real-Time Kinematic positioning for displacement detection. Using a dedicated slide which allows to define a micrometric displacement, several tests have been performed in a test-site at Politecnico of Torino (Italy), where different combinations of receivers and antennas (from geodetic to mass market) and displacement strategies have been considered. After this phase, some instruments are settled on a “real” landslide in the Verbano-Cusio-Ossola province (NW of Italy) in order to verify the feasibility of the employment of these devices and whose accuracies can be reached. Furthermore, data processing has been realized by means of different software (commercial and free and open source) and different kinds of solution. In this way, it could be possible to reduce costs for monitoring activities, improving the quality of the solutions, and to allow a “smart” use of GNSS technologies for monitoring.

Traditionally, multi-constellation and multi-frequency chipsets were only adopted on geodetic receivers, considering the high costs and limited number of mass applications. Nowadays, with a wide range of constellations available, satellite navigation has opened up to many civilian domains like navigation and positioning, surveying and mapping, weather prediction, mobile satellite communications, smart technologies, etc. Currently, many geodetic receivers are available and they can provide highly accurate results up to millimetre level. In addition, there are several low-cost solutions, which are able to work in multi-constellation and multi-frequencies domain. Usually the accuracy of receivers, especially low-cost ones, is not very high in harsh urban environment due to low visibility of satellites, frequent signal blockages and increasing multipath effects. In this paper the accuracy and the reliability of multi-GNSS (GPS/GLONASS/BeiDou/Galileo), low-cost single and dual frequency receivers are investigated and analysed for kinematic positioning. Different datasets have been collected by single (Emlid Reach GNSS) and dual frequency GNSS receivers (i.e. Tersus Precis BX306 and Piksi multi GNSS) in a harsh urban environment and then analysed using real time and post-processed solutions. This work shows that under suitable conditions, mass-market sensors could be a valid alternative to a more expensive receiver for many environmental applications.

The use of multiple GNSS constellations has been beneficiary to positioning performances and reliability in recent times, especially in low cost mass-market setups. Along with GPS and GLONASS, GALILEO and BDS are the other two constellations aiming for global coverage. With ample research demonstrating the benefits of GALILEO in the European region, there has been a lack of study to demonstrate the performance of BDS in Europe, especially with mass-market GNSS receivers. This study makes a comparison of the performances between the combined GPS-GLONASS and GPS-BDS constellations in Europe with such receivers. Static open sky and kinematic urban environment tests are performed with two GNSS receivers as master and rover at short baselines and the RTK and double differenced post processed solutions are analyzed. The pros and cons of both the constellation choices is demonstrated in terms of fixed solution accuracies, percentage of false fixes, time to first fix for RTK and float solution accuracies for post processed measurements. Centimeter level accuracy is achieved in both constellations for static positioning with GPS-BDS combination having a slightly better performance in comparable conditions and smaller intervals. GPS-GLONASS performed slightly better for longer intervals due to the current inconsistent availability of BDS satellites. Even if the static tests have shown a better performance of GPS-BDS combination, the kinematic results show that there are no significant differences between the two tested configurations. Keywords: GNSS, BDS, GLONASS, NRTK positioning, Accuracy

The Global Navigation Satellite System (GNSS) receiver is one of the many sensors embedded in smartphones. The early versions of the Android operating system could only access limited information from the GNSS, allowing the related Application Program Interface (API) to obtain only the location. With the development of the Android 7.0 (Nougat) operating system in May 2016, raw measurements from the internal GNSS sensor installed in the smartphone could be accessed. This work aims to show an initial analysis regarding the feasibility of Zenith Total Delay (ZTD) estimation by GNSS measurements extracted from smartphones, evaluating the accuracy of estimation to open a new window on troposphere local monitoring. Two different test sites have been considered, and two different types of software for data processing have been used. ZTDs have been estimated from both a dual-frequency and a multi-constellation receiver embedded in the smartphone, and from a GNSS Continuously Operating Reference Station (CORS). The results have shown interesting performances in terms of ZTD estimation from the smartphone in respect of the estimations obtained with a geodetic receiver.

The geologic investigation of water-covered areas is often difficult and inefficient with only the use of traditional surveying techniques (i.e., local drilling and sampling). Waterborne geophysical surveys can offer a valuable alternative to achieve adequate data coverage in a cost-effective way. Two geophysical waterborne methods were combined in this study for the delineation of the submerged subsurface geology along a 5 km stretch of the Po river, within the urban area of Turin. The adopted methods were: continuous vertical electrical sounding (CVES) and ground-penetrating radar (GPR). Special attention was devoted to the accurate geo-referencing of both surveys for combined interpretation. GPR results provide a high-quality representation of the river bed forms, with identification of clear sand dunes in the finer alluvial sediments. CVES resistivity sections enable a deeper characterization, identifying the interface between the shallow alluvial deposits and the deeper low-resistivity marls of the Turin-Hill succession. Our work strengthens the effectiveness of waterborne surveys for geologic prospecting of water-covered and difficult-to-access areas.

Forests are significant resources from an ecological, economic and social point of view. Their protection and management could greatly benefit from a complete knowledge of the shape and distribution of trees in forest stands. To this purpose, aerial surveys, especially through Airborne Laser Scanning (ALS), were carried out in the last years to acquire point clouds to be used in 3D models aimed at achieving an accurate description of tree crowns and terrain. However, airborne data acquisition is expensive and may provide poor results in case of dense foliage. Further, point cloud resolution is not very high, as models with a grid of 2-3 m are usually obtained. In order to implement more accurate 3D forest models, a feasible solution is the integration of point clouds obtained by aerial acquisition (ALS or photogrammetry) for the treetops and the terrain description, with information from terrestrial surveys. In this paper, we investigated the possible integration of point clouds obtained by Terrestrial Laser Scanner (TLS) with those collected by photogrammetric 3D models based on images captured by Unmanned Aerial Vehicle (UAV) in a test site located in northern Italy, with the aim of creating an accurate dataset of the forest site with high resolution and precision. The limits of ALS and TLS were bridged by aerial photogrammetry at low altitude (and vice versa). A 3D model of the study area was obtained with a resolution of 5 cm and a precision of 3 cm. Such model may be used in a wide range of applications in forestry studies, e.g., the reconstruction of 3D shapes of trees or the analysis of tree growth throught time. The implications of the use of such integrate approach as a support tool for decision-making in forest management are discussed.

Global Navigation Satellite System (GNSS) positioning is currently a common practice thanks to the development of mobile devices such as smartphones and tablets. The possibility to obtain raw GNSS measurements, such as pseudoranges and carrier-phase, from these instruments has opened new windows towards precise positioning using smart devices. This work aims to demonstrate the positioning performances in the case of a typical single-base Real-Time Kinematic (RTK) positioning while considering two different kinds of multi-frequency and multi-constellation master stations: a typical geodetic receiver and a smartphone device. The results have shown impressive performances in terms of precision in both cases: with a geodetic receiver as the master station, the reachable precisions are several mm for all 3D components while if a smartphone is used as the master station, the best results can be obtained considering the GPS+Galileo constellations, with a precision of about 2 cm both for 2D and Up components in the case of L1+L5 frequencies, or 3 cm for 2D components and 2 cm for the Up, in the case of an L1 frequency. Moreover, it has been demonstrated that it is not feasible to reach the phase ambiguities fixing: despite this, the precisions are still good and also the obtained 3D accuracies of positioning solutions are less than 1 m. So, it is possible to affirm that these results are very promising in the direction of cooperative positioning using smartphone devices.