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Landslide Monitoring Using Low Cost GNSS Equipment-Experiences from Two Alpine Testing Sites
... Whereas the dual-frequency station tracks both L1 and L2 carrier signals, the singlefrequency devices are able to track only the L1 carrier from the GPS satellites. However, their capacity for measuring relative positions reaches centimeter-level repeatability for hourly sessions, and millimeter-level repeatability for daily sessions [27] in the post-processing mode if their data are calculated with respect to a reference station placed at a distance not exceeding 10 km [28]. It is worth noting that all of the movements measured at each station refer to the first measured position (time differencing) and that the differential approach over short baselines allows attenuating or eliminating common-mode errors (such as atmospheric biases, antenna phase center offsets and variations, etc.). ...
... Recently, the staff of CRS installed the station of TOLS (located less than 1.5 km south-east of FUSE, see Figure 1a) to ensure the functioning of the system in the case of unexpected failures at the FUSE station. As we are using single-frequency devices, we had to ensure that we relied on short baselines, i.e., less than 5 km with at least 1 h of data, and on GPS stations located roughly at the same latitude, in order to provide a significative reduction of the measurement errors induced by the troposphere and the ionosphere [28][29][30][31][32][33][34][35][36][37][38], and to ensure centimeter-level accuracy. ...
The constant monitoring of active landslides, particularly those located in the proximity of populated areas or touristic places, is crucial for early warning and risk-management purposes. The commonly used techniques deploy expensive instrumentation that can be hardly afforded, especially by small mountain communities in which landslide events often occur repeatedly. In recent years, the scientific community, as well as the private sector, have devoted growing effort to reducing the costs of monitoring systems. In this work, we present a monitoring network based on single-frequency Global Positioning System (GPS) sensors that have been activated to monitor an active landslide in the Carnic Alps, North-Eastern Italy. The system, which was composed of 12 single-frequency GPS stations, one seismometric station coupled with a single-frequency GPS instrument for real-time monitoring, and one permanent dual-frequency GPS station located in a stable area, provided daily reports of the landslide motion to the local authorities and administration. We show that this system is a valuable, flexible, and cost-effective tool for quick landslide characterization, and has high potential to be used as a landslide early warning system in case of emergency situations.
... In 2011, two projects of Aggenalm landslide and Hornbergl Mountain have been carried out to test u-blox LEA-4T receivers for landslide monitoring application. Though accuracies in millimeter range obtained, the full potential of quality and reliability is not exploited yet (Heunecke et al. 2011). evaluated the performance of L1u-blox 5T receiver for landslides monitoring and proved that it was possible to reach millimetre accuracy with the singlefrequency mass-market GNSS receivers, under appropriate operative conditions. ...
In the field of geomechanics engineering, slope stability monitoring is important to ensure structures such as embankments remain stable and safe. The main purpose of slope monitoring is to help geomechanics engineers identify potential hazards and take steps to mitigate them. In high-risk environments, like those that could potentially have a translation or rotational failure, it is risky for personnel to gather data. Capturing that data becomes a potential hazard. Geodetic Global Navigation Satellite System (GNSS) technique can be considered as an appropriate solution due to the accurate results, however, they are complex, bulky and expensive. The Kurloo system combines the advantages of GNSS with power and cost effectivity of the Internet of Things (IoT). With the uptake of this simpler GNSS-IoT solution, geomechanics engineers have a new tool to collect long-term accurate daily displacement (X, Y, Z) data to support their qualitative predictions. This work presents the Kurloo system and results of a field campaign performance with approximate 2 years of data at Froggy Beach. The objective was to assess the performance of Kurloo system in the real field monitoring conditions and identify potential hazards. Slope movement events are detected and correlated to heavy rainfall periods.
... Jo et al. (2013) analysed the feasibility of displacement monitoring using low-cost GPS receiver. Other studies mostly focused on geohazard monitoring such as landslide monitoring (Biagi et al. 2016;Cina and Piras 2015;Heunecke et al. 2011). Also, few studies tested the low-cost GNSS receivers in civil engineering-related SHM applications requiring continuous monitoring apart from Manzini et al. (2022), Poluzzi et al. (2019), and Xue et al. (2022). ...
The monitoring of bridges is a crucial operation for their structural health examination and maintenance. GNSS technology is one of the methods which are applied with the main advantage that the direct measurement of the bridge displacement is conducted in an independent global coordinate system. However, the high cost of the GNSS stations, which are consisted of dual-frequency receivers and geodetic GNSS antennas, is the main reason of the limited application of GNSS for bridge monitoring. In this study, we assessed the performance of low-cost multi-GNSS receivers in monitoring dynamic motion, similar to that of bridge response. The performance of the low-cost GNSS receivers was assessed based on controlled experiments of horizontal and vertical motion. For the horizontal motion, controlled experiments of circular motion of various predefined radius between 5 and 50 cm were executed where the low-cost GNSS receivers were assessed against dual-frequency geodetic receivers. For the vertical motion, manually controlled experiments of vertical oscillations of amplitude 8 and 15 mm were executed where the low-cost GNSS receivers were assessed against the Robotic Total Station (RTS). Finally, a low-cost monitoring system formed by two closely spaced low-cost GNSS receivers was applied in dynamic displacement monitoring of the Wilford Suspension Bridge. The analysis of the low-cost GNSS data revealed the beneficial contribution of (i) the multi-constellation on the accuracy and precision of the GNSS solution and (ii) the combination of closely spaced low-cost GNSS receivers, to limit potential cycle slips and the low-cost GNSS noise level and reach accuracy and precision similar to that of geodetic-grade GNSS receivers. This was confirmed in the bridge monitoring application, where the main modal frequency and the response amplitude of the bridge were identified successfully by the low-cost GNSS receivers’ data analysis.
... Although the standard deviation for some solutions was particularly high (e.g., 0.249 m for the N coordinate in 2022), showing that there were some outliers probably caused by the large distance between BRU1 and UDI2, the average values were only a few centimeters (0.024 m at most for the E coordinate in 2022, the cause of which is probably also related to the reference coordinates). Considering that the recommended baseline for a GNSS monitoring system is about 5 km [25,36,37], these performance test results are encouraging, taking into account the long baseline tested (58 km) and the fact that the solution was obtained with a single-frequency GNSS. Table 4. ...
Recent advances in Global Navigation Satellite System (GNSS) technology have made low-cost sensors available to the mass market, opening up new opportunities for real-time ground deformation and structure monitoring. In this paper, we present a new product developed in this framework by the National Institute of Oceanography and Applied Geophysics–OGS in collaboration with a private company (SoluTOP SAS): a cost-effective, multi-purpose GNSS platform called LZER0, suitable not only for surveying measurements, but also for monitoring tasks. The LZER0 platform is a complete system that includes the GNSS equipment (M8T single-frequency model produced by u-blox) and the web portal where the results are displayed. The GNSS data are processed using the RTKLIB software package, and the processed results are made available to the end user. The relative positioning mode was adopted both with real-time and post-processing RTKLIB engines. We present three applications of LZER0—cadastral, monitoring, and automotive—which demonstrate that it is a flexible, multi-purpose platform that is easy to use in terms of both hardware and software, and can be easily deployed to perform various tasks in the research, educational, or professional sectors.
... High-precision displacement determination has become even more reliable and available since low-cost GNSS receivers entered the market. First, the single-frequency receivers appeared [6,7]. Over the years, these devices have been improved and have achieved a positioning accuracy sufficient for some applications in geodetic monitoring of natural hazards [8]. ...
The capabilities of global navigation satellite systems (GNSS) are still increasing. This is due to their continuous development - new satellites are sent into space, new constellations are created, and they transmit new signals on previously unused frequencies. Receiving devices - receivers with antennas - are also improved. They are smaller, consume less power, calculate their position faster and better, and are also getting much cheaper and thus more accessible.
The main objective of this paper was the evaluation of u-blox ZED-F9P, low-cost RTK (real time kinematic) GNSS receiver, which is relatively new in comparison to geodetic ones. The tests were conducted in motion, under demanding conditions, in conjunction with a low-cost patch antenna u-blox ANN-MB-00 and a Leica AS10 high-precision geodetic one. A total of three test runs were performed:
·two short ones (approx. 900 m each) in which reference data was provided by a Leica MS50 robotic total station and the 360-degree prism, coaxially mounted with the tested antenna,
·a long one (approx. 12 km long) in which positioning was simultaneously performed using a Leica GS18T high-end geodetic receiver.
As a result, it is concluded that the low-cost GNSS receivers, in particular equipped with a geodetic-grade antenna, constitute a valuable alternative to the high-quality positioning receivers. Moreover, they might act even better in some situations, which are described in the article. Thanks to comprehensive tests, it is shown that the u-blox ZED-F9P receiver can be successfully used in all projects requiring positioning accuracy of approximately ±2 cm.
... In the past, total stations have been usually adopted for landslide monitoring but starting from the XXI century, GPS (before) and GNSS (now) techniques have replaced them and it is recently the most used monitoring system for different applications (Gili et al. 2000;Heunecke 2011;Wang 2013;Gassner et al. 2002). ...
Shallow landslides are land instability phenomena provoked by extreme precipitation events of either short duration and significant intensity or milder but longer lasting ones. Those slope failures generally involve limited volumes of terrain which could however induce significant amount of damage to property and cause casualties. In this work, we present an experimental study of the onset of shallow landslides under heavy precipitation in controlled laboratory conditions. The main objective of the work is to explore the applicability of an optical fibre strain sensor interrogated with an innovative low-cost technology. Thus, the system permits the exploitability of the otherwise costly and often unsuitable for field use interrogators. The optical fibre strain sensors were installed within the slope at different locations along the length of the plane. A second set of a more conventional optical fibre sensing system was used for a comparison. The results obtained indicate the ability of both devices to reflect the instabilities developing during the experiments and therefore encouraged the development of further investigation of the proposed sensors’ applicability.
... In the past, total stations have been usually adopted for landslide monitoring but starting from the XXI century, GPS (before) and GNSS (now) techniques have replaced them and it is recently the most used monitoring system for different applications (Gili et al. 2000;Heunecke 2011;Wang 2013;Gassner et al. 2002). ...
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.
... Modern monitoring systems are mostly based on terrestrial or satellite-based surveying methods [Stempfhuber, 2009]. But the sensor technology is no longer confined to classical geodetic instruments, such as robotic total stations, digital inclinometers or GNSS receivers [Heunecke, 2011]. Increasingly, geotechnical and inertial sensors are now used as a standard, including, in particular, acceleration and rotational speed sensors. ...
... Il team OGS ha ipotizzato che molte applicazioni professionali possano essere eseguite con strumentazione economica (Heunecke et al. 2011). I tempi sono maturi per un ingresso nel settore dei sistemi GNSS di precisione a basso costo perché, come si vedrà in seguito, il mercato è in forte crescita in quest'ambito. ...
OGS team hypothesized that many professional GNSS applications, such as structural monitoring and topographic surveys, can be performed with cost-effective instrumentation. The time is ripe for an entry into the cost effective precision GNSS systems sector because the market is growing rapidly in this area.
According to these hypotheses, the OGS group has developed a, single frequency GNSS prototype for topography and monitoring.
Il team OGS ha ipotizzato che molte applicazioni professionali GNSS, ade esempio monitoraggi strutturali e rilievi topografici, possano essere eseguite con strumentazione economica. I tempi sono maturi per un ingresso nel settore dei sistemi GNSS di precisione a basso costo perché il mercato è in forte crescita in quest’ambito.
Secondo tali ipotesi, il gruppo OGS, ha realizzato un prototipo GNSS a basso costo e in tecnologia a singola frequenza per la topografia e il monitoraggio.
... Nevertheless, the still high cost of dual- frequency geodetic class receivers very often limited their deployment and use (especially -but not only -in developing countries), preventing from using them in vehicle (e.g. in the field of the autonomous driving) and pedestrian (e.g. for assisting disabled persons) navigation, and from realizing dense permanent networks, which are of high relevance both for long term geodynamic monitoring/earthquake hazard assessment, and for GNSS seismology ( Rebischung et al. 2012, Tsuji and Hatanaka 2018, Devoti et al. 2012). The usage of single-frequency low-cost receivers for static applications was investigated by several authors in recent years, for both positioning ( Heunecke et al. 2011;Buchli et al. 2012;Benoit et al. 2014;Cina and Piras 2014;Caldera et al. 2016) and atmospheric sensing ( Krietemeyer et al. 2018; Wang et al. 2018). In order to make feasible these navigation applications and the realization of such networks, with a density of GNSS permanent stations one order of magnitude higher than actual ones, a new and very low-cost dual-frequency receiver working at present on the L1/L2C pair but easily amenable to GALILEO E1/E5a operation has been designed and successfully tested by Saphyrion SAGL and Geomatics Research & Development srl (GReD) in the framework of the EUROSTARS project EDWIGE. ...
A new low-cost L1/L2c receiver board is presented in this short letter, along with its first tests. The main strength of the board is its low price tag (around 200 EUR, in quantities of hundreds) as an effective dual-frequency receiver. The effectiveness of the receiver was at first proven by a pedestrian walk experiment on a closed loop, allowing the evaluation of closure errors. Raw measurements were collected and processed in a real-time scenario through a variometric approach implemented in VADASE software. Epoch-by-epoch velocities were estimated on the basis of dual-frequency phase observations and then the trajectory was reconstructed by numerical integration of the estimated velocities. A horizontal closure error lower than 25 cm was achieved; also, a global assessment of the overall 3D trajectory was carried out, performing a comparison to a standard differential solution with respect to a permanent GNSS station, and standard deviations of the differences between 10 and 20 cm for the 3D components (east, north and up) were achieved. Further, static experiments, both in terms of relative positioning and water vapor monitoring by precise point positioning, confirmed the good performance of the new receiver, with coordinates repeatability of a few millimetres for daily solutions, and estimated water vapor behaviour compatible with local rain events.
... Moreover, Global Navigation Satellite System (GNSS) has been proposed to overcome the need of line of sight (LOS) condition and to provide high-precision 3D monitoring [11][12][13][14]. The development of low-cost GNSS equipment, opened new possibilities for the application of such technology to landslides monitoring [15][16][17]. ...
An innovative wireless sensor network (WSN) based on Ultra-Wide Band (UWB) technology for 3D accurate superficial monitoring of ground deformations, as landslides and subsidence, is proposed. The system has been designed and developed as part of an European Life+ project, called Wi-GIM (Wireless Sensor Network for Ground Instability Monitoring). The details of the architecture, the localization via wireless technology and data processing protocols are described. The flexibility and accuracy achieved by the UWB two-way ranging technique is analysed and compared with the traditional systems, such as robotic total stations (RTSs), Ground-based Interferometric Synthetic Aperture Radar (GB-InSAR), highlighting the pros and cons of the UWB solution to detect the surface movements. An extensive field trial campaign allows the validation of the system and the analysis of its sensitivity to different factors (e.g., sensor nodes inter-visibility, effects of the temperature, etc.). The Wi-GIM system represents a promising solution for landslide monitoring and it can be adopted in conjunction with traditional systems or as an alternative in areas where the available resources are inadequate. The versatility, easy/fast deployment and cost-effectiveness, together with the good accuracy, make the Wi-GIM system a possible solution for municipalities that cannot afford expensive/complex systems to monitor potential landslides in their territory.
... Landslides are the most frequent geomorphological hazard in Italy and despite casualties and economic losses are less than those caused by earthquakes, an higher frequency of events has been detected since the early 2000s: only in Liguria Region, many landslides were triggered by heavy rainfall events, whose number is rising year after year, such as those of 2000, 2002, 2007, 2010, 2011(Guzzetti & alii, 2005Brandolini & alii, 2005;Faccini & alii, 2005Faccini & alii, , 2015Cevasco & alii, 2013Cevasco & alii, , 2014Galve & alii, 2015;Raso & alii). ...
The San Bernardino-Guvano landslide is one of the wider slope mass movements located along the eastern Ligurian coast between Vernazza and Corniglia, Cinque Terre National Park. It is an ancient and complex landslide that has been studied since 1853, when a catastrophic event occurred. This paper aims to describe the geomorphological evolution and monitoring of this coastal landslide: both geological and geomorphological field surveys supported by airborne imagery were carried out, as well as bibliographical research about past geotechnical investigations and topographical monitoring; furthermore, a new single-frequency Global Navigation Satellite System (GNSS) low-cost monitoring started in October 2015. Structural geology heavily influences the stability of this coastal slope: a fault cuts the landslide area N-S, as well as low-angle thrust fault planes with NE dip direction. The slope is affected by landslides with different intensity and kinematic evolution, in particular rockfalls and debris avalanches along the scarp and right flank and earth flow along the central sector and at the slope toe. Man-made structures are relevant and they mainly consist of retaining walls, drainage channels, buildings, hiking trails, roads and railway infrastructures. Data obtained by GNSS receivers have shown remarkable displacements during the last year, according to the results of previous topographical and geotechnical monitoring campaigns. Deep analysis of GNSS data, together with the support and maintenance of the actual monitoring program, will allow a better comprehension of the slope stability condition, essential for supporting the design of proper risk reduction interventions.
... Landslides are the most frequent geomorphological hazard in Italy and despite casualties and economic losses are less than those caused by earthquakes, an higher frequency of events has been detected since the early 2000s: only in Liguria Region, many landslides were triggered by heavy rainfall events, whose number is rising year after year, such as those of 2000, 2002, 2007, 2010, 2011(Guzzetti & alii, 2005Brandolini & alii, 2005;Faccini & alii, 2005Faccini & alii, , 2015Cevasco & alii, 2013Cevasco & alii, , 2014Galve & alii, 2015;Raso & alii). ...
The San Bernardino-Guvano landslide is one of the wider slope mass movements located along the eastern Ligurian coast between Vernazza and Corniglia, Cinque Terre National Park. It is an ancient and complex landslide that has been studied since 1853, when a catastrophic event occurred. This paper aims to describe the geomorphological evolution and monitoring of this coastal landslide: both geological and geomorphological field surveys supported by airborne imagery were carried out, as well as bibliographical research about past geotechnical investigations and topographical monitoring; furthermore, a new single-frequency Global Navigation Satellite System (GNSS) low-cost monitoring started in October 2015. Structural geology heavily influences the stability of this coastal slope: a fault cuts the landslide area N-S, as well as low-angle thrust fault planes with NE dip direction. The slope is affected by landslides with different intensity and kinematic evolution, in particular rockfalls and debris avalanches along the scarp and right flank and earth flow along the central sector and at the slope toe. Man-made structures are relevant and they mainly consist of retaining walls, drainage channels, buildings, hiking trails, roads and railway infrastructures. Data obtained by GNSS receivers have shown remarkable displacements during the last year, according to the results of previous topographical and geotechnical monitoring campaigns. Deep analysis of GNSS data, together with the support and maintenance of the actual monitoring program, will allow a better comprehension of the slope stability condition, essential for supporting the design of proper risk reduction interventions.
... A detailed study of the application of GNSS to landslides can be found in Gili et al. (2000) and examples of application in Malet et al. (2002), Mora et al. (2003), Squarzoni et al. (2005). In recent years, the development of low-cost GNSS equipment provided new possibilities for the application of such technology to landslides (Günther et al., 2008;Heunecke et al., 2011;Cina and Piras, 2015). ...
Ground displacement monitoring is one of the most important aspects of early warning systems and risk management strategies when addressing phenomena such as landslides or subsidence. Several types of instrumentation already exist, but those able to provide real-time warnings on multiple time series are typically based on expensive technology, highlighting the need to develop a low-cost, easy to install system suitable for emergency monitoring. Therefore, a wireless network based on ultra-wideband impulse radiofrequency technology has been realized. The novelty of this network consists of its ability to measure the distance between nodes using the same signals used for transmission without the need for an actual measurement sensor. The system was tested by monitoring a mudflow in Central Italy and revealed its suitability as an early warning tool. More research on the integration of future low-cost hardware and eventual industrialization would provide further improvement to this promising technology.
... The use of single-frequency GNSS (Global Navigation Satellite System) receivers and antennas for high-precision static applications, such as geodetic monitoring, is becoming more and more important due to the extremely low cost of single-frequency hardware, originally designed and produced for the mass-market, and to the increasing number of GNSS systems available. Such applications require, in order to reach millimeter-level accuracy, the deployment of stationary GNSS units, delivering raw observations, and the processing of sufficiently short baselines [1][2][3][4][5][6][7]. However, for more traditional surveying operations, such as map updates [8], cadastral or archaeological surveys [9,10], or surveys to support other measurements, e.g., gravimetric networks [11], significantly lower accuracies, e.g., of the order of tens of centimeters, are sufficient. ...
The recent access to GNSS (Global Navigation Satellite System) phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether this is feasible, and which positioning accuracy can be achieved by relative positioning of the smart device with respect to a base station. Positioning of a Google/HTC Nexus 9 tablet was performed by means of batch least-squares adjustment of L1 phase double-differenced observations, using the open source goGPS software, over baselines ranging from approximately 10 m to 8 km, with respect to both physical (geodetic or low-cost) and virtual base stations. The same positioning procedure was applied also to a co-located u-blox low-cost receiver, to compare the performance between the receiver and antenna embedded in the Nexus 9 and a standard low-cost single-frequency receiver with external patch antenna. The results demonstrate that with a smart device providing raw GNSS phase observations, like the Nexus 9, it is possible to reach decimeter-level accuracy through rapid-static surveys, without phase ambiguity resolution. It is expected that sub-centimeter accuracy could be achieved, as demonstrated for the u-blox case, if integer phase ambiguities were correctly resolved.
... The high costs for each antenna per observation point may be reduced by using upcoming low-cost systems (Heunecke et al., 2011). Furthermore, GNSS can only be applied point-wise; therefore, the dense mapping of large areas is not possible. ...
Image Assisted Total Stations (IATS) unify geodetic precision of total stations with areal coverage of images. Photogrammetric image measurement methods to detect signalized as well as non-signalized targets can be combined with functions of the total station like precise angle and distance measurements. The instruments are ideally suited for automatic and autonomous operation in monitoring systems. This thesis presents four new geodetic monitoring approaches in the fields of structural monitoring and geo-monitoring. It is shown that IATS offer much greater potential than currently used.
... In general, the final accuracy of the solution is influenced by baseline length, satellite visibility, nearby environment and can be even better than 1 cm in perfect working conditions [14]. Furthermore, two experiments carried out in the Alps, provided a first, satisfactory guess of the accuracy of low-cost, single frequency receivers in landslide monitoring [15]. A recent research is presented also in [16]: in this case, the accuracy of low-cost receivers is assessed for local monitoring by processing daily sessions: accordingly to the baseline length, the final accuracy range from 1 mm (very short baseline) to 1 cm (30 km long baseline). ...
The geodetic monitoring of local displacements and deformations is often needed for civil engineering structures and natural phenomena like, for example, landslides. A local permanent GNSS (Global Navigation Satellite Systems) network can be installed: receiver positions in the interest area are estimated and monitored with respect to reference stations. Usually, GNSS geodetic receivers are adopted and provide results with accuracies at the millimeter level: however, they are very expensive and the initial cost and the risk of damage and loss can discourage this approach. In this paper the accuracy and the reliability of low-cost u-blox GNSS receivers are experimentally investigated for local monitoring. Two experiments are analyzed. In the first, a baseline (65 m long) between one geodetic reference receiver and one u-blox is continuously observed for one week: the data are processed by hourly sessions and the results provide comparisons between two processing packages and a preliminary accuracy assessment. Then, a network composed of one geodetic and two u-blox receivers is set up. One u-blox is installed on a device (slide) that allows to apply controlled displacements. The geodetic and the other u-blox (at about 130 m) act as references. The experiment lasts about two weeks. The data are again processed by hourly sessions. The estimated displacements of the u-blox on the slide are analyzed and compared with the imposed displacements. All of the results are encouraging: in the first experiment the standard deviations of the residuals are smaller than 5 mm both in the horizontal and vertical; in the second, they are slightly worse but still satisfactory (5 mm in the horizontal and 13 mm in vertical) and the imposed displacements are almost correctly identified.
... This restricts the possibility of its application to institutions that can afford it and reduces the number of permanent stations that can be built, with a correspondent decrease in the efficiency of the monitoring system. In recent years, however, the attention of the GNSS community has been drawn to the possible application of low-cost GNSS receivers, which for such small networks might be capable of producing useful results (Heunecke et al. 2011;Buchli et al. 2012;Benoit et al. 2014;Cina and Piras 2014). For this reason, the authors of this paper have started studying the problem to show that the approach can be very advantageous from an economic standpoint when low-cost receivers are used and an inexpensive (or even free) open-source software package is applied to build an authentic low-cost monitoring system. ...
The use of geodetic techniques and in particular of the Global Positioning System (GPS), or other Global Navigation Satellite Systems (GNSS), to monitor different kinds of deformations is a common practice. This is typically performed by setting a network of geodetic GPS/GNSS receivers, allowing accuracies in the order of millimeters. The use of lower cost devices has been recently studied, showing that good results can be achieved. In this paper the impact of the software used for the data analysis is also investigated with the purpose of verifying whether a fully low-cost monitoring system, i.e.~both hardware and software, can be set up. This is done by performing a series of relative positioning experiments where data are processed by different software packages. The main result is that using a low cost u-blox EVK-6T GPS receiver and analyzing its data with the free and open source goGPS software, one can detect movements of the order of few millimeters when a short baseline with daily solutions is used.
http://dx.doi.org/10.1061/(ASCE)SU.1943-5428.0000168
... However, site access and energy provision for each receiver is necessary. The high costs for each antenna per observation point may be reduced by using upcoming low cost systems [5]. Furthermore, GNSS can only be applied point-wise; therefore, the dense mapping of large areas is not possible. ...
Image Assisted Total Stations (IATS) unify geodetic precision of total stations with areal coverage of images. The concept of using two IATS devices for high-resolution, long-range stereo survey of georisk areas has been investigated in the EU-FP7 project DE-MONTES (www.de-montes.eu). The paper presents the used methodology and compares the main features with other terrestrial geodetic geo-monitoring methods. The theoretically achievable accuracy of the measurement systemis derived and verified by ground truth data of a distant clay pit slope and simulated deformations. It is shown that the stereo IATS concept is able to obtain higher precision in the determination of 3D deformations than other systems of comparable sensor establishment effort.
... The use of less expensive single-frequency GNSS receivers is possible in case of landslides monitoring because their small size (a few hundreds of meters to 1 or 2 km) allows a relative positioning with short baselines (typically less than 5 km) which mitigates spatially correlated errors (such as ionospheric disturbances) and makes the use of L2 frequency unnecessary. Single-frequency receivers have been successfully used in the past for different landslide surveying tasks (Malet et al., 2000(Malet et al., , 2002Squarzoni et al., 2005;Heunecke et al., 2011). ...
... With regard to the positioning systems for landslide monitoring, the use of GNSS receivers has been a common practice for several years [17]. Low end receivers are suitable for utilization, but there are no examples showing both very low cost and accuracy: actually, in several recent applications, it is foreseen the use of Original Equipment Manufacturer (OEM) receivers, whose cost is not really low [18]; in other cases, a permanent stations network [19] or a reference station [20] is needed. Anyway, a center for data processing and transmission is foreseen, for applying the Real Time Kinematic (RTK) method. ...
An integrated sensor for the measurement and monitoring of position and inclination, characterized by low cost, small size and low weight, has been designed, realized and calibrated at the Geomatics Lab of the University of Calabria. The design of the prototype, devoted to the monitoring of landslides and structures, was aiming at realizing a fully automated monitoring instrument, able to send the data acquired periodically or upon request by a control center through a bidirectional transmission protocol. The sensor can be released with different accuracy and range of measurement, by choosing bubble vials with different characteristics. The instrument is provided with a computer, which can be programmed so as to independently perform the processing of the data collected by a single sensor or a by a sensor network, and to transmit, consequently, alert signals if the thresholds determined by the monitoring center are exceeded. The bidirectional transmission also allows the users to vary the set of the monitoring parameters (time of acquisition, duration of satellite acquisitions, thresholds for the observed data). In the paper, hardware and software of the sensor are described, along with the calibration, the results of laboratory tests and of the first in field acquisitions.
Rock cliff monitoring on the Yangtze riverside is of crucial importance for the inhabitant’s life, waterborne transportation and the Three Gorges Dam. The Lianziya Cliff is in a high-risk area and requires geodetic monitoring for collapse predictions. This is achieved with different measurements techniques that co-work with the purpose of determining cliff movements. This publication shows the fusion of tachymeter, GNSS (Global Navigation Satellite System), GB-SAR (Ground based Synthetic Aperture Radar) and TLS (terrestrial laser scanner) data and reaffirms the stability of the cliff within a period of one year. One challenge is to combine data represented in different dimensions, for e.g. GB-SAR data which gives line-of-sight displacements and area-wise TLS point clouds that are directly in 3D, as well as point-wise Total Station (TS) and GNSS. Another challenge was to define a common geodetic reference for the two epochs and to detect movements or deformations between two epochs. In principle, this should not be so difficult, but often, as in this case, the measurements are inhomogeneous or even not complete in each epoch. In this contribution the authors focus on solving these issues e.g. by TS measurements and the Iterative Closest Point (ICP) algorithm. The two epochs took place in 2018 and 2019; time interval that is too small to detect deformations. Therefore, statements regarding the required temporal distance to detect deformations are also made.
Current deformation monitoring applications adopting GNSS technology are usually conducted with high-grade GNSS sensors, consisting of both geodetic receiver and geodetic antenna. However, the high-cost feature of the equipment constrains its broader application. With the development of state-of-art low-cost GNSS receivers/antennas in recent years, especially those with multi-GNSS precise carrier phase measurement, the potential for its application in deformation monitoring is expected. However, compared to conventionally adopted survey-grade equipment, most low-cost receivers have the major drawback of single-frequency and larger background noise in the signal processing phase, and the patch antennas have the major disadvantage of the less gain, less multipath suppression, etc. Despite the comparatively poorer quality, empirical research has demonstrated its feasibility in landslide monitoring within centimetre level of accuracy. To test the feasibility and accuracy of the low-cost equipment in other deformation applications, a systematic approach is adopted by carrying out several experiments. Experiments are conducted sequentially from zero-baseline test for internal receiver noise evaluation, short baseline static test to identify and mitigate the practical GNSS monitoring errors majorly consisted of multipath, short baseline dynamic test to determine the precision of low-cost equipment in dynamic monitoring scenario, and finally, the low-cost equipment is tested on a real bridge monitoring project to assess its feasibility and evaluate its accuracy. It is concluded that the modal frequencies from deformation monitoring could be revealed from measurements of a single low-cost rover, and with proper multipath mitigation technique, displacement amplitude could be obtained within centimetre accuracy by a closely-spaced dual low-cost system. The difference of low-cost rover measurement is quantified to be within around 3mm compared to geodetic GNSS sensors. This finding is quite promising for low-cost GNSS deformation monitoring applications. However, future investigation still needs to be carried out with a calibrated patch antenna or with a geodetic antenna to examine further improvement and possibly explore the potential of applying it in real-time.
Positioning with low-cost GNSS (Global Navigation Satellite System) receivers is becoming increasingly popular in many engineering applications. In particular, dual-frequency receivers, which receive signals of all available satellite systems, offer great possibilities. The main objective of this research was to evaluate the accuracy of a position determination using low-cost receivers in different terrain conditions. The u-blox ZED-F9P receiver was used for testing, with the satellite signal supplied by both a dedicated u-blox ANN-MB-00 low-cost patch antenna and the Leica AS10 high-precision geodetic one. A professional Leica GS18T geodetic receiver was used to acquire reference satellite data. In addition, on the prepared test base, observations were made using the Leica MS50 precise total station, which provided higher accuracy and stability of measurement than satellite positioning. As a result, it was concluded that the ZED-F9P receiver equipped with a patch antenna is only suitable for precision measurements in conditions with high availability of open sky. However, the configuration of this receiver with a geodetic-grade antenna significantly improves the quality of results, beating even professional geodetic equipment. In most cases of the partially obscured horizon, a high precision positioning was obtained, making the ZED-F9P a valuable alternative to the high-end geodetic receivers in many applications.
Geologically, La Paz City is located in an unstable area. During the history of La Paz city, many landslides have destroyed houses and valuable infrastructures. In the last decades, time series Interferometric Synthetic Aperture Radar (InSAR) technologies have demonstrated a great capacity for detecting slow ground displacement, achieving an accuracy of millimetre-level. In order to have a better landslide monitoring of La Paz city, in this study, the Sentinel-1 SAR images have been processed by Persistent Scatterer Interferometry (PSI) and the Small Baseline Subset (SBAS) techniques. The time span of the datasets is from March 2015 to August 2016. Both ascending and descending Synthetic Aperture Radar (SAR) images have been processed to obtain the line of sight (LOS) ground velocity, and then the results have been combined to estimate the up-down and east-west displacement. Several active movement areas have been identified, showing a surface velocity up to 158 mm year−1 westward and 49 mm year−1 eastward. Furthermore, two important findings have been discovered. First, the InSAR result has detected movement in Auquisamaa hill before the area collapsed (15 February 2017), where five houses are buried. Second, the InSAR result has identified that there are still some unstable sites in Callapa area, where a mega-landslide has destroyed more than a thousand of houses in February 2011. In conclusion, we have verified that the InSAR technology could be a very useful tool to help La Paz public institutions for a better management of urban planning, landslide areas delimitation and landslide risk mitigation.
In order to optimise the selection of landslide monitoring points and save the cost of monitoring, a geological constitutive model was constructed by using 3D laser scanning and geological borehole data to simulate the relationship between rainfall and deformation. Thus, the main occurrence area and maximum deformation of the landslide were determined. Aiming at the deficiency of the single-epoch redundancy of the single-frequency GNSS receiver and the poor accuracy, this paper proposes a single-frequency BDS/GPS combined positioning and monitoring scheme with constraint of deformation features to restrict the search range of single-frequency ambiguity, obviously increase the ambiguity fixed success rate and then improve the BDS/GPS positioning accuracy. By contrast experiments, the landslide area obtained by numerical simulation basically matches with the on-site landslide area. The BDS/GPS combined positioning with constraint is consistent with the deep displacement changes, which can well reflect the displacement of the landslide body and make an early warning of disasters.
Continuous GNSS networks provide unique information about the crustal dis-placements, of use for studies concerning plate motions, tectonic processes, and earthquake cycle understanding. The Istituto Nazionale di Oceanografia e di Geofisca Sperimentale—OGS, since 2002, is responsible for the installation, maintenance, and development of FReDNet (Friuli Regional Deformation Network), the system for crustal deformation monitoring in the Friuli Venezia Giulia Region. The main objective of the network is the detection of tectonic plate movements in this collision area: such movements can give some guidance to quantify the seismic hazard. The infrastructure currently consists of 16 permanent stations located in the Friuli Venezia Giulia and Veneto regions, all equipped with GNSS receiver (Global Navigation Satellite Systems) capable of tracking satellite systems GPS, GLONASS and Galileo. The system includes a central server for collecting, processing and distributing of data and results. FReDNet, furthermore, provides a service for browsing high-precision real-time positioning in the most common differential correction RTK (Real Time Kinematic) modes. The current document will briefly describe the technical implementation of FReDNet in the last years with new stations, new features (high-frequency sampling and monumentation) and upgraded services.
Fast displacements detection in real-time is a very high challenge due to the necessity to preserve buildings, infrastructures and the human life. In this paper this problem is addressed using some statistical techniques and a GPS mass-market receiver in real-time. Very often, most of landslides monitoring and deformation analysis are carried out by using traditional topographic instruments (e.g. total stations) or satellite techniques such as GNSS geodetic receivers, and many experiments were carried out considering these types of instruments. In this context it is fundamental to detect whether or not deformation exists, in order to predict future displacement. Filtering means are essential to process the diverse noisy measurements (especially if low cost sensors are considered) and estimate the parameters of interest. In this paper some results obtained considering mass-market GPS receivers coupled with statistical techniques are considered in order to understand if there are any displacements from a statistical point of view in real time. Instruments considered, tests, algorithms and results are herein reported.
Monitoring small size area deformations calls for
increasingly precise data with greater space and time resolution.
To this aim, a GPS data processing method designed
for wireless networks of mono-frequency GPS receivers
is proposed. The different steps of the method are
explained: the GPS processing is first detailed with the design
of parametric and stochastic models, their inversion
by an extended Kalman filter and the mitigation of the
main errors: multipath. A parsimonious radio data transfer
protocol is then proposed. It allows a real-time positioning
thanks to a wireless transfer of GPS carrier phases
data from receivers to a processing computer. Finally the
method is tested on a network of mono-frequency receivers
developed by the French National Mapping Agency (IGN).
Tests prove its ability for real-time positioning with a fifteen
receivers network, and a precision under the centimeter
level is reached.
Landslides are one of the major geo-hazards which have constantly affected Italy especially over the last few years. In fact 82% of the Italian territory is affected by this phenomenon which destroys the environment and often causes deaths: therefore it is necessary to monitor these effects in order to detect and prevent these risks. Nowadays, most of this type of monitoring is carried out by using traditional topographic instruments (e.g. total stations) or satellite techniques such as global navigation satellite system (GNSS) receivers. The level of accuracy obtainable with these instruments is sub-centimetrical in post-processing and centimetrical in real-time; however, the costs are very high (many thousands of euros). The rapid diffusion of GNSS networks has led to an increase of using mass-market receivers for real-time positioning. In this paper, the performances of GNSS mass-market receiver are reported with the aim of verifying if this type of sensor can be used for real-time landslide monitoring: for this purpose a special slide was used for simulating a landslide, since it enabled us to give manual displacements thanks to a micrometre screw. These experiments were also carried out by considering a specific statistical test (a modified Chow test) which enabled us to understand if there were any displacements from a statistical point of view in real time. The tests, the algorithm and results are reported in this paper.
Mainly in the context of global climate change the awareness of
landslide hazards has risen considerably in most mountainous regions
worldwide in the last years. National and regional hazard mapping
programs were set up in many countries and most of the potentially
endangered sites have been identified. Although exclusive geodetic and
geotechnical instrumentation is available today, due to some economical
reasons only few of the identified potentially risky landslides are
monitored permanently. The intention of the alpEWAS research project is
to develop and to test new techniques suitable for efficient and
cost-effective landslide monitoring. These techniques are combined in a
geo sensor network with an enclosed geo data base and a developed
software package to use the whole system for stakeholder information and
early warning purposes. The core of the project is the development and
testing of the three innovative measurement systems time domain
reflectometry (TDR) for the detection of subsurface displacements in
boreholes and reflectorless video tacheometry (VTPS) and a low cost GNSS
sensor component for the determination of 3D surface movements.
Essential experiences obtained during the project will be described.
In context of global climate change and the continuous extension of settlement areas in the Alps especially due to tourism, an increasing conflict between land use and natural hazard prevention can be observed. This also includes deep seated landslides, which if activated can cause considerable damage to settlements and infrastructure and even can endanger lives. To date the hazard potential of slow deep seated landslides often is underestimated. Due to economic reasons such potentially dangerous instable slopes if at all often are only monitored sporadically. The alpEWAS project ("development and testing of an integrative 3D early warning system for alpine instable slopes") is currently developing a low cost 3D monitoring and early warning system for landslides based on three innovative economic continuous measurement systems for underground and surface deformations: Time Domain Reflectometry (TDR), Reflectorless Video Tacheometry (VTPS) and Low Cost Global Navigation Satellite System (GNSS). These are merged with other sensors, which monitor typical trigger mechanisms (e.g. precipitation), into a geo sensor network, which provides remote online access to all data in near real time. The alpEWAS system has been installed at the Aggenalm landslide, located in the Bavarian Alps near Bayrischzell, for a first field test. To date the system has reliably produced data for about 8 months, of which the first time series are presented. The amount of data is currently still not sufficient for a final evaluation of the new measuring systems during field use, but the preliminary results concerning the reliability and accuracy of the measurements are promising. The experiences made at this first field test will be of great importance for the medium-term goal: the development of a market-ready, flexible, economic early warning system for landslides.
The paper reports on the principles, experiences and first results made
with a low cost satellite based sensor network recently developed
especially for landslide monitoring. Central idea of the system is the
permanent broadcast of carrier phase (CP) raw data from the sensor nodes
to a base station, where an automated near real time processing (NRTP)
takes place. Low cost means the utilization of simple navigation
receivers with the required capability of read-out the CP raw data.
Depending on the different filter options during analysis the system
generates sensor node positions with sub centimetre accuracy. The
challenge of the still ongoing development is to have a flexible, robust
(weatherproof), commercial off-the-shelf GNSS sensor network of
high-quality available - concerned not only for landslide
monitoring in future.
Simple navigation receivers can be used for positioning with sub-centimeter accuracy in a wireless sensor network if the read-out of the carrier phase (CP) data is possible and all data are permanently broadcast to a central processing computer. At this base station an automated near real-time processing takes place and a precise differential GNSS-based positioning of the involved sensor nodes is computed. The paper describes the technical principles of such a system with its essential demands for the sensing, the communication, and the computing components. First experiences in a research project related to landslide monitoring are depicted. Of course the developed system can also be embedded for location finding in a widespread multifunctional geo sensor network. The quality of the obtained result is restricted due to the fact that the CP measurements must be recorded over a certain time span, usually a few minutes for every independent position solution. As far as possible a modular structure with commercial off-the-shelf components, e.g. standard wireless local area network for communication, and in cooperation of existing proofed and powerful program tools is chosen. Open interfaces are used as far as possible.
Developments towards a low cost GNSS Based Sensor Network for the monitoring of landslides
- J Günther
- O Heunecke
- S Pink
- S Schuhbäck
J. Günther, O. Heunecke, S. Pink and S. Schuhbäck,
Developments towards a low cost GNSS Based Sensor
Network for the monitoring of landslides, in: 13th FIG
International Symposium on Deformation Measurements
and Analysis, Lisbon, May 12-15, 2008.
Development and testing of a low cost sensor PDGNSS landslide monitoring system using the example of the Aggenalm Landslide in the Bavarian Alps
- J Glabsch
- O Heunecke
- S Schuhbäck
J. Glabsch, O. Heunecke and S. Schuhbäck, Development
and testing of a low cost sensor PDGNSS landslide
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Copenhagen, 2010, pp. 63-70.
Treatment of diffraction effects caused by mountain ridges
- R Klostius
- A Wieser
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R. Klostius, A. Wieser and F. Brunner, Treatment of
diffraction effects caused by mountain ridges, in:
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May 22-24, 2006.
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- M Moser
- Th Wunderlich
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Low cost 3D early warning system for alpine instable slopes-the Aggenalm Landslide monitoring system
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- O Wunderlich
- J Heunecke
- S Singer
- P Schuhbäck
- J Wasmeier
- J Glabsch
- Festl
K. Thuro, Th. Wunderlich, O. Heunecke, J. Singer, S.
Schuhbäck, P. Wasmeier, J. Glabsch and J. Festl, Low cost
3D early warning system for alpine instable slopes-the
Aggenalm Landslide monitoring system, Geomechanics
& Tunnelling 3 (2009) 221-237.