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In order to find a possible relation between the reservoir level and the deformation of the Sanalona dam, the horizontal and vertical displacements for a period of 3.5 years using GPS observations were calculated. The GAMIT/GLOBK scientific software was used for the relative processing of GPS observations and annual speeds over the dam of −6.77 mm/yr, −9.95 mm/yr and −1.62 mm/yr were calculated for the N, E and U components, respectively. In addition, the GNSS reflectometry inversion technique was applied to determine the daily reservoir level of the dam, the values obtained were compared with the real reference values of graduated rulers in situ. The GNSS-R achieved a correlation coefficient ( ρ ) of 0.97 with a root-mean-square error (RMSE) of 1.36 m and a regression slope of 0.932 m/m. The deformation in the x Dam component obtained a greater relation with the reservoir level due to the thrust force generated on the crest. The results demonstrate that it is possible to use a GPS antenna to carry out two monitoring processes together on a dam: (1) determination of displacements and (2) calculation of reservoir level.

Earthquakes are a major danger in a constantly growing society due to their imminent impact and power of destruction. Therefore, the idea of successfully forecasting an earthquake continues to motivate the multidisciplinary study of phenomena proposed as possible earthquake precursors such as ionospheric anomalies. In that sense, total electron content (TEC) has demonstrated to be an efficient parameter for investigating the state of the ionosphere by making use of the Global Positioning System receivers. In the present study, raw vertical TEC data obtained from the standard RINEX files of the GPS constellation are used to examine the state of the ionosphere during the occurrence of light to moderate earthquakes in Mexico from years 2008 to 2015 with the aim of search for possible ionospheric anomalies related to seismic activity. In order to evaluate the impact at the geomagnetic and ionospheric environments, the Geomagnetic Equatorial Dst index, which is considered to have a great influence on TEC during geomagnetic storm period, and solar activity parameters, have been considered. The results indicated that 17 (74%) of the studied events presented not quiet geomagnetic conditions for the days before the earthquake. Thus, the changes in VTEC are most likely related to geomagnetic anomalies which rules out its possible seismic origin. Contrariwise, 3 (13%) of the events presented geomagnetic anomalies the days after the earthquake. For the remaining 3 (13%) events, these presented particular characteristics, such as: not quiet geomagnetic condition for the earthquake day, geomagnetic anomalies throughout the period and the opposite.

During the last two decades, Global Positioning System (GPS) geodetic-grade receivers and accelerometers have been implemented in Structural Health Monitoring (SHM). Most recently, the use of sensors integrated in smartphones has been evolving. Although some of their capabilities are validated for small and local structures, there is a gap in knowledge about the use of sensors embedded in smartphones and other electronic devices for SHM of complex structures as bridges. To contribute in this area, this paper demonstrates the application of GPS receivers, accelerometers, and smartphones, integrating a smart sensor for the SHM of bridges. In order to validate its capabilities, the alternative smart sensor is used to study a particular bridge with vibration problems. Semistatic and dynamic displacements are obtained by means of GPS measurements. Accelerations in three directions of the bridge are determined using the accelerometer and the smartphone. Based on the results of the alternative smart sensor, inappropriate structural behavior is detected in the vertical direction of the bridge. In addition, dynamic characteristics are extracted using the smart sensor applying the Fast Fourier Transformation (FFT) and periodogram to the structural responses. As a result, it is verified the applicability of the fused smart sensor for SHM on real-scale bridges.

Global Positioning System (GPS) technology is reported in the literature as a reasonable alternative for the structural health monitoring (SHM) of bridges. However, more validations of GPS ...

Global Positioning System (GPS) naturally produces position estimates representing a considerable advantage in comparison with others assessment instruments such as accelerometers, where double integration is required. Several investigations have demonstrated that GPS is an accurate and efficient tool for the evaluation of civil infrastructure. Therefore, an alternative bridge structural evaluation focused on in-service conditions of the Juarez Bridge located in Culiacan, Mexico by using GPS is addressed in this research. The Juarez Bridge connects two important zones of the city, it is a reinforced concrete structure constructed approximately 45 years ago, and it has a length closely to 200 m. The assessment process consisted in collecting continuous GPS data during one consecutive hour at three different periods of the day (rush hours) from Monday to Sunday under critical traffic loading. Since the response of a structure subjected to loads may result in different types of displacements, GPS time series were used for the proper calculation of dynamic and semi-static displacement at the center deck of the Juarez Bridge. However, GPS displacements obtained in terms of coordinates may not accurately reveal the behavior of the bridge without considering prior filtering of the data. Hence, two post-processing reliable filtering techniques: the moving average and Chebyshev filter were applied to improve the time series. It was observed that the vertical displacements were critical during the evaluation. Hence, vertical semi-static displacements were compared with respect to the AASHTO (American Association of State Highway and Transportation Officials) deflection limits, and probability of failure was properly calculated.

The use of geodetic-grade GNSS (Global Navigation Satellite System) receivers is increasingly evolving in the Structural Health Monitoring (SHM) of infrastructure. In this sense, the Precise Point Positioning GNSS (PPP-GNSS) is becoming very popular since it requires only one GNSS receiver. This paper presents a novel SHM technique by integrating the PPP-GNSS measurement technology and an alternative probabilistic approach. Such an approach is based on the study of the stochastic behavior of displacements and their corresponding probability density functions. As a case of study, the El Carrizo Bridge is studied. Results validate the accuracy of the PPP-GNSS measurement technology, and the potential benefits of the alternative probabilistic SHM approach since risk can be extracted using a single GNSS receiver in terms of reliability index and probability of failure. Finally, based on the probabilistic evaluation, it is demonstrated that the El Carrizo Bridge presents an adequate behavior after its rehabilitation.

Northwestern Mexico experiences large variations in water vapor on seasonal time scales in association with the North American monsoon, as well as during the monsoon associated with upper-tropospheric troughs, mesoscale convective systems, tropical easterly waves, and tropical cyclones. Together these events provide more than half of the annual rainfall to the region. A sufficient density of meteorological observations is required to properly observe, understand, and forecast the important processes contributing to the development of organized convection over northwestern Mexico. The stability of observations over long time periods is also of interest to monitor seasonal and longer-time-scale variability in the water cycle. For more than a decade, the U.S. Global Positioning System (GPS) has been used to obtain tropospheric precipitable water vapor (PWV) for applications in the atmospheric sciences. There is particular interest in establishing these systems where conventional operational meteorological networks are not possible due to the lack of financial or human resources to support the network. Here, we provide an overview of the North American Monsoon GPS Transect Experiment 2013 in northwestern Mexico for the study of mesoscale processes and the impact of PWV observations on high-resolution model forecasts of organized convective events during the 2013 monsoon. Some highlights are presented, as well as a look forward at GPS networks with surface meteorology (GPS-Met) planned for the region that will be capable of capturing a wider range of water vapor variability in both space and time across Mexico and into the southwestern United States.

A network adjustment analysis was derived for a GPS network called TAMDEF (Trans Antarctic Mountains Deformation), located in Victoria Land, Antarctica. The network adjustment strategy involved the careful selection and application of the appropriate approach to process the TAMDEF network. Therefore, for the first part of the presented study, four cases denoted as Cases I–IV were investigated for the TAMDEF network processing with respect to the IGS (International GNSS Service) sites inside and outside the Antarctic continent. Here, the GPS data processing relied on the PAGES (Program for Adjustment of GPS Ephemerides) software, which was set up to run using the Least-Squares adjustment with Stochastic Constraints (SCLESS). The second part of the study focus in considering alternative network adjustment approaches: the Minimum-Norm LESS adjustment (MINOLESS); the Partial Minimum-Norm LESS (Partial-MINOLESS) and the Best LInear Minimum Partial-Bias Estimation (BLIMPBE) to validate results from the SCLESS approach (Case I) for IGS sites inside the Antarctica. Based on the applied network adjustment approaches within the Antarctic tectonic plate, it can be demonstrated that the GPS data used is clean of bias after properly taken care of ionosphere, troposphere and some other sources that affect GPS positioning.