PARTIALLY RETRACTED ARTICLE: NORTE project: first reference center for space technologies in the region bordering the Itaipu hydroelectric power plant reservoirAbstract:
The NORTE (Reference Center for Space Technologies) is a project between ITAIPU Binational, UTFPR (Federal University of Technology - Parana) - Santa Helena Campus - and FUNTEF-PR (UTFPR Support Foundation). Conceived to support the implementation of the RAIB (ITAIPU Binational High Precision Vertical Network), the project aims to build classrooms/research laboratories, implement GNSS (Global Navigation Satellite System) station infrastructure, develop applied research in process improvements in geodetic surveys, operate laboratories for teaching practices and contribute to the training of human resources. The project currently manages 3 GNSS-MET (Geodesic and Meteorological sensors) stations: GUAI (Guaira/PR), ITAI (Foz do Iguaçu/PR) and STHA (Santa Helena/PR), with data used in 4 thematic axes: Vertical Reference System, GNSS Surveys, Development of Applied Solutions for Geospatial Data in GIS (Geographic Information System) and LiDAR (Light Detection and Ranging) Survey Applications. Since 2023, seven research projects have been under development, four of which will have their initial results presented: the development of a technical specification for gravimetric densification, programs for monitoring ionospheric and tropospheric activities, a geospatial data management platform and three-dimensional modeling of the hydroelectric plant based on LiDAR data.
Keywords:
GNSS; Gravimetry; ITAIPU; Ionosphere; Troposphere
1. Introduction
The NORTE (Reference Center for Space Technologies) (Figure 1) is a three-part project between ITAIPU Binational, UTFPR (Federal University of Technology - Parana) - Santa Helena Campus - and FUNTEF-PR (UTFPR Support Foundation), started in April 2023.
The project was conceived to support the implementation of the RAIB (High Precision Vertical Network of ITAIPU Binational), which is made up of approximately 1,450 stations between Foz do Iguaçu/PR and Presidente Prudente/SP and which aims to improve the hydrodynamic model for forecasting inflow.
NORTE primarily aims to (a) build classrooms and training and research laboratories in the area of Geodesy, (b) implement infrastructure for GNSS (Global Navigation Satellite System) stations along the ITAIPU Binational hydroelectric reservoir, (c) the development of applied research into process improvements in geodetic surveys, with a focus on productivity gains and automation, (d) the operation of modern laboratories and pedagogical spaces for teaching practices, on subjects that can be applied or reversed to the benefit of ITAIPU’s protected areas and (e) the contribution to the training of human resources specialized in the use of space technologies.
The center is located at UTFPR, Santa Helena Campus (φ = -24° 50’ 46.38”; λ = -54° 20’ 33.97”), due to its location close to the ITAIPU areas (Biological Protection and Refuge) and because it is in the geographic center of the Reservoir (between the cities of Foz do Iguaçu/PR and Guaira/PR). In addition, the Campus provides the necessary infrastructure for its operation, such as electricity, internet and security for equipment and members. The 245 m2 building contains 1 classroom (50 students), 2 research laboratories, 1 equipment room, 1 meeting room and 1 forced-centering geodesic pillar (Figure 2).
(a) NORTE project building. (b) Meeting room. (c) Classroom 50 students. (d) and (e) research laboratories. (f) Equipment room. (g) Forced-centering geodesic pillar.
2. Managed GNSS-MET Stations
In total, the project manages three GNSS-MET stations (Figure 3): ITAI (Foz do Iguaçu/PR), GUAI (Guaira/PR) and STHA (Santa Helena/PR). It is worth noting that all stations have been in operation since 2017, 2022 and 2024, respectively, with the first two being incorporated into the RBMC (Brazilian Network for Continuous Monitoring of GNSS Systems). The Santa Helena station, in turn, is in the approval phase by the IBGE (Brazilian Institute of Geography and Statistics), with availability to users expected by the end of 2025.
All stations are equipped with Trimble Alloy multi-frequency and multi-constellation receiver, choke ring antenna, thermometer, barometer and psychrometer. Figure 4, for example, shows the receiver and meteorological sensors of the STHA station.
(a) STHA GNSS-MET station. (b) Thermometer, barometer and psychrometer, (c) Trimble Alloy receiver and (d) meteorological processing unit.
3. Thematic Axes and Project Forms
Four thematic axes guide the project’s research and innovations: (1) Vertical Reference System, (2) GNSS Surveys, (3) Development of Applied Solutions for Geospatial Data in GIS (Geographic Information System) and (4) LiDAR (Light Detection and Ranging) Survey Applications.
For each axis there are two PF (Project Forms), with the exception of LiDAR applications, which have a single PF. These PF aim at the development of specific applied research, with quarterly deliveries of products and reports. Figure 5 presents the thematic axes and the respective PF.
4. Equipment and Staff
For the development of research for each PF, the project has several pieces of equipment, Information Technology (IT) and transport resources, both from ITAIPU and UTFPR, with emphasis on: 3 geodetic receivers, 1 digital level, 3 total stations, computers, software among others.
The NORTE team is currently composed of representatives from ITAIPU (General Coordination), UTFPR (Technical and Operational Coordination) and FUNTEF-PR (Administrative Coordination). The team also includes 4 professionals (1 engineer, 2 analysts and 1 technician) hired, in addition to 7 scientific initiation scholarship holders. One of the objectives is to train human resources to work in public and private centers that use space technologies. It is also worth mentioning that professors from other higher education institutions also collaborate, such as from UNESP (Sao Paulo State University) - Presidente Prudente Campus, UFPR (Federal University of Parana) - Polytechnic Center Campus, UFU (Federal University of Uberlandia) and USP (University of Sao Paulo), all as volunteer researchers.
5. Research Developed
Having 4 thematic axes, as mentioned in item “3. Thematic Axes and Project Forms”, the research developed will be explained according to its propositions.
5.1 Vertical Reference System
Uncertainties regarding the heights of the benchmarks date back to the construction of the ITAIPU Hydroelectric Power Plant. At that time, the decision was made to adopt a single vertical reference system for the project area in Brazil and Paraguay, which over the years remained independent of the official Brazilian reference network created by the IBGE. The vertical component was called CMT (Comissão Mista de Trabalho - Joint Working Commission), whose height values, called CMT heights, were used in the construction of the plant and to this day by ITAIPU operations.
To make the best use of the gravitational potential energy of water, ITAIPU’s operation constantly monitors two regions:
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The basin directly contributing to the reservoir, in both Brazilian and Paraguayan territories, with their respective tributary rivers;
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The area of the Parana river foodplain, which extends from the Airton Sena bridge, in the municipalities of Guaira/PR and Mundo Novo/MS, to the Rosana/SP and Porto Primavera hydroelectric plants, also with their tributary rivers.
These two regions are monitored by limnimetric stations and bathymetric sections. For both types of monitoring, it is essential that their heights have physical values in a unified reference. Officially, in Brazil, the normal height is adopted for the SGB (Brazilian Geodetic System). However, ITAIPU coexists with two vertical components originating from more than one Vertical Datum. For the set of limnimetric stations and RRNN (acronym in Portuguese for vertical benchmarks) located on the banks of the ITAIPU reservoir, used as starting points for the bathymetric sections, the vertical system called CMT prevails, whose Datum point of origin is not known and is materialized by several historical benchmarks implanted in the area of the plant and region of interest of ITAIPU. For the other stations and RRNN, the height is linked to the SGB and the RRNN linked to the IBGE leveling network, whose Datum point is the tide gauge of Imbituba/SC.
In the thematic axis of the vertical reference system, the project aims to determine the quasi-geoidal model in the ITAIPU area of operation to improve the hydrodynamic and inflow forecast models, supporting decisions regarding the methods and procedures adopted by the RAIB Project. However, as ITAIPU still has many benchmarks in the reference frame from the time of construction and there is interest in the transformation between reference systems, the geoid model will also be determined.
The constant need for greater precision in geodetic surveys led to the contracting of gravimetric survey services in the western region of Parana, with the aim of determining the geoidal and quasi-geiodal model of the area. To this end, it is necessary to know the geoid models existing in the ITAIPU area of operation, the types of gravimetric data, software for calculating gravitational and geopotential components, etc.
In addition to in-depth studies on gravimetry and report preparation, this thematic axis produced a technical specification for contracting the provision of survey services for gravimetric densification and subsequently hiring a specialized company for such survey. Figure 6 represents the area of the contracted survey and which stations have been surveyed to date.
The contract includes the gravimetric survey of 900 densification stations and 523 RAIB stations, totaling 1,423 gravimetric stations. The densification stations are spaced approximately 5 kilometers apart and the RAIB stations are spaced approximately 2 kilometers apart along highways.
Subsequently, the gravimetric data obtained by the survey will be validated and consequently the geoidal and quasi-geoidal models of the area of interest will be determined. This stage is in partnership with two higher education institutions: UFU and UFPR.
The thematic axis also analyzes the gravimetric densification survey for the purpose of calculating height linked to the IHRF (International Height Reference Frame) for one of the RBMC stations implemented by ITAIPU.
These activities are extremely important for the compatibility of the ITAIPU vertical reference (CMT) and the global and regional vertical references that contain a physical component in their determination (geopotential).
5.2 GNSS Surveys
The use of data from GNSS networks is essential for processing geodetic and topographic surveys, monitoring structures, georeferencing of rural properties, monitoring of ionospheric layer, among others. In the case of GNSS stations equipped with meteorological sensors, it is also possible to monitor tropospheric indices, such as IWV (Integrated Water Vapor), which in turn allows the development of studies to identify severe meteorological events, such as gales and storms.
Another benefit of such stations is the dissemination of differential corrections and GNSS signals in real time, as well as post-processed, enabling the development of autonomous applications, mainly in Precision Agriculture. Thus, demonstrating the potential of using such data in Space Geodesy applications in the western region of Parana, with the possibility of expansion to the east of Paraguay and northeast of Argentina, mainly in relation to the ionospheric and tropospheric layers, is of great importance to support the actions of public and private agents, such as ITAIPU.
Several national and international research and scientific projects on the subject have been carried out or are under development, with emphasis on the CALIBRA Project (Countering GNSS high Accuracy applications Limitations due to Ionospheric disturbances in BRAZIL), funded by the European Community’s Seventh Framework Programme and supervised by GSA (European GNSS Agency) (Vani et al. 2017), and the current INCT GNSS-NavAer (National Institute of Science and Technology “GNSS Technology in Support of Air Navigation”), composed of UNESP, INPE (National Institute for Space Research), ITA (Aeronautics Institute of Technology), IAE (Institute of Aeronautics and Space), PUC-Rio (Pontifical Catholic University of Rio de Janeiro), IFSP (Federal Institute of Sao Paulo), UFRGS (Federal University of Rio Grande do Sul), UTFPR and UFPR (Monico et al. 2022). The aim of this axis is to apply the knowledge already developed and consolidated in this area, validate it for the region of interest of ITAIPU and implement tools for the calculation and dissemination of this information, with the purpose of providing information for technical work and for the community as a whole.
To date, two programs have been developed in C Language for monitoring ionospheric activities from data from GNSS stations, namely Ion_Index and RTIon, and a program for monitoring tropospheric activities to obtain meteorological information from data from GNSS stations, called PPPWV.
The Brazilian territory, located largely in the equatorial region and low latitudes, subject to the effects of the EIA (Equatorial Ionization Anomaly) and due to the peak of solar cycle 25 in 2024-2025 (SILSO 2025), monitoring ionospheric activities from data from GNSS stations becomes essential for autonomous activities that demand high accuracy, such as positioning of agricultural and mining machinery, air navigation, dam monitoring, among other activities (Monico et al. 2022).
The Ion_Index estimates, from the GPS and GLONASS observables in the L1 and L2 carriers, the TEC (Total Electron Content) (Matsuoka & Camargo 2004), ROT (Rate Of TEC) (Stuani Pereira & Oliveira Camargo 2017), ionospheric delay (Monico 2008), FP (Mendillo et al. 2000) and ROTI (Pi et al. 1997) for any RBMC station, for any date. The RTIon, in turn, calculates in real time from the GPS observables in L1 and L2 the ROTI irregularity index, for any RBMC-IP (RBMC in Real Time - Internet Protocol) station. Versions of these programs will be available to users soon.
To validate the post-processed and real-time methods, internal and external checks were carried out. In the internal check, for the same date, time interval and season, the ROTI was estimated in real time (with RTIon) and on the following day the post-processed one (with Ion_Index); considering the post-processed one as a reference, the RMSE (Root Mean Square Error) was calculated, in addition, the Pearson correlation coefficient (ρ) was also obtained. In the external check, the results were compared with the S4 scintillation index of the nearest INCT GNSS-NavAer station (Monico et al. 2022). In this sense, six RBMC-IP stations with latitudinal distribution were selected: CEEU, SSA1, MGUB, PPTE, PRCL and POAL. Consequently, the six closest INCT GNSS-NavAer stations were identified: FRTZ, UFBA, STMC, PRU4, STSH and POAL. Figure 7 shows the locations and Table 1 presents the distances between the aforementioned stations.
RBMC-IP and INCT GNSS-NavAer network stations selected for validation of the Ion_Index and RTIon programs.
The validation took place from June to September 2024, comprising periods of winter solstice and spring equinox in the Southern Hemisphere. For each station, two time intervals of each month were processed, between 10 pm and 2 am UT (Universal Time) approximately. A 10° elevation mask to minimize multipath effects was applied. Figures 8 and 9 present the results of the 6 RBMC-IP stations, ordered by latitude, for the months of June and September, for example. It should be noted that TR in the figures refers to real time.
Real-time (TR) and post-processed (PP) ROTI index of selected RBMC-IP stations for June 2024.
Real-time (TR) and post-processed (PP) ROTI index of selected RBMC-IP stations for September 2024.
The agreement of the internal check is noted at all stations, both at times of low and moderate ionospheric irregularities, which is corroborated by the RMSE values (less than 0.03 ROT/s) and correlation (greater than 0.92) presented in Table 2.
RMSE and correlation of real-time and post-processed ROTI index of selected RBMC-IP stations.
When performing the external check with the S4 scintillation index, Figures 10 and 11 show some correspondence with the results obtained in Figures 8 and 9.
The consolidations of Ion_Index and RTIon will provide users with means of mitigating the effects of the ionosphere on positioning, such as by applying geometric screening (suppression of satellites aligned with irregularity regions) or weighting in the stochastic model, providing high accuracy in geodetic coordinates.
Regarding the troposphere, different methodologies can be applied to GNSS data in order to obtain meteorological information. An important example is the estimation of the ZTD (Zenithal Tropospheric Delay) in GNSS signals and through it, together with temperature and pressure information measured during collection, to obtain estimates of PWV (Precipitable Water Vapor), whose potential has been investigated in immediate storm forecasting activities (Sapucci et al. 2019).
Thus, the PPPWV was implemented in C Language, which estimates from the GPS and GLONASS observables on the L1 and L2 carriers, the metrics ZTH (hydrostatic component of the ZTD) (Davis et al. 1985), ZTW (wet component of the ZTD), ZTD (Davis et al. 1985), IWV (Integrated Water Vapor) (Bevis et al. 1992; Davis et al. 1985; Sapucci et al. 2019) and PWV (Sapucci et al. 2019) for any RBMC-MET station, for any date. It is noteworthy that to determine the ZTD, the program automatically performs a PPP (Precise Point Positioning) through the RTKPOST module of the RTKLib software.
Figure 12 shows, for example, the ZTD and PWV graphs of the GUAI station, referring to March 26, 2025. It can be observed that close to 10 am UT (7 am local time), the PWV values show a sudden rise, forming a crest. According to Sapucci et al. (2019), this rise is called “PWV-GPS-jump”, which reveals in advance the occurrence of a severe storm, which was therefore corroborated by the Instituto das Águas do Paraná, with an accumulated precipitation of 51 mm in the municipality of Guaira (AGUASPARANÁ 2025).
This thematic axis also aims to document improvements in the installation of continuous GNSS-MET monitoring stations by ITAIPU (ITAI, GUAI and STHA), through quantitative and qualitative analysis of the operation of the three GNSS-MET stations distributed throughout the reservoir, understanding which users within the company and the community can benefit from this initiative. This enables the development of geospatial applications and tools to make better use of this data, since these activities together contribute to climate forecasts (important for Civil Defense, airports in the region, water balance) and directly influence the quality of GNSS positioning.
Within the ITAIPU technical team, several GNSS-MET applications were identified, including: infrastructure control and monitoring, conducting studies and research on GNSS-MET applications, performing geodetic surveys, climate monitoring, monitoring ITAIPU boundaries, monitoring the boundaries of specific use areas.
Thirteen sectors, distributed across five directorates, were identified that benefit from or use data from GNSS-MET stations directly or indirectly. Such data are essential for obtaining various solutions, such as georeferencing for various purposes, control and monitoring of structures, climate forecasts, among many other applications.
The department responsible for conducting geodetic surveys is the Studies Division (ODRE.CD), part of ITAIPU’s Coordination Directorate. It is one of the departments that utilizes the most geospatial and GNSS-MET data. ODRE.CD is responsible for various high-precision surveys, such as long-distance transportation, RPAS (Remotely Piloted Aircraft), LiDAR, and GNSS collection. Therefore, it plays a fundamental role in obtaining accurate and up-to-date data that assists in the development of activities involving the direct use of GNSS-MET data to generate solutions both for internal departmental demands and in supporting surveys and data processing to meet the demands of other departments and departments within ITAIPU.
Additionally, ODRE.CD is responsible for the development and territorial management of cartographic bases, including the surveying, processing, storage and provision of geospatial data. It manages vertical and horizontal reference systems, as well as the GNSS-MET continuous monitoring bases. These bases are essential for any geodetic and topographic survey in the region. Regarding the meteorological stations, ODRE.CD uses meteorological data from existing stations to forecast and monitor extreme weather events.
5.3 Development of Applied Solutions for Geospatial Data in GIS
With the use of GNSS-MET data in the prediction of extreme weather events and positioning quality control, the capacity and need to use GNSS data for purposes that are not limited to determining positions on the Earth’s surface was identified, but also the potential for using these data in the prediction and monitoring of extreme weather events and events that may harm real-time positioning, necessary for several areas, such as precision agriculture, mining and aviation.
Therefore, it is necessary to structure and standardize the geospatial data under the responsibility of the ITAIPU Studies Division, in order to enable the acquisition, consultation and use of data in an efficient manner and focused on the needs of the users of these products and the development of a platform that can present the related data and indexes, which can be consumed by ITAIPU’s technical teams, the academic community and the community in general that can benefit from access to this information.
To date, some automation flows have been developed for data acquisition in the Python programming language, such as verification of the leveling sections of the RAIB project, which should be used on an online platform for data acquisition and later on a desktop for program execution and updating of results and validation of geometric leveling.
There is also the development of the geospatial data platform, containing reservoir analysis of multiple-use areas and flooded areas and forest stratification, both with three-dimensional availability (Figure 13).
5.4 LiDAR Survey Applications
LiDAR uses laser pulses to locate objects of interest, offering a large amount of information in a short period of time. It operates based on the same fundamental principles as the RADAR system, however, the RADAR system uses radio waves, while the LiDAR system uses laser pulses (Giongo et al. 2010).
The use of LiDAR technology for mapping was initially developed to carry out terrain surveys, such as the DTM (Digital Terrain Model), in which traditional survey methods were expensive and time-consuming (Giongo et al. 2010).
The adoption of LiDAR technology in topographic surveys has been adopted in several applications, this is due to its advantages, which include high speed of data collection and processing, high point density, accuracy and precision necessary for high-precision surveys.
All this technology benefits several technical areas such as civil construction, environmental, forestry, agriculture and meteorology. For ITAIPU, it allows structural monitoring, with the use of precise relief models; inspections of dams and structures, to detect deformations or displacement of structures; vegetation analysis, with mapping of vegetation cover and integrity of transmission lines or preservation areas; safety planning, identifying obstacles or objects that may pose risks; and energy efficiency, with the evaluation and monitoring of turbines.
ITAIPU has LiDAR data acquired through aerial photogrammetric surveys covering the entire protected area of the ITAIPU lake and the floodplain of the Parana river. These three-dimensional data have been used to define reservoir elevation curves and in other specific studies. It is known that these surveys have great potential for generating spatial data and information that can be useful in other areas, both in terms of extractable products and in terms of access to processed point clouds.
The systematization and establishment of solid methodologies for the processing and provision of these LiDAR data are fundamental for the organization and accessibility of these data, as well as in the planning of new surveys that occupy a large volume and storage space.
There was a great need to map the demands and potential of the products extracted from the LiDAR data and that may be of interest to ITAIPU and the academic and local community or for cadastral purposes in areas with buildings, access to the ITAIPU lake and other possible interferences in the protection strip of the ITAIPU reservoir in areas with vegetation (ex: irregular constructions in the protection strip of ITAIPU).
Thus, the modeling and implementation of the database with products and information extracted from LiDAR data and surveys was carried out (Figure 14).
There is also an intention to carry out further studies directed at LiDAR data applications, as well as methodologies and procedures for LiDAR data acquisition, including flight plan, configuration parameters according to accuracy, procedures and care for using LiDAR equipment in the field, procedures for cleaning, storage and preventive maintenance; and for automating the obtaining of products from LiDAR point clouds containing data classification and modeling, software, etc.
6. Final Considerations
The western region of Parana requires greater gravimetric densification in order to obtain greater precision in geodetic surveys and determination of the geoidal and quasi-geiodal models. The hiring of the company to provide gravimetric services was a great step forward in obtaining this data and benefits not only ITAIPU, but also the entire community and institutions that require a greater volume of information.
To date, approximately 73% of the area of interest has been surveyed and the full survey of the area is scheduled for completion in September 2025. It includes the development of a pilot project to identify improvements in vertical positioning and unification of the different reference systems. In the future, the surveys may be extended to the ITAIPU contribution area, which includes the reservoir and its tributaries.
In addition, the implementation of the STHA station linked to RBMC-MET is in the approval phase by IBGE. It has been in operation since August 2024 and its implementation represents a major advance in GNSS coverage in the west of the state, in addition to the gains in ionospheric and tropospheric monitoring.
The use of LiDAR technology allows structural monitoring, with the use of precise relief models; inspections of dams and structures, in the detection of deformations or displacement of structures; vegetation analysis, with mapping of vegetation cover and integrity of transmission lines or preservation areas; safety planning, identifying obstacles or objects that may pose risks; and energy efficiency, with the evaluation and monitoring of turbines. Through its coefficients, it is possible to extract various information that contributes to the inventory of forest and mineral resources, monitoring and mapping of forests and changes in vegetation cover.
Having easy and structured access to the large volume of data generated will make it possible to improve geospatial platforms and tools geared towards user needs.
ITAIPU, as a Brazilian and Paraguayan public company, has as its mission: “To generate quality electrical energy, with social and environmental responsibility, boosting sustainable economic, tourist and technological development in Brazil and Paraguay.” The project seeks to develop, with technical improvement, tools that can be used in the company and in collaboration with other sections of society that can benefit and boost the development of the region of influence of ITAIPU.
All of the project’s initiatives, within the socio-environmental scope, contribute to achieving the SDG (Sustainable Development Goals), especially SDG 4 - Quality Education and SDG 9 - Industry, Innovation and Infrastructure.
For ITAIPU, the project allows parameterization and documentation of each of the methodological procedures that will be applied in the RAIB Project and in activities developed by ITAIPU in the area of Geodetic Sciences; structuring and enabling access to products, data and information arising from surveys carried out by the NORTE Project and will also allow the monitoring and provision of atmospheric and climate data identifying extreme climate events in the region of direct influence of ITAIPU near its reservoir.
For UTFPR, it will mean the consolidation of the regional institution in the area of applied research, in addition to institutional intensification in the training and qualification of students and professionals in the area of geotechnologies, contributing directly to sustainable regional development.
ACKNOWLEDGEMENT
The NORTE project is being funded by agreement ITAIPU-UTFPR-FUNTEF, process number 4500069287-3793-1-14077-5.
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Data availability
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
Publication Dates
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Publication in this collection
03 Nov 2025 -
Date of issue
2025
History
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Received
29 Apr 2025 -
Accepted
28 Aug 2025 -
Retracted
05 Nov 2025
