Research of timewise transpositions of the İSKİ UKBS network stations

Since 1980s space and satellite technologies have been used effectively in zonal studies or examination and monitoring the whole earth and also engineering studies. Recently along with technological progress GIS/GNSS system and applications,in such areas earth sciences, geodetic surveying, remote sensing, data gathering for GIS applications etc., have been systematized in order to collect and evaluate data according to the specific standards and to be delivered to the users for various methods.Coordinates of the receivers can be specified precisely by transmitting the data collected from reference stations that their coordinates had been specified precisely before and adjustments calculated with this data to the other receivers via any communication networks.Accuracy to be achieved in this way changes because of the atmospheric actions as moving away from the fixed reference point. As a result of establishing more than onefixed reference points in order to increase the accuracy, fixed reference GNSS networks have been created. GNSS systems, which is providing uninterrupted service for 24/7, ensuring fast and reliable surveying and used in plenty of areas, are started to be used commonly through the TUSAGA-Aktif (CORS-TR) and İSKİ-UKBS networks in our country. İSKİ-UKBS was established with the aims of firstly ensuring GNSS technologies to be used in ĠSKĠ works effectively and productively, secondly making it a sub-network for increasing the frequency of TUSAGA-Aktif via working with the TUSAGA-Aktif integratedly as well in order to provide a service for all those people, institutions and agencies to be able to use this data in İstanbul. İSKİ-UKBS network ensures surveying with only one itinerant receiver at every points within the boundaries of İstanbul and it is used very actively in İstanbul. İSKİ-UKBS is a perfect service without any alternatives for İstanbul city. Establishing this kind of networks in other cities of Turkey will make sense. Deformation measurements have a crucial role for engineering surveying as well. Especially in recent years emphasis of this subject continues increasingly. Various types of methods are used to specify the movements of the earth crust and the variations that could occur in the course of time on the engineering structures. Surveyings made periodically in order to determine the horizontal and vertical position differences at geodetic methods should be evaluated. Monitoring possible geometric changes to be occurred on bridge, tunnel, dams and multistory constructions is very important. In this study, it is wished to be able to test the reliability of İSKİ-UKBS network used for many engineering measurements and providing service for İstanbul region. For this purpose by processing the measures taken from the reference points of İSKİ-UKBS network at certain periods, movements of the points assumed fixed at a certain period of time are monitored and points expected to be fixed After eliminating the continental move are analyzed. Firstly it was decided that data would be examined in what range and in what dates data would be gained. Program was scheduled as three months difference would be between the first two periods. In this way it was decided that six months difference to be between the next periods according to the movement observed during this three-month process. Measurement days of the İSKİ-UKBS reference points had been scheduled. By obtaining the data belongs to the one day before and after of the determined measurement days. In this time schedule, totally 3-day data was obtained for each point at each period. This 30-second GPS data was obtained from archive data in İSKİ system. Three-day GPS data in each period was examined as one evaluation. In this way bases of the İSKİ-UKBS reference points were evaluated in an intense data frequency via 72-hour data. In addition to the data of the İSKİ-UKBS network reference points, data at the 2005.0 epoch of the ISTA point was downloaded as well. ISTA point was preferred since it is a point remained within the İSKİ-UKBS network. The data obtained was evaluated at measurement epochs by using Leica Geo Office. Strategy to be followed in analyzing the bases that forming the İSKİ-UKBS network was specified and the same analytical geometry was applied at each measurement epoch. In this way, errors to be arised from analytical geometry of the bases during the balancing were eliminated. Firstly evaluation was made at measurement epochs and coordinates were obtained. And then by using the speeds and the ISTA point coordinates accepted motionless at the ITRF 2005 and 2005.0 epoch, coordinates at the measurement epochs of the reference points were dislocated to the 2009/12 epoch which was the first measurement day. Thus, by eliminating the usual continental move happened averagely 2-3cm in each year, other movements occurred -except this move- were determined. Gained coordinate differences were interpreted in conclusion part. In this scope, purpose and strategy of the study is explained in the first chapter. In the second chapter, general information about global navigation satellite systems (GNSS) are included and global systems and error sources of the GNSS are mentioned. In the third chapter, positioning methods are mentioned. In the fourth chapter, real-time fixed GNSS networks and network principles are mentioned and real-time fixed GNSS networks activating at national scale in the region are included. In the fifth chapter, establishment steps of the global navigation satellite systems (GNSS) of İSKİ called İSKİ-UKBS, designing processes of the reference network making observation continually, hardware and software choices, establishing the points and steps of the system service are examined. In this chapter, detailed information about the historical progress of the İSKİ-UKBS since its establishment date is explained. In the sixth chapter, our implementation with the purpose of testing the network is explained. In this section, how the measure times are specified, parameters used in making process on LeicaGeo Office program and information about base geometry analyzed are explained and measure times coordinates and coordinate differences are included as well. Also, it is known that our country is moving towards northwest averagely 2-3 cm every year. By eliminating this usual move, in order to monitoring the move to be occurred at other points, all coordinates obtained by using 2005.0 coordinate and speeds of the ISTA point before were brought to the first measure date 2009/12. Thus, usual continental move was eliminated. Graphics of the coordinates brought to 2009/12 are drawn by finding out their differences from the coordinates of the first period. Thus, measure differences and first measure differences at 2009/12 epochs are determined for all points at İSKİ-UKBS network. Additionally visualization of direction and magnitude of the move are provided by uploading the coordinates at the measure times and the ones brought to 2009/12 to the NetCad. Finally, measurements and evaluations are discussed in chapter seven including conclusion and recommendations. 8 period meaures from İSKİ-UKBS network are evaluated on LeiceGeo Office program and coordinate differences are examined. Compatibility of the reference points with the expected moves at the region is examined. Examining the coordinate differences according to the seasons would make results more meaningful.