Investigation of velocity changes of cadastral sites on the scale of Türkiye

In this study, the differences between the velocities of cadastral sites established in different periods were investigated. For this purpose, velocity data of 482 C1 and C2 sites distributed throughout Turkey were obtained from the Mapping Information Warehouse. The current velocities of these sites were estimated using the National Geodetic Velocity Field data produced by General Directorate of Mapping. The differences between the two velocity fields were calculated for each site on a component basis and difference maps were generated. The maximum differences for X, Y and Z components are 25, 39 and 37 mm/year, respectively. These differences indicate that epoch transformation in the long term may cause errors at decimeter-level.