## 6 Conclusions  
The results of this research show the continuation of displacements in the area of Wroclaw after the last levelling measurements in 1999. Based on previous research, the results are interpreted to be mainly vertical displacements, which were recorded since 1930, and are estimated at a velocity of up to 3 mm/year. To a limited degree, the results may also be affected by horizontal displacements, whose intraplate velocities do not exceed 1 mm/year. The calculated displacement values do not exceed measurement accuracy estimated by other authors at 3 mm [22; 27]. However, due to a relatively long observation period (1995-2002 and 2002-2008), as well as to a significant number of persistent scatterers and a standard deviation of 0.5-0.7 mm/year, the following conclusions are justified:  
* the displacements, which continue to occur in the area of Wroclaw have a cyclic character with 4-5 years long period of subsidence and 2-3 years long periods of stabilization or uplifted.
* the displacement trends indicate that the area of the city gradually subsides in relation to the reference area located on the Fore-Sudetic Block.  
In previous studies [34; 41; 43], it was assumed that, in the city area, there are subareas with permanent subsidence or uplift. Current research, in contrast to these assumptions, indicates periodic changes in direction of displacements.  
Potential causes of the ground surface displacements include large-scale and long-term cyclical deformation and compaction of Cenozoic sediments. Surface displacements resulting from new infrastructures investment can influence deformation values locally, but their range and duration could not significantly affect the obtained results for the entire area. The cause-effect model development must be preceded by modelling and removal of periodic displacements.  
For a detailed interpretation including tectonic factors, further research covering the entire area of southwestern Poland is required. This will demand solving several problems related to the conversion of LOS displacements into vertical displacements, integration of results from neighboring scenes, and integration of results from different sensors.  
Conceptualization, P.G. and J.B. ([PERSON]); methodology, P.G., [PERSON] ([PERSON]) and [PERSON]; software, P.G., [PERSON]; visualization P.G.; formal analysis P.G. and T.G.; validation [PERSON]. ([PERSON]); supervision [PERSON]; writing--original draft preparation, [PERSON]; writing--review and editing [PERSON]. ([PERSON]), [PERSON], [PERSON], and [PERSON] All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Calculations were carried out at the Wroclaw Centre for Networking and Supercomputing [[http://www.wcss.wroc.pl](http://www.wcss.wroc.pl)]([http://www.wcss.wroc.pl](http://www.wcss.wroc.pl)) (Grant No. 336). Data provided by the European Space Agency (Data Service Request id. 34518 \"The use of InSAR data to supply the information about the ground surface deformation for integrated model of surface and buildings deformations\"). The Corine Land Cover 2000, 2006, 2012 and 2018 project in Poland was carried out by Chief Inspectorate of Environmental Protection. The works were contracted to Institute of Geodesy and Cartography. Polish project no. CLC2006 was financed by the European Environment Agency and the National Fund for Environmental Protection and Water Management. The project results were obtained from the clc.gios.gov.pl website of the Chief Inspectorate of Environmental Protection.  
The authors declare no conflict of interest.