Assessing reservoir dam stability using C-band permanent scatterers INSAR

Abstract

The purpose of this article is to analyze the results of processing time series of radar images using the Persistent Scatterer method to assess the stability of the vertical position of the reservoir dam. The object of this study is the dam of the cooling pond at the Khmelnytskyi Nuclear Power Plant. Due to production needs, the task arose to analyze the dam's stability in the vertical position using an independent method for the 2016-2022 period. Implementing such a task became possible only by utilizing a satellite radar image database for the specified area. The input data for the analysis consisted of 13 radar images of the specified area obtained from the Sentinel-1 satellite, covering the period from May 2016 to May 2022 with a six-month interval. Processing satellite radar data using the StaMPS algorithm allowed for creation of maps of average surface movement velocities. After applying spatial-correlated and tropospheric corrections, the vertical velocity range of the developed deformation maps for the investigated area was [-9.0; +8.3] mm/year. At the industrial site area, the average velocities of vertical displacements are close to zero, this indicates the stability of the specified area according to InSAR observations. Analyzing the plots of vertical movements of the dam it was observed that the displacements exhibit a cyclic pattern, which is associated with seasonal influences on the structure. The magnitude of maximum displacements during the investigated period ranged from [-10 mm; +10 mm]. The obtained data indicate the absence of hazardous deformation processes that could affect the operational reliability of the reservoir dam. A comparative analysis of the results with time series of vertical movements of reservoir dams in Poland (Niedzica Dam, Solina Dam, Włocławek Dam) was performed. The time series obtained from the European Ground Motion Service data confirm the presence of seasonal cyclic movements of the dams. The practical significance of the research results lies in confirming the effectiveness of using a time series of C-band radar images for geodetic monitoring of reservoir dam stability. Due to access to the existing database of radar images of the Sentinel-1 satellite, the task of assessing the stability of the vertical position of the dam of the cooling reservoir of the Khmelnytsky NPP for the period from 2016 to 2022 was solved.