Analysing topo-geodetic, GPR and InSAR method integration for hydropower dam deformation monitoring: Case study on the Poiana Mărului Dam, Romania

Abstract

In Romania, dams undergo extensive evaluations and rigorous surveillance on an annual basis to assess their structural integrity and safety. Conventional monitoring practices primarily involve topo-geodetic techniques, which are crucial for assessing both vertical and horizontal shifts in these structures. However, the application of geophysical methods, such as Ground Penetrating Radar (GPR), has not yet been standardised in their analysis and monitoring protocols. This study explores the feasibility of the GPR surveys and their integration with data from annual levelling surveys from the Poiana Mărului dam, an embankment dam (rockfill with clay-core) located in Caraș-Severin County. Topo-geodetic data are instrumental in providing insights into surface-level changes. Our findings indicate that the GPR approach can significantly augment the existing monitoring framework. It offers valuable insights into the internal composition of specific dam segments, thereby enhancing our understanding of observed phenomena, such as displacements and deterioration, initially identified through topo-geodetic methods. Advanced Differential Interferometric SAR (A-DInSAR) processed data, publicly available from the European Ground Motion Service (EGMS) as a key component of the Copernicus Land Monitoring Service, are considered as well for assessing their suitability in highlighting relevant information about dam deformation monitoring, therefore complementing the ground penetrating radar and topo-geodetical surveys. All of the three methods seem to be correlated in overall general trend in terms of displacements throughout the dam’s body, offering insights and information from different perspectives and complementing for providing a much clearer overview of the behaviour of the vertical displacements in time of the dam.