Reconstruction of Waste Rock Dump Deformation Stages Based on Multi-Temporal UAV Photogrammetry, Terrestrial Laser Scanning, and Mine Surveying

This study investigates the development of deformation in the southern waste rock dump of the Western Open Pit of the Zhairem Mining and Concentrating Complex through the integrated analysis of multi-temporal geospatial data. The study addresses the need to move beyond the identification of surface changes toward the reconstruction of deformation development and the interpretation of the processes linking changes in dump geometry with the initiation of active displacements. The research is based on the combined use of mine surveying measurements, aerial survey data acquired using UAV, and terrestrial laser scanning. The methodology included the generation and spatial co-registration of multi-temporal digital models, the construction and analysis of cross-sections, the assessment of changes in dump lift geometry and crest positions, and the quantitative evaluation of displacements during the active stage of deformation. The results made it possible to establish the temporal sequence of changes preceding the deformation of the upper dump lift: changes in the geometry of the lower part of the waste rock dump, subsequent restoration of the previously disturbed area through renewed material deposition, and an increase in the height of the upper dump lift. These changes may be considered possible factors contributing to deformation development; however, the available data do not allow their direct causal role to be established. Cross-section No. 2 proved the most informative for reconstructing the deformation sequence, revealing characteristic morphological features, including disturbance of dump lift geometry, elevation loss within the failure zone, and displacements confirmed by terrestrial laser scanning. A comparison of two consecutive terrestrial laser scanning datasets showed pronounced displacements during the first observation interval, whereas during the second interval, the magnitude of the detected changes decreased substantially and was close to the level of metric uncertainty associated with the TLS comparison. The main outcome of this study is the retrospective reconstruction of the successive stages of a deformation event through the integrated analysis of datasets with different spatial and temporal resolutions. The results demonstrate the practical applicability of this approach for analyzing deformation development and supporting the monitoring of waste rock dumps at active mining operations.