Measurement of spatio-temporal changes of cave ice using geodetic and geophysical methods: Dobšiná Ice Cave, Slovakia

Abstract

Abstract. Dobšiná Ice Cave has attracted the attention of many researchers since its discovery more than 150 years ago. Although the cave is located outside the high-mountain area, it hosts one of the largest blocks of underground perennial ice. The topographic mapping of this unique UNESCO Natural Heritage site has led to several historical surveys. In the last decades of rapid climate change, this natural formation has been subject to rapid changes that are dynamically affecting the shape of the ice body. Not only increased precipitation, the rise in year-round surface temperatures, but also the gravity cause significant shape changes in the ice filling. This paper describes modern technological tools to comprehensively survey and evaluate interannual changes in both the floor and wall of the underground ice block. Technologies such as digital photogrammetry, in conjunction with precise digital tacheometry, make it possible to detect ice accumulation and loss, including the effect of sublimation due to airflow, as well as sliding movements of the ice block to the lower part of the cave. In the last two years, geophysical methods (microgravimetry and ground penetrating radar) have been added to determine the thickness of the floor ice in the upper parts of the cave due to the complexity of the measurements. The paper not only highlights the current technological possibilities but also points out the limitations of these technologies and then sets out solutions with a proposal of technological procedures for obtaining accurate geodetic and geophysical data.

Cross-Polarized SfM Photogrammetry for the Spatial Reconstruction of Challenging Surfaces, the Case Study of Dobšiná Ice Cave (Slovakia)

“…For example, in ice caves, the structure and texture of the ice can cause problems in capturing the progression of the ice surface, resulting in data with significant noise or areas with no data. Dobšiná Ice Cave is a typical example where TLS was used to obtain an overall model of the cave, and digital photogrammetry was used for a more detailed modelling of selected sites for the purpose of the long-term monitoring of ice-filling dynamics [38,67]. However, in some parts of the cave, these technologies also failed, and their results were not applicable (Figure 7), especially in the tunnel cut in the ice filling.…”