Carst subsidence hazard assessment of the Kurtatinsky gorge (Republic of North Ossetia - Alania)

Introduction. The widespread distribution of limestones in the Republic of North Ossetia - Alania predetermined the active development of karst on its territory. Karst research is an important scientific task, the solution of which is necessary to ensure human safety. Materials and methods. Based on the results of field research in 2023 and during the interpretation of high - resolution satellite images (Landsat, Sentinel, GeoEye and WorldView-1,2), the parameters and distribution zones of karst subsidence in the Kurtatinsky Gorge were identified. A systematic analysis of the karst hazard was carried out based on structural, geological and geomorphological data, as a result of which a corresponding map was compiled. Results and discussion. The highest density of karst subsidences (15-20 subsidences per 0.01 km2) is observed on the rounded, flattened summit surfaces of the Bakhty-Laparyrag and Khoshkharanrag ridges, composed of Cretaceous rocks of the Barremian stage (K1br). On the Khosavdrag ridge with a similar geological structure, but with a more dissected topography, subsidence is sporadic and located mainly on the structural steps of the slopes. In the lower flattened parts of the slopes, karst subsidence is not observed due to the active accumulation of demolished loose clastic material. The diameter of individual karst subsidences ranges from 5-7 to 60 m, the depth does not exceed 4 m, and there is a wide distribution of subsidences associated with small erosion forms. Almost all subsidences are located north of the watershed line of the Kurtatinsky Gorge, and this reduces the danger of karst for the study area. But due to the high density of subsidence, it is in the upper reaches of small erosion forms that the formation of a summit interception is possible due to the activation of regressive erosion. The territory was divided into five categories based on the following factors: rock composition and parameters of their occurrence, steepness, density of karst subsidence. The greatest karst hazard is typical for the Bakhty-Laparyrag and Khoshkharanrag ridges. The settlements of GornyKartsa and Gusyr are located in the safe zone. Conclusion. The formation and development of karst in the Kurtatinsky Gorge is largely influenced by the nature of the relief relative to the composition of the rocks. Planning and implementation of measures to protect infrastructure facilities is required. Particular attention should be paid to the safety of the road network of the Kurtatinsky Gorge, which crosses an area of high karst danger. The results of the study can be useful for effective land use planning, development of measures to prevent and reduce the risks of karst manifestation, as well as for ensuring safety in mountain regions.