Long-term monitoring of torrential rainfall effects on talus cones stability in the alpine terrain (the High Tatras)

Abstract Incoherent masses stability of the talus cones in the high alpine environment is essential to slope movement study, landform changes, physical principles, and mountain rescue service forecasts. Climate changes cause increased torrential rainfalls, linked with frequent falls and landslides in the mountain environment and fatal injuries. Long-time monitoring of two neighboring talus cones situated opposite each other in the Little Cold Valley, High Tatras National Park, at an altitude of more than 1600.0 m a.s.l. has produced unique different results and methodology that would be expected in similar environments. In the talus cones, 93 samples were marked and arranged in 14 lines. During the period between 06/2018 and 10/2021, selected samples were monitored by precise geodetic methods. The highest rate of sample movement was measured from 11.18 to 81.59 m. The movements are affected by (a) torrential rainfalls with precipitation of more than 40.0 mm per square meter per day, (b) surface depth and inclination of solid granite basement, (c) different gravity/flooding influences where high rates are in the front, (d) slope orientation, and (e) accumulation area. Paradoxically, the steepness of the talus cones (46–47° in transportation; 21–31° in accumulation zones) is not the most important parameter for the debris movement. These conditions (precipitation, orientation, and slope) limit the talus cone stability and the movement and safety of tourists in the alpine terrain.