Panta Rhei: Movement Change of Tschadinhorn Rock Glacier (Hohe Tauern Range, Austria), 1954–201

In this paper we present a reconstruction of the kinematics of the Tschadinhorn rock glacier using multi-temporal conventional (metric) aerial photographs (1954–2015) and additional non-metric aerial photographs (2016, 2017) taken with in-house unmanned aerial vehicles (UAVs). A rotary-wing aircraft (hexacopter twinHEX v.3.0) was used in 2016 and a fixed-wing aircraft (QuestUAV) in 2017. The historical image data was acquired from the Austrian Federal Office of Metrology and Surveying (BEV). Both a digital orthophoto (DOP) and a digital terrain model (DTM) were computed for each given epoch. Precise georeferencing of the image data was carried out in the Austrian Gauss-Krüger M31 coordinate system using available aerotriangulations (ATs) of BEV and additional ground control points (GCPs) measured geodetically during both UAV campaigns. Change detection analysis provided multi-temporal 2D flow velocity fields. Subsequently, these data were collated to produce a simpler velocity graph showing clearly the temporal evolution of the flow velocity of Tschadinhorn rock glacier: A maximum mean annual flow velocity of 3.28 m/year was obtained for 2014–2015, while the lowest annual flow velocity of 0.16 m/year was observed for 1969–1974. The velocity graph also revealed that 1954–2009 was characterized by generally moderate activity (0.16 – 0.79 m/year) and that much higher flow velocities have prevailed since 2009. The present value for 2016–2017 is 1.92 m/year. U radu se prikazuje rekonstrukcija kinematike kamenog glečera Tschadinhorn upotrebom viševremenskih konvencionalnih (mjernih) fotografija snimljenih iz zraka (1954–2015) i dodatnih nemjernih fotografija snimljenih iz zraka (2016, 2017) bespilotnim letjelicama (unmanned aerial vehicles – UAV). Letjelica s rotirajućim krilima (hexacopter twinHEX v.3.0) upotrebljena je 2016. godine, a letjelica s nepokretnim krilima (QuestUAV) upotrebljena je 2017. Povijesni slikovni podaci dobiveni su od Austri­jskog federalnog ureda za metrologiju i izmjeru (Bundesamt für Eich- und Vermessungswesen – BEV). Za svako su razdoblje izračunani digitalni ortofoto (DOP) i digitalni model reljefa (digital relief model – DTM). Precizno geo­re­­­­­­ferenciranje slikovnih podataka provedeno je u austrijskom koordinatnom su­­stavu Gauss- Krüger M31 upotrebom aerotriangulacija (AT) do­bi­venih od BEV-a i dodatnim kontrolnim točkama na tlu (ground control point – GCP) geodetski izmje­re­nih tijekom obaju izmje­ra bespilotnim letjelicama.