ZOFIA RĄCZKOWSKA 1 , JAROSŁAW CEBULSKI 1 , WOJCIECH RĄCZKOWSKI 2 , TOMASZ WOJCIECHOWSKI 2 , ZBIGNIEW PERSKI 2 (KRAKÓW) USING TLS FOR MONITORING TALUS SLOPE MORPHODYNAMICS IN THE TATRA MTS. Abstract. This paper presents changes of surface relief of talus slopes in the Tatra Mts. based on terrestrial laser scanning (TLS) surveys conducted over five years. The changes are results of rapid mass movements, mainly debris flows and rockfalls. The results of the TLS surveys were analyzed with regards to meteorological conditions. It was found that debris flow activity is strongly related both to rainfalls and loose debris availability. The usefulness of the TLS survey for evaluation of the volume of rock material transported by rapid mass movement as well as the way this transport takes place was proven. Keywords: talus slopes, TLS surveys, mass movements, meteorological conditions, Tatra Mts. INTRODUCTION Debris flows and rockfalls are typical of steep mountain environments with rapid, high energy mass movements. Debris flows belong to the most spectacu- lar and important geomorphic processes in the Tatra massif, which is evidenced by numerous, active (fresh or renewed) and inactive debris-flow tracks (K o- t a r b a 2004; R ą c z k o w s k a 2006; H r e š k o et al. 2008; K a p u s t a et al. 2010; K o t a r b a et al. 2013; D ł u g o s z 2015). The debris flow tracks transport huge masses of weathered material across the slope system, supplying and covering the bottom of glacial cirques and valleys. High magnitude rainfalls are consid- ered a direct trigger of debris flows (I n n e s 1983; I v e r s o n 1997; K o t a r b a 1992a; F r a t t i n i et al. 2009). Based on some 20 years of observations in the High Tatras, the debris flows which extend over the full length of the debris slope are triggered by rainfall of 35–40 mm h –1 intensity or at least 80–100 mm d –1 (K o- t a r b a 1992a, 2002). Occurrence of debris flows depends also on the availability of debris material to be transported (I n n e s 1983; J a k o b, B o v i s 1996; I v e r- s o n 1997; B o v i s, J a k o b 1999; G l a d e 2005). However, talus slopes are not affected by debris flows even during heavy rainstorms, when they are covered and protected by snow cover ( K o t a r b a e t a l. 2 0 1 3). Rockfalls are presently S T U D I A G E O M O R P H O L O G I C A C A R P A T H O - B A L C A N I C A Vol. LI/LII, 2017/2018: 179–198 PL ISSN 0081-6434