The amount of large woody debris in selected Alpine torrents

Na območju Alp so bile v zgornjih tekih Radovne, Triglavske Bistrice in Završnice opravljane sistematične meritve lesenega plavja. Posameznim kosom lesenega plavja, ki so se nahajali v strugi in v 10 m pasu ob njej, je bil izmerjen premer in dolžina. Za analizo značilnosti razporeditve lesenega plavja so bili vsi kosi locirani s pomočjo mobilne GIS aplikacije in zunanjim GNSS sprejemnikom. V raziskavo so bili vključeni kosi z minimalno dolžino 0,5 m in minimalnim premerom 10 cm. Ocenjeni so bili tudi parametri, kot so stopnja razkroja, izvor lesenega plavja, položaj glede na strugo in ali je leseno plavje sečni ostanek. Skupno je bilo popisanih 18,633 km dolžine vodotokov oz. 2937 kosov lesenega plavja. Celoten volumen vseh zajetih kosov je znašal 196,35 m3. Povprečna gostota lesenega plavja na 100 m struge je bila ocenjena na 15,8 kosa oz. 1,05 m3. Rezultati kažejo, da se leseno plavje v strugi in na njenih pobočjih pojavlja neenakomerno. Leseno plavje se v vodotok vključuje zaradi posledic bočne erozije, naravnih procesov odmiranja dreves in vremenskih pojavov, kot so snegolom, vetrolom in žledolom. Prevladujejo kosi lesenega plavja višjih stopenj razkroja. Leseno plavje iz strug in pobočij ni odstranjeno, zato je prepuščeno naravnim procesom premeščanja, trohnenja in razpadanja, kar lahko predstavlja tveganje za poplavno varnost.In the Alps, systematic measurements of large woody debris have been carried out in the upper course of the Radovna, Triglavska Bistrica and Završnica streams. The diameter and length of individual pieces of wood in the channel and a 10 m buffer along the channel were measured. To analyse the distribution characteristics of the large woody debris, all pieces were located using a mobile GIS application and an external GNSS receiver. Pieces with a minimum length of 0.5 m and a minimum diameter of 10 cm were included in the survey. Other parameters such as the degree of decomposition, the origin of the large woody debris, the position in relation to the channel and whether the woody debris is logging residue were also assessed. A total of 18,633km of stream sections and 2937 pieces of large woody debris were inventoried. The total volume of all pieces collected was 196.35 m3. The average density of woody debris per 100 m of channel was estimated at 15.8 pieces or 1.05 m3. The results show that large woody debris occurs unevenly in the channel and on its slopes. Large woody debris is incorporated into the watercourse due to the effects of bank erosion, natural tree dieback processes and weather events such as snowfall, windstorm and ice storm. The predominant pieces of large woody debris material are of higher decomposition class. Large woody debris is not removed from the streams and slopes, leaving it to the natural processes of relocation, decay and decomposition. Unremoved large wood debris represent risk for flood control