Estimation of the return period of selected avalanches in the Zgornji Soča Valley

Na območju Zgornje Soške doline sta bila s pomočjo dendrokronologije analizirana dva snežna plazova. Oba snežna plazova sta evidentirana v lavinskem katastru in poimenovana – snežni plaz Kraj Planje se nahaja v dolini Zadnja Trenta, snežni plaz Skok pa v dolini Lepena. Oba spadata med stalno aktivne snežne plazove in se ob ustreznih vremenskih razmerah in dovolj debeli snežni odeji prožita vsako leto, včasih večkrat letno. Januarja 2021 je bil obseg številnih plazov v Zgornji Soški dolini izjemen, snežna plazova Kraj Planje in Skok pa sta v dolino transportirala tudi veliko količino debel podrtih dreves, iz katerih smo s Presslerjevim svedrom odvzeli izvrtke. Na območju odlaganja snežnega plazu Kraj planje smo odvzeli 98 izvrtkov ter prav toliko na območju odlaganja snežnega plazu Skok. Skupno smo starost v prsni višini določili za 97 dreves. Povprečna starost v raziskavo zajetih dreves v prsni višini znaša 82,4 leta (Kraj Planje) oz. 71,4 leta (Skok). V primeru snežnega plazu Kraj Planje smo v raziskavo zajeli 12 dreves s starostjo v prsni višini nad 100 let, v primeru snežnega plazu Skok pa 9. Najvišja starost drevesa v prsni višini je bila v primeru snežnega plazu Kraj Planje 186 let, v primeru snežnega plazu Skok pa 222 let.In the area of the Zgornja Soča Valley, two avalanches were analyzed with the help of dendrochronology. Both avalanches are recorded in the avalanche cadastre and named - the Kraj Planje avalanche is located in the Zadnja Trenta valley, and the Skok avalanche is in the Lepena valley. Both belong to the permanently active avalanches and, given the right weather conditions and a sufficiently thick snow cover, are triggered every year, sometimes several times a year. In January 2021, the scale of numerous avalanches in the Zgornja Soča valley was extraordinary, and the Kraj Planje and Skok avalanches also transported a large amount of fallen tree trunks into the valley, from which we took core samples with a Pressler drill. We took 98 core samples in the Kraj Planje avalanche deposit area and the same number of samples in the Skok avalanche deposit area. In total, we determined the age at breast height for 97 trees. The average age of the trees included in the study at breast height is 82.4 years (Kraj Planje) or 71.4 years (Skok). In the case of the Kraj Planje avalanche, we included in the research 12 trees with an age at breast height of over 100 years, and in the case of the Skok avalanche, 9. The highest age of a tree at chest height was 186 years in the case of the Kraj Planje avalanche, in the case of the Skok avalanche it was 222 years