Holec J., Bednarik M., Liščák P. & Žilka A., 2018: Assessment of debris flow susceptibility using bivariate and multivariate statistical analyses and verification based on catastrophic events from 2014 in the Krivánska Malá Fatra Mountains, Slovakia. Acta Geologica Slovaca, 10, 1, 1–19.

Assessment of debris flow susceptibility using bivariate and multivariate statistical analyses and verification based on catastrophic events from 2014 in the Krivánska Malá Fatra Mountains, Slovakia

Juraj Holec¹, Martin Bednarik², Pavel Liščák³, Andrej Žilka³ & Ladislav Vitovič¹

¹Comenius University in Bratislava, Faculty of Natural Sciences, Department of Physical Geography and Geoecology, Ilkovičova 6, SK-842 15, Bratislava, Slovakia; juraj.holec@uniba.sk, vitovic2@uniba.sk
²Comenius University in Bratislava, Faculty of Natural Sciences, Department of Engineering Geology, Ilkovičova 6, SK-842 15 Bratislava, Slovakia; mbednarik@fns.uniba.sk
³State Geological Institute of Dionýz Štúr, Mlynská dolina 1, SK-817 04 Bratislava, Slovakia; pavel.liscak@geology.sk, andrej.zilka@geology.sk

Abstract

The presented study shows using of bivariate and multivariate statistical analyses in mountain area of the Krivánska Fatra Mountains affected by debris flows. Three generations of data were studied in order to assess the debris flows in the area, from these two main periods of debris flows were taken into the analysis: the debris flows from 1950s to 1970s and catastrophic debris flows from July 2014. Various input data were used in the statistical analyses: elevation, slope angle, plan curvature, topographic wetness index, flow accumulation, lithology, and land cover. Two main evaluations were made: first using the older debris flow data and second using debris flow data from the both periods. Receiver operating characteristic analysis was performed in order to assess the reliability of the models with the area under curve more than 95 % for both evaluations and more than 85% for the first evaluation checked by both periods of debris flows in case of multivariate analysis, respectively almost 83% and 80% in case of bivariate analysis. The comparison with existing avalanche tracks was performed as well and shows satisfactory results. The tracks of debris flows from July 2014 show the extraordinariness of the event in comparison with older debris flows. Experimental assessment of natural hazard was performed using the map of difference between the two susceptibility maps in order to find out the areas of possible high magnitude low frequency events.

Key words: Krivánska Fatra Mts., debris flow, susceptibility map, multivariate analysis, bivariate analysis, validation processes

Manuscript received: 2017-10-01

Revised version accepted: 2018-05-11