Morphometric characteristics of block streams: A case study of the Vladayska River basin, Vitosha Mountain (Bulgaria)

Abstract

Block streams, also known as stone rivers, are common periglacial landforms in the alpine and subalpine zone of the Balkan Peninsula. These features are especially widely spread in the valleys, slopes and summit of Vitosha Mountain. The presented research aims to estimate the total area of block streams and perform morphometric analysis of these landforms within the basin of Vladayska River. Block streams are digitized man-ually from orthophotographs and topographic maps using GIS software. Morphometric parameters such as area, length, width, elongation ratio and mean elevation are calcu-lated or extracted from a digital elevation model for each polygon. A linear regression test was conducted to evaluate the relationship between morphometric properties. Results indicate a significant correlation between the area and perimeter (R2 = 0.93) and between the length and width (R2 = 0.94) of the block streams. Block streams are present in the elevation range between 1177 and 2244 m, covering a total area of 169.7 ha. The largest ones occupy the area of Zlatnite Mostove and Yurushki Most, as well as the vicinity of Cherni Vrah Peak. Their length varies from 5–6 m up to 2.2 km, while their width changes from a few meters up to 0.6–0.7 km. Comparisons between block streams from different sites within the catchment area yield new insights into the diver-sity of these landforms. Their dimensions and spatial distribution are key to understand-ing the processes of their formation and evolution.