Recent evolution of the Geomorphic process in the Mountain space in Braşov County (Central Romania)

Abstract

The relief of Braşov County includes two basin units, drained by the river Olt and its tributaries. One is bordered by piedmonts (Bârsa Country and Fӑgӑraş Country), being a wide hilly habitat (the southeastern part of the Transylvania Plateau) and the other is a mountain area with a great morphogenetic and altitudinal diversity (Fӑgӑraş, Piatra Craiului, Bucegi, Bârsei, Ciucaş, Întorsurii, Perşani and Baraolt Mountains). The main ecosystems of Braşov county are well balanced, corresponding to the relief steps: mountain (over 700 m represent 40% of the county surface), hills and basins (around 400 and 700 m, extending on around 60% of the county surface). Territorial units of the county overlap on two morphostructural units: the Carpathians mountains and the Transylvanian Depression. This disposal favors specific ecosystems diversification: The mountain area of the county belongs to the two mountain building structures: crystalline - Mesozoic unit belonging to the Oriental and Southern Carpathians and the Cretaceous flysch unit of the Curvature Carpathians. Their characteristics define the environment conditions, differentiated in their turn according to the petrographic formation, detailed relief, bio-climate range. Based on a sequential series of observations undertaken by the authors during the last 40 years, there has been discovered a series of changes, both in the rhythmical nature and amplitude of the geomorphic processes as well as in their typology. In the alpine and sub-alpine floor of the Fӑgӑraş, Bucegi and Piatra Craiului Mountains there has been observed an intensification of the debris flow rhythmicity, on the avalanche lanes, as well as an increase in the quantity of materials transferred by the low basins floods. As an exemplification, there have been offered several case studies made in the Fagarar Mountains (Sâmbӑta glacial cirque). On the low and medium mountains level of the Braşov county (Întorsurii, Perşani, Baraolt Mountains), in addition to the debris flow processes, there have also many gravitational processes have also occurred, affecting the forests (Perşani, Vârghiş, Gӑunoasa and Vulcӑnița basins), analyzed by the authors during the years 1968, 1977, 2003, and 2005. The studies of the geomorphological processes are accompanied by in analyses of the environmental factors that favored their evolution.