Assessment of vulnerability for rockfalls in Cozia Gorge (Southern Carpathians, Romania)

Rockfalls represents a sudden, extremely important geomorphological hazard and may become a threat for people’s life, as well as goods and transport. The present study aims to assess the rock surfaces stability in relation to a series of variables: resistance of intact rock determined in the field by geotechnical test—the SCS value obtained with Schmidt hammer; weathering degree, as visually assessed; characteristics of fissures—density, width, orientation, continuity; lithological and tectonic conditions—characteristics of rocks and the distance in relation with the faults; angle and exposure of slopes, their cover with vegetation, dimension of blocks identified close to the roadside and the volume of material accumulated in the protection mesh. In order to achieve the objective and determine the susceptibility of slopes to rockfalls, we run two campaigns of field measurement using a Schmidt hammer and microtectonic mapping based on GPS and feller gauge. The data integration was accomplished in the GIS environment, by applying the multi-criteria techniques. The results highlight the susceptible areas which allow us to map it and analyze the efficiency of the slope arrangement work made for rockfall prevention and identify new areas that require prevention measures. Finally, all the data were reported to a segment of the E81 highway and mapped the vulnerability to rockfall. The Olt Valley in the Cozia Gorge is one of the most important transversal valleys in Romania and a linking road between regions of both side of Carpathian range. The results of the study emphasize the anthropic pressure exercised in the analyzed Gorge section which created imbalances in terms of cut slopes.