Extended Abstract

Introduction

The transportation industry is an important element of development and a criterion for measuring countries in terms of politics, economy, and society, and railway lines can be considered one of the basic characteristics of the transportation industry (Mahboub Sardroudi, 2019). Rock falls are one of the most common and dangerous slope movements and the most damaging natural phenomena (Bayani Khatibi, 2007). The occurrence of this type of movement is considered a threat to railway lines in many mountainous areas. In this regard, identifying areas susceptible to this hazard, using zoning techniques, is necessary in order to manage this risk (Rabi et al., 2022; Nasiri et al., 1401). The railway route from Khorasanak village to Mianeh city in East Azerbaijan province has a high potential for rock fall due to its steep mountainous terrain with fractured rocks and specific climatic conditions. Therefore, the aim of this study is to identify areas prone to rock fall hazards on this communication route.



Methodology

The present study, considering the nature of the problem and the subject under study, is of a research-applied type, and its research method is an analysis based on the integration of data analysis, geographic information systems, and the use of multi-criteria analysis techniques. Arc GIS, Idrisi, and Excel software were used for image processing and data analysis. Considering that rock fall occur under the influence of ten factors, identifying the factors effective in the occurrence of rock fall is of great importance. First, after reviewing similar scientific research in the field of the subject, conducting field observations, and considering the natural and human conditions of the region, 10 factors of of Dem, slope, aspect, precipitation, temperature, geology, distance from river, distance from road, distance from fault, and land use were identified as effective factors in creating rock fall risk in the railway axis from Khorasanak village to Mianeh city. In the next stage, information layers related to each factor were prepared in the geographic information system environment. The weighting of the factors studied was done according to the CRITIC method, and the final analysis was done using the MARCOS multi-criteria method. After preparing the rock fall susceptibility map, the accuracy of the models was examined using the ROC curve.



Results and discussion

The results of the MARCOS model evaluation in five rockfall susceptibility classes show that 109.53 km2 of the study area has very low potential, 183.54 km2 has low potential, and 232.08 km2 has medium potential. The high-risk and very high-risk classes cover 222.11 km2 and 116.75 km2 of the area, respectively. Matching the distribution of rockfall points in the area and the areas at risk based on the zoning map obtained from the study shows that the largest number and percentage of sliding surfaces are located in the two very high-risk (58.33% of the fall points) and high-risk (33.33% of the fall points) classes.

The research findings also showed that the railway line located within the Khorasanak village to the city of Mianeh passes through a mountainous area dominated by steep slopes (30 to 123 percent), altitudes of 1,000 to 2,100 meters, diverse and susceptible land uses (especially pastures and agriculture), trenching and destruction of the slopes following road construction and development activities, susceptible geological formations (mostly fissured igneous rocks), underscoring of the slope support by flowing water, fault structures and slope direction (especially; southern and eastern directions due to lower humidity, high energy absorption and greater evaporation), and specific climatic conditions (physical weathering processes) have increased the potential for rockfall in the area.



Conclusion

The results of determining the weighting coefficients of the slope instability components indicate that the slope and the geological formation are the two main arms involved in the occurrence of rockfall in the study area. From a spatial perspective, the rockfall hazard map indicates that a major part of the studied railway axis is at risk of rockfall and the operational safety of this route faces significant challenges. Given the large extent of areas with a risk of rockfall in the studied area, it is necessary that the results of this research, in order to introduce important criteria involved in the creation of rockfalls and identify areas with a high probability of this hazard, be given serious attention by relevant organizations (including the Crisis Management Organization, the General Administration of Natural Resources and Watershed Management of East Azerbaijan Province, the General Administration of Roads and Urban Development of the province, the Regional Water Organization, and other organizations related to environmental hazard issues) in order to carry out protective and management measures.