Analyzing the rate of concentration and pollution of heavy metals of sediments ( case study: Gelian catchment in North Khorasan province )

Rockfall is one of the most important geomorphological hazards in mountainous areas, which always causes great financial and human losses, especially for communication lines (roads and railways). Zanjan - Teham and Tarem are also one of the most dangerous mountain roads in Ardabil province, where the risk of falling rocks seriously threatens the road. Therefore, the purpose of this research is to identify the danger zones along this road. For this purpose, in addition to a field visit to the desired area and using the 2021 Landsat OLI sensor satellite images, the layers and maps that are effective in rock fall, including: geology, slope, elevation levels, slope direction, land use and vegetation, fault, distance from Road, distance from watercourse, precipitation levels, isothermal, freezing data were used. The drop points collected with dual - frequency GPS (mapping tool) were checked in the ArcGis pro software environment with the aforementioned criteria. Then, using the statistical method of frequency ratio coefficient, information value method and Shannon's entropy, which uses environmental data, zoning of the risk of falling was carried out through combining and algebraic summing of the maps in five risk classes from very low to very high. According to the results obtained in the information value method, 64.23% of the area was assigned to high to very high risk areas. In the case of frequency ratio method, this number was 41.7% and Shannon's entropy method was 44.01%. In order to evaluate the zoning accuracy of the mentioned methods, two total quality indicators and accuracy index (experimental probability) were used. The evaluation of the models showed that, in the information value model, the mentioned indices were obtained as 0.34 and 0.95, respectively, which have higher quality and accuracy compared to the frequency ratio and Shannon entropy models.