عنوان مقاله [English]
Tabriz-Marand road is one of the important connecting networks in Iran which is not only significant inner and communications but also in abroad relations. This road rests on loose Quaternary formations and sometimes experiences landslides. The aim of this paper is to identify areas which are susceptible to slides. This paper evaluated the natural disasters that are threatening the confine of Tabriz-Marand road and railway, with the use of different data such as lithology, the slope of foothills, land use, land cover, the distance from linear features (road, river, and fault) and overlaying of them, with the emphasis on landslides and using remote sensing and GIS capabilities.
My study area has been selected between Tabriz- Marand approximately 65 km length and 5 km wide in east Azarbayjan province that the main road and railway rests in this limit and the Tabriz- Bazargan highway is under construction. In this research, used the topography maps in 1:25000 scale, geology maps in 1:100000 scale, SPOT-5 satellite images with 10 meters spatial resolution, climatology data from Tabriz and Marand station and GPS. The overlaying and weighed methods were used for analyzing data.
Results and Discussion
The evaluations showed that in study area, the height deference is 1000 meters, and 20 percent of area has slope between 20-60 persent. It is also recognized that more landslides occurred between 1600-1900 meters height and 25-60 percent of slope range.
Furthermore, it is recognized that average annual precipitation in Tabriz station is 327 mm and in Marand station is 243.4 mm that 40.6 percent of this, occurred in spring and caused slope instability. The northern fault of Tabriz as a main individual tectonic feature that determinately continues to- Moro and Misho mountains, on the side of Quaternary loose formations accounted for a trigger in slope movement's occurrence. According to the NDVI produced from SPOT image, the vegetation index of study area determinate between -0.96 to +0.96.
The region between Sofeyan and Marand due to southern steepness slope that connecting to stream network and main road, being unstable because of spring and winter precipitations. Force of gravity is main factor to occur mass movement and falling weathered materials in this region. Feet cutting due to road and railway passes from hill slope feet and along the river, and seasonal flooding accelerated route instability.
In this paper, the road between Tabriz - Marand Was studied using topography and geology maps, climatologic dada, satellite images and the overlaying and weighed methods. 13.6 percent of this section is unstable that placed around of main road and Yam village. The results showed that the specific geological formation, the regional climate conditions and the density of quaternary deposits on the sides of the road along with the factor of slope gradient are among the factors that cause mass movements which are intensified by human construction activities. It was also determined that the parts located in areas with higher danger are in coincidence with areas where landslides had taken place.