Document Type : Research Paper
Authors
University of Tehran
Abstract
Occurrence of avalanches in mountainous areas is one of the most important natural hazards that cause a lot of human and financial losses. The study of affecting factors on avalanche occurrence and simulation is very important to manage this phenomenon. In this study, the affecting factors on the occurrence of snow avalanche (terrestrial and meteorological factors) and its simulation have been studied using the RAMMS simulation model in the Central Alborz Velayat Rood (Dizin Road), Alborz Province. Topographic and geomorphological factors such as slope, aspect, curvature, topographic position index (TPI), terrain roughness index (TRI) and topographic wetness index (TWI) using 6 ×6 cm2 pixel size of digital elevation model (DEM) were prepared by using a drone. Meteorological factors such as rainfall, temperature and wind were also considered. Then, using RAMMS simulation model, avalanche components such as avalanche speed, pressure and height were estimated in the study area. The results showed that the amount of slope and aspect as a topographic indicator have a great impact on the formation and occurrence of the snow avalanche. The largest part of the region with an area of 5.7 hectares (54.6% of the study area) with a northeast aspect and slope of 60 to 120%, the accumulation and track areas, has the greatest potential for avalanche. Also, the results of RAMMS simulation model showed that the average speed and maximum avalanche speed in the region were 5.3 m/s and 16 m/s. The average effective avalanche pressure was 7 and the maximum avalanche pressure in the region was 45 KPa. Estimation of avalanche height in the region also showed that the average avalanche height in the runout area (residential areas) was 4.5 meters and the maximum avalanche height in the region was 10 meters, which is classified as a large avalanche.
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