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University of Mazandaran
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Introduction and Objectives: debris are one of the important phenomena of slope movements in mountainous areas. Studying this process by relying on two patterns of opportunity and threat is particularly important. Therefore, the current research tries to analyze the susceptibility of the occurrence of the Haraz Valley debris flow in the range of Plour to Baijan and by providing a suitable index to prioritize the effective factors in the formation and expansion of debris, achieve its more accurate zoning. 
Materials and methods: Using the geological map of Damavand, with a scale of 1:100,000 and Google Earth images, the location of the deposits in the area was identified and the distribution map of the deposits was prepared after field survey and recording of points by GPS device and transferred to the GIS environment. Maps of independent and influential variables on the spread of deposits, including lithology and distance from the fault, were prepared from Damavand's geological map, and the height, slope and direction of the range were prepared using ASTER digital elevation model. The vegetation and land use map were prepared from the national coverage map of Iran by processing Sentinel images on the Google Earth Engine Cloud platform. In the next step, the distribution map of the deposits was combined with each of the maps of the effective factors and the weight of each class of independent variables was obtained based on the density area model. Then a zoning map of the susceptibility of the spread of debris was prepared in five classes. Also, in order to determine the prioritization of effective factors and prepare a more accurate map of the zoning of the expansion of debris, the average effective weight of the deposit sensitivity index was calculated.
Results: According to the results of density area model analysis, Melafir rock unit, altitude of 2400-2700 meters, slope of 10-20 degrees, slope facing northwest, distance of up to 500 meters from the fault line and pasture lands had the most spread of deposits. According to the debris susceptibility Index (DSI) model, land use, lithology and slope have the highest priority with average effective weight of 21.04, 20.12 and 18.72, respectively, and are the main factors controlling the spread of debris in the area. The factors of slope, height, domain direction and distance from the fault were the next priorities.
Conclusion: The evaluation of the accuracy of the models using the empirical probability (P) showed that the surface density and DSI models are suitable for zoning the susceptibility of debris in the area with a probability of 0.79 and 0.80, respectively. The layers of high sensitivity to very high expansion of the deposit cover about 26% of the area, which is considered an environmental resource from one point of view, so that it can be exploited as a sedimentary deposit for use in engineering structures by forming a volume reserve, and from another point of view, it is a risk. It has potential in agricultural fields, residential areas and hydraulic structures.
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Type of Study: Research | Subject: بلايای طبيعی (سيل، خشکسالی و حرکت های توده ای)
Received: 2023/03/21 | Revised: 2024/01/19 | Accepted: 2024/01/20

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