Journal of Spatial Analysis

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Investigation of desertification trend needs an understanding phenomena creating changes singly or action and reaction together in the manner that these changes end up in land degradation and desertification. In the investigation of pedological criterion affecting on land degradation in alluvial fans, first, maps of slope classes, land use and geology were created, then a map of units was founded by overlaying and crossing these maps and grid layer created by extension of ET GeoWizards in ArcGIS 10.3 software. In this research three indices of erodibility, salinity and permeability of soil were considered, finally according to the seven level scales, each of them was shown as the classified map. In this research, nonparametric methods of Friedman and Kendalls' W rank tests were used to prioritize the options, in the manner that after defining crisp numbers in seven level scales, the rank means were calculated. The rank means obtained from Friedman and Kendalls' W rank tests alter from 7/00 to 17/33. Obtained results from the nonparametric methods showed that 74/18 % (4245/77 ha) and 25/82 % (1477/67 ha) of the area were classified into two classes of medium and very heigh desertification potential, respectively. The results also showed that the youngest and old gravel fans of the area have desertification potential of very high (798/75 ha) and low (152/23 ha), respectively.

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Soil erosion is one of the environmental problems that is a threat to natural resources, agriculture and the environment, and in this regard, assessing the temporal and spatial amount of soil erosion has an effective role in management, erosion control and watershed management. The main aim of this study was to estimate soil erosion in Amoqin watershed and its relationship with well-known vegetation-based and topographic-related indices. The meteorological data has been used to determine the rainfall erosivity. The rainfall erosivity index was calculated using the modified Fournier index during the 10-year available recorded rainfall data. The value of LS factor has been calculate using digital elevation model. Meanwhile, C and P factors were determined based on the utilization scheme and condition of the study area. Data were analyzed and processed using ArcMap 10.1, ENVI 5.3, and Excel software. In this study, RUSLE model was used to estimate soil erosion, in GIS environment. According to the results, the amount of factor R in Amoqin watershed varies from 12.32 to 50.52 MJ/ha/h per year. The variation of soil erodibility index (K) over the study area is between 0.25 to 0.42. The amount of LS factor varies between 0.19 and 0.38, which is more in high slopes, especially around the waterways and uplands of the study area. The variation of C factor was estimated to be around -0.18 to 0.4. In general, it can be said that the central part of Amoqin watershed has less C value due to the greater area of agricultural activities and the highest amount is related to western areas, especially southwest areas because existing the rangeland areas. Due to the lack of protective measures in the study area, the amount of factor P was considered as unity for the whole region. The base layers of RUSLE factors were obtained and overlayed in GIS to calculate the soil loss in tons per hectare per year. The map of annual soil loss indicate that the erosion amounts varies between 1.21 to 5.53 tons per hectare per year in different parts of the study area. According to the results, the vegetation factor with a coefficient of determination 0.47% had a significant correlation with soil loss. The stream power index with the coefficient of determination of % 0.07% had the lowest correlation with soil erosion values.

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Abstract
Many villages in the country are faced with a series of dangerous factors and elements due to their location and settlement method, the most important of which are natural disasters such as earthquakes, floods, landslides, subsidence, rockfalls, avalanches and snadstorms. A set of biological, environmental, social, economic, and physical factors and processes can also increase the level of risk and vulnerability of villages.. Therefore, it is necessary to take steps to reduce the effects and consequences of accidents by using scientific methods of crisis management based on risk management. Experience shows that the huge costs of reconstruction after disasters can be reduced with prevention, prediction and preparation and according to the sixth development plan, 30% of villages and 20% of the border villages must be secured. The current plan is carried out referring to the sixth development program (clause 8th of article 27th) with the aim of securing villages exposed to the risk of natural disasters in order to identify the villages with the characteristic of being exposed to natural hazards, prioritizing and presenting suggestions regarding how to reduce the risk at the villages are exposed the risk of natural disasters in cooperation with the Islamic Revolution Housing Foundation and the National Disater Management Organization. The priority natural disasters in this plan are: floods, subsidence and sinkholes, earthquakes, sandstorm and slope movements (including landslides, rockfalls, creeping and mudflows) in rural areas. At first, a list of villages at risk of natural disasters was prepared and reviewed through inquiries from provincial disaster management and housing foundations. This project was based on appropriate models and methods and with using of disaster risk zoning maps, screening and selecting the list of villages that are more at risk than others  and by combining risk assessment indicators and criteria with environmental, physical, demographic indicators and risk incident records, the villages with the first priority of risk are extracted separately for each province, and then the results of this stage were checked for accuracy in a collaborative process with related organizations at each province and the project entered the phase of field collection and providing implementation solutions. In this plan, out of 48,857 villages with more than 20 households across the country, about 9,000 villages are at risk with high risk categorized in 5 classes and 1,418 villages across 31 provinces with the first priority visited after verification, in order to local check and providing solutions for risk reduction. These villages were visited by experts from different fields and detailed risk assessment was done. In order to obtain the same and comprehensive information by the referring experts for the field visiting, field evaluation forms were designed with a multi-risk management approach.
 The results of the field visits and the proposed solutions were prepared separately for each village according to the environmental characteristics with the aim of reducing the risk and securing and presented to the Islamic Revolution Housing Foundation, the Disaster Management Organization and the Program and Budget Organization. Also, by designing and establishing a spatial information system for monitoring and evaluating rural settlements at risk, on the web-GIS platform (WEB GIS) at the same time as visiting the mentioned villages, the information collected according to the field collection forms was loaded into the system and according to the characteristics This system, such as designing in the Oracle environment, defining the access level for different stakeholders from national to local levels, the possibility of updating information, having different modules, reporting, spatial analysis of risks and producing thematic and combined maps, it is possible to use this system as a decision support system in all stages of crisis management, before, during and after the disaster, at the country level. Increasing and completing the required information in analyzes related to risk assessments, simultaneously with entering the information collected during field visits, as well as updating the information, will lead to an increase the empowerment of the society regarding the risk management of natural disasters and an increase Speed and accuracy in the analysis of the effects, management decisions and as a result reduce the costs of reconstruction and rehabilitation. It is worth mentioning that in order to create the ability to register information collected online, the mobile application system of rural settlements at risk was also designed and operated.

Key words: villages at risk of natural disasters, immunization,identification, prioritization, webGIS