Journal of Spatial Analysis

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In many areas, snow cover in the mountains is a major source of surface and underground water supply. Due to climate change and its effect on the time of melting ,it  is very important for environmental planning to predict the arrival time of water from snow melt to water consumption cycle. The purpose of this study is to investigate the volumetric changes and time distribution of snow flood flows in future by integrating remote sensing , GIS and climatic models.The studied area is the Upper Basin of Amir Kabir Dam, which is located on the southern slopes of Alborz Mountains. In this study, digital elevation maps (DEM) and GIS software were used to estimate parameters such as area, environment, main length, highest and lowest elevation points. In order to complete the snow cover data, MODIS products (MOD10A100) were extracted and the snow cover was extracted in the Upper Basin of Amir Kabir Dam. Next, runoff and snow melting models were simulated using SRM software. Calibration and validation of the model's acceptable performance were estimated. Then, in order to investigate the effects of climate change on the future of snowmelt runoff production in the basin of Amir Kabir Dam, the latest CMIP5 climatic models were used under four scenarios RCP2.6, RCP4.5, RCP6.0 and RCP8.5. A survey on the relationship between snow cover area , temperature and precipitation was used to predict snow cover in the future. The increase in temperature in the autumn and winter season has led to a reduction in the shape of precipitation in the form of snow, and as a result, the amount of snow storm is reduced. The results show that the amount of runoff in the autumn and winter increases due to increased rainfall in the form of rain, and it will be  increased late winter and spring due to the increase in the amount of water resulting from snow melting. The results of this study are based on the increase of snow melt as a result of increased runoff volume, reduction of snow reserves and maximum flow transmission to earlier than normal conditions due to early snow melting due to temperature rise. Generally, in the future, the average annual runoff will be decreased about 1.1 cubic meters per second, and the average annual melting share will be about 13.9%

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The growth of settlements and the increase of human activities in the floodplains, especially the banks of rivers and flood-prone places, have increased the amount of capital caused by this risk. Therefore, it is very important to determine the extent of the watershed in order to increase risk reduction planning, preparedness and response and reopening of this risk. The present study uses the common pattern of the machine and the classification of Sentinel 2 images to produce land cover maps, in order to construct sandy areas and determine land issues affected by the flood of March 2018 in Aqqla city. Also, in order to check and increase the accuracy of the algorithms, three software indices of vegetation cover (NDVI), water areas (MNDWI) and built-up land (NDBI) were used using images. The different sets of setting of each algorithm were evaluated by cross-validation method in order to determine their effect on the accuracy of the results and prevent the optimistic acquisition of spatial correlation from the training and test samples. The results show that the combination of different indices in order to increase the overall accuracy of the algorithms and to produce land cover maps, the forest algorithm is used with an accuracy of 83.08% due to the use of the collection method of higher accuracy and generalizability than compared to. Other algorithms of support vector machine and neural network with accuracy of 79.11% and 75.44% of attention respectively. After determining the most accurate algorithm, the map of flood zones was produced using the forest algorithm in two classes of irrigated and non-irrigated lands, and the overall accuracy of the algorithm in the most optimal models and by combining vegetation indices (MNDWI) was 93.40%. Then, with overlapping maps of land cover and flood plains, the surface of built-up land, agricultural land and green space covered by flood was 4.2008 and 41.0772 square kilometers, respectively.
 

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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