فصلنامه جغرافیای طبیعی
پیاپی 51 (بهار 1400)

The phenomenon of dust has become one of the natural hazards in the country today; A phenomenon that affects natural and human conditions with its harmful effects in various ways. Therefore, in this study, the continuity of dust spatial patterns in Kermanshah was investigated and analyzed. For this purpose, dust statistics of 12 synoptic stations of the province during the statistical period 1987 to 2017 were obtained from the Meteorological Organization and after creating databases to identify the spatial patterns of dust in the province, the Moran spatial index (I) was used. Linear regression trend analysis was also used to examine the trend of changes. The results showed that the maximum incidence of dust in the province is mostly limited to the western half and the minimum incidence is more related to the eastern half of the province. Also, most of the persistence of dust in the province has been observed in the areas adjacent to the Iraqi border, which indicates that the dust of the province is trans-local. The results of spatial autocorrelation patterns also showed that the occurrence of two and ten days continuity in the western half of the province, ie Qasr Shirin and Sarpol-e-Zahab regions, formed a high (positive) cluster pattern and in the eastern half of the province, ie Songhar and Harsin regions, formed a low (negative) cluster pattern. Is. Spatial patterns on a monthly scale have also experienced a situation similar to spatial patterns lasting two to ten days. Examination of the change trend also showed that on a monthly basis, except for November and December, in other months, a significant upward trend is observed at the 95% confidence level. Also, in terms of seasonality, the most intense increasing trend of dust events is related to spring and summer seasons.

GCM models have obvious differences in estimating meteorological variables. For this purpose, in this study, the models of the fifth climate change report of Birjand synoptic station using the next three periods of 2040-2010, 2070-2040 and 2100-2070 against the base period of 1975-2005 and two scenarios of RCP 4.5 and RCP 8.5 to determine the variables The meteorology of GCM models was investigated. For this purpose, first a comparison was made between the baseline data of the synoptic station and the baseline data of the model and then to ensure the results of the models for each of the temperature and precipitation variables, the certainty or uncertainty of the models was determined using a box diagram. The results showed that for precipitation, CESM1-CAM5 and CANESM2 models have large box bands and low uncertainty and BNU-ESM and MIROC-ESM-CHEM models have more certainty than other models. In terms of minimum temperature and maximum temperature, GFDL series models have the lowest certainty and GISS-E2 series have the best certainty. The results also showed that the reliability of the models for estimating the minimum temperature and maximum temperature is higher than precipitation. It was also found that in addition to the RCP 8.5 scenario compared to the average RCP 4.5 scenario, the average temperature changes show more than the base period. In the RCP 8.5 scenario, the model deviation is higher than the average value.

< p >Due to the ability of data mining techniques, their application in the field of earth sciences has been widely developed. The purpose of this study is to zoning landslide sensitivity using stochastic forest algorithm in Larestan city, Fars province. Random forests are a modern type of tree-base that includes a host of classification and regression trees. The random forest algorithm is based on a bunch of decision trees and is currently one of the best learning algorithms. For the present study, information layers of slope degree, slope direction, altitude, slope shape, distance from fault, distance from waterway, distance from road, rainfall, lithology and land use as factors affecting landslide occurrence were identified and its maps in software. ArcGIS10 / 2 digit and were prepared. Then, using a random forest algorithm, the relationship between the effective factors and the location of landslides and the weight of each of them were calculated in R statistical software and finally transferred to the GIS environment to prepare a landslide susceptibility map. The results of evaluating the accuracy of the zoning method using the relative yield detection curve and 30% of the slip points not used in the modeling process, indicate the excellent accuracy of the random forest model with the area below the curve being 98.8%. The executive recommendation is to reduce the risk of stabilization of unstable areas and to avoid these areas; And any planning in the future development of the physical elements of urban infrastructure should be done with regard to the possibility of landslides.

Drought is a climatic phenomenon that is likely to occur in any region and leads to social, economic and environmental damage. Due to the importance of remote linking patterns and their impact on climate, therefore, the present study aimed to investigate the relationship between remote linking patterns and drought in northwestern Iran. In this regard, the precipitation statistics of 17 synoptic stations located in the provinces of East Azerbaijan, West Azerbaijan, Ardabil and Zanjan during the statistical period 1988 to 2018 and the statistics of 16 connection patterns from the Northern Hemisphere during the same period were used. First, using the drought index (SPI) of the study area on an annual scale, with a delay of one month and a delay of two months. Then, the relationship between drought and remote grafting patterns was investigated using Pearson correlation and linear regression methods. The results show that on a monthly scale, the PNA pattern showed a correlation with the studied stations more than other patterns in the one-month delay time of the TNA pattern and in the two-month delay time of the NAO pattern. Spatially, Maragheh and Jolfa stations have shown more correlation with remote connection patterns than other stations. Examination of seasonal correlation coefficients also showed that in winter HCNA and SNA patterns; NAM, NPI and PN patterns in spring; In summer, the SNAO pattern and in autumn, the POL / PEP pattern were more correlated with the drought of the studied stations than other patterns.

The energy released during the rapid movement of the fault is the cause of most earthquakes. In our country, which has active faults and many seismic areas, recognizing the fault movements of the results of these movements is of special importance. In this study, using up and down images of Sentinel-1 satellite and using multi-diaphragm radar interferometry techniques and ordinary radar interferometer, the 1397 Yasuj earthquake was studied and an isothermal deformation was prepared in both directions of the satellite line of sight and the azimuth path; And three orthogonal components of the displacement field were extracted using geodetic measurements. Then, in order to obtain the fault geometry and slip distribution on the fault plane, these components were analyzed using collocation optimization method and Akada elastic half-space analytical model. The displacements made due to the displacement of the fault due to the Yasuj earthquake in the study area show that the geological structure of the area after the earthquake has changed from its structure before the earthquake from -80 to -20 cm. Elements of surface displacement components obtained from the model, amount of displacements for Yasuj fault in the study area, the farther the distance from the fault across the Zagros, the less and less displacements, and the closer the adjacent faults, the displacements increase, the maximum altitude displacements for The image frame is equal to 0.45 to -0.45 m and the maximum amount of horizontal displacement is about 18 cm, which is more as it moves from the fault to the plain areas.

Droughts are one of the most devastating weather events, causing significant damage to both natural resources and human life. The purpose of this study is to analyze and compare meteorological drought and groundwater of Mehran plain using standardized precipitation index (SPI) and groundwater index (GRI). In order to study the meteorological drought, the monthly rainfall information of Mehran synoptic station was used and in order to study the dryness of the groundwater of Mehran plain, the changes of groundwater level of Mehran plain were analyzed based on water level data of 23 observation wells. Also, SPI index was used for meteorological drought monitoring and GRI index was used for hydrological drought monitoring of Mehran plain. The statistical period required for drought analysis of a 25-year statistical period from the water year of 75-74 to 97-96 was selected. After determining the moisture periods of the indices, monthly groundwater zoning maps were prepared. To prepare these maps, the kriging model was selected from among different models. Finally, by applying the optimal half-change model in kriging and entering groundwater data as a point layer, raster maps were prepared using Arc GIS software. The results of the study of SPI index show that during the statistical periods in question, 4 severe droughts occurred, the most severe of which was 90-91, with a value of SPI index of -1.73. Also, the results obtained from the GRI index in the region show that an 11-year drought period of groundwater occurred, ie it started from the water year 88-87 and continued until the water year 98-97, the most severe of which was 90-91 with the amount of The index is -1.11.

Rising global warming is one of the greatest challenges facing humanity in the 21st century. Therefore, it is very important to predict the maximum temperatures in order to know the amount of changes and, as a result, to take the necessary measures to adapt and moderate the adverse effects caused by it. Therefore, in this study, maximum temperatures were predicted in three provinces of Kurdistan, Kermanshah and Ilam in the west of the country. For this purpose, the data of two global models HadGEM2 and CanESM2 were used under three scenarios: RCP2.6, RCP4.5 and RCP8.5, as well as two microscale models of LARS-WG and SDSM, and changes in maximum temperatures on a monthly and annual basis in the future 2050-2021) compared to the base period (2018-1989) were examined in 17 meteorological stations. MAE, MSE, RMSE and R2 indices were used to calibrate and validate SDSM and LARS-WG models. The results showed that both models have a high ability to simulate the maximum temperatures of the study area. However, the SDSM model is more accurate than the LARS-WG model, with the lowest and highest accuracy for Bijar and Tazehabad stations with RMSE of 0.02 and 0.18, respectively. The results of maximum temperature forecasting also showed that according to both models, the maximum temperature in the future period will increase compared to the base period, which is the average of the studied models between 0.8 to 1.9 degrees Celsius in the region. Will be studied. The highest rate is estimated based on the RCP8.5 scenario. Spatially, the most changes are related to the northern and eastern areas of the study area and the least changes are related to the western areas of the study area.

Groundwater is the single water resource in many regions of Iran. This is considered to be a major limitation in the social and economic development of the country. Destructive floods and water shortage necessitate suitable strategies against flood control. Selecting suitable areas for artificial recharge and directing the floodwater into permeable formations are amongst the most effective strategies in flood spreading projects. Having combined GIS and MCDA approaches, the present study sought to locate the most suitable areas for artificial groundwater recharge operation in the Garabaygan Basin of Iran. To this end, the data layers relating to the eight effective factors were prepared in GIS environment. This stage was followed by elimination of the exclusionary areas for artificial recharge while determining the potentially suitable ones. Having closely examined the potentially suitable areas using the PROMETHEE II-SAW and Fuzzy-AHP methods, the land suitability map for artificial groundwater recharge was produced. The results of the study showed that most suitable areas for the artificial groundwater recharge are located in Quaternary Qg and Qgsc geologic units and in geomorphological units of pediment and Alluvial fans with slopes not exceeding 3 percent. Furthermore, significant correspondence between the produced map and the control areas, where the artificial groundwater recharge projects were successfully performed, provided further evidence for the acceptable efficiency of the integrated PROMETHEE II-SAW method in comparison with Fuzzy-AHP in locating suitable artificial recharge areas.