نشریه جغرافیا و مخاطرات محیطی
پیاپی 45 (بهار 1402)

In the beginning of spring, floods are the most important geomorphic hazards in Iran, destructing propertiesas and human lives. Aland Chai basin, located in Khoy County (northwest Iran), is also known as one of the basins with high potential for flood hazard due to its special geographical situation. This study tried to model spatial variation in flood hazard susceptibility in this basin using the ensemble model, FURIA-GA-LogitBoost. For this purpose, 13 effective parameters of flooding including lithology, soil hydrological groups, NDVI, land use, slope, aspect, elevation, distance to the river, river density, precipitation, topographic wetness index, stream power index, and sediment transport index were used. WEKA software was used to implement the research model and the final flood hazard susceptibility map was prepared. The study found that downstream areas of the basin have a high flood hazard susceptibility. These areas contain the most important human settlements (Khoy city) and agricultural lands and flood as a geomorphic hazard can seriously damage them. Considering the ROC curve and area under the curve (AUC), it was found that the FURIA-GA-LogitBoost model performed well in the preparation of flood hazard susceptibility map with coefficients of 0.861 and 0.895, respectively, in training and validation data.

Tectonics geomorphology is one of the most important modern scientific disciplines. Quantitative analysis based on defined morphometric indices is an available and relatively low-cost and fast method that is used to understand the differences in the amount of tectonic activities in young landscapes. These indices are used as a basic identification tool to detect tectonic deformations or to estimate the relative variations of tectonic activity in a particular area. However, these studies are more sensitive in areas consisting of volcanic rocks, especially for the precise definition of sub-basin boundaries. The study area that consists of outcrops of volcanic rock and young deposits is located in the south of Salafchegan; on the border of Qom-Markazi provinces. Six morphometric indices were measured to determine neotectonic activity: Stream length gradient index (SL), Ratio of valley Floor width to valley height (Vf), hypsometric integral (Hi), drainage basin shape (Bs), drainage basin asymmetry (Af), and transverse topographic symmetry (T) for each sub-basins. After calculating the indices, averages of them, and the relative active tectonic index (Iat), the area was divided into four different tectonic zones based on activity ratio. In this categorazation, category 1 to 4 respectively represent the highest to lowest tectonic activity. It was also found that 2.86% of the basins are in category 2, 51.43% in category 3, class and 45.71% in category 4.

Protected areas are defined as a pattern of land use in the environmental planning process. However, they are excluded from any physical exploitation or their use is conditional. They are no less important than other lands. This study aimed to evaluate the ecological degradation of Kosalan protected area using remote sensing and GIS techniques. Images of two time periods 1989 and 2020 were prepared. For this purpose, after radiometric and atmospheric corrections of NDVI index, changes of vegetation in the region in the two time periods were evaluated. Then, to model the ecological degradation, eight criteria including distance from the village, distance from the road, landslide points, erosion intensity, slope, direction, altitude and vegetation were used. The criteria were weighted by hierarchical analysis process method and standardized by fuzzy model. Vegetation changes at different thresholds were analyzed. According to the vegetation situation in the region, 3 thresholds of 0.1-3, 0.1-1 and 0.1-1 were used. The results of this evaluation showed that the quality and density of vegetation has decreased a lot during 31 years. The results of ecological degradation modeling showed that the most effective criterion in causing degradation is distance from the village. In general, 50% of the area has a high potential for ecological degradation. The results showed that the greatest potential for ecological degradation was in the central areas of the southeast and center of the region, where the slope and altitude are high. The impact of slope is so high in these places.

Flood zoning maps are among the basic and important sources of information for studying development projects in the world. In the conventional method of determining flood zoning maps, calculations are performed on the basis of a steady flow, assuming a fixed bed (without considering sediment transport). This study aimed to investigate the impact of river erosion and sediment transport on river flood zoning. So, the flood zoning calculations of Ajichai River were done using HEC-RAS model and the conventional method of steady flow with a fixed bed. In the next step, flood zoning calculations were performed using quasi-steady flow with moving bed and compared with the results of the previous step to determine the impacts of sediment transport on flood zoning. Comparison between the results obtained from steady flow (fixed bed) and quasi-steady flow with moving bed showed that in sedimentation sections, the width of the water surface increases in the flow mode with moving bed. The maximum rate of this increase in width is 19%. In other words, in the mentioned river, the width of flood zoning is less in the conventional method. This issue confirms the necessity of studying the river conditions in terms of erosion and sedimentation so that the amount of flood zone could be determined more accurately while the river is sedimentary. The increase of flood zone in sedimentation sections is due to the accumulation of sediments and consequently the increase of flow level and width of flood zonation. Therefore, it is suggested that in sedimentary rivers, a quasi-steady flow model (mobile bed) be used to prepare flood zoning maps for providing more safety.

Silvicultural treatments have been applied in the last decades to broadleaf and conifer plantations to increase resilience by enhancing structural and age-class diversity in northern Iran. The treatments included mechanical thinning manipulations, not followed by surface fuel reduction treatments like prescribed burning. The goal of this study was analyzing  the impact of stand-level silvicultural thinning on landscape-scale wildfire behavior. FlamMap minimum travel time (MTT) fire modeling system was used to simulate the impacts of thinning on fire growth and behavior based on spatial and temporal patterns of historical fire ignitions and associated weather and fuel moisture conditions within a forest landscape. Simulations were done by setting two different fuel moisture scenarios: 1) fuel moisture is fixed as the stands thinned, and 2) fuel moisture is reduced with the same degree of thinning. The results showed that thinning alone can be somewhat effective at mitigating the wildfires; as the landscape proportion with low burn probabilities (BP), conditional flame lengths (CFL), and fire sizes (FS) increases. This trend was not the same at higher values of these parameters. Although fine fuel moisture in thinned stands was lower than in unthinned stands, the fuel moisture difference resulting from stand thinning did not substantially influence fire behavior at the landscape level. The findings of this study can be used for better fire and fuel management and other land-use objectives in fire-prone areas.

Landslide risk zoning plays a significant role in the development of safe and sustainable infrastructure, urbanization, land use, and environmental planning. Identifying and determining sensitive and landslide-prone areas not only prevents damages but also provides a basis for the implementation of slope stabilization plans. Landslide risk zoning is done through different methods including statistical, expert evaluation and definitive methods. Choosing appropriate zoning method depends on the type of analysis, study area, experts’ skills and knowledge, and the type of geological and geomorphic parameters affecting landslide risk.  The main goal of this study were preparing a landslide distribution map, identifying the factors affecting landslides, and zoning its danger in Khorramabad-Arak Freeway (Khorramabad to Boroujerd). Using satellite images and field studies as well as frequency ratio (FR) model, a landslide distribution map was prepared, and the factors influencing landslides including slope, lithology, slope direction, elevation classes, land use, rainfall, distance from fault factors and the network of waterways were analyzed. Fuzzy gamma (0.9) was used for zoning the landslide risk. The landslide hazard map was divided into very low (18.55%), low (30.67%), medium (26.51%), high (18.15%) and very high category (6.12%) and finally validated by ROC curve. The results of ROC curve analysis for Fuzzy GAMMA showed that the landslide sensitivity map in the study area has excellent predictive power with area under the curve of AUC=0.94. Therefore, it is suggested to apply the obtained results for freeway security and regional planning.

Flood as a natural disaster with the highest relative frequency of occurrence has always threatened human life. The purpose of this study was discovering the relationship between atmospheric circulation patterns and floods in the Balikhlochai watershed of Ardabil in order to prevent its dangers with an environmental approach to circulation. For this purpose, discharge data for three stations of Almas, Nir, and Gilandeh from the period 2009-2017 were obtained from the regional water department of Ardabil province. Using the ward hierarchical clustering method, two floods occurred on March 7, 2010 and December 8, 2010 were selected and analyzed. The data related to the upper levels of the atmosphere were obtained from the National Center for Environmental Prediction (NCEP-NCAR) website and combined maps of sea level pressure with geopotential height of 500 hectopascals, wind vector with precipitable water, omega with tawai and half-molar specific humidity in Gardes software were drawn. The results of the synoptic analysis showed that the dominance of the Mediterranean thermal low pressure system and the Chinese thermal high pressure system were important factors in the atmospheric disturbance, and besides that, the location of the studied area in front of the landing axis of the Eastern Mediterranean fleet resulted in rotating air movements. And the vertical air velocity of the studied area showed an unstable atmosphere. The specific humidity has also increased since the day before the flood in the lower layers of the atmosphere, and the flow of moisture from the Mediterranean Sea through the western subtropical winds on the atmosphere of the studied area has played an important role in causing torrential rains.

A basic critical phase in watershed monitoring is choosing the most suitable observation points which are followed by monitoring the natural resources with a wide range of view using visibility spatial analysis. Moitoring towers are crucial assets in detecting forest fires, in addition to other technological advancements. For this study 30 villages, located in Chehelchai watershed, were selected as the observation points along with 26 convenient and accessible perspective points as the observer points. For this purpose, visibility analysis lookout towers were determined using QGIS software and the percentages of visible and unvisitable areas were determined for the study area. Four scenarios were employed aimed at looking into the good visibility of the points for indirect watershed monitoring using Viewshed analysis in QGIS software; First scenario: Offset A = 1.6M, Radius 2 = 1200M; Second scenario: Offset A = 11.6M, Radius 2 = 1200M, Third scenario: Offset A = 1.6M, Radius 2 = 10000 and Fourth scenario: Offset A = 1.6M, Radius 2 = 10000M. The results shwed that the Viewshed side program makes it possible to locate visible and invisible areas from the observer points according to different scenarios. Moreover, it was concluded that visibility analysis is a very useful and practical method for evaluating monitoring  lookout towers and determining the potential location of the towers.

In order to investigate dust storms in Khuzestan plain, statistics of 13 synoptic stations in a period of 17 years (2000-2000) were used. One day was chosen as a stormy day when the horizontal visibility of less than 200 to 100 meters was reported in more than 70% of the stations. To analyze the weather conditions, the networked data of the European Center for Medium-Term Forecasting were used. To show the spatial pattern of dust, the AOD values ​​of the MODIS sensor were used. Studies have shown that four spatial patterns in the region cause such conditions. Dust transfer from the north and west of Iraq and eastern Syria as the main centers and dry border areas between Khuzestan province and Iraq are considered as intensifying dust activities. Increased unstable conditions in the lower levels and the existence of a series of atmospheric disturbances that have taken place in a dry manner have caused dust to rise from possible areas and flow into the area. By indexing, the relative fineness parameter of 850 hPs was found to be suitable in identifying possible foci of fine dust. Thus, to predict dust in the region when the wind speed reaches its maximum on the dust centers, it is expected to witness the occurrence of severe dust storms with a delay of 24 to 48 hours in the region. However, the existence of instabilities and the increase of relative equilibrium on the foci have caused the mentioned process to increase and the particles to flow to the region in less than 24 hours.

The basis of estimating the future climate is the evidence of today’s climate. The more stable the evidences, the more accurate the perceptions will be. Reconstructing the past climate of hundreds to millions years ago, paleoclimatology can help reconstructing the future climate. In this research, 120 surface samples were used to analyze modern pollen rain and determine the relationship between pollen and climatic variables. Extraction of pollen from surface samples was done using a combination of standard methods of Faegri and Iverson (1975) and Moore et al. (1991). To reconstruct climatic variables, MAT method in PAST software was used as an environmental transfer function. By implementing the results of modern pollen rain analysis on the fossil pollens of Parishan Lake, the climatic variables of the region were reconstructed during the Holocene. The results showed that since about 10,000 years ago, temperature and precipitation have fluctuated a lot in southwest Iran. At this time, the rainfall fluctuated between 316 and 750 mm. There has been three periods of heavy rainfalls in southwest Iran: 8000-9500, 6200-6800, and 2200-4500-years ego. In all the periods, the rainfall average had been more than today’s rainfall average. The minimum rainfall was 550 and the maximum was 750 mm. In all the periods with an increase in precipitation, the temperature has decreased, and there is a strong inverse relationship between them; the greater the decrease of temperature, the greater the increase of precipitation. The decrease of temperature in the Holocene occurred at least up to 19 degrees Celsius and increased up to 26 degrees at the maximum. The temperature increase that matches with the decrease of precipitation occurred in three periods: The early Holocene to 9500 years ago, 6800-8000 years ago, and 4500-6200 years ago.

This research was conducted with the aim of investigating the day and night temperatures in Iran. For this purpose, the minimum and maximum temperatures during 40 years (1981-2020) were examined using the AgERA5 dataset. Then, the diurnal temperature range (DTR) was calculated. In order to evaluate the performance of the AgERA5 dataset, the data from 56 meteorological stations and RMSE and R2 metrics were used, and the Theil-Sen test was used to analyze the average trend. The results of the evaluation of the minimum and maximum temperatures showed that the AgERA5 dataset has high accuracy for temperature estimation. The trend showed that the monthly trend of minimum and maximum temperatures in Iran is increasing. The increasing trend of temperature over time is not constant and its rate varies in different months. However, the increasing trend of temperature during different months of the year is consistent for the two variables of minimum temperature and maximum temperature. In all months, the maximum temperature increase is observed in winter and March. The DTR index in Iran is a minimum of 0.48 and a maximum of 16.6 °C, which occurs in December and July, respectively. The maximum DTR occurs in the interior dry regions and the minimum occurs in northern and northwestern Iran. The maximum increasing trend of minimum and maximum temperatures is in March, which increases by 0.8 oC/decade and 1.2 oC/decade, respectively. In contrast to the maximum temperature, there is a decreasing trend of the minimum and maximum minimum temperature in November, which decreases by -0.1 oC/decade and -0.2 oC/decade, respectively.

Today we are witnessing a multitude of destructive natural meteorological and hydrological phenomena that cause more financial and environmental losses to human life. One of the atmospheric phenomena that can have a direct impact on flight safety, transportation, structures, energy and many other aspects of human life is wind gust. The aim of this study was to investigate the temporal and spatial distribution of wind gust in Iran over a period of 15 years and to evaluate an experimental method called WPD to predict this phenomenon using the output of the WRF model. For this purpose, the data recorded in 32 synoptic stations between 2004 and 2018 were studied. The results showed that the number of wind gusts occurred in the southeast and northwest Iran was much higher than other regions, while the frequency of convective wind gusts has been higher in the western half of Iran. In general, the frequency of wind gust had an increasing trend during the studied period and reached its maximum in 2018. Moreover, most convective wind gust reports have been related to spring. The highest number of wind gust reports with 67% belonged to the first half of the year. However, only 13% of the reports belonged to the autumn. Most of the wind gusts were reported between 12:00 and 18:00 local standard time (0800 to 1400 UTC). Among several wind gust forecasting methods, the relationship used in the WRF post processing system (WPD) was selected and its performance in Iran was evaluated. The results of the method on 885 non-convective wind gust indicated the optimal performance of the method for forecasting wind gust in Iran (RMSE=3.23, MAE=2.83, MSE=13.4 and R=0.71).

Precipitation is one of the main components of the hydrological cycle. Rainfall distribution plays a significant role in the Earth’s energy balance and human access to water resources, but rainfall is not always promising for humans. Floods cause a lot of human and financial losses to people and infrastructure all over the world annually. Planning for the damage reduction must be done with some measurements. It is necessary to record the amount of rainfall in high resolution, but measuring precipitation in high spatial and temporal resolution is a costly process. Scientists have developed many models to estimate precipitation values. It is necessary to evaluate the output data of these models and their performance before using them. In this study, the performance of two precipitation estimation products, PERSIANN-CCS and PDIR-Now, was evaluated against precipitation recorded in all synoptic stations of Iran for the devastating flood events from 2017 to 2019. For comparing precipitation estimations with the ground data, 9 indices (PC, BIAS, FAR, POD, HSS, , ME, MAE & RMSE) were used. The results showed high variability of indicators in different events. On average, PERSIANN-CCS and PDIR-Now products have a coefficient of determination of 0.16 and 0.19 and RMSE of 9.38 and 12.78, respectively. The values are not desirable, even though the average of PC is high. Moreover, the results showed that the PERSIANN-CCS and PDIR-Now products do not perform well due to the statistical indexes for all stations, and further researches for better heavy rainfall estimation are needed.

Combat readiness in military units indicates the ability of the unit to perform military missions. To study and extract climatology threats in the southeastern Iran, data from 19 synoptic stations with a statistical period of 22 years were used and to prioritize climatology threats, combat readiness criteria were used. Dust storms, heat stress, heavy rainfall and sultry conditions were identified as the most important climatology threats affecting combat readiness in the region. Based on the hierarchical analysis of dust storms, the most important and effective threat to the combat readiness of military units was identified. The incompatibility rate was calculated and its value was less than 0.1, so the pairwise comparison, weighting, and prioritization of threats were confirmed. The zoning map of each climatology threat was prepared by GIS software. Using the weight of each climatology threat, combining the zoning maps of the identified threats, and using fuzzy hierarchical analysis, a comprehensive map of climatology threats was prepared. Zabol and Zahak synoptic stations in spring, the whole region in summer, Saravan station in autumn and Iranshahr, Saravan, Minab, and Kahnooj stations in winter are the worst places for military units. Moreover, in autumn the lowest frequency of hazards is in the region. Based on climatology maps, autumn was recognized as the best season for the deployment and operation of military units in the region. The most weather threats such as dust storms, heat stress and sultry conditions occur in summer. In this season, the combat readiness of the units stationed in the southeast Iran is extremfly reduced.

Urban systems are currently facing major challenges regarding increasing the types of hazards and their effects. Therefore, planning to improve the resilience of urban systems according to the principles of the organizations and international discourses and their applying in the management system of cities is an necessity. The purpose of this study is to identify components effective in the application of the principles of emerging resilience discourses (Hugo) on the management system of Tabriz metropolis. Mixed method was used for the descriptive-analytical study. Questionnaire was used to collect the required data. Academic elites, managers and officials of crisis management in Tabriz were included to answere the questions iusing Delphi method. The sample consisted of 100 participants. Moreover, content validity method was used to check the validity of the research, Cronbach's alpha method was used to measure the reliability of the research, and structural equation modeling in Amos software was used for data analysis. The results showed that 10 principles of resilience management in management system of Tabriz metropolis is not good, especially regarding such dimensions as organization and coordination, information updating, training local communities, and supervising measures. The most important component that affects the application of the principles is the existence of a uniting and supportive management with a coefficient of 0.83, followed by “systemic attitude”, “institutional coordination and synergy”, and “participation and integrated organizational structure” with coefficients of 0.69, 0.63, and 0.58, respectively.