نشریه جغرافیا و مخاطرات محیطی
پیاپی 43 (پاییز 1401)

Prioritization of Flood Risk in Ganjvan Watershed of Ilam Province Using ELECTRE MODELToday, environmental hazards and dealing with them is one of the most important concerns of researchers in the field of environmental planning and crisis management. Among these hazards, the phenomenon of flood is one of the most dangerous natural disasters that should be given special attention in crisis management. Therefore, prioritizing sub-basins for watershed management operations with a view to flood control and control seems necessary. In this research, an attempt has been made to prioritize the Ganjvan watershed basins in Ilam province to implement flood control management plans against floods using the multi-criteria Electre decision-making method. For this purpose, the studied watershed was divided into five sub-basins of Rizevand, Sarcham Deh Haroon, Sarpetak, Sartang Bijar and Ganjvan. Criteria for prioritization include lithology, slope, height, precipitation, land use and drainage density. The weights of the criteria were obtained based on their entropy model and using the Electre model of watershed sub-basins in the prioritization area, the study and then the prioritization map of these sub-basins was prepared. Flood risk prioritization map in the study area shows that Ganjvan sub-basin with the highest flood potential has the first priority and Sartang Bijar sub-basin in the second priority to implement flood control watershed management plans.The method used in this research can be a practical method to study and implement watershed management operations and flood control in the studied watershed and similar to this basin can be used. By performing watershed management and flood control operations in sub-basins located at the mentioned levels, in accordance with the priorities set by this method, while achieving the desired goals, it can have a direct impact on reducing the executive costs of projects.

Precipitation is one of the main factors of floods which due to the lack of proper dispersion of the rain gauge stations and the newly established some of these stations in most basins of the country, the use of these precipitation data faces serious challenges . Therefore , the use of remote-sensing methods is one of the ways that can be used for these fields. In the present study, the reanalysis rainfall data of ERA 5 for Kashaf rood catchment were evaluated in daily and monthly time steps and then its streamflow hydrograph was evaluated by using the rainfall data of Zoshk station and the Zoshk watershed parameters in the HEC - HMS software . The results showed that the reanalysis rainfall data of ERA 5 underestimated and overestimated and also had better accuracy in monthly time step (R = [ 0.87 - 0.99 ] ) than daily one ( R = [ 0.89 - 0.62 ] ) ; and its flow hydrograph compared to the observational hydrograph was satisfactory ( NSE = 0.49 and PBias = -26.46 ). The flood zone of reanalysis precipitation data ERA 5 in relation to the reference flood zone was obtained equal - 0.07 , which was obtained due to the underestimation of precipitation data and the subsequent underestimation of its hydrograph peak flow in the HEC - HMS model . Future studies can be used to evaluate the flood zone resulting from precipitation data of various products in the HEC - RAS model.

The results of studies conducted in this region show that the climate of the region is semi-arid and cold, and its rainfall regime is in the Mediterranean. Its geomorphology is young and its topography is directly related to geological structures, i.e., most folds and fractures make up the heights. The lithology of the formation, along with the action of tectonic processes that have led to the dissolution and creation of joints and cracks in the rocks, has provided the necessary conditions for the formation of less developed karst forms. The region's most significant karst forms are Karen, pinnacles, channels, dissolution doline and dissolution cavities, karst springs, and caves that have spread along joints, cracks, and faults and indicate the connection between these landforms and the region's tectonic structures. In this study, to find out the relationship between tectonics and karst formation, the dip and strikes of fractures (joints and faults) were measured in 7 areas. The results obtained from field studies and their comparison with the information contained in remote sensing documents show that the direction of most joints in the region is consistent with the direction of faults. It has also been found that more Karst landforms have formed along these joints. On the other hand, most of the valleys are consistent with the geological structures of the region, i.e., faults and folds. Therefore, tectonics has played an effective role in creating Karst landforms and their hazards in the region. According to the rockfall risk zoning map, 3.77% of the total area is in the high-risk zone.

In recent years, the occurrence of several destructive floods in the southeastern plain of the Caspian Sea, caused by the flood of the Gorganrood River, has caused many casualties and damage. Predicting the future morphological conditions of the river and its surroundings is one of the essential factors in planning and arranging the coastal plains. In this research, Landsat 5, 7, and 8 satellite images of 1987, 2002, and 2018, with field studies, software studies, and CA Markov automated cells model were used as research materials. The accuracy of the modeling was confirmed using random ground control points. Also, the reaction of the river canal at the flood events was examined based on the satellite image of April 3, 2019. The results showed that the most probable changes in the study area are in river, plains, and man-made facilities units around Voshmgir Dam Lake. Also, the very low hydraulic slope of Gorganrood in the downstream areas of Voshmigir Dam prevents the rapid evacuation of floods and creates a reverse flow and flooding of the surrounding lands. This phenomenon causes the Gorganrood flood and Qarasoo tributaries to interfere in the area between Salagh-Yelghi and Aq Qala. Therefore, increasing the height level of the river shores between the tributaries of Gorganrood and Qarasoo can prevent the flow of interference in them and reduce the risk of flooding of the Qarasoo around lands. Due to water flooding and flood transmission through abandoned canals of Gorganrood in the northern lands of Aq Qala to Siminshahr, the construction of an emergency flood drainage canal through abandoned canals can be a permanent solution to control floods in these areas.

Alluvial fans can be known as non-equilibrium landform resulting from the spatial-temporal variability erosional and depositional processes, weathering processes, and drainage patterns on them. Formation and evolution of the alluvial fans is effectively affected by climate changes. These landforms play an important role in the exchange of carbon between the atmosphere and pedosphere. The aim of this study was to evaluate how the evolution of alluvial fan ages can affect soil carbon dynamics. The present study measured factors controlling the C mineralization ratio and carbon dioxide flux within the soil environments belonging to different alluvial fan ages (including young fan, intermediate fan, and old fan) located at the base of the Aladagh Mountain hillslope. The intermediate alluvial fans exhibited more stable environment compared with other fans. Furthermore, the position of the intermediate fans on lowlands of the old fans increased the organic carbon concentration, exchangable cattions, and fine fraction. On the other hand, the lower transport capacity of the erosion processes decreased lower micro-aggregate losses compared with other fans. As a result, the organic carbon contained in the micro-aggregates is inaccessible to microbial decomposition over long-term timescale. The old fans exhibited a significant decrease of clay fraction, which could be due to their positions on uplands and their susceptibility to gully erosion processes, causing the transportation of a larger amount of OC-rich topsoil. This condition degrades soil structure and weakens aggregate stability within the old fans, encouraging more vulnerability of organic carbon to microbial decomposition. The geomorphological differences of the alluvial fan surfaces in different ages stimulated the variation of soil carbon dynamics. This conceptual approach of combining our field survey data with an empirical model aids in a better understanding of the biochemical mechanisms controlling the C dynamics under the evolution of geomorphic landforms.

Dust entrainment, transport, and deposition are important geomorphic surface processes that have adverse environmental effects and consequences. Various natural environments are resistant to wind erosion until they lose their stability, but when human activities change the stability of these geomorphic surfaces, areas prone to wind erosion increase and the potential for dust emission increases. In this study, we tried to evaluate the dust emission potential of geomorphology classes in Ilam province with emphasis on land use change. For this purpose, at first, the geomorphology map was produced based on the preferential dust sources geomorphic (PDS) classification scheme with a combination of remote sensing data and a number of thematic maps (lithology and soil). Then, using Landsat 7 (ETM +) and Landsat 8 (OLI) images, land use was extracted for 2000 and 2015, respectively, and by comparing them, a land use change map was produced. Finally, the land use change map was overlaid on the geomorphology map to determine the status of land use change in each geomorphology class. The results showed that in Ilam province there are 6 classes of geomorphology based on the preferential dust sources geomorphic (PDS) classification scheme. In most of these classes, the most important change of land use that has taken place has been the change of land use from rangeland to agriculture. Although geomorphology classes of 2a, 3c and 7 have little potential for dust emission, land use change not only in these three classes but also in other geomorphology classes has increased the dust emission potential of geomorphology classes.

gully erosion is one of the most important land degradation processes that leads to reduced land use. The southern and southeastern parts of the Shoor -Mohr basin have been affected by gully erosion. The consequences of this type of erosion include disturbing the ecological balance of the region, endangering biological resources, which has necessitated the study of gully erosion in the region. The purpose of this study is to prepare a zoning map for gully erosion sensitivity using the maximum entropy model and GIS. To achieve this goal, 15 variables including height, slope, slope direction, distance from waterway, drainage density, distance from road, soil texture, geology, land use, rainfall, distance from fault, vegetation, cross section curvature, flow strength index (SPI), Topographic Moisture Index (TWI) was selected and linearity test was performed using (Variance Inflation Factor) and (Tolernace) indices. Out of 100 selected gullys, 70% were randomly selected for educational data and 30% for classification validation and Bootstrap sampling method was used to run the model. Jackknife test was used to determine the most important variables and ROC curve was used to determine the predictive power of the model. Test results showed alignment between vegetation, fault distance, cross-sectional curvature, SPI and TWI were thus omitted. According to Jack Knife test, the variables of height, average annual rainfall, soil texture, drainage density, geology, distance from the road, distance from the river had the greatest effect on gully erosion, respectively. The ROC curve represents 95% accuracy in the validation stage of the model. According to this model, more than 15% of the basin (8445.83 hectares) is very sensitive to gully erosion.

Land use change is one of the most important factors affecting ydrological conditions, erosion and sometimes causing biodiversity destruction. The purpose of this research is evaluation of run off generation process in current land use condition in comparison to the optimized land use condition in Shiraz Nahre Azam watershed. To do this, after preparation of current and optimized (land use types regarding to land capability) land use maps, the effects of land use on run off generation was evaluated for the mentioned two conditions using SCS hydrological model. Comparison of the land uses in two conditions show that the area of agricultural areas do not show considerable differences. However, there is 8.1% decrease in urbanized area and 17.18% increase in range lands in optimized land use condition comparing to the current land use condition. Results also show that the overall value of CN in current land use condition is 82.6 where it is 75.2 in the optimized land use condition. The percentage of decrease in run off in optimized land use condition over the current land use condition decreases as the return period is increased, and the highest decrease of run off belongs to return periods of 2, 5, 10 and 25 years which is respectively 37.47, 29.97, 26.54 and 23.32%. The results of this research show that identification of the capability of the the lands is very important and the land use planning based on the land potential plays an important role on reduction of flood damages and run off loss.

Water transfer of mountainous regions of Lorestan province to other provinces, the arrival of non-indigenous farmers to the region, along with the occurrence of drought, reduced the water levels of the rivers of Lorestan province, as well as the River. This has encountered farmers who use surface water resources for agriculture. To adapt to this challenge, water management is one of the important issues that can help the optimal productivity of agricultural water. The purpose of this study was to evaluate agricultural water management in the Karakan River Basin in Pulmer County. The present research is in terms of purpose, applied and method of doing it (qualitative and quantitative). The tool for collecting data and information is a questionnaire and interview. The present study has two sociology. The first statistical population of farmers in the River Basin of the River is selected through the Cochran formula 354 farmers for quantitative analyzes. The second statistical population includes agricultural experts and water management, selected by targeted sampling of 30 experts for qualitative analyzes. To answer the research questions, an unlimited exploration and qualitative analysis was used to answer the research questions. The results of the research indicate that the use of pipes for water transfer, reducing irrigation, irrigation during the evolving time, the cement of water atmospheric juices, dredging water channels and the use of small water tanks are the most important ways of managing agricultural water resources They are in the region. Qualitative results showed that engineering, technology, institutional, social, social and economic, environmental and economic measures are the most important steps that can be used to optimize agricultural water in the Karakan River basin by farmers.

In this study, the relationship between meteorological drought index (SPI index) and remote sensing indices of VCI, TCI and VHI in Isfahan, Chaharmahal and Bakhtiari, Markazi and Qom provinces has been investigated. In this regard, using the satellite images of Modis Terra sensor and precipitation data of rain gauge and synoptic stations located in the study area, the detection of changes occurred over a period of 10 years was calculated. For this purpose, four months (April, May, June and July) were selected as a sample by reviewing the data of existing stations and using the standardized precipitation index (SPI) model. In this study, due to time accuracy, high spectrum coverage, ease of access, no need for atmospheric correction and ground reference, images with code (MOD11A2 and MOD13A2) of Modis satellite sensor products related to the years 2011 to 2020 due to Confidence of wet and drought phenomena was used and then SPI index was compared with VCI, TCI and VHI indices in combination. The results of drought monitoring showed that during this ten-year period, there was severe drought in some years, and in the same year, less rainfall occurred. In 2020, for example, the drought was very severe, and in 2011 it was very wet. The results of the correlation between SPI index and remote sensing indices showed that SPI index has the highest correlation with VCI index at the level of 0.01. It was found that MODIS images and constructed indices have the necessary capability for drought monitoring. The results of this study can be a good option for decision makers to monitor, investigate and resolve drought conditions and double the need to define an index.

One of the most dangerous atmospheric hazards that can cause so much damage is the flood phenomenon. Heavy rainfall has been a risk factor for flooding. Floods are one of the most severe and destructive atmospheric hazards that have financial and physical harmful effects and affect humans and nature on a large scale. Heavy rainfall and thunderstorms are among the climatic features of the arid and semi-arid regions causing floods. Iran is also affected by the flood phenomenon because of this feature. Synoptic patterns, distances and proximity to sea, altitude, slope and direction of roughness are the most important backgrounds for the formation of precipitation events. Interaction of these factors can exacerbate this phenomenon and increase heavy rainfall. Studying the climatology of precipitation, while recognizing the characteristics and behavior of precipitation, it is possible to plan based on it. Therefore, the mechanism of precipitation, especially in critical conditions (such as drought and flood), has been of interest to researchers in Iran and worldwide. Many studies have been conducted in this regard with different attitudes and goals regarding the dynamic, thermodynamic and synoptic analysis of heavy rainfall. Therefore, despite the fact that floods are recognized as one of the natural hazards and their occurrence every year in Iran, not only the damage caused by this phenomenon has not diminished but it is also increasing. Therefore, planning and trying to reduce the damages caused by it is essential. Lorestan province in southwestern Iran, due to its geographical location and geological and geomorphologic conditions, is affected by devastating floods every year due to heavy rains and floods, which often cause a lot of casualties and financial losses. Therefore, understanding the regime and pattern of these types of precipitation and the synoptical-dynamical mechanisms that lead to their occurrence will help to identify and predict these types of precipitation.The purpose of this study was to investigate the synoptical - dynamical analysis of one of the heaviest rainfall in Lorestan province (April 2019), which was unprecedented in the last two hundred years, based on meteorological statistics.

Believing that heavy rainfall in each region is associated with high-altitude convective synoptic patterns and meteorological conditions in the region, assuming occasional heavy rainfall in the western half of Iran is affected by the Cut Off Low and Polar Front Jet Stream, Selected as the case study. For this purpose, four databases for a wide area focusing on Lorestan province include: daily atmospheric monitoring parameters such as maps of pressure, temperature, wind, precipitation, relative humidity, etc. at different levels from the National Center for Atmospheric Research and The National Center for Environmental Forecasting (NCEP / NCAR), GFS global numerical model overlay maps, TRMM 7 Level 3 satellite precipitation data, and weather data at the time of precipitation were used based on synoptic signs and meteorological codes (ww). In the final step, data are used with time steps (hourly and daily) and different locations (from 0.25 to 2.5 °) for different atmospheric levels (sea level, 850, 700 and 500 hPa) for a range of 0 to 70 East longitude and 10 to 60 degrees north latitude were extracted and processed using various statistical and graphical software.

Lorestan is a mountainous land that, with the exception of a number of alluvial valleys and a few small plains, has no smooth area, and almost all of it encompasses the central Zagros Mountains, which regularly extend northwest to southeast. These topographies associated with deep converging valleys are often compact, tall, and uneven, which increase the flood potential due to the high slope and the low permeability. The amount of rainfall that resulted from the floods of April 2019 was much higher than other flooding events in Lorestan province, according to unprecedented meteorological statistics.The results show the instability and ascension of humid air by two Cut Off Low (COL) atmospheric forcing and the Polar Fron Jet Stream (PFJ) and the convergence of moist currents from the three moisture centers of the northern Indian Ocean (Arabian Sea), the Red Sea and the eastern Mediterranean. These features provided the dynamical-synoptical conditions necessary for heavy rainfall occurrence in April 2019 in Lorestan province. However, other environmental factors such as saturation of the soil surface layer due to the high amount of precipitation in the days before the floods, etc. have also contributed to the intensification of the flood.

The results of the synoptic-dynamic analysis of the flood system (30 March to 1 April 2019) in Lorestan province showed that the precipitation was in the synoptic patterns middle level of the atmosphere and the occurrence of convective upward movements depend on the lower levels. In this rainfall, Cut Off Low formation in the vicinity of polar front Jet Stream provided the dynamic conditions necessary for the formation of significant Heavy rainfall in Lorestan province.In such conditions, the fusion of the unstable region due to the jet stream with the unstable region of the eastern part of the Cut Off Low has a great potential for destabilizing and uplifting the humid air below which the convergence of moisture flux originates from the foci of the northern Indian Ocean (Arabian Sea). Red and Mediterranean have increased its humidity to saturation. In other words, the aforementioned patterns provide the potential for sufficient and dynamical- synoptical potential for heavy rainfall events in the study area.On the other hand, Lorestan province is on the located of entry of numerous western rainy and continuous rainfall caused by these masses during most of the cold season (region saturation), mountainous region and topography with deep and converging Compact valleys, very low permeability of the region Due to its special lithology, reduction of surface runoff time due to deterioration of vegetation in the area and some other human factors has doubled the flood potential of Lorestan province.

Blizzards are severe forms of snowstorms that occur in the middle and upper latitudes of the northern hemisphere in winter season. The devastating disaster of a snowstorm with dangerous blizzard conditions on February 3 to 9, 1972, with more than 4,000 dead in Iran, is one of the most destructive snowstorms in the world. In this study, aspects of the synoptic scale at the time of occurrence of this phenomenon have been investigated using the reanalysis data of NCEP/NCAR and ECMWF databases. The variables used include geopotential height, sea level pressure, air temperature, specific humidity, relative humidity and zonal and meridional velocity of wind. In addition, the parameters of omega, relative vorticity, and zonal jet index have been calculated to explain the performance of the atmospheric system. The results indicate the dominance of atmospheric block (Rex) system in two separate phases from 3 to 6 February and from 7 to 9 February. The role of the artic polar vortex in injecting cold air into low latitudes and a noticeable decrease in temperature before a snowstorm and blizzard in saturating the atmosphere and providing the moisture needed for snowfall is quite evident. The zonal index of Jetstream showed the significant jump of the core of subtropical jet stream at the time of the occurrence of this extreme phenomenon.The zonal index of Jetstream showed the significant jump of the core of subtropical jet stream at the time of the occurrence of this extreme phenomenon.The zonal index of Jetstream showed the significant jump of the core of subtropical jet stream at the time of the occurrence of this extreme phenomenon.

One of the challenges for planners in this century is the rapid growth of urbanization. In Iran, the high growth of urbanization due to the influx of immigrants to cities and the lack of proper and efficient planning for the settlement of immigrants has led to the emergence of suburban areas around cities, urban sprawl and the destruction of quality lands and gardens. The purpose of this study is to analyze the pattern of urban development and expansion of Kashmar between 1379-1399 and to predict land use changes up to the horizons ahead. The results showed that according to Markov model, during the years 1379 to 1389 and 1399% of the area built, agriculture and gardens have grown and the amount of barren lands and pastures has decreased, as well as changes in land use for the horizon of 1420 compared to the present Is the face. Most of the changes are dedicated to the use of the built-in area. Also, for forecasting the year 1944, the growth of Kashmar city will be 7.12% of the type of expansion the present Is the face. Most of the changes are dedicated to the use of the built-in area. Also, for forecasting the year 1944, the growth of Kashmar city will be 7.12% city will be 7.12% of the type of expansion towards the outskirts of the city (infilling) and about 91.59% of the type of development from the edge of the city (edge-expansion) and about 1.28% of the outward development (Outlaying). ) Will have

Resilience is a new approach to assessing and enhancing the resilience and tolerability of the development foundations in cities. The purpose of this research is to model the key drivers effective in increasing the physical resilience of the 10th district of Tehran against earthquakes with a futuristic approach and designing relationships between these key drivers. The present study is conducted by descriptive-analytical method, and the key drivers affecting the increase of physical resilience have been identified as an example of earthquake study by content analysis method. In the modeling section, through the Delphi method, the opinions of academic experts in the field of physical resilience have been used. Data were collected using interview tools, a binary questionnaire, and the validity of the questionnaire was measured and evaluated using face validity criteria. Relationships between the key drivers affecting the increase of physical resilience of the studied sample against earthquakes have been determined and analyzed by the interpretive structural modeling (ISM) method. Finally, using Micmac analysis, the type of key effective drivers have been identified and classified in six levels according to their effect on other factors. Findings represent that the driver of “granulation class” with the highest penetration force, is infrastructure and the main stimulus of urban physical resilience and any action to increase the physical resilience of the study sample against earthquakes, requires modifications in this driver. The drivers of service distribution and the strength of public buildings have the least impact with 1 and 3 penetration force, respectively. The results also show that elements at higher levels have less stimulating power and more dependence.

Over the years, the corona virus has seriously jeopardized progress in reducing poverty, improving hunger, increasing health care, and improving the quality of education. The outbreak of the virus, according to international organizations, has increased the number of hungry, poor and malnourished people, and has left the world with a wave of food insecurity. In this regard, the role of urban resilience capacity at the household and community level in reducing the effects of the crisis on quality of life and restoring the original power and maintaining it during a pandemic is significant. Resilience capacity is a set of conditions that are thought to enable families to have the flexibility to deal with shocks. Resilience capacity in this paper includes three aspects of absorption, adaptiveness and variability as well as a wide range of specific capacities. The present research is descriptive-analytical, based on survey; Also, according to the analysis of the relationship between independent variables (resilience capacity) and dependent (dependent) is also in the category of correlation research. The statistical population of the study included heads of households in Masal city, sampling method, multi-stage clusters and sample size were determined based on Cochran's formula of 384 people. The aim is to explain the capacity of urban resilience to maintain food security during the Corona pandemic in Masal. SPSS and lisrel 8.80 were used for this purpose. Structural equations show that capacities have been effective in improving food security. The following capacities also reduced Corona's negative impact on food security: social and human capital, information, assets, livelihood diversity, safety nets, market access, women's empowerment, governance, and psychological capabilities such as trust for adaptation.