GEOGRAPHY AND ENVIRONMENTAL HAZARDS
Year:2022 | Volume:11 | Issue:3|Papers Count:15

Environmental hazards and dealing with them are among the most important concerns of researchers in the field of environmental planning and crisis management. Among these hazards, 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 considering flood control seems necessary. The study tried  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. The criteria for prioritization were 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 prioritization map of these sub-basins was then prepared. Flood risk prioritization map in the studied area shows that Ganjvan sub-basin with the highest flood potential has the first priority and Sartang Bijar sub-basin is the second priority to implement flood control watershed management plans.

Precipitation is one of the main causes of floods which due to the improper dispersion of rain gauge stations and the newly established ones in most basins of the country, the use of the precipitation data faces serious challenges. Remote-sensing method can be used in such cases. In this study, the reanalysis rainfall data of ERA5 for Kashafrood catchment were evaluated in daily and monthly timescales and then its streamflow hydrograph was evaluated using rainfall data of Zoshk station and Zoshk watershed parameters in the HEC-HMS software. The reanalysis rainfall data of ERA5 showed underestimation and overestimation and also had better accuracy in monthly timescale (R = [0.87-0.99]) than daily timescale (R = [0.89-0.62]) and its flow hydrograph compared to the observational hydrograph was more satisfactory (NSE = 0.49 and PBias = -26.46). Flood zone of reanalysis precipitation data of ERA5 in relation to the reference flood zone was -0.07, which was 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 HEC-RAS model.

The results of studies conducted in this regard 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 data 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. 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 in this research. The accuracy of the modeling was confirmed using random ground control points. Moreover, 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.

The formation and evolution of the alluvial fans is drastically 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 the way that the evolution of alluvial fan ages can affect soil carbon dynamics. This study measured factors controlling the C mineralization ratio and carbon dioxide flux within the soil environments belonging to different alluvial fan ages (including young fans, intermediate fans, and old fans) located at the base of the Aladagh Mountain hillslope. The intermediate alluvial fans exhibited more stable environments compared with other fans. Furthermore, the position of the intermediate fans on lowlands of the old fans increased the organic carbon concentration, exchangeable cations, and fine fraction. On the other hand, the lower transport capacity of the erosion processes decreased lower micro-aggregate losses in comparison 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.

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. When human activities change the stability of the geomorphic surfaces, areas prone to wind erosion and the potential for dust emission increases. This study tried to evaluate the dust emission potential of geomorphology classes in Ilam province with an emphasis on land use change. For this purpose, at first, the geomorphology map was produced based on the preferential dust sources (PDS) geomorphic 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. By comparing them, then, 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 (PDS) geomorphic 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 the biological resources, which have 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 were selected: 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), and Topographic Moisture Index (TWI). 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. 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, they were thus omitted. According to Jackknife 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 flow hydrology, erosion and sedimentatio that sometimes causes biodiversity destruction. The purpose of this research was evaluating runoff generation process in current land use condition in comparison with the optimized land use condition in Nahre Azam watershed of Shiraz. To do this, after preparating current and optimized (land use types regarding land capability) land use maps, the impacts of land use on runoff generation were evaluated for the two mentioned conditions using SCS hydrological model. The comparison of the land uses in these conditions indicates that agricultural areas do not show considerable differences. However, there is 8.1% decrease in urbanized area and 17.18% increase in range lands in optimal land use condition comparing to the current land use condition. The results also show that the overall value of CN in current land use condition is 82.6 while it is 75.2 in the optimized land use condition. The percentage of decrease in the runoff in the optimized land use condition over the current land use condition decreases as the return period is increased, and the highest decreas of runoff 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 show that identification of the capability of the lands is very important and land use planning based on the land potential plays an important role in reducing flood damages and runoff loss.

The transfer of water of mountainous regions of Lorestan province to other provinces, the migration of non-indigenous farmers to the region, and the occurrence of drought have reduced the water level of the rivers of Lorestan province. This has made problems for farmers who use surface water resources for agriculture. Water management is one of the most important issues that can help the optimal productivity of agricultural water. The purpose of this study was to evaluate agricultural water management in the Kashkan River basin in Poldokhtar. Questionnaire and interview were used in this applied mixed study to collect data. The first statistical population of this study included farmers of the basin of Kashkan river who were selected through the Cochran formula to be 354 farmers for quantitative part. The second statistical population of the study included agricultural experts and water managemers, selected by purposive sampling to be 30 experts for qualitative part. To answer the research questions, an unlimited exploration and qualitative analysis were used. The results show that using pipes for transferring water, reducing irrigation, irrigation during the evaporating time, the use of cement for water conduits, dredging water channels, and using small water tanks are the most important ways of managing agricultural water resources in this region. Qualitative results showed that engineering, technology, as well as institutional, social, economic, and environmental measures are the most important steps that can be used to optimize agricultural water in the Kashkan River basin by farmers.

Drought is a situation of lack of rainfall and rising temperatures that occurs in any geographical area and in any climate, even in humid areas. The frequency and severity of drought are higher in arid and semi-arid regions. Drought occurs without notice and has a wide range of impacts unlike other natural disasters. The damage caused by drought is intangible but very large and costly. Therefore, the basis of a regular program for better management according to past events requires drought monitoring. Meteorological drought indices are calculated directly from meteorological data such as rainfall. In the absence of such data, they will not be useful in monitoring drought. Therefore, remote sensing technique can be a useful tool in drought monitoring. In this study, the relationship between standardized precipitation index  (SPI index) and remote sensing indices of VCI, TCI and VHI in Isfahan, Chaharmahal and Bakhtiari, Markazi, and Qom provinces was investigated. Using satellite images of Modis Terra sensor and precipitation data of rain gauge and synoptic stations located in the studied area, the 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 the 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.

Heavy rainfalls are considered as a risk factor in the occurrence of floods and continuously cause irreparable damages in most areas, including Lorestan province. This study explored the role of interaction between Cut-Off Low (COL) coupled patterns and Polar Front Jet Stream (PFJS) in heavy rainfall event of April 2019 in Lorestan province. In order to achieve this goal, daily atmospheric monitoring parameters (pressure maps, temperature, wind, vorticity, relative humidity, etc.) NCEP/NCAR database with a spatial resolution of 2.5 degrees was used to identify the effective synoptic patterns on the meteorological condition of the studied area, GFS global numerical model overlay maps with a spatial resolution of 13 km was used to compare wind flow with the studied parameters, TRMM satellite precipitation data with a spatial resolution of 0.25 degrees was used to monitor the spatial distribution of precipitation, and observation data of Khorramabad meteorological station based on synoptic meteorological codes were used to analyze the weather conditions during heavy rainfall events. The obtained results show the instability and rise of moist air due to the two forcings of the COL and the PFJS and the convergence of moist currents from three moisture centers of the northern Indian Ocean, the Red Sea, and the eastern Mediterranean. These features provided the synoptic-dynamic conditions necessary for the occurrence of heavy rainfall. However, many other environmental factors like the saturation of the surface layer of the soil due to the high amount of precipitation in the days before the flood have played a role in the aggravation of the said flood.

Blizzards are severe forms of snowstorms that occur in the middle and upper latitudes of the northern hemisphere in winters. The devastating disaster of a snowstorm with dangerous blizzard conditions on February 3 to 9, 1972, resulting in more than 4,000 dead people in Iran, is one of the most destructive snowstorms in the world. This study investigated different aspects of the synoptic scale at the time of occurrence of this phenomenon, using the reanalysis data of NCEP/NCAR and ECMWF databases. The variables used are 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  were calculated to explain the performance of the atmospheric system. The results show 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 devastating phenomenon.

Rapid growth of urbanization is a big challenge for planners. 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 have led to the emergence of suburban areas around cities, urban sprawl, and the destruction of high quality lands and gardens. The purpose of this study was to analyze the pattern of urban development and expansion of Kashmar between 2000-2020 and to predict land use changes up to the horizons ahead. The results showed that according to Markov model, from 2000 to 2010 and 2020, agriculture land and gardens have grown and barren lands and pastures have decreased. Moreover, the changes in land use for the horizon of 2041 compared to the present is the same. Most of the changes belong to the use of the built-in area. Moreover, in horizon 2041 the growth of Kashmar will be 7.12% expansion towards the outskirts of the city (infilling), about 91.59% development from the edge of the city (edge-expansion) and about 1.28% outward development (Outlaying).

Resilience is a new approach for assessing and enhancing the resilience of cities’ development foundations. The purpose of this research is to model the key drivers effective in increasing the physical resilience of the district 10 of Tehran against earthquakes with a futuristic approach and designing the relationships between the key drivers. This study was conducted using descriptive-analytical method, and the key drivers affecting the increase of physical resilience were identified using content analysis method. In the modeling section, through Delphi method, the opinions of academic experts of physical resilience were obtained. Interview and a questionnaire were used to collect data. The validity of the questionnaire was evaluated using face validity criteria. Relationships between the key drivers affecting the increase of physical resilience of the studied sample against earthquakes were determined and analyzed by the interpretive structural modeling (ISM) method. Finally, using Micmac analysis, the key effective drivers were identified and classified in six levels according to their impact on other factors. The results show that the driver “granulation class” has the highest penetration force and is infrastructure and the main stimulus of urban physical resilience. Any action to increase the physical resilience of the sample against earthquakes requires modifications in this driver. 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 recent 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 impacts of the crisis on the quality of life and restoring the original power and maintaining it during a pandemic is significant. Resilience capacity is a set of conditions, considered to make families resilient enough to deal with shocks. Resilience capacity in this study have absorption, adaptiveness and variability aspects as well as a wide range of specific capacities. This survey is descriptive-analytical. Also, considering the analysis of the relationship between independent variables (resilience capacity) and dependent is also a correlation research. The statistical population of the study included heads of households in Masal city. The sampling method was multi-stage cluster sampling and sample size were determined using 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 the capacities have been effective in improving food security. The following capacities also reduced Corona's negative impacts on food security: social and human capital, information, assets, livelihood diversity, safety shelters, market access, women's empowerment, governance, and psychological capabilities like trust for adaptation.