Showing 389 results for Type of Study: Research
Ms. Sousan Heidari, Dr. Mostafa Karimi, Dr. Ghasem Azizi, Dr. Aliakbar Shamsipour,
Volume 9, Issue 4 (3-2023)
Abstract
Explaining the spatial patterns of drought intensities in Iran
Abstract
Recognition of spatial patterns of drought plays an important role in monitoring, predicting, confronting, reducing vulnerability, and increasing adaptation to this hazard. This study aims to identify the spatial distribution and analyze the spatial patterns of annual, seasonal, and monthly drought intensities in Iran. For this purpose, the European center Medium-Range Weather Forecast (ECMWF) data for the period 1979-2021 and the ZSI index were used to extract the drought intensities. To achieve the research goal and explain the spatial pattern of the frequency of drought intensities (Extreme, severe, moderate, and weak), spatial statistical methods such as global Moran’s I, Anselin local Moran’s Index, and hot spots were used. The results of the global Moran’s I showed that with increasing intensity, the spatial distribution of drought events has become clustered. The spatial distribution of the local Moran’s Index and hot spots also confirms this. Very clear contrast was observed in the local clusters of high (low) occurrence as well as hot (cold) spots of severe (Extreme) yearly droughts in the south, southeast, and east. In autumn, weak to Extreme droughts show a southeast-northwest pattern. But in spring and winter, the spatial pattern of drought is very strong as opposed to severe and moderate drought. Despite the relatively high variability of maximum positive spatial Autocorrelation of severe and Extreme monthly droughts, their spatial pattern is almost similar. The spatial clusters of severe and very severe droughts in the northwest, northeast, and especially on the Caspian coast, are a serious warning for the management of water resources, especially for precipitation-based activities, such as agriculture.
Introduction
Drought or lack of precipitation over some time is the most widespread natural hazard on the earth compared to its long-term average. This risk negatively affects various sectors such as hydropower generation, health, industry, tourism, agriculture, livestock, environment, and economy. To reduce these negative or destructive effects, it must be determined how often drought occurs during the period and in which areas it is most severe. Doing so requires determining the characteristics of the drought. These characteristics include area, intensity, duration, and frequency of drought. Discovering the geographical focus, recognizing the pattern governing the frequency of occurrence and temporal-spatial distribution as well as changes in the dynamics of this hazard facilitate an important role in drought monitoring, early warning, forecasting, and dealing with these potential hazards; this information can be used to create a drought plan by providing analysts and decision-makers with ideas about drought, helping to reduce the negative and vulnerable effects and ultimately make it easier to protect or replace for greater adaptation. Many researchers have been led by these approaches to the use of statistical analysis. Numerous studies have been conducted in the study of climatic phenomena such as drought with space statistics techniques in various regions, including China, India, South Korea, and even Iran. Part of the domestic research on spatial patterns of drought is without the use of spatial statistics and a limited number of others who have used these analyzes have only studied the overall intensity of drought and have not studied the spatial patterns of different drought intensities. The main purpose of this study is to identify the distribution and spatial patterns of drought intensities in Iran using spatial analysis functions of spatial statistics based on the frequency of drought intensities (Extreme, severe, moderate, and weak) with yearly, seasonal and monthly multi-scale approach. Therefore, this study will answer the questions: a) What is the spatial distribution of drought intensity data in Iran? And b) What is the variability of spatial patterns of Iranian droughts at different time scales?
Material &Method
ERA5 monthly precipitation data for a period of 43 years from 1979 to 2021 were used for this study. an array of dimensions of 78×59×504 of data were formed in MATLAB software in which 78×59 is the number of nodes with a spatial resolution of 0.25 degrees and 504 represents the month. After creating the database, the ZSI index was used to calculate the severity of drought in annual, seasonal, and monthly comparisons. Finally, to achieve the research goal and explain the spatial pattern governing the frequency of drought intensities (Extreme, severe, moderate, and weak), spatial statistical methods such as global Moran’s I, Anselin local Moran I and hot spots was used.
Discussion of Results
Due to its ecological conditions, geographical location, and location in an arid and semi-arid region of the world, Iran is among the most vulnerable countries due to natural hazards, including drought. It has experienced many severe droughts in the last century. The occurrence of drought and its effects is one of the major challenges of water resources management in this century. The results of the Global Moran’s Index for all three annual, seasonal, and monthly scales showed a highly clustered pattern of drought events in the country. Spatial clustering of the occurrence of severe and Extreme yearly droughts in the eastern, southeastern, and southern regions is also an interesting result. These conditions are due to low precipitation and high spatial variation coefficient in these areas. This contrast of spatial clusters of drought intensities indicates the relationship between drought and temporal-spatial anomalies of precipitation so that with increasing precipitation, spatial variability of precipitation decreases, and consequently spatial homogeneity of precipitation increases. severe and moderate-intensity spots in the south-southeast in autumn and spring can be affected by fluctuations in the beginning and end of the monsoon season in South Asia due to the high variability of atmospheric circulation at the beginning and end of precipitation in these areas. Some studies have also shown the relationship between precipitation in these areas and the monsoon behavior of South Asia. Extreme drought events in winter and spring have had a positive spatial correlation pattern in the southwest, west, and northwest. However, precipitation at this time of year is concentrated in these areas. Warm clusters or concentrations of very severe drought events in the northern strip of the country, especially in the Caspian region, can be due to the high variability of precipitation at the beginning of the annual precipitation season (late summer and early autumn). Observations of these conditions in the northern strip indicate that an event with a high frequency of severe droughts, even in rainy areas, should not be unexpected. Spatial clusters of Extreme, severe, moderate, and weak drought every month using both local Moran and hot spots statistics show the fact that in Iran, the most severe droughts have occurred in the western, northwestern, and coastal areas of the Caspian Sea. However, the absence of severe droughts or spatial clusters has been the occurrence of low drought in the southeast and to some extent in the south. On a yearly scale, the south, southeast, and east have played a significant role in the spatial cluster of severe and extreme droughts. So that these areas of the country have had positive spatial solidarity. However, in these areas, negative spatial correlation prevailed in the autumn for severe drought. This may indicate an anomaly and a tendency to concentrate more precipitation in Iran, as well as many changes in seasonal and local precipitation regimes. According to the research results, a high incidence of severe and extreme drought on all three scales (monthly, seasonal and annual) even in the wettest climate of the country (northern Iran, especially the southern shores of the Caspian Sea) shows that High-intensity droughts can occur in all parts of the country, regardless of the weather conditions.
Keywords: Natural hazards, spatial patterns, Moran statistics, spatial autocorrelation, hot spots
Roya Poorkarim, Hossein Asakereh, Abdollah Faraji, Mahmood Khosravi,
Volume 9, Issue 4 (3-2023)
Abstract
In the present study, the data of the ECMWF for a period of 1979 to 2018 was adopted to analyze the long term changes (trends) of the number of cyclones centers of the Mediterranean Sea.There are many methods (e.g. parametric and non- parametric) for examining changes and trends in a given dataset. The linear regression method is of parametric category and the most common nonparametric method is Mann-Kendall test. By fitting the Mann-kendall model and the linear regression model, the frequency of the cyclone centers of the Mediterranean basin was evaluated in seasonal and annual time scales. Analyzing the trend of changes of the number of cyclone centers on a seasonal scale showed that the five-day duration have had a significant trend in spring, autumn and summer. Whilest on an annual scale, there was no significant trend in any of the duration. By fitting the regression model on seasonal and annual scale, one- and two-day duration have a positive regression line slop.
Fateme Emadoddin, Dr Amir Safari,
Volume 9, Issue 4 (3-2023)
Abstract
Vulnerability assessment of karst aquifer using COP and PI model (Case study: Bisotun and Paraw aquifers)
Introduction
Drinking karst water resources, especially in arid and semi-arid regions, like Iran, are considered as valuable and strategic water resources. A sharp decrease in rainfall reduces the quality and quantity of karst water sources (Christensen et al., 2007). On the other hand, urban and industrial development, which is accompanied by the increase in population growth, increases the risk of underground water pollution caused by the dumping of chemicals, waste and change of use (McDonald et al., 2011). Protection of karst aquifer is one of the most important measures in the management of karst water resources due to its vulnerability and high sensitivity to pollution (Khoshakhlagh et al., 2014, Afrasiabian, 2007). Therefore, With the advancement of geographic information system technology, rapid progress was made in the ability to identify and model groundwater pollution, as well as the vulnerability of water sources from these pollutants (Babiker et al., 2004, Rahman, 2008). The pollution potential decreases from the center to the periphery (Saffari et al., 2021).
Materials and methods
In this study to evaluate the vulnerability of Bisotun and Paraw aquifer which is karstically developed and has, crack and fissure and various landforms; COP and PI vulnerability models have been used to identify areas at risk of contamination. The COP model includes three main factors including concentration of flow (C), overlaying layers (O) and precipitation (P). Factor C, which indicates surface features (Sf), slope and vegetation (Sv). It was obtained between 0.8-0.0 in 5 classes. From the overlap of the subfactores soil, layer index and lithology, the O factor map was prepared in three classes, including class 2 with low protection value, 2-4 with medium protection value and 4-8 with high protection value. The P factor, which is the temporal distribution of precipitation along with the intensity and duration of precipitation, can show the ability of precipitation to transfer pollutants from the surface to the underground water. P factor was 0.8 in 2 layers in the northwest of the study area and 0.8-0.9 with low protection value. Furthermore, top Soil, precipitation, net recharge, fracture density, bedrock and lithology maps were used for the protective cover factor (P) in the PI model. The zoning of the P factor showed 2 classes such as very low and low most of the study area is in the low class. The infiltration condition factor (I) using the characteristics of the soil, the slope layer, and the land use in four layers showed high, aamedium, low, very low, which due to the high slope of the area of the high layer has the highest dispersion, which causes the reduction of the protective cover.
Results and discussion
Consequently, COP vulnerability map in 5 classes with very high vulnerability (0-0.5) equal to 38774.74 hectares (41.4%) and very low vulnerability (4-9-4) with 57.86 hectares (0.06%) of the largest and smallest area respectively. Also, the PI vulnerability map of the combination of these two factors showed very high vulnerability with the largest area of about 68,783 hectares and 72.9% scattered throughout the study area and the high vulnerability class with an area of about 25,526 hectares and 27%.
Conclusion
The results of this research showed that the simulation performance of each COP and PI vulnerability model is closely related to the amount of pollution in the environment. It seems that the COP vulnerability model can better and more accurately showed the level of vulnerability in the karst aquifers of Bisotun and Paraw.
Keywords: karst aquifer, Bisotun and Paraw, COP model, PI model, vulnerability.
Dr Moslem Savari,
Volume 9, Issue 4 (3-2023)
Abstract
This regard, this research was conducted with the general purpose of designing a proposed sustainable food security model in drought conditions. The statistical population consisted of a number of food safety experts and agricultural experts. Therefore, for selecting the samples, targeted snowball sampling (chain referencing) was used. Sampling continued until data saturation, in the end, the number of participants in the study reached 31 . The research method was of qualitative type based on the data theory method of the foundation. The research data were collected using a deep interview and group discussion and analyzed with three open, axial and selective coding methods.
The results of the review of the requirements of sustainable food security in the form of data approach of the foundation consisted of 68 initial codes. Finally, in order to design a safety improvement model, the improvement of food security in drought conditions was subject to 8 requirements (managerial, technological, policy and supportive, infrastructure, cultural and empowerment requirements, Diversification, conservation, stabilization) and were inserted into the Strauss and Corbin model.
Access to adequate nutrition and nutritional health is one of the main pillars of development and is the basis for the future development of the country. According to studies on the role of nutrition in health, its efficiency and its relation with economic development has been confirmed. Also, access to adequate and desirable food is one of the earliest human rights, but various studies show that rural communities, which themselves are responsible for food security, face food insecurity, which is in a drought condition much more inferior to the situation. Because rural households are always at the forefront of drought vulnerability and, in the absence of risk mitigation systems, they quickly lose their resilience and go out of the agricultural sector. Therefore, measures must be taken to enable them to continue to operate in agriculture in drought conditions and to maintain the backbone of food security in the country.
Dr Ebrahim Yousefi Mobarhan, Dr Mansor Ghodrati, Dr Mohamad Khosroshahi,
Volume 9, Issue 4 (3-2023)
Abstract
In the study of the trend of dust storm index, the results showed that the study period of 2003-2007 in Semnan province has an increasing trend and has shown significant changes in the 95% confidence range, but the lack of significant changes in the last decade shows the effects of various events. In cross-cutting decisions in the field of dust in the region. The zoning of the DSI index changes in different regions of the province in a 15-year statistical period indicates that from the west to the east of the province due to the increase in the frequency of stormy days with moderate dust (MDS), dust has increased. The correlation between drought and DSI index in Semnan province showed that although DSI index increased during the period under analysis with increasing drought intensity and its correlation with drought during the 15-year period was not significant, but the pattern of DSI index is consistent with It is the pattern of the drought process. According to the results, it can be acknowledged that the dust situation has always been affected by climate, but the relationship between drought and the DSI index has always fluctuated with respect to droughts and wetlands. However, different climatic parameters are different and their impact is different. In addition to human activities, the main role of wind in the amount of dust or the existence of another source of dust should be considered.
Dr Kiomars Maleki, Dr Mostafa Taleshi, Dr Mehdi , Dr Mohammad Raoof Heidari Far,
Volume 9, Issue 4 (3-2023)
Abstract
The results of pathological evaluation of seismic zones in the terrestrial space indicate a significant concentration of residential spaces, especially cities. It has been economic and human. Therefore, one of the desirable models in identifying, analyzing and reducing damage in urban spaces is to use the structural and functional framework of passive defense. In many recent studies, the subject of reducing earthquake damage in the territory of the physical-spatial field has been to increase the building's resistance to earthquakes. While this study by recognizing environmental components, physical-spatial, social, economic and effective indicators in each component (45 indicators) to determine the pathology and risk areas of earthquakes in a comprehensive and desirable and based on that reduction strategies Redefines risk. In other words, by recognizing and analyzing the basic concept of threat network and risk ring with passive defense approach in earthquake assessment and vulnerability in Kermanshah metropolis to form the required database structure in appropriate software environment, appropriate policy and urban crisis management measures It is designed in proportion to the earthquake risk.
Dr Bromand Salahi, Mrs Mahnaz Saber, Dr Abbas Mofidi,
Volume 9, Issue 4 (3-2023)
Abstract
evapotranspiration is one of the most important components in water balance and management. In this research, to evaluate the effects of climate change on the amount of potential evapotranspiration in the southern part of the Aras River Basin using the downscaled data of the GFDL-ESM2M model in the CORDEX dynamic downscale under the RCP8.5 scenario during the period of 2021-2050 and its comparison. It is treated with the values of the base period (1985-2005). Data with a horizontal resolution of 22 x 22 km from the GFDL-ESM2M model were used in this research. The findings of the research showed that the minimum and maximum temperature and, accordingly, the ETp of the future period will increase compared to the base period in all six studied stations of Aras Basin (Ardebil, Ahar, Jolfa, Khoi, Mako and Pars-Abad). The value of this minimum temperature increase is estimated between 1.4 and 3.8 ºC and for the maximum temperature between 1.7 and 2.2ºC. The range of annual ETp increase varies from 133 mm to 189 mm. In the monthly ETp scale of all stations from January to July with an increase between 3.9 and 1.64 mm and from August to December with a decrease of 0.7 to 38.2 mm. Estimating the increase of ETp in the future period in the basin, especially in the months of spring, which is very important in terms of water demand, requires special attention to the possibility of this estimated increase in the planning of the water and energy sector.
Dr. Aliakbar Shamsipour, Dr. Hadis Sadeghi, Prof. Hosein Mohammadi, Dr. Mostafa Karimi,
Volume 9, Issue 4 (3-2023)
Abstract
Climate is one of the determining factors in the quantity and quality of agricultural products, therefore, in this study, the relationship between precipitation and temperature (as explanatory variables) with rice yield in 40 cities and wheat yield in 30 cities (as dependent variables) was investigated in the Caspian coastal area during 2000-2017. Spatial statistical analyses were performed with using the Moran autocorrelation test and geographically weighted regression. Based on the results (Moran index, z = 0.4342121 for rice and z = 0.719571 for wheat, respectively), it was revealed that the spatial distribution pattern of rice and wheat yield had a cluster pattern. The results of the geographic weighted regression analysis showed that the temperature increase was more desirable than the precipitation increase so the increasing temperature could lead to yield increases. In the eastern parts of the study area, the positive effect of precipitation on rice yield (with 0.020 to 0.540 regression coefficients) was remarkable; the results also revealed a negative relationship between temperature and rice yield in the southeast and eastern parts and a positive effect on rice yield in other areas. Also, the effect of precipitation on wheat yield was negative in the west and central parts of the study area (with -0.481 to -0.871 regression coefficients). According to the results, a negative relationship was dominant between temperature and wheat yield in the east and southeastern parts of the study area and a positive relationship was detected in other areas. Finally, the results indicated that in the western and central parts, due to heavy rainfall and a low number of sunny hours, an increase in temperature is more favourable than an increase in rainfall. In the eastern and southeastern regions of the region, where the amount of precipitation is lower than the threshold required for rice and wheat, an increase in precipitation is more desirable.
Dr Mohammad Mahdi Hosseinzadeh, Dr Ali Reza Salehipor Milani, Mis Fateme Rezaian Zarandini,
Volume 10, Issue 1 (5-2023)
Abstract
Introduction
A flood is a natural disaster caused by heavy rainfall, which causes casualties and damage to infrastructure and crops. Trend of floods in the world increasing due to climate change, changing rainfall patterns, rising sea levels in the future, and in addition, population growth and urban development and human settlements near river have caused floods to become a threat to humans. One of the most important and necessary tasks in catchments is to prepare flood risk maps and analyze them. In recent decades, researchers have been using remote sensing techniques and geographic information systems to obtain flood risk maps in an area. Due to the numerous floods that have occurred in the Neka river catchment, it is necessary to conduct a study entitled zoning of flood sensitivity in Neka river catchment for more effective management in this area.
Materials and methods
Study area: Neka river catchment area with an area of 1922 Km2 is part of Mazandaran province in terms of political divisions. This basin is between 53º 17´ 54 º44´ east and 36 º 28 ´to 36 º 42´ of north latitude. The highest point of the basin is 3500 m (Shahkuh peak) and the height of the lowest point of the basin in the Ablo station is about 50 m and at the connection to the Caspian Sea is -27 meters. The seven sub-basins of this basin are Laksha, Golord, Burma, Metkazin, Kiasar, Alarez and Sorkh Griyeh. Geologically, the basin is mostly of calcareous and marl formations. In the south and southwest of Neka River, the rock material is mostly clay and calcareous marl, which makes this basin has a high erosion potential
To study the flood zoning of the area using a multi-criteria decision model, 1: 25000 maps of the surveying organization and a digital elevation model with a resolution of 12.5 meters (Alos Palsar) were extracted. In order to study the flood risk in Neka river, 4 criteria of height, distance from the river, land use and slope have been used. In the present study, modeling and preparation of flood risk zoning map in 4 stage including descending valuation, normalization of each class, normalized index weight and integration of criteria has been done by the following linear weighting method. Performing linear weighting operations depends on the weighted average of a number of selected parameters in the opinion of the expert. According to the weight assigned to each criterion based on the expert opinion, each of the criteria was multiplied by the assigned weight and at the end the criteria were added together and the final zoning map was obtained.
Results and Discussion
In this study, using a multi-criteria decision-making system model, a flood risk zoning map in the Neka river catchment was prepared. According to the weight assigned to each criterion based on expert opinion, the final risk probability map has a value between 0.02 to 0.2, which is ultimately divided into 5 classes in terms of flood risk. Value range 0.02 to 0.06 component of very low risk zone, range 0.08 to 0.11 component of low-risk zone, range 0.11 to 0.13 component of medium-risk zone, range 0.13 to 0.16 component of high-risk zone, and finally domain 0.16 to 0.20 components of the area with very high risk potential have been obtained. According to the final divisions in the flood risk zoning map of the catchment area, a safe area means areas where the probability of flooding is very low and close to zero, and in contrast, the area with a high and very high risk potential for flooding has the probability of high-risk floods. According to the final flood risk zoning map, about 982 Km2 (51%) has high and very high vulnerability, as well as about 510 Km2 (26.69%) has medium vulnerability in Neka catchment area.
Conclusion
The results obtained from the model indicates that the highest risk of flooding points are located in the western parts of the Neka catchment area and the end of the catchment area that reach the city of Neka. According to the research findings, the most important factors in increasing the risk of floods were the slope in this area and the distance from the drainage network. According to the results of the model, a large area of the basin is a component of high risk zone, that means the Neka river watershed has a high potential for floods. Evidence and documented reports show that the Neka river Basin has experienced several floods in the last two decades. The major part of the occurrence of floods is due to the natural conditions of the basin, thus it is necessary to reduce flood damage by changing the locations of various land uses based on flood vulnerability maps. Using multi-criteria decision making method can be used to prepare flood risk zoning maps in basins that do not have hydrometric data; It is also a more cost-effective method in terms of time. One of the important issues in the final result of this model is due to the weight of the layers, which should be used by experts, who are familiar with the region and this method and adapt to field evidence.
Keyworlds: Flood, Multi-criteria decision making system(MCDA), Hazard zoning, Nekarod, Natural hazard.
Dr Javad Mozaffari, Mohamad Pooranvari, Dr Seyed Asadolah Mohseni Movahed,
Volume 10, Issue 1 (5-2023)
Abstract
Introduction
Soil erosion is the process by which soil particles and components are separated from their main bed by an erosive agent and transported to another location. In the soil erosion process, there are three distinct phases: 1- separation of soil particles, 2- particle transfer and 3- sedimentation of transported materials. In water erosion, the erosive factors are rainfall and runoff. Erosion and the consequent reduction of soil fertility are among the issues that make it difficult to achieve sustainable agricultural development and environmental protection. It is important to study the quantity and quality of erosion in the country's watersheds and to prevent the loss of one of the richest and most valuable natural resources of the country, namely soil, and to fight against this process. (Tabatabai, 1392). Therefore, to calculate the rate of erosion and sediment production in most watersheds of the country that lack statistics or lack of statistics, the use of experimental models to estimate erosion and sediment is required. According to what has been said, the present study was conducted based on the following two main objectives: 1- Estimation of erosion and sediment in Adineh Masjed watershed, which is one of the main sub-basins of Kamal Saleh Dam, using EPM and MPSIAC experimental models and 2- Investigation and comparing two models and choosing a better model for similar regions and climates.
Materials and methods
Adineh Masjid watershed is one of the sub-basins of Dez and the main sub-basin of Kamal Saleh dam. Temperature, isotherm, geology of the area, slope and available information were performed and finally, by interpreting the photos, types, land units, current land use were determined and updated with field control. For a more detailed study, first, according to the condition of the main waterway and changes in the appearance of the land and vegetation and new land material, the ridges separating the basin were divided into 15 sub-basins. In EPM model, four watershed erosion coefficient (Ψ), land use coefficient (Xa), rock and soil susceptibility coefficient to erosion (Y) and average basin slope (I) and in MPSIAC model, nine geological, soil, climate factor (Climate), runoff, slope, vegetation, land use, current erosion status and waterway erosion are examined. Each model was scored according to data analysis and digital images and then placed in the relevant formula. Finally, the amount of erosion and sediment in the basin was estimated and the sedimentation class of the area was determined.
Results
To determine the score of nine factors affecting soil erosion using MPSIAC method and the four factors of EPM model, each of the factors affecting erosion in units were analyzed. Finally, by weighting, the points of each factor in the models were calculated. The degree of R deposition from the sum of the nine factors of MPSIAC model and the degree of Z erosion was obtained by combining the four EPM factors. Then, the amount of sediment production and erosion in the field of relationships related to each model was calculated and compared and analyzed. In MPSIAC model, the amount of specific sediment (M3 / Km2 / year) was calculated as 112.713 and the specific erosion (M3 / Km2 / year) was calculated as 375.71. In the EPM model, the amount of specific sediment (M3 / Km2 / year) was calculated as 213.95 and Specific erosion (M3 / Km2 / year) was calculated to be 395.86.
Discussion and conclusion
The results of sediment and erosion estimation were estimated separately for each sub-area using two models and it was found that the two models are somewhat relatively compatible with each other. The results of MPSIAC model, have more accuracy and reliability, and therefore the results of the MPSIAC model can be used to estimate the amount of sediment entering the Kamal Saleh Dam. However, due to the small distance between the results of the two models, if we do not have access to MPSIAC model data in similar areas, the EPM model can be used with less data and more easily accessible. It was also observed that in the upper and entrance parts of the basin, where the slope is higher and the vegetation is less, the amount of sediment production and erosion is higher in these areas. So that the upper parts of the basin are in the medium erosion class and the rest of the basin is in the low erosion class.
Keywords: watershed, erosion and sediment, modeling
Leyla Babaee, Nahideh Parchami, Raoof Mostafazadeh,
Volume 10, Issue 1 (5-2023)
Abstract
Changes in the hydrological response due to climatic parameters and human induced activities can be derived from indicators based on the analysis of flow duration curves. The purpose of this research is to determine the flood and the low flow parameters using the flow duration curves. The trend detection technique can be used as a useful tool in deterimining the temporal changes of the different hydro-meteorological parameters. The river gauge stations of the Ardabil province were used for the analysis of high and low flow occurrence in this study. The spatial variations of the flood events can be used as a preliminary guideline for the prioritization of the watershed in the vulnerability assessment and management-oriented measures. Also, the assessment of low flow condition is a useful tool in the allocation of environmental flow allocation and utilization of river surface water resources.
Methodology:
In this research, temporal and spatial changes of Q10, Q50, Q90, Q90/50 and Lane indices in 31 hydrometric stations of Ardabil province during the period from 1993- 2014 were evaluated. The flow duration curve of each river gauge stations was derived. The flow duration curves also were plotted based on the dimensionless flow divided by the mean discharge and the upstream area of each river gauge station. Also, the temporal variations of the of Q10, Q50, Q90, Q90/50 and Lane indices were analysed using non-parametric Man Kendall trend test. Then the significant level of upward and downward trend directions were determined. In this study, the results of 5 river gauge stations were presented as example based on the the river flow ranges, which includes low, medium and high river flow discharge (Hajahmadkandi, Nanakaran, Shamsabad, Polesoltani, and Booran).
Results:
Based on the results, the trend of Q10 (Flood flow index) was significant at the stations located on the main trunk of the Qarehsou river. Meanwhile the Q50 (average flow index) has a significant decreasing trend in most of the studied river gauge stations. In addition, Q90 and Q90/50 indices have a significant decreasing trend in most stations. In addition, Q90 and Q90/50 indices had a significant decrease at (p<0.05) regarding the Lane index as a flood related indicator in the Arbabkandi and Dostbeglo stations, which are affected by the dam construction there is a significant decreasing trend.
Conclusion:
I summary, the values of flood flow index in the upstream rivers of the Ardabil province had a increasing trend.
Prof Bohloul Alijani,
Volume 10, Issue 1 (5-2023)
Abstract
Abstract
During the recent decades the discipline of geography has lost its priority and position to some degree in Iran. Most of the graduates could not enter into the work in the universities and other organizations. The human-environment system, the main area of geographical specialty - has experienced many crises and hazards among which the global warming and climate change being the most destructive. This means that the ongoing curriculum is not working well and needs to experience a fundamental change. To implement this operation some points should be cleared out: The hazardous condition of the world and especially Iran, the education history and state of geography in Iran, and the relation between geography and sustainable development of the world. The discipline of geography has changed its approach according to the circumstances of each period several times. For example, at the beginning of the twenty-century due to the dominance of the environmental determinism, the dominant approach of geography was the relation between man and environment. But since the 1970’s the earth has encountered with different hazards and crises to the extent that it is named as the period of Anthropocene. Accordingly, the dominant approach of geography during this Anthropocene era is to identify and solve the hazards and crises and lead the man- environment system towards the sustainability as once was requested by the secretary general of the United Nation. In this regard the geography should adopt the sustainable development concepts and goals. For this reason, the geography of Iran should make a switch from its very specialized approach to a relatively wholistic view and pay more attention to the human- environment paradigm. To implement this order, the following assumptions should be considered.
- The applied objective of the discipline should be defined as “locating the suitable place for the living and activities of man without endangering the sustainability of the natural environment. This objective is not clear at the present curriculum. Defining this objective will clearly show students what is their job after finishing the career.
- The main vision of geography education is the creation of the sustainable geographical space or environment.
- The research approach is problem solving. Because most of the laws and concepts are identified and defined. Due to the hazardous nature of the earth system geographers should identify the problems and research to solve them via geographical thought and knowledge.
- The terrestrial unit for working is region. This is very important concept in geography. We cannot prescribe one sustainability procedure for all of the world. But we do one for each region. When regions became sustainable, all the world will be sustained.
- In any region the hazards and crises will be identified and described through the spatial analysis methods and will be conducted towards sustainable human – environment system. This monitoring is composed of the stages of spatial analysis, spatial planning, and spatial managing.
- All of the geography subjects and materials are necessary for sustainable development goals. The only criteria will be added is the environmental ethics in all of the geography activities and applications.
- Instructors and students should be familiar with the techniques of integration and multi-dimension modelling.
- All geography graduates will respect the nature and its resources and should consider the environmental ethics during their academic career. They should be able to identify and solve the environmental problems through the geographical thinking. Geographical thinking means asking geographical question, gathering geographical data, processing the data with geographical (spatial) methods, and presenting the results in the geographical forms, i.e., maps. All the graduates should be creative and critical and should have the power of scientific challenging and discussions.
- Geography is one independent and overarching discipline and we will offer only one total geography in bachelor level. The master career can be specialized according to the applied objectives of the societies. The doctoral program is also one integrated discipline. The specialty of graduates will be defined according to their dissertation.
- The subjects include the fundamental courses such as physical geography and sustainable development, regional courses such as the human geography of Iran, technical courses such as remote sensing, GIS, and statistics, the applied courses such as evaluating the natural resources, and so for. The students with any high school background should pass all the courses with high quality so that after graduation they have the potential to analyze the human- environment problems and recommend the required solutions.
Key words: geography curriculum, sustainable development, geography of Iran, twenty first century, environmental ethics, geographical thinking, Geography and sustainable development.
Dr. Seyed Amirhossein Garakani, Dr. Fatemeh Falahati,
Volume 10, Issue 1 (5-2023)
Abstract
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
Hasan Jems, Saman Maleki, Abuzar Nasiri, Soraya Derikvand,
Volume 10, Issue 1 (5-2023)
Abstract
1- Introduction
Desert dust is formed under the influence of the special weather and environmental conditions of desert areas, enter the atmosphere. Localized hurricanes caused by ground air instability and sweeping dry deserts clear silt and sand particles enter the atmosphere from the surface. Ecologically as well as physically desert dust Effects such as pulmonary heart disease, disruption of plant physiological circulation, and erosion of growing structures include heavy metals deposited on soil surfaces, water surfaces, and canopies Plant surfaces that cause chemical changes and physiological damage to environmental ecosystems. Difficult Metal generally refers to a group of metal elements with a specific gravity of 6g/cm3 or more. Atomic weight greater than 50 g. Heavy metals important from an environmental point of view Cadmium, arsenic, cobalt, vanadium, zinc, mercury, iron, manganese, nickel, lead, chromium, copper, that do not decompose naturally. In addition, the long life of heavy metals is also considered. In the studies that have investigated the effect of dust on citrus fruits, it has been very few and even garden plants have been done on a case-by-case and limited basis. Citrus and especially oranges are one of the important and economic garden products in Iran, which are cultivated in tropical areas with mild and cold winters. Khuzestan plain, especially Dezful, is one of the poles of citrus and orange cultivation. But in Khuzestan, it is under the influence of many environmental stresses, which can be mentioned as drought stress and air pollution in the region. The rising trend of the phenomenon of desert dust in recent years has been shown as a danger and its effect on the environmental health and economy of the region is very severe, and the most damage has been reported to the agricultural sector. Although the damage caused by micro-pollens to the agricultural sector is expressed as an economic figure, the effect on plants, especially citrus fruits, remains unknown. Although researchers have studied the effect of fine dust on sugarcane, grapes, legumes, nectarines and peaches in Iran, India and Pakistan, the effect of fine dust on vegetative traits and orange fruit has not been investigated in Khuzestan. Considering that the first step in controlling the effect of air pollution on plants and horticultural crops is to know how it affects the plant, on this basis, the main goal of the current research is to reveal and evaluate the effect of micro-pollens. Desert is on vegetative and reproductive characteristics of Thomson orange in Dezful.
2- Methodology
In order to evaluate the effect of desert pollen on the quantitative and qualitative yield of orange fruit, Thomson variety, a field experiment in the form of randomized complete block design with four treatments and three replications was carried out in Dezful in 2018-2019. The treatments included 1) road dust and desert fine dust, 2) desert fine dust, 3) washing after the occurrence of fine dust and 4) control away from fine dust. The chemical and functional characteristics of the trees were measured after applying the treatments, which included chlorophylls a and b, relative water content of the leaves, number of fruits, diameter and weight of the fruit, soluble solids of the fruit and the final yield of the tree.
3- Results
The results showed that chlorophyll a decreased by 21% and 11%, respectively, in the road dust and desert fine dust treatments compared to the control. Chlorophyll b also decreased to the same amount compared to the control. The diameter of the fruit also decreased by 20% in the desert dust treatment compared to the control. The number of fruits per tree also decreased by 22 and 20% in the treatments of pollen and fine desert dust compared to the control. In the product yield of each tree, in the treatments of road dust combined with desert fine dust and the second treatment, which was only desert fine dust, it decreased by 22 and 17 percent, respectively, compared to the control. Tukey's mean comparison showed that the difference of all quantitative and qualitative characteristics between the treatments was significant and Desert dust has a negative and decreasing effect on the yield of Thomson orange trees; However, washing the trees after the occurrence of micro-pollen removed the effects of micro-pollen on the performance of trees and it even increased compared to the control; So, washing increased the yield of oranges by 40, 35, and 12 percent compared to the first and second treatments of road dust and fine dust, as well as the control.
4- Discussion & Conclusions
Plant growth cycle and biochemical interactions of plants show different reactions under the influence of environmental stresses. The results of previous studies indicated that fine dust and dust storms have been identified as an environmental stress for plants that have a negative effect on grapes, medicinal plants, sugarcane, nectarines, peaches and legumes. The effect of fine dust on the plant can be investigated in several characteristics and periods of plant phenology. In the first stage, the deposition of desert fine dust on the leaves of the plant causes shading and reducing the light received by the leaf pigments. Fruit formation is the most important phenological period of the plant, and the occurrence of environmental stress can affect the yield and products of the plant. The present research showed that the number of fruits in orange trees showed sensitivity to desert pollen and the settling of soil particles on orange flowers reduced the amount of fruit formation and finally the number of healthy and ripe fruits in the trees treated with road dust and Desert fine dust decreased compared to the control. Finally, the yield of control orange trees decreased by 17% and 22%, respectively, compared to desert dust and road dust treatment with desert dust. The yield of cotton plants in China decreased by about 28% compared to Desert dust. It can be concluded that although desert dust and road dust reduce the yield of Thomson orange fruit, washing it compensates for the damage and will be economical from the economic point of view.
Key words: Citrus, Photosynthetic pigments, Fruit yield, Dust, Dezful
Dr Seyed Keramat Hashemi Ana,
Volume 10, Issue 1 (5-2023)
Abstract
Abstract
Introduction and issue: In today's century when the effects of climate change on different sectors are undeniable, investigating and analyzing the behavior during dry spells is always of special importance and basic priority. On the other hand, the occurrence of extreme events such as precipitation can accelerate the occurrence of climate change. In Iran, rainfall is one of the basic variables for evaluating the potential availability of water resources, but its temporal and spatial distribution is very uneven. The change of dry Spells depending on precipitation always have different fluctuations in different seasons of the year. It seems that this is due to the inherent behavior of precipitation, which generally shows itself as an unstable and unruly variable. This feature causes changes and differences in the temporal and spatial distribution of precipitation in arid and semi-arid regions such as Iran. This inconsistency will face fundamental challenges to regularize dry spells on a seasonal and monthly scale. With a detailed understanding of the behavioral mechanism of dry spells, it is possible to know more precisely the climatic condition of different regions in order to plan in sectors such as; Water resources, agriculture, health, transportation and etc we able to do basic and preventive measures compatible with climate change. It is hoped that this research and related studies will be a positive step towards a more accurate understanding of the climate and its behavior in different seasons of the year.
Data and method: In order to investigate the seasonal behavior of the duration of dry spells, we used daily precipitation data for 44 synoptic stations of Iran and a 30-year statistical period (1988-2018). To reveal the behavior of dry spells, the precipitation data after validation and temporal integration were classified on a seasonal scale.
After the statistical integration of the data, dry spells related to precepitation were extracted and long-term periods lasting more than 20 days were the basis of the study. In the next step, to determine the seasonal weight of courses was used, the step-by-step evaluation method of Swara's fuzzy-numerical logic (SWARA). Thus, in the first step, the longest and most frequent periods are sorted based on relative importance. In the second step, the initial weights of the courses are determined, and in the third and fourth steps, the final and normalized weights of the courses in different seasons are determined, and unrealistic results are removed from the final analysis for proper explanation.
Findings and Results: The effectiveness and weight of each of the criteria with the Swara method in the fuzzy environment showed that in the western and northern regions of the country, winter and spring seasons and criteria such as reversibility and percentage of probability of occurrence have the most initial weight in explaining the periods. In the final explanation, these two season,s had a high weight. These two seasons explain more than 65% of the weight of courses in these regions. In the southern regions and parts of the center (Isfahan, East Fars and West Kerman), winter and autumn explain more than 71% of the weight of periods. Among the criteria explaining the weight of the courses, the reversibility criterion and the probability of occurrence have taken more than 55% of the weight. The northern and humid regions of the country vary in criteria from periods such as; Reversibility, continuity and probability of occurrence are more apparent and this indicates that the border of dry areas in the future of Iran's climate will move towards northern areas. It can be acknowledged that the behavior of long-term dry periods is more a function of two criteria of reversibility and probability of their occurrence. The weighting of the criteria affecting dry periods showed that the return period and the continuation of periods in the cold seasons of the year in dry areas have a more irregular behavior than in wet areas and have more weight in explaining the periods. By determining the weight of seasons in explaining dry periods, we can have better planning and management in related sectors such as water and agriculture.
Key words: dry spells, weighing, precipitation, climate, Swara method, Iran.
Mr Abolghasem Firoozi, Dr Akram Bemani, Dr Malihe Erfani,
Volume 10, Issue 1 (5-2023)
Abstract
Introduction:
The growth rate of urbanization during the recent decades of metropolises has had many destructive effects on the urban environment, among which we can mention the change of temperature of surfaces and local climates. The increase in the urban population, the rapid growth of industrialization and the increase in the concentration of pollutants in the lowest level of the atmosphere have affected the severity of the city's heat islands. Land surface temperature (LST) is a key variable to control the relationship between radiant, latent and sensible heat flux. Analyzing and understanding the dynamics of LST and identifying the relationship between it and changes of human origin is necessary for modeling and predicting environmental changes. The heat of urban surfaces is affected by various characteristics of urban surfaces such as color, surface roughness, humidity level, possibility of chemical compounds, etc. In addition, the changes between LST in a city and its surrounding area are due to surface changes, heat capacity and topography. Since the surface temperature regulates the temperature of the lower layers of the atmosphere, it can be considered as a weather indicator and an important factor in the urban environment. Changes in land use by changing the features of the surface cover such as the shape of the constructed areas, the amount of heat absorption, building materials, surface albedo and the amount of vegetation lead to changes in the temperature of the earth's surface. Barren lands with soil cover, on the contrary, increase the surface temperature of the earth. Climatic characteristics at the time of satellite image imaging also play a role in the extent and intensity of urban cold islands, so that satellite imaging in the middle of hot summer days shows urban cold islands better. The innovation of the research is in the large area of the investigated area, which includes eight urban areas, in order to examine the pattern of temperature changes on a wider level.
Materials and methods
Considering the rapid development of urban and industrial areas in the Ardakan-Yazd plain in recent decades, this study aims to investigate changes in the surface temperature pattern using Landsat 7 and 8 satellite images for both winter and summer seasons. It was done in 2002 and 2019. In addition, the relationship between land use/land cover and surface temperature was also investigated. Geometrical correction of satellite images was done using topographic map 1/25000 of Mapping Organization and atmospheric correction using FLAASH method in ENVI software. Algorithms used to obtain land surface temperature for Landsat 7 images were single-window method and for Landsat 8 images, the Landsat Science Office model was used. Land use/land cover layers related to the years 2002 and 2019 were used, and central statistical profiles and LST distribution were extracted for pasture, agricultural land, blown sands, industrial areas, rock outcrops and cities. In addition to examining temperature changes in different uses, it is also possible to compare over time.
Results and discussion
The results of this study showed that the area of cold islands and thermal islands in winter and summer of 2002 is not much different, so that in winter 10.8 percent and in summer 10.4 percent of the area were cold islands and thermal islands in winter 9.02. It was 8.5% of the region in summer, while this difference is huge in 2019. Thus, 9.4% of the area in winter and 12.1% in summer are covered by cold islands, and thermal islands are 8.3% in winter and 1.6% in summer. Changing land use and increasing the size of urban and industrial areas and reducing agricultural land is one of the main reasons for the increase in cold islands. The survey of land use/land cover changes between these years showed that the extent of urban areas increased from 22,045 to 23,714 hectares, and industrial areas also grew by about two times, from 4,615 in 2002 to 8,187 hectares in 2019. However, during this period, the area of agricultural land has decreased from 1161 hectares in 2002 to 793 hectares in 2019. Also, the results show that the percentage of heat islands is higher in winter than in summer. The main reason for this can be the much less vegetation covers in the winter than in the summer, because the vegetation cover acts as a moderator of the earth's surface temperature. Cold islands are formed in the built-up areas in the winter and summer. From 2002 to 2019, the extent of cold islands decreased in winter and increased in summer, while the extent of thermal islands decreased in winter and summer. Also, the results of the validation section of the single-window method and the model of the Landsat Science Office in calculating LST showed that for both summer and winter seasons, Landsat 8 has a higher accuracy than Landsat 7, and the LST estimation model is based on the exclusive method of this The Landsat series of satellites (Landsat Office of Science model) has a higher efficiency than the single-window method.
Conclusion
The results showed that cities play an important role in changes in the temperature pattern of the earth's surface, and the phenomenon of urban cold islands is not exclusive to big cities in hot, dry and semi-arid regions, but also occurs in medium-sized cities. The temperature variability of eight cities located in the Ardakan-Yazd plain with the land use/cover of the suburbs also showed that the cities are colder than the suburbs in both winter and summer seasons. This study showed the role of vegetation in hot and dry areas in reducing LST and also provided evidence for the change in the degraded state of pastures in this area.
Keywords: Urban climate, Land use, Land surface temperature, surface urban cool island (SUCI), surface urban heat islands (SUHI)
Dr Abdolmajid Ahmadi, ,
Volume 10, Issue 1 (5-2023)
Abstract
Extended abstract
Landslide risk zoning is one of the basic measures to deal with and reduce the effects of landslides. Vernesara watershed is one of the areas where many landslides have been observed in different parts of it. In this research, in order to zone the risk of landslides using the entropy index, first the ranges of landslides were determined, then the effective factors in the occurrence of range movements were prepared in the ArcGIS software environment, and a landslide susceptibility map of the studied area was prepared. . The prioritization of effective factors using Shannon's entropy index showed that the slope layers, land use, surface curvature, topographic humidity index and topographic position index had the greatest effect on the occurrence of landslides in the region. Also, zoning landslide sensitivity with the mentioned model and evaluating its accuracy using the ROC curve shows the very good accuracy of the model (79.6 percent) with a standard deviation of 0.0228 for the studied area. The zoning map shows that the low-risk areas cover only 13% of the area and more than 56% of the area is in the area with high risk of landslides, which indicates the high potential of the area in the occurrence of landslides. . Construction at a distance from fault lines, waterways and the steep Asmari Formation and safety of communication routes are the most important measures to reduce the amount of damage caused by landslides in Vernesara watershed.
Key words: natural hazards, landslide, entropy, folded Zagros.
Seyed Hedayat Sheikh Ghaderi, Toba Alizadeh, Parviz Ziaeian Firoozabadi, Rahman Sharifi,
Volume 10, Issue 1 (5-2023)
Abstract
Abstract
The aim of this study was to analyze the temporal and spatial nature of dust storms during the period 2016 to 2018 in Kermanshah Using the HYSPLIT routing model and the MCD19A2 product, the Modis sensor was performed in the Google Earth web engine.In order to route the origin of dust particles, the Lagrangian method of HYSPLIT model was used in 48 hours before the occurrence of dust phenomenon in Kermanshah at three altitude levels of 200, 1000 and 1500 meters.Findings from HYSPLIT model tracking maps indicate that the general route for dust transfer to the study area is the north-west-southeast route with the origin of the deserts of Iraq and Syria at three altitudes of 200, 1000 and 1500 meters. On June 17, 2016 and October 27, 2018, as well as the southwest-west route originating in Kuwait, Northern Saudi Arabia and part of Iraq on November 2, 2017.The results of the maps obtained from the MCD19A2 product of the Modis sensor, especially the maps of periodicity, cumulative concentration, spatial variation and the highest AOD map, show a high correlation with the routed maps extracted from the HYSPLIT model. In general, based on the findings of the maps extracted from the product MCD19A2, Modis sensor during the period 2016 to 2018 in Kermanshah, the central and eastern regions have always been more affected by dust storms than in other parts of the city. On average, they were more exposed to dust pollution than other parts of the city. In this regard, the final results show a high correlation between the actual PM10 data and the AOD values derived from the MODIS sensor.
Keyword: Dust, AOD, Modis, HYSPLIT, Kermanshah, Google Earth Engine
Dr Ghasem Azizi, Dr Samaneh Negah, Dr Nima Farid Mojtahedi, Mr Yossef Shojaie,
Volume 10, Issue 1 (5-2023)
Abstract
Abstract
The continuous and expanding process of global warming, especially in the Asian region, has provided the conditions for increasing drought and the spread of desertification. Many deserts had ecologically balanced soil conservation conditions that until recently have become new sources of dust generation now. Numerous examples have occurred in Iran due to its special geographical location among some of the most important deserts in the world. Temperature anomaly (about 8º C) last winter in the Caspian Sea basin has created new dust sources for the southern coastal of the Caspian Sea. On 30-31 May 1400, dust emission was recorded in meteorological stations of Gilan province in terms of area and concentration. The implementation of HYSPLIT chemical backward models shows the emission of dust from the northwestern region of the Caspian Sea to the southern coastal of the Caspian Sea (Guilan province) for the first time with such intensity. The source and origin of this dust was identified in the Rhine desert in the northwest of the Caspian Sea. Continuous and unprecedented warming in the region and accompanied by strong north-south currents provided the conditions for the emission of this dust. Due to the origin of the emitted dust as well as the geographical and topographical conditions of the Caspian Sea basin, the level of this dust was assessed from the ground level to an altitude of less than 1500 meters. Analysis of synoptic conditions using NCEP / NCAR analysis data with 1 degree horizontal resolution indicates the establishment of high pressure air mass with a center of 1018 hPa on the northwestern parts of the Caspian Sea and the penetration of high pressure to the southern coastal areas of the Caspian Sea. Due to the appropriate pressure gradient and increasing wind speed, dust-producing springs are formed on the desert areas of the Rhine and with the dominance of the northern currents (south-south), the dust mass is sent to Gilan province.
Keywords: Global Warming, Dust emission, Russian Rhine Desert, Gilan.
Dr Masoud Moradi, Dr Mohammad Hosein Gholizadeh, Mr Meysam Rahmani,
Volume 10, Issue 2 (9-2023)
Abstract
Investigation of the Temporal and Spatial Variation of Maximum Soil Temperature in Iran
Extended Abstract
Introduction
The study of soil temperature in different depths of soil is important in climatology, hydrology, agrometeorology and water resource management. Different depths has a different temporal and spatial soil temperature variation. It represents the regional ground temperature regime. Furthermore, due to its rapid response to environmental changes, soil temperature is one of the most important indicators of climate change. The increase in soil temperature because of global warming can promotes disasters such as drought by increasing the water demand of agricultural products during the plant growth period. The increase in soil temperature also have a various consequences, include increasing evaporation from the soil surface, soil salinity in susceptible areas, which can lead to a decrease in soil yield and failure in plant growth. Therefore, knowledge of soil temperature changes in different environments is very important in climate studies. The aim of the current research is to analyze the spatial and temporal variations of soil temperature at different depths from five to 30cm of the ground and to investigate the existence of any kind of increasing or decreasing trend at different climates of Iran.
Methodology
Hourly soil temperature data (depths of 5, 10, 20 and 30 cm) were used in this research for the period of 1998-2017. The soil depth temperature is measured three times a day at 6:30 am, 12:30 pm, and 6:30 pm local time (3, 9, and 3 p.m. UTC). These data have been received for 150 synoptic stations of Iran on a daily basis from the Iran Meteorological Organization (IRIMO). IRIMO monitored the quality of soil temperature for data entry, data recording, and data reformatting errors. Data availability, discrepancies, errors, and outliers were identified during the second stage.
At the first step, temporal coefficient of variation were calculated for available soil temperature time series from five to 30 cm depths of each station. For this purpose, the average of three daily measurements of soil temperature was calculated and then the temporal coefficient of variation was obtained. In the next step, trend analysis of soil temperature has been investigated using the non-parametric Mann-Kendal test. The trend slope was calculated using Sen’s slope for each station in seasonal time scale. Trend analysis has been done for all three observations of the day.
Results and Discussion
The studied stations show significant spatial patterns in the temporal variability of soil temperature. In all four investigated depths, from five to 30 cm, the northwest parts of Iran, and some parts of Zagros and Alborz mountain ranges have high temporal coefficient of variation. In contrast, the stations located on the southern coasts and southern islands had the lowest temporal variability. In warm and cold seasons (summer and late autumn to mid-winter), the spatial changes of soil temperature at different depths are lower than spring and early autumn. However, in the warm period of the year, the soil temperature experiences lower spatial variations at different depths. Spring and autumn seasons, as the transition period from cold to warm and warm to cold seasons, show the most spatial temperature variations in Iran. Detected trends do not have significant differences among the three observations of the day. Soil temperature Trend analysis at different depths showed positive values for two seasons of summer and winter over most of the stations throughout Iran. Extreme trends are more frequent in the summertime of Zagros and Alborz mountainous regions, while in the winter season the stations located at the southern latitudes of Iran have experienced the most positive trends. In the summer season, higher trends with 99% confidence are more frequent in the mountainous areas. These positive trends in soil temperature have occurred in all studied depths. The negative trend at different depths is a distinct feature of the autumn season, which is significantly more prevalent than other seasons throughout Iran. The analysis of soil temperature trends in different depths shows that values above 1 degree Celsius often occur in 5 to 20 cm deeps. The increasing trend of soil temperature in winter shows a greater spatial expansion, which is indicate increasing annual minimum soil temperatures and the increasing trend of Iran's soil temperature.
Keywords: Soil Temperature, Spatiotemporal Variations, Man-Kendal Test, Sen's Slope, Iran