hasan izanloo; kaka shahedi; karim solaimani
Abstract
Assessment of metals absorbed to suspended solids in urban floods, allows managers to take measures to improve the quality of the urban environment. This article examines the changes in the concentration of heavy metals such as lead, zinc and copper in suspended load of runoff from the Bojnourd urban ...
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Assessment of metals absorbed to suspended solids in urban floods, allows managers to take measures to improve the quality of the urban environment. This article examines the changes in the concentration of heavy metals such as lead, zinc and copper in suspended load of runoff from the Bojnourd urban watershed in autumn and spring seasons. For this reason, 52 samples were collected. After preparing the samples, separation of suspended sediment using the Whatman filter paper and then weighing the amount of sediment in runoff, using atomic absorption, the amount of heavy metals dissolved in runoff and heavy metals absorbed to suspended solids in runoff were measured in terms of ppb. The results showed that the amount of suspended sediment weight is higher in spring than autumn. Results indicated that the maximum concentration of insoluble heavy metals and attached to sediments is more than soluble heavy metals in runoff. On the other hand, the results revealed that the mean maximum concentration of zinc and copper, except lead attached to sediments, is higher in the spring than autumn and the spatial concentration of zinc and copper in samples of runoff suspended sediments from Sandalabad Stream (FC3S) is higher. While on the lead, concentration for the samples taken from the runoff pathways and drainage network (FB2S) was higher. However, the difference in location of data for heavy metals absorbed to suspended sediments is not statistically significant. The Pearson correlation test results showed that there is a positive but low correlation between lead and zinc (r =0.166) in the autumn and the lead and copper (r=0.271) in the spring. Significance of this correlation is certified using hierarchical cluster analysis method.
sohrab jamalpour bergai; hassan ahmadi; Aboalfazl Moeini; mohammad faraji
Abstract
Dust storms is one of the most important environmental hazards, especially in arid and semi-arid climates, which causes irreparable damages to the various dimensions of the environment. The aim of this study was to identify dust sources in south-east Ahwaz, using a remote sensing technique and fuzzy ...
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Dust storms is one of the most important environmental hazards, especially in arid and semi-arid climates, which causes irreparable damages to the various dimensions of the environment. The aim of this study was to identify dust sources in south-east Ahwaz, using a remote sensing technique and fuzzy logic. For this purpose, the satellite images of dust events of Ahwaz City were investigated and the wind characteristic of the study area were studied by plotting the storm rose of Ahvaz Synoptic Station. In the next step, the criteria were categorized into two categories: soil moisture, land surface temperature and vegetation constitute the main layers and land use, spatial data of soil, climate, slope and sedimentology were used as constraint layers. The main layers were extracted from Landsat OLI-TIRS satellite images. The Boolean method were used to standardize the constraint layers, and the fuzzy membership functions were used to standardize the main layers. Also, main layers weighting was done using fuzzy analytic hierarchy process. Finally, the dust sources map was obtained by overlapping the layer. To validate the results, 44 ground control point were selected from the study area that showed high accuracy (81.8%) for identified areas. Based on investigating of satellite image and storm rose of Ahvaz Synoptic Station, the south-east of Ahwaz was recognized as dust-generating source and 145162.01 ha of lands are dust generating sources from which 69343/01 ha (47.77%) belongs to destroyed rangelands and 335.99 ha (0.23%) belongs to Canebrake, contains the highest and lowest level of sources of dust production in the study area, respectively.
Mohammad Jafar Soltani; Baharak Motamedvaziri; Ali Akbar, Noroozi; Hassan Ahmadi; Jamal, Mosaffaei
Abstract
One of the natural and common hazards in recent years is the phenomenon of dust, which causes damage, especially to urban and human environments, and is very difficult to control and manage. One of the main and effective factors in the occurrence of this phenomenon is the geographical location and climatic ...
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One of the natural and common hazards in recent years is the phenomenon of dust, which causes damage, especially to urban and human environments, and is very difficult to control and manage. One of the main and effective factors in the occurrence of this phenomenon is the geographical location and climatic conditions of the regions of origin and the areas affected by this phenomenon. In this research, which has been done in Hindijan City of Khuzestan Province, first, issues and problems have been identified based on library studies, questions from experts, referring to the research area. Then, the Driving force-Pressure-Status-Impact-Response (DPSIR) framework was used to analyze the most important factors that have caused the occurrence of dust in the city of Hindijan. The DPSIR framework is an analysis of the "cause-effect" relationship of factors for policy-making and management planning. In this study, the factors related to each of the components of the DPSIR framework were identified and prioritized using a questionnaire of experts with a Likert scale and based on nonparametric Friedman tests. Explain that, to complete the questionnaire of experts, experts from the Departments of Natural Resources, Environment, Regional Water and Agricultural Jihad of Khuzestan Province were surveyed. Results showed that population growth, agricultural development, livestock development, industrial development and climate change are important from maximum to minimum, respectively, the most important drivers affecting the occurrence of dust in the study area. Attention to both reactive and preventive responses has an important role in improving the situation and reducing the adverse effects of dust occurrence in the research area.
Amirhossein Halabian; Ali Ghasemi Siani
Abstract
In this research, for analysis the spatial- temporal trend of precipitation in Caspian basin, the monthly data of GPCC data base in the spatial resolution of 0.5°×0.5° during 63 years period(1951- 2013) have been used. In order to analyze of the spatial- temporal trend of precipitation, ...
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In this research, for analysis the spatial- temporal trend of precipitation in Caspian basin, the monthly data of GPCC data base in the spatial resolution of 0.5°×0.5° during 63 years period(1951- 2013) have been used. In order to analyze of the spatial- temporal trend of precipitation, the mean of annual, seasonal and monthly amounts of precipitation were prepared and then by applying Mann-Kendall nonparametric test at 0.95 level of significance, 17 maps precipitation spatial trend were produced in GIS. To examine the temporal trend of precipitation, first 17 graphs were prepared using the weighted amount of precipitation and then the trend was evaluated using Mann-Kendall nonparametric test at 0.95 level of significance. The evaluation of monthly precipitation spatial trend maps indicated a significant downward trend at 0.95 level of significance in March and April on the western, eastern and southwest regions of Caspian basin. Only in spring and autumn there have been a significant downward trend and in none of the other seasons no meaningful trend was detected. Also, the analysis of yearly precipitation spatial trend illustrated a significant downward trend on western region. The analysis of precipitation revealed significant downward trend on monthly time series at the 0.95 level of significance in March on Caspian basin.
Mohammad Rasoul Rajabi; Ali Nasiri Khiavi; Mahin Kalehhouei; Sonia Mehri; Azam Mumzaei; Khadijeh Haji; Abdulvahed Khaledi Darvishan
Abstract
The present research aimed at presenting a new SWOT strategy for integrated watershed management of Asiabrood in Mazandaran Province. At first, the SWOT matrix and the tables identifying the strategic indicators of internal and external factors were formed and then internal and external evaluation matrices ...
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The present research aimed at presenting a new SWOT strategy for integrated watershed management of Asiabrood in Mazandaran Province. At first, the SWOT matrix and the tables identifying the strategic indicators of internal and external factors were formed and then internal and external evaluation matrices were analyzed. A new strategy used in the discussion of the weighting of SWOT strategies was based on the fact that the final value of each strategy was multiplied by the number of effective strengths and opportunities and the final results were analyzed based on these priorities. Based on analysis of strengths and weaknesses, nine strengths and eight weaknesses were identified. The suitable water quantity and quality with a weight of 0.444, low air temperature with a weight of 0.395, mineral water utilization with a weight of 0.288 and economic poverty with a weight of 0.493, respectively, were the most important strengths, weaknesses, opportunities and threats. According to the internal-external factors evaluation matrix in the SWOT model, the strategy of increasing the sense of satisfaction of residents, based on the conventional method and the new strategy, gave the highest value. With a careful look, it can be concluded that strengthening the sense of satisfaction between residents happens when People problems in different sectors of livelihoods, including economic, social and cultural, have been considered more and, by presenting correct programs, have increased satisfaction and reduced migration to urban areas. In general, it can be concluded that due to the problems and solutions presented in this study, proper and applied planning should be used to compensate for the weaknesses and to strengthen the strengths as much as possible in the development of Asiabrood watershed.
Sayed Naeim Emami; Hamidreza Peyrowan
Abstract
Marls are one of the main causes of sediment production and subsequent soil erosion in watersheds. Researchs shows that there is a close relationship between the rate of marls sediment yield and their physical and chemical characteristics. With the aim of determining the expansion of marly formations ...
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Marls are one of the main causes of sediment production and subsequent soil erosion in watersheds. Researchs shows that there is a close relationship between the rate of marls sediment yield and their physical and chemical characteristics. With the aim of determining the expansion of marly formations and a quantitative assessment of the mentioned indices role on the sediment yield of marls in Chaharmahal and Bakhtiari Province, a comprehensive study was conducted and its outstanding results are presented in this study. After identifying and separating the marly formations in Chaharmahal and Bakhtiari Province and performing systematic sampling, necessary physical and chemical experiments were performed and the results were analyzed using statistical methods. Then, using a rainfall simulator, the sediment production rate of each marly stratigraphic units was measured in the field. Results showed that about 1073.95 Km2 (equal to 6.5%) of province rocks has devoted to marly lithological units. On the basis of analyses, Razak, Pabdeh, Hormoz, Mishan and Gurpi formations with mean of 96.34, 94.41, 87.1, 76.17 and 33 grm-2 are the most sensitive marly formations, respectively. Sediment yield is directly related to silt amounts, total lime, active lime, exchangable sodium and reverse related to clay amounts. The presence of Kaolinite and Illite clay minerals is one of the intensifying factors in sedimen yeild in marly formations.
Mina Jafari; Mohammad Reza Ekhtesasi; Ahmad Fatahi Ardakani
Abstract
Today, various watershed management projects are being implemented in watersheds which sometimes, despite high study and cost, they are inefficient for various reasons and face economic failure. In the present study, first, different watershed projects in the Parcel A of Gheshlagh Dam in Sanandaj were ...
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Today, various watershed management projects are being implemented in watersheds which sometimes, despite high study and cost, they are inefficient for various reasons and face economic failure. In the present study, first, different watershed projects in the Parcel A of Gheshlagh Dam in Sanandaj were evaluated. Then, their evaluation was examined by determining internal and external factors. The aim is to extract the most important factors and provide strategies that make projects economically viable and functionally effective. Weaknesses, strengths, opportunities, and threats of the region were extracted by experts and, using the SWOT analysis model and quantitative matrix of QSPM, economic-applicable solutions were presented. Results showed high value of management factors, so that the highest final value in external factors was inefficient study projects and the lack of funds for maintenance and repair of projects after implementation with scores of 0.50 and 0.43, respectively, and internal factors had the highest final value related to destruction and burial of dams due to the low quality of construction with a score of 0.59 which had the most impact on strategy selection. Based on the results of the model, the strategies are located in the ST quarter and are of a conservative method, in order to reduce the damage caused by threats and weaknesses by using the strengths of the domain. In accordance with this strategy, solutions were given by experts and prioritized by the quantitative matrix QSPM. The implementation of projects on land owned by individuals or the assignment of the right to maintain them to the owners with a final score of 8.76 was ranked first. The results of this research in the present economic situation of the country are very useful for informing authorities about how to optimize the implementation of watershed projects and will improve the instructions and implementation and the best use of projects.
Mehdi Teimouri; Omid Asadi Nalivan
Abstract
With the increase in population, the importance of groundwater resources as one of the most important sources of drinking water in the arid regions becomes apparent. In this research, in order to determine the areas with groundwater potential in the city of Torbate Jam and prioritizing the effective ...
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With the increase in population, the importance of groundwater resources as one of the most important sources of drinking water in the arid regions becomes apparent. In this research, in order to determine the areas with groundwater potential in the city of Torbate Jam and prioritizing the effective factors, hierarchical analysis methods and maximum entropy method using MaxEnt model and the factors of distance from fault and fault density, lithology, slope, slope direction, distance from the waterway and drainage density, elevation, land use, slope curvature, topographic humidity index and topographic position indicator was used. Also, for assessing these two methods, the Receiver Operating Characteristic (ROC) was used. From 220 sources, 30% were randomly assigned as validation data and 70% were categorized as test data in maximum entropy method. Results showed that 29.6% of the watershed had high groundwater potential according to the maximum entropy method. Based on Jack-Knife Diagram, DEM, slope, distance from fault and lithology were the most important factors affecting groundwater potential, respectively. The Area Under the Curve (AUC) in the maximum entropy method indicated a precision of 91% (excellent) at the training period and 80% (very good) in the validation period to determine areas with potential for groundwater. Based on AHP method, 34.4% of the area has groundwater potential, and the slope layers, lithology, elevation and distance from the faults were the most important factors, respectively and accuracy of this method was 73%. The results showed that applying AHP and maximum entropy methods, while saving time and cost, have a good ability to predict the potential of groundwater and the maximum entropy method has more superiority than the hierarchical analysis method.
pedram esmaeli; siamak Boudaghpour; mehdi Mirzaee
Abstract
The spur dike has been known as one of the most common organizing constructs of the river to reduce the erosion of coasts and river banks. These structures are developed with the right lengths and angles towards the flow of the natural walls of the river that cause flow deviation from the sides and lead ...
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The spur dike has been known as one of the most common organizing constructs of the river to reduce the erosion of coasts and river banks. These structures are developed with the right lengths and angles towards the flow of the natural walls of the river that cause flow deviation from the sides and lead it toward the central river axis. In this experimental study, the flow pattern around the simple series spur dike in the meandering channel with a sloped erodible wall consisting of three consecutive arches with angles of 45, 90 and 45 degrees, has been studied for 40, 35 and 30 liter/sec rates. The results indicate that the collision position of the first line of flow in the near bed to the inner wall of bend no. 2 in discharge 40 liters per second earlier than discharge 35 liters per second and in discharge 35 liters per second earlier than the discharge 30 liter per second. So that the collision position of the first line of flow in the near bed to the inner wall of bend no. 2 in discharge, 40, 35 and 30 liters per second, respectively, in the -18, -15 and -10 degree sections compared to the central arc of the mentioned bend. In conditions of the presence of spur dikes, the vortex dimensions change with the depth of movement, so that moving towards the surface of the water in a fixed discharge, due to the tendency of flow to the outer wall, the slope of the bend wall and increasing the level of contact surface of the spur dike length, the vortex dimensions are increased.
mohammad hedayatfard; Hamid Gholami; Seyed Masoud Soleimanpour; Arashk Holisaz
Abstract
Gully erosion is one of the most important phenomenons in land degradation and desertification, which upsets the balance of environmental resources and its sustainability. The aim of this study was to determine the effective factors on creation of gully erosion using data mining methods in Bayan Watershed ...
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Gully erosion is one of the most important phenomenons in land degradation and desertification, which upsets the balance of environmental resources and its sustainability. The aim of this study was to determine the effective factors on creation of gully erosion using data mining methods in Bayan Watershed in the north of Fars Province. K-Means clustering algorithms and CART decision tree were used to model gully erosion. The estimated accuracy based on the parameters affecting the creation area in the final model is 100% for the educational data set and 71.43% for the experimental data set. Results from measuring different variables from 40 selected gullies, including a target variable (creation area) and twelve predictive variables, like creation slope, vegetation, bare soil, surface gravel, surface litter, EC, pH, SAR, OM, clay, silt and sand in field and laboratory operations and the use of data mining techniques, showed that the creation of gullies in this watershed is a function of silt, acidity, bare soil, gravel and organic matter. These results showed the effect of vegetation and consequently, the presence of adequate organic matter in the soil as the most appropriate method for controlling gullies and the destructive and intensifying effect of bare lands without vegetation in intensifying gully erosion. Therefore, it is necessary to establish and establish permanent and compatible vegetation, to stabilize and improve soil structure and increase organic matter, and control and management programs, in lands with more silt, to be operated more carefully.
Somayeh Shariati; Abolfazl Azizian; Najmeh Yarami; Abbas Paydar Ardakani
Abstract
Rainwater harvesting using micro-catchment is one of the water resources development options in arid regions that can partly supply water requirement of rain-fed agriculture. Some operations can be performed for increasing the harvesting rainwater in micro-catchment. In this study, the effect of simple ...
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Rainwater harvesting using micro-catchment is one of the water resources development options in arid regions that can partly supply water requirement of rain-fed agriculture. Some operations can be performed for increasing the harvesting rainwater in micro-catchment. In this study, the effect of simple treatments including furrowing, clay cover, furrowing and clay cover and control treatments on runoff production were investigated in the form of a complete randomize design with three replications during 2014 and 2015 in Zarrin-Dasht region of Fars Province. Results confirmed the potential of rainwater harvesting in the region. The highest runoff coefficient was observed in control treatment as 6.5 and 9.3% in 2014 and 2015, respectively. Disturbing of surface soil (in various treatments except control) led to average reduction of 11 and 14% runoff amount and coefficient, respectively compared to the control treatment. Threshold Precipitation for Runoff Production (TPRP) was 1 mm in control treatment during two years of the experiment. In other treatments TPRP values reduced in the second year. In view point of the runoff amount and coefficient and also TPRP, control treatment is recommendable in the region. The catchment area varied almost between 15 and 150 m2, respectively, for supply water requirement of 300 and 600 mm with rainfall occurrence probability of 0.50 and 0.67 and runoff storage efficiency of 25 and 50%. In fact, micro-catchment area can be economically determined with crop type.
Heidar Ghafari; Mahmood Arabkhedri; Manouchehr Gorji
Abstract
Tolerable soil erosion is the boundary between natural and accelerated erosion and is one of the most fundamental yet complex issues in soil erosion research. The tolerable erosion threshold is an essential criterion for awareness and judgment about the state of soil erosion and the extent of its potential ...
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Tolerable soil erosion is the boundary between natural and accelerated erosion and is one of the most fundamental yet complex issues in soil erosion research. The tolerable erosion threshold is an essential criterion for awareness and judgment about the state of soil erosion and the extent of its potential economic, social and environmental risks and damages. Therefore, it is very important to determine it accurately and correctly using appropriate methods. For this purpose, various methods have been developed, which can be divided into three general groups including methods based on soil formation rate, methods based on agricultural soil productivity and methods based on off-site effects of erosion. First, the details of the various methodologies along with their disadvantages and advantages were examined, and finally, research challenges and opportunities in this field were presented. Various scientists in recent years have emphasized the need for comprehensiveness in determining tolerable thresholds, but existing methodologies have so far failed to achieve this, and are still at the beginning of the road. Thus, the main challenges and opportunities are mainly related to methodology and the presentation of new integrated and applied approaches to determine tolerable erosion.
Mohsen Farzin
Abstract
The aim of this study was to investigate the ability of different supervised and unsupervised classification algorithms of remote sensing data for detecting and separating of land cover on Beshar River Basin using Landsat 8 data. For this purpose, after checking the geometric accuracy and radiometric-atmospheric ...
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The aim of this study was to investigate the ability of different supervised and unsupervised classification algorithms of remote sensing data for detecting and separating of land cover on Beshar River Basin using Landsat 8 data. For this purpose, after checking the geometric accuracy and radiometric-atmospheric corrections on satellite data, the data set was created to the combination of spectral bands (bands 2, 3, 4, 5, 6, 7 and 8) and thermal (band 10). Next, pixel-based classification using supervised algorithms including maximum likelihood, support vector machine, mahalanobis distance, minimum distance, neural network, parallelepiped, spectral angle mapping, spectral information divergence, binary coding, and unsupervised algorithms including K-Means and IsoData was done. The accuracy of the algorithms for identifying each land use /land cover based on the error matrix analysis was evaluated using the producer's accuracy, user accuracy and overall accuracy based on the omission and commission errors, and the kappa coefficient. The results showed that the most appropriate algorithm for separation and identification of land use/land cover including agriculture, construction, cliff, forest, orchard, rangeland, water body and fallow is maximum likelihood, mahalanobis distance, maximum likelihood, mahalanobis distance, neural network, support vector machine, support vector machine, and maximum likelihood, respectively. The percentage of overall accuracy and Kappa coefficient shows that the four algorithms including maximum likelihood, support vector machine, mahalanobis distance and neural network with overall accuracy 77.25, 75.9, 69.59, 68.26 and the Kappa coefficient 0.72, 0.69, 0.63, 0.58, respectively, is better than other algorithms. Generally, the integration of appropriate classification algorithms in mountainous areas increases classification accuracy and will have better results.
Maryam Sanjari Banestani; Vahedberdi Sheikh; Arash Zare Garizi; Amaneh Avarand
Abstract
The aim of this study is to assess the feasibility of monitoring precipitation, temperature and river stage variables in the Chehl-Chai Watershed with the participation of citizens/stakeholders. Simple and low-cost measurement tools were designed and provided to the local volunteers (two students, three ...
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The aim of this study is to assess the feasibility of monitoring precipitation, temperature and river stage variables in the Chehl-Chai Watershed with the participation of citizens/stakeholders. Simple and low-cost measurement tools were designed and provided to the local volunteers (two students, three women and one man) and they monitored the variables for five months. The data were recorded on paper forms and/or communicated through cellphones (text messages and social media applications of WhatsApp and Telegram). The citizen-collected data were compared with formal gauging stations using different statistical metrics including correlation coefficient, paired-sample t-test and kappa index. Results revealed that, the difference between the recorded data by the participants and those of gauging stations were not statistically significant. A female citizen with academic education of bachelor’s degree recorded the highest frequency of data that had the highest correlation with the recorded data in the formal precipitation and temperature monitoring stations, while the technical staff man from the Natural Resources Management Office recorded the least frequent data that had the least correlation with the recorded data in the formal monitoring stations. In overall, the promising level of citizens’ performance in monitoring the watershed, suggests that it is really feasible to collect reliable, on-time, and long-term data that can be used to obviate lack of data, particularly in remote mountainous areas and facilitates the decision-making and watersheds management process.
Mahmood Damizadeh; Rasool Mahdavi; Ali Akbar Noroozi; Hamid Gholami; Arshk Hollisaz
Abstract
Dust storms are one of the atmospheric phenomena which has many negative effects for Hormozgan Province, as one of the most important population and tourism centers in the south and with significant and strategic facilities in the country. For this reason, todays determining the hotspots and areas affected ...
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Dust storms are one of the atmospheric phenomena which has many negative effects for Hormozgan Province, as one of the most important population and tourism centers in the south and with significant and strategic facilities in the country. For this reason, todays determining the hotspots and areas affected by the storm, as well as identifying important routes of entry and movement is one of the most important needs of relevant organizations in this province. In order to study the dust phenomenon in Hormozgan Province, first, all meteorological data of 12 synoptic stations in the region between 2000 and 2018 were analyzed and 48 dust storm events were identified that their horizontal visibility has decreased to less than 1000 meters and dust mass detection operations were performed using MODIS satellite images and four detection algorithms of Ackerman, TDI, TIIDI and NDDI and areas affected by storm as well as areas of origin were identified. HYSPLIT particle Lagrangian diffusion model was used to route the motion of the dust storm and the entry routes of dust storms into the province also, its routes and areas that have the most impact in this area were identified. Comparing results of four dust detection algorithms indicated better performance of TDI algorithm compared to other algorithms in detecting the focus and mass of dust in the area. According to the results, eastern regions of Hormozgan Province, Jazmourian Wetland, eastern Sistan and Baluchestan, western regions of Afghanistan and Pakistan, as well as central and southern regions of Saudi are one of the most important centers of dust production in the region. Investigating HYSPLIT model maps indicates the existence of three general routes of entry and creation of dust storms in the area which includes the southwestern regions of the country, the south-north route and the north and northwest route. Also, based on model results, about 53.7% of the path of movement and the release of dust after a storm is to the north and northeast direction which causes the spread of pollution and intensification of dust concentration in cities such as Bandar Abbas, Qeshm, Minab, Rudan, Jiroft, Kahnooj, Bam, Iranshahr, Khash, Mirjaveh and Zahedan. Also, about 22.3% of the storms in the region consider the southern route, 14.8% the south-west route and 9.2% the east route to continue their navigation.
Reza Bayat; Afsaneh Alinejadian; majid soufi; abbas maleki; Omidali Akbarpour
Abstract
Recognition of influential factors is required for management of gully erosion. The purpose of this study was gully classification and determining the most effective variables on the soil loss in the Fath Abad, Buin Zahra in Qazvin Province. Twenty four gullies were selected, surveyed and recorded by ...
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Recognition of influential factors is required for management of gully erosion. The purpose of this study was gully classification and determining the most effective variables on the soil loss in the Fath Abad, Buin Zahra in Qazvin Province. Twenty four gullies were selected, surveyed and recorded by GPS, and their morphologic characteristics including length, width and depth were measured. Surface soil samples were taken from headcut and were analyzed for texture, EC, pH, organic matter and some anions and cations. Indices related to the form of watershed were extracted from the digital elevation model which derived from UAV image processing. The Ward method was used for cluster analysis of gullies and their properties. Factor analysis, the correlation between factors and multivariate regression were performed to determine important and effective factors on the formation of gullies in SPSS. The results of the research indicated that gullies have vertical headcuts, trapezoidal cross-sections and linear general plans. The average depth of headcuts, depth at 50% of the gully length and the average gully length were 0.4, 0.6 and 25 m, respectively. Soil texture was loam and average soil texture components including sand, silt and clay were 30, 46 and 24%, respectively. The mean EC and pH of the samples was 8 dSm-1 and 8.4 respectively. Linear correlation between the total volume of soil loss and other gully characteristics showed that the average cross section, average gully lower width and upper width, sand content, average gully depth and total length have meaningful correlation coefficients greater than 0.6 at 1% percent level. Also, multivariate regression results showed that the most effective factors on soil loss by gully erosion were saturation percentage, sand content, roundness coefficient, basin length and area respectively, which had more effect on soil loss prediction, which entered into the loss prediction equation.
Mehdi Khalajzadeh; Gorban Vahabzadeh; Sadat Feiznia; Aliakbar Nazarisamani; Seyed Ramzan Mousavi
Abstract
Identification of hydrogeomorphic processes such as normal flood, debris flood and debris flow on alluvial fan (at the outlet of the watershed) is essential due to the type of sedimentary regime and various hazards. In recent years, the lack of field information has led to the need to use models based ...
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Identification of hydrogeomorphic processes such as normal flood, debris flood and debris flow on alluvial fan (at the outlet of the watershed) is essential due to the type of sedimentary regime and various hazards. In recent years, the lack of field information has led to the need to use models based on basic watershed information. The aim of this study is to develop a practical method for predicting the occurrence of various types of flood flow, using physical and geomorphological characteristics of watersheds. In this study, a descriptive-analytical method and some of tools, such as aerial photographs, satellite images, topographic maps were used. First, by descriptive method, field evaluation of sediments of various types of flood currents was carried out on July 19, 2015 in 70 sub-watersheds of in Karaj Dam Watershed. Results showed that out of 70 sub-basins, 30 sub-basins, debris flow, 16 sub-basin debris flood and 24 sub-basins were normal floods. Then, in the analytical method, 32 geomorphometric features of watersheds by 25-meter spatial digital model (DEM) and five geomorphological features of sub-watersheds by mass movement maps were extracted and then were transferred to the SPSS statistical program to determine the relationship with the type of flood flow. The results of ANOVA and Bonferroni multiple comparisons showed that four morphometric factors “main channel length, basin perimeter, mean basin width and basin length” were identified in differentiation of flood flow types. To achieve the two appropriate key parameters and threshold values, four variable pairwise were copaird by pair in six triple scatter plots. The results showed that “The main channel length (Lm) and the mean basin width (Wb)” has the least total errors of the observation streams, were selected as the most appropriate factors for predicting flood flows. In long basins with Lm>4 km, normal flooding occurs, and in short basins with Lm1 km, floods occur, and if Wb
Davood Nikkami; Samad Shadfar
Abstract
Soil, as one of the components of any ecosystem and an important source of food production, has a very serious role in the continuation of human life. Therefore, the need to support and protect the soil and prevent its erosion is essential. Regarding the amount of soil erosion and sediment yield in the ...
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Soil, as one of the components of any ecosystem and an important source of food production, has a very serious role in the continuation of human life. Therefore, the need to support and protect the soil and prevent its erosion is essential. Regarding the amount of soil erosion and sediment yield in the country, different figures have been mentioned and in some studies, the difference is with several times. These figures vary from less than one to more than five billion tons per year. Therefore, calculating and plotting erosion and sedimet yield maps provides important information that is used in the design of dams, reservoirs, canals, soil protection operations, onsite and offsite erosion damage assessment, and land use planning and land capability assessment projects. Soil erosion map is one of the basic, scientific and applied maps in various executive, research and educational sectors. Due to the need of determining the amount of soil erosion and sediment yield for the entire country and determining the executive priorities in areas with high soil erosion potential, this project was defined and carried out by the Soil Conservation and Watershed Management Research Institute. Accordingly, the watersheds of the seventh category were divided into seven regions or districts, including 1) Eastern Alborz 2) Middle Alborz 3) Western Alborz 4) Central Iran 5) North Zagros 6) Middle Zagros and 7) South Zagros. Long-term sedimen data of 118 hydrometric stations in these areas were analyzed and the amount of sediment in each station was determined by the logged mean load within discharge classes method. According to the amount of river bedload rates and using EPM model, the amount of sediment yield and cosidering sediment delivery ratio of watersheds, the amount of soil erosion were etermined and the soil erosion map of watersheds overlooking hydrometric stations was prepared. Results showed that the average sediment yield and soil erosion in the watersheds overlooking hydrometric stations are 3.3 and 16 tons per hectare per year, respectively. The lowest and highest soil erosion rates of 9 and 32.4 tons per hectare, belong to the Middle Zagros and South Zagros regions, respectively.
Davood Niknezhad
Abstract
Optimal use of rainfall in arid and semi-arid regions can play an important role in meeting the water needs of green space in low water seasons. On the other hand, poor vegetation can cause erosion and destruction in sloping lands that can be partially resolved if water and soil resources are properly ...
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Optimal use of rainfall in arid and semi-arid regions can play an important role in meeting the water needs of green space in low water seasons. On the other hand, poor vegetation can cause erosion and destruction in sloping lands that can be partially resolved if water and soil resources are properly managed. Rainfall is one of the most important sources of water supply for various uses. One of the methods of collecting rainwater is to make the ground impermeable and to maximize rainwater runoff. Impermeable surfaces can exist naturally like rock surfaces, or can be artificially created by covering the ground with materials such as asphalt, concrete, insulation sheets such as plastic, geomembrane and decamond. This study, which was carried out in the northern part of Tabriz, was conducted in four treatments, each with three replications of 4 m2 (2m×2m), including geomembrane cover area, plastic cover with sand protection, natural surface and natural surface with sand mulch. Results of 78 rainfall events over two years showed that in intermediate slopes of 33-38.6%, runoff from rainfall for geomembrane, plastic cover with sand protection, natural surface and natural surface with sand mulch were 84, 67, 3 and 2% of rainfall respectively and rainfall threshold for runoff at mentioned surfaces was 0.28, 2.56, 9.95 and 11.12 mm, respectively. Therefore, with respect to annual normal rainfall (245.7 mm), the volume of runoff accumulated for geomembrane, plastic cover with sand protection, natural surface and natural surface with sand mulch will be 206, 164, seven and five Lm-2 ina year, respectively. Comparing the means, the geomembrane cover treatment was identified as a suitable option for runoff production. Also, sand mulch on the natural surface reduces soil erosion from 97 to 9.5 grm-2 in two years.
Amin Salehpour Jam; Hamid Reza Peyrowan; Mahmoud Reza Tabatabaei; Amir Sarreshtehdari; Jamal Mosaffaie
Abstract
The desertification process, by reducing the biological production potential, leads to the destruction of ecosystems. In this research, to assess the role of edaphic factors on desertification in rangelands surrounding Eshtehard, Halgh-e-Darreh highlands, first, the map of units was created by crossing ...
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The desertification process, by reducing the biological production potential, leads to the destruction of ecosystems. In this research, to assess the role of edaphic factors on desertification in rangelands surrounding Eshtehard, Halgh-e-Darreh highlands, first, the map of units was created by crossing maps of slope classes, land uses, and geology using ArcGIS 10.3 software. Three indices of erodibility, salinity and permeability for each land unit were considered and classified. 185 and 179 samples were taken during 2018 and 2019 for indices of salinity and permeability for zoning of the study area, respectively. Then, weights of indices and consistency ratio were calculated by the AHP method. Method of multicriteria optimization and compromise solution, VIKOR method was used to prioritize the alternatives. After calculating the weighted normalized values, priority was given to desertification potential of the units. Also, the results of AHP showed that from the experts' point of view, salinity is the most important factor in desertification. Other factors such as susceptibility to erosion and permeability coefficient are in the next rank order, respectively. The AHP-VIKOR model has very high degree of adaptation to the corresponding classes in the control map. The percentage of compliance and non-compliance of the classes of the potential of desertification risk were 92.91% and 7.09%, respectively. The range of changes of Vikor index based on AHP-VIKOR method varies from 0.443 to 0.967. Accordingly, the study area has three classes of potential or severity of desertification areally 0.5% moderate, 7.06% high and 92.43% very high class respectively.
