Showing 405 results for Om
H. Ahmadzadeh, A. Fakheri Fard, M.a Ghorbani, M. Tajrishy,
Volume 25, Issue 3 (12-2021)
Abstract
In drought risk management, the regional analysis of drought is significant. In this paper, this important issue is investigated by presenting the new hydrological regional drought index (RDI). For this purpose, the Ajichai basin was selected as the study area. First, the time series of the streamflow drought index (SDI) was calculated for each of the hydrometric stations in the basin f regional analysis of hydrological drought. Then, to determine the homogeneous regions in terms of hydrological drought, the k-means method was used for clustering analysis. Based on the clustering results, 6 Homogeneous regions were identified in the basin. For each of these regions, the time series of the RDI index was calculated from 1365 to 1393. The results showed that during the study period in each of the regions 1, 2, 3, 4, 5, and 6, mild Wet and mild drought has occurred at 82.1, 80.1, 78.9, 83.3, and 84.3 percent of regions, respectively. Also, the total percentage of drought events (moderate and high) is higher than the total percentage of wet events (moderate and high) in all regions. So, during the study period, the total percentage of drought events (moderate and high) is more than twice the total percentage of wet events (moderate and high) in regions 2 and 3.
M. Abedinzadeh, A. Bakhshandeh, Mr B. Andarziyan, Mr S. Jafari, M Moradi Telavat,
Volume 25, Issue 3 (12-2021)
Abstract
Iran is located in the dry belt of the earth and is predicted to face water stress in the next half-century. Currently, the area of sugarcane cultivation in Khuzestan is over 85,000 hectares and due to the high water needs of sugarcane and drought conditions, optimization of water consumption and irrigation management is necessary to continue production. Therefore, in this study, the values of soil moisture, canopy cover, biomass yield in five treatments and irrigation levels (start of irrigation at 40%, 50%, 60%, 70%, and 80% soil moisture discharge) during 2 planting dates in the crop year 2015-2016 on sugarcane cultivar CP69-1062 in Amirkabir sugarcane cultivation and industry located in the south of Khuzestan was simulated by AquaCrop model. The measured data on the first culture date (D1) and the second culture date (D2) were used to calibrate and validate the model. The results of NRMSE statistics in canopy cover simulation in calibration and validation sets with values of 2.1 to 15.6% and 3.8 to 18.3%, respectively, and in biomass simulation with values of 6.2 to 15.2%, and 9.5 to 12.6%, respectively and coefficient of determination (R2), range 0.98 to 0.99 indicated that the high ability of the AquaCrop model in simulation canopy cover and biomass yield. whereas, the values of NRMSE of soil depth moisture in the calibration and validation sets ranged from 11.6 to 23.8, and 12.2 to 22.7, respectively, with a coefficient of determination (R2), 0.73 to 0.96 (calibration) 0.8 to 0.93 (validation) showed less accuracy of the model in the simulation. The best scenario is related to the third proposal that water consumption, water use efficiency, and yield are 1710 mm, 1.53, and 42.27 tons per hectare, respectively, which shows a reduction in water consumption of 360 mm.
F. Sadeghdoust, N. Ghanavati, A. Nazarpour,
Volume 25, Issue 4 (3-2022)
Abstract
Street dust is mainly affected by the pollution of polycyclic aromatic hydrocarbons (PAHs). PAHs are a group of organic pollutants consisting of two or more benzene rings and are mainly produced during incomplete combustion. PAHs have attracted widespread attention due to their high carcinogenic and mutagenic properties in humans. Therefore, the purpose of this study was to investigate the sources and extent of the impact of these compounds on human health and the environment. To achieve this goal, 30 dust samples were collected from the sidewalks of the main streets of Dezful and the concentration of PAHs was determined by gas chromatography-mass spectrometry (GC-MS). The total concentration of PAHs in street dust of Dezful varied from 562.85 to 51447.10 μg / kg. The ratio of carcinogenic compounds to total PAHs was in the range between 0.73 to 0.91. Low molecular weight and high molecular weight PAHs accounted for 12% and 88% of total PAHs, respectively. The most important sources of PAHs in Dezful are the combustion of fossil fuels and petroleum products and emissions from vehicles and traffic. Moreover, incremental lifetime cancer risk (ILCR) in pathways ingestion in children was higher than in adults, but the ILCR in pathways dermal contact and inhalation in adults was higher than in children. The total cancer risk (CR) for children (5.77×10-3) was higher than adults (5.56×10-3), which shows the high potential for CR in the study area.
A.r Modares Nia, M. Mirmohamad Sadeghi, A. Jalalian,
Volume 25, Issue 4 (3-2022)
Abstract
Desertification has become one of the main problems of human societies living in the vicinity of desert areas in recent years. One of the methods that have been considered in recent years and are rapidly expanding in the field of soil mechanics is the Microbial Induced Carbonate Precipitation (MICP). In this method, urea-positive organisms that are naturally present in the soil can stabilize the soil and improve its engineering parameters by using urea and calcium chloride. Recently, attempts have been made to use this method to create a crustal layer on the soil to prevent wind erosion. In the present study, the effect of environmental conditions in deserts such as temperature and sand bombardment on microbial soil treatment has been investigated using this new method. The soil of the Segzi region as one of the main centers of dust in the Isfahan region was studied in this research. Therefore, the improved samples are subjected to regional temperatures which increased the surface layer resistance with increasing temperature. Also, the sandstorm conditions of the region were simulated using three different grain sizes of sand inside the wind tunnel. The results of these experiments showed that stabilized soil could withstand the conditions at wind speeds of 7 and 11 m/s. However, by increasing the wind speed to 14 m/s and the grain size, the crustal layer destroys and increases the wind erosion of the soil. Also, the resistance of the surface layer increased by increasing temperature in the tested samples. This increase in resistance continued up to 24 degrees with a high slope, but from 24 degrees onwards, this slope decreases. Based on the results of this research, it can be said that the microbial improvement method can be used as an alternative method in the future to stabilize desert soils.
K. Ghaderi, B. Motamedvaziri, M. Vafakhah, A.a. Dehghani,
Volume 25, Issue 4 (3-2022)
Abstract
Proper flood discharge forecasting is significant for the design of hydraulic structures, reducing the risk of failure, and minimizing downstream environmental damage. The objective of this study was to investigate the application of machine learning methods in Regional Flood Frequency Analysis (RFFA). To achieve this goal, 18 physiographic, climatic, lithological, and land use parameters were considered for the upstream basins of the hydrometric stations located in Karkheh and Karun watersheds (46 stations with a statistical length of 21 years). The best Probability Distribution Function (pdf) was then determined using the Kolmogorov-Smirnov test at each station to estimate the flood discharge with a return period of 50-year using maximum likelihood methods and L-moments. Finally, RFFA was performed using a decision tree, Bayesian network, and artificial neural network. The results showed that the log Pearson type 3 distribution in the maximum likelihood method and the generalized normal distribution in the L moment method are the best possible regional pdfs. Based on the gamma test, the parameters of the perimeter, basin length, shape factor, and mainstream length were selected as the best input structure. The results of regional flood frequency analysis showed that the Bayesian model with the L moment method (R2 = 0.7) has the best estimate compared to other methods. Decision tree and artificial neural network were in the following ranks.
A. Kasra, A. Khosrojerdi, H. Babazadeh,
Volume 26, Issue 1 (5-2022)
Abstract
N. Azadi, F. Raiesi,
Volume 26, Issue 1 (5-2022)
Abstract
Biochar as an efficient strategy for the improvement of soil properties and organic waste management may reduce the potential effects of abiotic stresses and increase soil fertility. However, the effects of this organic amendment on soil microbial indicators under combined salinity and pollution have not been studied yet. Therefore, the objective of this study was to evaluate the influence of sugarcane bagasse biochar on some soil bioindicators in a Cd-polluted soil under saline and non-saline conditions. A factorial experiment was carried out with two factors, including NaCl salinity (control, 20 and 40 mM NaCl) and sugarcane bagasse biochar (soils unamended with biochar, amended with uncharred bagasse, 400 oC biochar, and 600 oC) at 1% (w/w) using a completely randomized design. Results showed that salinity increased the mobility of Cd (12-17%), and subsequently augmented its toxicity to soil microorganisms as indicated by significant decreases in the abundance and activities of the soil microbial community. Conversely, sugarcane bagasse biochar application reduced the concentration of soil available Cd (14-18%), increased the contents of soil organic carbon (89-127%), and dissolved organic carbon (4-70%), and consequently alleviated the effect of both abiotic stresses on soil microbial community and enzyme activity. In conclusion, this experiment demonstrated that the application of sugarcane bagasse biochar could reduce the salinity-induced increases in available Cd and mitigate the interaction between salinity and Cd pollution on the measured soil bioindicators.
S. Azadi, H. Nozari, S. Marofi, Dr. B. Ghanbarian,
Volume 26, Issue 1 (5-2022)
Abstract
In the present study, a model was developed using a system dynamics approach to simulate and optimize the profitability of crops of the Jofeyr (Isargaran) Irrigation and Drainage Network located in Khuzestan Province. To validate the results, the statistical indicators of root mean square error (RMSE), standard error (SE), mean biased error (MBE), and determination coefficient (R2) were used. To validate the simulation results of the benefit-cost ratio, the values of these indicators were obtained 0.25, 0.19, 0.005, and 0.96, respectively. Then, to determine the optimal cultivated area of the network and increase the profitability, the cropping pattern was determined both non-stepwise and stepwise in 2013 to 2017 cropping years. In the non-stepwise, the cultivated area of each crop changed from zero to 2 times of current situation. In stepwise, due to social and cultural conditions of inhabitants, this change was slow and 10% of the current situation every year. The analysis of the results showed the success of the model in optimizing and achieving the desired goals and the total benefit-cost ratio increased in all years both non-stepwise and stepwise. For example, in 2017 compared to 2016, production costs decreased by 7.1 percent and sales prices increased by 5.8 percent, and increased the benefit-cost in 2017 compared to the previous year. The results showed that the present model has good accuracy in simulating and optimizing the irrigation network, its cropping pattern, and defining other scenarios.
M. Sabouri, A.r. Emadi, R. Fazloula,
Volume 26, Issue 2 (9-2022)
Abstract
A compound sharp-crested weir is often used to measure a wide range of flows with appropriate accuracy in open channels. In this study, experiments were performed to investigate the hydraulic flow through a compound weir of circular-rectangular with changes in hydraulic and geometric parameters in free and submerged flow conditions. The characteristics of the weirs include rectangular spans width of 39 cm, a circular radius of 5, 7.5, and 12.5 cm, and heights of 10 and 15 cm. The results showed that by increasing the radius and height of the Weir, upstream water depth increases around 28.4%. At a constant h/p, the discharge coefficient increases with the increasing radius of the circular arc. Also, in the submerged conditions, the discharge coefficient is less (around 40%) than in the free flow condition, which is due to the resistance of the depth of the created stream against the passage of the flow.
M.h. Sadeghi Ravesh,
Volume 26, Issue 2 (9-2022)
Abstract
The optimal strategy selection is an influential factor to enhance the efficiency of land reclamation projects. On the other hand, the process of desertification of the land during environmental degradation is the consequence of the interaction between various factors that make it challenging to select appropriate solutions. Therefore, this study aimed to provide systematic optimization strategies in the form of a group decision-making model in the Yazd-Khezrabad plain. The important strategies were identified using the Delphi model. Then, the alternative initial ranking was formed by Cook and Seiford method framework using the vote taken from the decision makers on strategies. Finally, by estimating the linear distance of each option and including the matrix of the intervals, the last priority of the strategies was obtained from solving the assignment problem. The results indicated that the strategies of "prevent land use inappropriate change" (A18) and "the regeneration of vegetation cover" (A23) with Value=1 and Reduced Cost=0, were identified as the most important combating-desertification strategies in the region, respectively. The results of this study help desert managers to utilize limited facilities and capital dedicated to controlling the desertification process efficiently and effectively.
J. Abedi Koupaei, M.m. Dorafshan, A.r. Gohari,
Volume 26, Issue 3 (12-2022)
Abstract
One of the most significant techniques for saline wastewater treatment is bioremediation. Halophytes are known as the plants that can tolerate the high concentration of salts, in such salinity common plants cannot be often able to survive. In this research, the feasibility of desalination by using halophyte (Chenopodium quinoa Willd.) was studied. Quinoa plants were grown in the hydroponic system in 12 containers including 9 containers with plants and 3 containers without plants as control. Fifteen plants were planted in each container and three salinity levels including 2, 8, and 14 ds/m for two different periods (15 and 30 days) were studied in a multi-factors completely randomized design. Three replications of each salinity level were conducted and the Electrical Conductivity (EC) parameters, including Calcium, Magnesium, Sodium, and Chloride ions were determined before and after treatment by Quinoa plants. The results showed that the Quinoa plants reduced 5.33%, 8.12%, and 9.35% of the EC at EC~2 dS/m (Marginal Water), EC~8 dS/m (Brackish Water), and EC~14 dS/m (Saline Water), respectively. Moreover, Calcium, Magnesium, Sodium, and Chloride ions decreased up to 10%, 7.62%, 5.60%, and 7.01%, respectively depending on the salinity levels. Therefore, the Quinoa plant has a relatively low potential in unconventional water treatment especially saline wastewater.
H. Daghigh, H. Mousavi Jahromi, A. Khosrojerdi, H. Hassanpour Darvishi,
Volume 26, Issue 3 (12-2022)
Abstract
The existence of silty sand in the infrastructure under concrete constructions, hydraulic structures, and irrigation systems has always caused challenges. Improving this kind of soil is always a challenging approach to increase compressive strength and shear stress. There is a conception that adding some extra material such as concrete can increase the stability of this soil against contributed forces. The present study investigated the effects of curing time (3, 7, 14, 21, and 28 days) and different percentages of various additives (3%, 5%, and 7%) on the strength of the silty sand soils. A series of laboratory tests were carried out to measure the Uniaxial Compressive Strength (UCS) and California Bearing Ratio (CBR) by evaluating the effect of additives on the strength parameters of silty sand soil. In total, 299 experimental tests have been conducted in the soil mechanics laboratory of SRBIAU. Results indicated that adding additives such as concrete to silty sand soil improved significantly the compressive strength and shear strength. The comparisons among the experimental test illustrate that due to increasing the curing time, the aforementioned parameters were increased significantly; however, Confix and Bentonite aggregates did not have a marginal effect on the compressive strength and shear strength. Also, after the 21st day of the curing time, the rate of increment of the UCS and CBR reached slightly and then attained a constant value. Also, after this duration, the curing time is an independent factor in the variation of the UCS and CBR tests. Furthermore, the addition of 5% Pozzolana cement and 7% Portland cement with 28 days of curing had the highest CBR number and UCS resistance of 176.26 and 17.58 kg/cm2, respectively. Also, the sketch of the different failure patterns was shown during the curing time. Finally, by increasing the curing time, the behavior of specimens from semi-brittle to brittle made them harder.
A. Esmali Ouri1, P. Farzi, S. Choubeh,
Volume 26, Issue 3 (12-2022)
Abstract
Planning and providing appropriate tools to reduce the adverse effects of natural hazards including floods is inevitable. Achieving the above goal depends on having sufficient and accurate knowledge and information about the vulnerability of different ecosystems (watersheds) to various destructive factors. Vulnerability assessment by identifying potential stresses and disturbances (natural and man-made) as well as estimating the sensitivity of watersheds allows for predicting the effects and selecting appropriate solutions for the sustainable management of these ecosystems. Therefore, this study has been designed to identify and rank vulnerable sub-watersheds to floods in the Ardabil plain, taking into account social, economic, infrastructural, and ecological dimensions. First, the indicators and criteria of each dimension were identified taking into account the conditions prevailing in Ardabil plain. Then, information and data on climatic, hydrological, demographic, economic, infrastructure, and land use were obtained from relevant authorities. Then, the mentioned criteria were standardized and the weight according to their importance was calculated based on the BWM method the data obtained from this stage were performed using the TOPSIS technique to rank flood vulnerability for different sub-watersheds in Ardabil plain for the period 2007-2017. Finally, a map of Ardabil's plain vulnerability to floods was prepared and presented. According to the results, the criteria of building density, rainfall, population density, and the unemployment rate were the most important criteria of vulnerability and among the studied dimensions, the infrastructure dimension is too significant in flood vulnerability in Ardabil plain. Based on the comprehensive vulnerability map, sub-watershed 7 in Ardabil plain was identified as the most vulnerable sub-watershed in the study area.
M. Kyanpoor Kal Khajeh, Me. Pajouhesh, S. Emamgolizadeh,
Volume 26, Issue 3 (12-2022)
Abstract
Humans are always trying to change land to use natural resources to meet their needs. One of the land use changes that take place in order to benefit from sustainable water resources is dam construction. Dam construction has many positive and negative consequences for the environment from the beginning to use. The objective of this study was to investigate the effect of Gotvand Dam on the problem of collision of water flow path with salt domes and large volume accumulation of salt behind the dam lake. Images of the Landsat 5 satellite TM sensor for 1991, Landsat 7 satellite ETM+ sensor for 2008, and Landsat 8 satellite OLI sensor for 2020 were used to classify images, and prepare land use maps of the studied basin. Reviewing and evaluating the land use maps of the study area showed that agricultural lands are being developed after the operation of the dam. Also, barren lands were decreasing as well as the area's water content was increasing during the study period. In the second period of study (2008-2020), the population of the regions with an increasing area has been increasing. Also, the rangeland and meadows had a decreasing trend during the first and second periods. The results of classification accuracy using the object-oriented method for three periods of 1991, 2008, and 2020 were obtained as 0.92, 0.97, and 0.93, respectively. In general, it can be stated that the construction of the dam has increased the area under cultivation of land and by increasing population and urbanization in the construction area of the dam, destruction and reduction of rangelands occurred.
E. Masoumi, R. Ajalloeian, A.a. Nourbakhsh, M. Bayat,
Volume 26, Issue 3 (12-2022)
Abstract
Since clay is widely used in most construction projects, the issue of improving clay soils has considerable importance. This study aimed to optimize the variables affecting the properties of geopolymer and improve their mechanical properties using Isfahan blast furnace slag. Taguchi's statistical design method was used to model three process variables (blast furnace slag, water, and alkali sodium hydroxide agent) with four different values in the mixing design. Geopolymer was used to optimize the uniaxial compressive strength. Sixteen geopolymer compositions determined by mini-tab software were prepared and their uniaxial compressive strength was measured. The obtained results were modeled by analysis of variance, and then the interactions of the three variables on the uniaxial compressive strength of geopolymer were investigated using two and 3D diagrams. Then, the variables were optimized and the proposed values for the optimal sample were examined at temperatures of 25, 50, and 70°C and at times of 3, 7, 14, and 28 days of operation. A comparison of the results predicted by the models and the results of the experiments confirmed the validity of the models. Also, the scanning electron microscopy (SEM) images showed that the porosity will reduce from 7 to 28 days. It indicated that the use of the geopolymerization method has a significant role in stabilizing weak clay soils with low plasticity. The effect of fibers and geopolymer to reinforce was also investigated and for better evaluation, it was compared with soil stabilization with Portland cement. The results showed that in the most optimal geopolymer composition, the bearing resistance of clay has increased by more than 3400%. Meanwhile, fibers along with geopolymer with optimal percentage and length (0.1% by weight of geopolymer composition and length of 12 mm) were able to increase the uniaxial compressive strength of clay by nearly 4000%, which shows the excellent effect of using cellular fibers parameter whit the geopolymer in this research.
Mrs Soghra Bagheri, M.r. Ansari, A. Norouzi,
Volume 26, Issue 3 (12-2022)
Abstract
Soil erosion has been one of the most important problems of watersheds in the world and is considered one of the main obstacles to achieving sustainable development in agriculture and natural resources. Identifying and prioritizing regions sensitive to soil erosion is essential for water and soil conservation and natural resource management in watersheds. The present research was performed in 2021 year to prioritize the soil erosion susceptibility in 12 sub-watersheds of the Roudzard watershed in Khouzestan province using morphometric analysis and multiple criteria decision-making (MCDM) methods. In this regard, 11 morphometric parameters including shape parameters such as compactness constant (Cc), circularity ratio (Rc), form factor (Rf), elongation ratio (Re), linear parameters such as drainage density (Dd), stream frequency (Fs), drainage texture (Dt), bifurcation ratio (Rb), Basin length (L), Length of overland flow (Lg), and topographic parameter including Ruggedness number (Rn) were extracted and their relative weights were calculated using Analytic Hierarchy Process (AHP). The prioritization sub-watershed to soil erosion was performed using TOPSIS, VIKOR, and SAW methods, and the results were combined using rank mean, Copeland, and Borda methods. The final prioritization was compared with the amount of specific erosion in the MPSIAC model by determining Spearman's correlation coefficient. The result of the evaluation of morphometric parameters by using the AHP model showed that drainage density (0.161), drainage texture (0.158), and stream frequency (0.146) had the greatest effect on the erodability of the sub-watersheds. In contrast, the form factor (0.049), Elongation Ratio (0.036), and shape factor (0.026) had the least effects on erodability of the study area. In this research, the Spearman correlation coefficient between the final result of prioritizing the sub-watershed and the MPSIAC model was obtained as 0.8 in p-value<0.01. The results of prioritization of the sub-watersheds in terms of their sensitivity to soil erosion showed that sub-watersheds 11, 12, and 10 with an area of 191.83 km2 are categorized as very sensitive to soil erosion due to high value of linear parameters, low value of shape parameters, sensitive geology formation, and poor vegetation cover and located in rank 1 to 3, respectively. According to the results sub-watersheds 11, 12, and 10 have the highest amount of specific erosion equal to 16.03, 12.48, and 11.6 tons per hectare per year, respectively. Therefore, these sub-watersheds are a priority for watershed management operations. The results of the present study showed that MCDM methods and morphometric analysis are suitable tools for identifying areas sensitive to soil erosion and using the combined methods of the results and it is possible to take advantage of each of the different multi-criteria decision-making methods.
S. Parvizi, S. Eslamian, M. Gheysari, A.r. Gohari, S. Soltani Kopai, P. Mohit Esfahani,
Volume 26, Issue 3 (12-2022)
Abstract
Investigation of homogeneity regions using univariate characteristics is an important step in the regional frequency analysis method. However, some hydrological phenomena have multivariate characteristics that cannot be studied by univariate methods. Droughts are one of these phenomena their definition as univariate will not be effective for risk assessment, decision-making, and management. Therefore, in this study, the regional frequency analysis of drought was studied in multivariate methods using SEI (Standardized Evapotranspiration Index), SSI (Standardized Soil Moisture Index), and SRI (Standardized Runoff Index) indices in the Karkheh River basin from 1996 to 2019. The indices calculated probabilistic distribution between the variables of evapotranspiration, runoff, and soil moisture using multivariate L-moments method and Copula functions and considered meteorological, agricultural, and hydrological droughts simultaneously. The results of multivariate regional frequency analysis considering the Copula Gumbel as the regional Copula showed that the basin is homogeneous in terms of severity of SEI-SSI combined drought indices and is heterogeneous in terms of severity of SEI-SSI combined drought indices. However, after clustering the basin into four homogeneous areas in terms of characteristics of SPI (Standardized Precipitation Index), the basin is homogeneous in all areas in terms of univariate SEI, SSI, and SRI indices and is heterogeneous in the third and fourth clusters of SRI and SSI drought indices. Pearson Type (III), Pareto, normal, and general logistics distribution functions were found suitable to investigate the characteristics of SEI, SSI, and SRI drought indices in this case. Finally, large estimates of the types of combined droughts and their probability of occurrence showed that the northern and southern parts of the Karkheh River basin will experience short and consecutive droughts in the next years. Droughts in areas without meteorological data can be predicted in terms of joint probability using the multivariate regional frequency analysis method proposed in this study.
S. Falahati, E. Adhami, H. Owliaie,
Volume 27, Issue 1 (5-2023)
Abstract
Due to the importance of nickel (Ni), and the effect of common soil additives on Ni fractions distribution, the present study was conducted to evaluate the effect of zeolite and vermicompost on nickel fractions over time. The experimental design consisted of a factorial combination of two levels of vermicompost (zero and 2% by weight), three levels of zeolite (zero, 4% by weight of Firoozkooh zeolite, and 4% by weight of Semnan zeolite), and two soil texture (clay and sandy loam) in a completely randomized design in triplicates. Treatments were contaminated with 50 and 100 mg nickel/kg soil. Ni fractions were extracted and measured at 20 and 60 days. The results showed that in initial soils, Car-Ni in sandy loam soil was higher than in clay soil, while the content of Fe, Mn- Ox Ni, OM-Ni, and Res-Ni in the clay soil was higher. In sandy loam soil, more nickel was recovered in Exch- and Car-fractions, while nickel recovery was higher in Mn, Fe-Ox Ni, OM-Ni, and Res-Ni in the clay texture. Zeolite addition caused a significant decrease of Exch- and Car-Ni in the clay soil on 60d and 100 mg/kg Ni level. Exch-Ni was reduced due to vermicompost application. Vermicompost application caused the decrease in Fe, Mn Ox-Ni in both studied soils and times, and OM-Ni increased by vermicompost application. Aging generally reduces the Exch-Ni but changes in Car-Ni over time depending on the soil texture. Aging did not affect Mn, Fe-Ox Ni, and Res-Ni, while OM-Ni increased over time in clay soil.
S. Jalali, K. Nosrati, Z. Fathi,
Volume 27, Issue 2 (9-2023)
Abstract
The geomorphic characteristics of the watersheds are interrelated and the temporal and spatial scale in the form of season and sub-basins affect the concentration of suspended sediment. One of the objectives of this study was to investigate the relationship between suspended sediment concentration and watershed characteristics of Kan River using principal components regression and to recognize the effect of seasons and sub-basins on sediment concentration. The concentration of suspended sediment during four rainfall-runoff events in three seasons and in sub-basins was measured and calculated. The sixteen physiographic and land use characteristics were determined in the sub-basins and the main factors were identified and the scores of each factor for each feature were calculated using principal component analysis (PCA). The results of variance analysis showed that the concentration of suspended sediment was significant in terms of time scale and spring had the highest rate of sedimentation. Redundancy analysis and canonical analysis on the properties that participate in the first factor (PC1) showed the characteristics of the percentage of erodible formation, relatively erodible formation, and percentage of free construction activity, respectively. Road (slope leveling) and stream length are the most essential attributes of sub-basins in the production and concentration of suspended sediment in the study area.
Z. Feizi, A. Ranjbar Fordoee, A.r. Shakeri,
Volume 27, Issue 2 (9-2023)
Abstract
Maintaining soil structure and stability is essential, especially in arid and semi-arid regions with poor soil structural stability. Destruction of soil and its crust can cause wind erosion and desertification. The objective of this study was to investigate the effect of using hydrogel nanocomposite mulch on the stabilization of sand surfaces. A wind tunnel test was used to evaluate the erodibility of samples treated with different amounts of hydrogel nanocomposite. The compressive strength of the samples was measured by a manual penetrometer. The prepared nanocomposites were examined using scanning electron microscopy (FE-SEM), infrared spectroscopy (FTIR), and X-ray diffraction (XRD) images. The results of the wind tunnel showed that the addition of hydrogel nanocomposite to the samples improved the soil erosion rate by 100% at a speed of 15 m/s compared to the control sample. Bonding between sand particles by spraying hydrogel nanocomposites improves the erodibility of sand. Measurement of mechanical strength of treated samples after 30 days showed that the resistance of the crust increased with increasing the amount of nanocellulose in the composite, which can be expressed due to the increased surface area of the nanoparticle and the possibility of further bonding of the nanocomposite polymer bed with sand particles. While the crust diameter showed no significant difference with increasing concentration and the sample treated with nanocomposites containing 3% nanoparticles was thicker compared to other samples.
