Showing 2384 results for Type of Study: Research
S. Okhravi, S. Gohari,
Volume 24, Issue 4 (2-2021)
Abstract
In regard to wide piers, the pile group rather than single pile is used frequently to bear the loading of the structure in a particular arrangement; piles group composed of only one column of piles in the flow direction has a great effect on supporting the bridge deck. In this study, local scour at a single column arrangement of the piles group made up of four rows of piles characterized by different piles spacing was studied for clear-water conditions with two flow discharges of 20 and 35 l/s (the effect of increasing the flow depth with the same flow intensity). The results indicated that an increase in the flow depth not only greatly enhanced the scour depth and the width of the scour hole. Besides, the investigation of the relative flow depth on scour extent showed the need for revision in deep water conditions, as reported in the literature. The results of the pile group experiments revealed the noticeable impacts of piles spacing on the local scour. The bigger pile spacing caused a feeble interaction of wake-horseshoe vortices, leading to a decrease of the scour depth; the separate view of the scour holes was generated at individual piles. Finally, the results were compared with commonly used comprehensive models. The findings of this study can be applied for the appropriate selection and positioning for the countermeasure of the scour at bridge piers.
M. Mokari,
Volume 24, Issue 4 (2-2021)
Abstract
Optimal use of water resources seem to be necessary due to climate change and the recent drought conditions. One of the most important and effective management strategies is increasing water productivity in agriculture. Irrigation method and the use of different levels of nitrogen fertilizer are the effective factors in increasing the water productivity. Therefore, this study was conducted to investigate the effect of the irrigation method and nitrogen fertilizer on the harvest index and water productivity of two wheat cultivars with 36 treatments as a split-split plot based on a completely randomized design with three replications in the research farm of Natural Resources and Agricultural Research Center of Kashmar, during the 2018-2019 time period. The treatments were two irrigation methods including end blocked border and drip irrigation (tape) as the main plots, three levels of the nitrogen fertilizer from urea source including 0, 50 and 100 kg/ha as the sub plots and two cultivars of wheat including Pishgam and Sirvan as the sub-sub plots. The results showed that by changing the border irrigation method to the drip irrigation (tape) method, the harvest index and water productivity were increasesignificantly. The results also showed that grain yield and its components, including harvest index and water productivity, had no significant difference in 50 and 100 kg/ha nitrogen levels. On the other hand, grain yield and its components, harvest index and water productivity, were significantly higher in the Sirvan cultivar rather than the Pishgam one (P<0.01). According to the results obtained from this study, the drip irrigation method, 50 kg/ha nitrogen level and Sirvan cultivar could be recommended for the study region.
Z. Ghorbanpour, O. Abessi, F. Kardel,
Volume 24, Issue 4 (2-2021)
Abstract
Drilling material from the tunnel of the Tehran-Shomal highway was estimated to be about 2.5 Million Cubic Meters by the project authorities. Sadly, from the beginning, the drilling materials had been deposited on the open space in the floodplain of the Chaloos river with slightest environmental considerations. During the previous years, weathering and leaching from the drilled materials besides the discharge of drain water from the tunnel had led to seriouse contaminations and the deterioration of the water quality of the Chaloos river. In this paper, the ecological risk of nonorganic pollutants due to drilled materials was investigated. The sampling was done from the excavated materials and river sediment in five different locations throughout a complete year. From the many pollutants, Nickel, Cadmium and Copper were chosen to be investigated. The results showed that almost 15 percent of the samples had a high degree of pollution, while 60 percent of them were clean and the other 25 percent included the highly contaminated ones. All samples were also estimated to have a low to high ecological risk.
S. Shakeri, A. Azadi, M. Saffari,
Volume 24, Issue 4 (2-2021)
Abstract
Determining the relative distribution of each chemical form of the elements and their relationship with the physical, chemical, and clay mineralogical properties of soils can help researchers to achieve the sustainable agricultural management. The present study was conducted to evaluate the chemical forms of four micronutrients (Zn, Cu, Fe and Mn) in some surface and subsurface soils of Kohgiluyeh and Boyer Ahmad province and their relationship with the physical, chemical and mineralogical properties of the soils. The results showed that the exchangeable and sorbed chemical forms of the studied elements were very low and negligible, but the residual, carbonate, and organic forms had the highest to lowest values of the chemical forms of these elements, respectively. Examination of the correlation of the chemical forms of these elements with soil properties showed the effective correlation of organic carbon values with the Zn chemical forms; also, there was a correlation between clay, silt, cation exchange capacity and calcium carbonate and the chemical forms of Cu, Fe and Mn. The correlation between the quantities of clay minerals and the chemical forms of these elements showed that the amounts of different forms of the studied elements were directly related to 2:1 clay silicate minerals (especially vermiculite). Evaluation of Fe and Mn chemical forms also showed that the amounts of these elements were higher in the soils with developed profiles (Alfisol and Mollisol), the wetter climate and zeric moisture regime rather than in soils with non-developed profiles (Entisols and Inceptisols) and a drier climate and a ustic moisture regime. In general, the results showed that variations of soil forming factors such as climate (as well as the total amount of each micronutrients), could be effective on the chemical forms of micronutrients (especially on Mn and Fe); these can be effective in the management of weakly to highly-developed soils orders.
H. Sadoghi, T. Rajaee, N. Rouhani,
Volume 24, Issue 4 (2-2021)
Abstract
Identification and investigation of changes in the area under cultivation of various crops seem to be essential for the management supply of crop production. In this study, r to identify and investigate change of the area under cultivation in major crop Hoseynabade Mishmast region in Qom province, we used the time series images of OLI and ETM sensors of landsat 8 and 7satellites, according to the crop calendar of this region. By using the vegetation index (NDVI) in the decision tree algorithm, the thresholds of this index were adjusted according to the major crops of this region; then a map of the cultivation pattern of the crop of this region was prepared. In order to evaluate the results, the statistics of the provinces agricultural jihad were used during 2005, 2009, 2014 and 2019 crop years. The results showed that by using the threshold of NDVI index, crops in this region in 2005 included wheat and barley and alfalfa, and their areas had an error of 17/1 and 6/1 percent in comparison with the statistics of agricultural Jihad, respectively; in 2009, wheat and barley, alfalfa and corn had an error of 0/5, 9/6 and 0/1 percent. Also, in 2014, wheat and barley, alfalfa, corn and sophie crops had an error equal to 4/9, 0.4, 11/4 and 2/4 percent, and the same crops in 2019 had an error 0/04, 11/6, 1/4 and 17/5 percent; that error was not significant. According to the results, the appropriate efficiency NDVI index in estimating crop cultivation area was determined by their phenology. Also, in 2009 and 2014, corn and sophie crops were added to the regions crops, and the area under crops cultivation in 2019 was increased, as compared to 2014.
S. Khalilian, M. Sarai Tabrizi, H. Babazadeh, A. Saremi,
Volume 24, Issue 4 (2-2021)
Abstract
In the present study, the SWAT hydrological model was developed for the upstream of the Zayandehrood dam to evaluate the inflow to this dam. Accordingly, after entering the meteorological and hydrometric information of the region, the runoff simulation was performed. Due to the high volume of entrances to the Zayandehrood Dam, Shahrokh Castle hydrometric stations were selected as the base station for calibration and validation during the statistical period of 1990-2015. After hydrological simulation and accuracy of results, climate prediction was performed using the fifth model of the climate change for the RCP scenarios. According to the forecast, by using climate change models, the temperature could be assumed to increase in all models and the highest rate of increase would occur under the RCP 8.5 climate scenario. After evaluating climate change in different diffusion scenarios, the runoff of the basin was simulated in the SWAT model. The simulation results of runoff in the catchment area showed that although the amount of rainfall was increased in the region, increasing the temperature had a greater effect, reducing the amount of runoff in the basin. Based on the results of climate change, hydrological simulation was performed using the SWAT model. The results showed that the effect of diffusion scenarios in the region was different, causing an increase in temperature and precipitation. The highest increase was observed in the RCP8.5 scenario, which was consistent with the nature of this emission scenario, with the highest emission of greenhouse gases and carbon dioxide. Then, the evaluation of the hydrological model was done; the results showed that although the amount of rainfall in the region had been increased, the increase in temperature of this basin had a greater effect and efficiency in reducing the amount of runoff.
F. Kaboudvand, S. S. Mehdizadeh,
Volume 24, Issue 4 (2-2021)
Abstract
The Khanmirza plain is one of Iran’s fertile plains that is located in Chaharmahal Bakhtiari province. Agriculture in the area is very prosperous, but the lack of rain and over-harvesting from consumption wells has led to a reduction in groundwater levels, even causing land subsidence. Moreover, the high usage of chemical manures, especially nitrate manures, has increased the number of solutes and chemical materials in the groundwater. Thus, for this plain, making artificial ponds is important to modify the storage of the aquifer. In this study, to define the optimum locations of the artificial ponds, the effect of 12 factors was considered. The analytic hierarchy process (AHP) method was used to introduce the weight of each parameter in comparison to other factors. Afterward, the spatial priority of all factors was derived using the Geographic Information System (GIS) technique. The produced GIS layers were laid on each other and the optimum locations were obtained. Agricultural drainage was an effective index for recharge purposes. The results of the study demonstrated that groundwater level decline got the maximum weight (40%), while the land slope had the minimum weight, since the vicinity to available floodways was considered as an independent criterion. The results also showed that regions with a total area of 18 km2 in north and north-west of the Khanmirza plain could be the optimum and most suitable places for artificial ponds construction.
A. Donyaii, A. Sarraf, H. Ahmadi,
Volume 24, Issue 4 (2-2021)
Abstract
Optimizing the water resources operation, especially in the agricultural sector, which has the largest share in the water resources operation, is extremely important. Therefore, in this research, while introducing Whale, Gray Wolf and Crow Search Optimization Algorithms, their performance in the optimum operation of Golestan single-reservoir system Dam was evaluated with the aim of providing water demand for the downstream lands based on reliability, Reversibility, and vulnerability indices. In this optimization problem, the objective function was defined as the minimization of the total deficiency during the operation period. Meanwhile, the constraints of continuity equation, overflow, storage and reservoir release volume were applied to the objective function of the problem. Then, the results were compared with the absolute optimal value based on the nonlinear programming method obtained from GAMS software; finally, a multi-criteria decision-making model was developed to rank the optimization algorithms in terms of performance. The absolute optimal response obtained by the GAMS software based on the nonlinear programming method was 19.41. The results showed that the Gray Wolf algorithm performed better than the other algorithms in optimizing the objective function, so that the average responses in Gray Wolf, Crow Search and Whale algorithms were 92, 84 and 67% of the absolute optimal response, respectively. Furthermore, the Gray Wolf optimization algorithm performs better than the Whale and Crow Search algorithms in all parameters. In addition, the coefficient of variation of the responses obtained by the Gray Wolf algorithm is 2 and 1.43 times smaller than that in the Whale and Crow Search Algorithms, respectively. Finally, the results of the multi-criteria decision-making model showed that the gray wolf algorithm had the first rank, as compared to the other two algorithms studied in solving the problem of the optimal operation of the Golestan dam reservoir.
M. Jamali Jezeh, Mohammad Shayannejad, S. M Hejazi,
Volume 24, Issue 4 (2-2021)
Abstract
Water resources are limited in many areas of the world; sometimes, even these limited resources are negligently contaminated. One of the polluting factors of water is oil and its derivatives. Oil absorption using textiles is one of the common ways to separate oil from water. In this study, we used three types of textiles with different properties in order to make the filter. The experiments were performed using three different concentrations of 10, 20 and 30% oil. In this study, three types of BC, PET and PP textiles in the presence of horizontal and vertical drainages were investigated. The PET and PP textiles were made of nonwoven polyester and polypropylene fibers, respectively, and the BC textile was a two-component nonwoven textile of both polyester and polypropylene fibers that was used for the first time. Flow through the textiles was turbulent. Coefficients of flow were calculated using non-Darcy flow relations and the optimization method. The results showed that at low oil concentrations, the oil absorption had an inverse relation with the porosity and turbulent flow coefficients, but at higher concentrations, the effect of these agents was less; instead, the effect of the concentration and the intrinsic ability of the non-woven fibers was greater. The best performance was related to PP and PET with the horizontal drainage that had 95 and 91 absorption rates, respectively.
M. Akbari,
Volume 24, Issue 4 (2-2021)
Abstract
The objective of this research was the development of a hydraulic-economic simulation-optimization model for the design of basin irrigation. This model performed hydraulic simulation (design of basin irrigation), using Volume Balance model, economic simulation through calculating sum of four seasonal costs and optimization using NSGAII multi-objective meta-heuristic algorithm. For programming, MATLAB programming software was applied. The optimizations of functional, multi-dimensional, static, constraint, continuous, multi-objective and meta-heuristic were applied for the optimization of the objective functions. Decision variables selected from simulation inputs were calculated in such a way that the hydraulic objective function (minimizing linear combination of seven performance indicators) and economic objective function (total seasonal cost based on sum of water cost, labor cost, basin preparing cost and channel drilling cost) were minimized. Data of one the experimental field was used for the purpose of simulation. After initial simulation, optimization of the experimental field was done using NSGAII multi-objective meta-heuristic algorithm with tuned parameters. Optimization using the suggested model shoed the decrease (improvement) of objective functions rather than initial simulation performance. As a result, the suggested model could be regarded as is a specialized tool for basin irrigation, showing a good performance, despite its simplicity.
E. Yarmohammadi, S. Shabanlou, A. Rajabi,
Volume 25, Issue 1 (5-2021)
Abstract
Optimization of artificial intelligence (AI) models is a significant issue because it enhances the performance and flexibility of the numerical models. In this study, scour depth around bridge abutments with different shapes was estimated by means of ANFIS and ANFIS-Genetic Algorithm. In other words, the membership functions of the ANFIS model were optimized using the genetic algorithm, finding that the performance of ANFIS model was increased. Firstly, effective input parameters on the scour depth around bridge abutments were defined. Then, by using the input parameters, eleven ANFIS and ANFIS-GA models were produced. Next, the superior ANFIS and ANFIS-GA models were introduced by analyzing the numerical results. For example, the correlation coefficient and scatter index for ANFIS model were calculated to be 0.979 and 0.070; for ANFIS-GA, these were 0.986 and 0.056, respectively. In addition, the average discrepancy ratio (DRave) for ANFIS and ANFIS-GA models was 0.984 and 0.988, respectively. Also, it was shown that the ANFIS-GA models had more accuracy, as compared to the ANFIS models. Moreover, a sensitivity analysis showed that Froude number (Fr) and ratio of flow depth to radius of scour hole (h/L) were the most influential input parameters for simulating the scour depth around bridge abutments.
F. Soroush, F. Fathian,
Volume 25, Issue 1 (5-2021)
Abstract
In the present study, the spatial and temporal changes of climate variables such as pan evaporation (Ep), temperature (T), relative humidity (RH), sunshine duration (SD), wind speed (W) and precipitation (P), as well as their relationship with altitude, were investigated. For this purpose, 68 meteorological stations with 30 years of data (1987-2016) throughout Iran on both seasonal and annual time scales were selected. Trend analysis of climate variables showed that over the past 30 years, most areas of Iran have become warmer and drier although all trends have not been significant. Investigation of the relationship between the trend slope of climate variables and altitude illustrated that there was no significant relationship between them during the study period on the annual time scale (p>0.1). However, in winter, the rate of increase in T (minimum, maximum and mean temperatures) and SD (p<0.1), as well as the rate of decrease in P (p<0.01), was significantly enhanced by increasing the altitude. The increase in mean and maximum T (p<0.1) and SD rates (p<0.001) in summer were significantly lower in the highlands than in the lowlands. In autumn, the trend slopes of minimum and mean T (p<0.05) were negatively correlated with altitude; in addition, the rates of increase in P and RH (p<0.05) in the highlands demonstrated a sharper increase. It seems, therefore, that most changes in climate variables have occurred in both autumn and winter. The results also showed that in winter, the highest rates of increase in Ts were related to the altitude of 1500-2000 m; however, the highest decrease in P belonged to the altitude of 2000-2500 m. In autumn, the highest rates of decrease in minimum and mean Ts had occurred in the altitude of 2000-2500 m; as well, he highest rate of increase in P was observed in the altitudes of both 0-500 m and 2000-2500 m.
F. Hayati, A. Rajabi, M. Izadbakhsh, . S. Shabanlou,
Volume 25, Issue 1 (5-2021)
Abstract
Due to drought and climate change, estimation and prediction of rainfall is quite important in various areas all over the world. In this study, a novel artificial intelligence (AI) technique (WGEP) was developed to model long-term rainfall (67 years period) in Anzali city for the first time. This model was combined using Wavelet Transform (WT) and Gene Expression Programming (GEP) model. Firstly, the most optimized member of wavelet families was chosen. Then, by analyzing the numerical models, the most accurate linking function and fitness function were selected for the GEP model. Next, using the autocorrelation function (ACF), the partial autocorrelation function (PACF) and different lags, 15 WGEP models were introduced. The GEP models were trained, tested and validated in 37, 20- and 10-years periods, respectively. Also, using sensitivity analysis, the superior model and the most effective lags for estimating long-term rainfall were identified. The superior model estimated the target function with high accuracy. For instance, correlation coefficient and scatter index for this model were 0.946 and 0.310, respectively. Additionally, lags 1, 2, 4 and 12 were proposed as the most effective lags for simulating rainfall using hybrid model. Furthermore, results of the superior hybrid model were compared with GEP model that the hybrid model had more accuracy.
B. Torabi Farsani, M. Afyuni,
Volume 25, Issue 1 (5-2021)
Abstract
Compost leachate is a liquid resulting from physical, chemical and biological decomposition of organic materials. The main objective of this study was to evaluate the influence of leachate compost on the physical, hydraulic and soil moisture characteristic curves. Also, the effect of leachate on the aerial organ fresh weight of corn was investigated. Leachate was added to clay loam and sandy clay loam soils at the rate of zero, 1.25 and 2.5 weight percent. The soil water characteristic curve and the estimation of the parameters of the van Gnuchten and Brooks and Corey models were performed using RETC software. Leachate increased the bulk density and decreased the available water of the clay loam soil. Only 1.25% of the leachate increased the available water in the sandy clay loam soil. Two levels of leachate decreased the bulk density of sandy clay loam soil. Leachate decreased the saturation hydraulic conductivity of the clay loam and increased this parameter of sandy clay loam soil. Leachate was more successful in increasing the aerial organ fresh weight of corn in the sandy clay loam soil. Therefore, leachate was more useful in sandy clay loam than in clay loam soil, and 1.25% treatment was better in the sandy clay loam soil. Also, the used leachate increased the repellency of both soils. Leachate caused the parameters of van Gnuchten and Brooks and Corey models to increase, as compared to the control in both soils.
O. Asadi Asadabad, S. H. Matinkhah, Z. Jafari, H. Karim Mojeni,
Volume 25, Issue 1 (5-2021)
Abstract
In order to investigate the effect of the type drip of irrigation methods, subsurface irrigation and furrow irrigation on the domestication of Hedysarum criniferum Boiss., an experiment with a randomized complete block design with three replications was implemented at Isfahan University of Technology for two years (2016 to 2018) . For this purpose, clay pipes were made and the plant was cultivated on the sides of clay pipes and types. Also, furrow irrigation treatment was applied as the control. During the experiment, all treatments received the same water and finally, some growth parameters were measured. The results of the study showed improvement in height (0.43 and 0.34), canopy cover (0.66 and 0.52), stem number (0.44 and 0.85), chlorophyll index (0.45 and 0.45), seed emergence (0.75 and 0.30), plant survival (0.78 and 0.55), yield (0.23 and 0.35), and water use efficiency (0.25 and 0.25) under type drip irrigation treatment, as compared to subsurface and furrow irrigation, respectively (P<0.05). In general, the type drip treatment is recommended in the early years of planting; however, since the maximum production potential of this plant is in the third year onwards, it is necessary to examine the results in the following years to recommend the proper irrigation method, especially the use of subsurface irrigation.
S. Jamali, H. Ansari, M. Zeynodin,
Volume 25, Issue 1 (5-2021)
Abstract
The goal of this study was to investigate the effects of treated urban wastewater and different harvesting times on the yield and yield components of Sorghum (cv. Speed feed) in the greenhouse condition. The research was done based on a completely randomized design including 3 replications as pot planting in Ferdowsi university of Mashhad in 2016. In this study, the effects of four mixtures consisting of the moderations use of the treated urban wastewater and freshwater (0, 25, 75 and 100 percent mixture of treated urban wastewater and freshwater) and three harvesting times level (pre-flowering, after 50 percent of the plant to flowering, and grain filling stage) on the yield and yield components of Sorghum were evaluated. The results inducted that the effect of different moderations of irrigation regimes on all of them parameter was highly significant (P<0.01), but plant height was non-significant; it was also revealed that the effect of harvesting times on all of the parameters was highly significant (P<0.01), but leaf width was non-significant. The results also exhibited that the interaction effects of irrigated regimes and harvesting times on the leaf number, panicle length and width, leaf, panicle, and stem was highly significant (P<0.01), but plant height, stem diameter, branches number, and leaf length and width were significant at the 5 percent level (P<0.05). Also, the use of 25, 75, and 100 percent mixture of wastewater resulted in the forage yield of 37.5, -29.3, and 12.9 percent (pre-flowering); -31, -15.3, and -47.4 percent (after 50 percent of the plant to flowering), and -11.8, -35.7 and -28.4 percent (grain filling stage), respectively. The highest forage weights (46.2 g per plant) showed, in the study, irrigated by a mixture of 75 treated wastewater and 25 freshwater, and harvesting the plant after 50 percent in flowering stage; on the other hand, the best treatment in this study irrigation by the mixture of 75 treated wastewater and 25 freshwater and harvesting the plant after 50 percent in the flowering stage, Thus, using the treatment in farm experiment required the field research.
B. Khalilimoghadam, A. Siadat, A. Yusefi,
Volume 25, Issue 1 (5-2021)
Abstract
Dust deposited on the leaves of trees can be effectively used as the monitors of polycyclic aromatic hydrocarbons (PAHs). The dust deposited on the leaves can be used as an appropriate index for evaluating PAHs in the atmosphere. This research was conducted to determine the origin and health risk assessment of PAHs accumulated on the leaves of trees in the city of Ahvaz. For this purpose, samples were taken at leaves on 10 points with different land uses including industrial, recreational, high-traffic and residential ones. After preparation, to determine the type and concentration of PAHs, the compounds were analyzed by GC-MS. The results showed that 15 types of PAHs had been identified from 16 important compounds identified by EPA in the dust samples. The concentration of compounds was the range of 3.3-110 microgram per kilogram. The maximum and minimum of PAHs carcinogenic in particles trapped on leaves were in the Kut-Abdolah with 530 ppb and Shahrvand Park Station with 5.13 ppb, respectively. Also, the average relative of LMW/HMW in the aromatics contained in the deposition of particles on trees was 0.5; further the analysis of the main components of aromatic hydrocarbons (PAHs) showed that there was no specific source for these compounds in Ahvaz, and these compounds could be from fossil fuels, urban traffic, natural gas, generally showing a pyrogenic origin.
N. Hasanzadeh, L. Gholami, A. Khaledi Darvishan, H. Yonesi,
Volume 25, Issue 1 (5-2021)
Abstract
Soil erosion is one of the most serious environmental issues in the world, causing soil degradation, reduction of land productivity, increasing flood, water pollution and pollutions transportation; it is also a serious threat to sustainable development in the world. Therefore, the soil conservation and the prevention of soil erosion and use of conditioners as the nanoclay can be considered as a solution to improve land productivity and protect environment. The present study was, therefore, conducted to address the effect of the application of montmorillonite nanoclay with three rates of 0.03, 0.06 and 0.09 t ha-1 on changing runoff and soil loss variables under laboratory conditions. The results showed that the nanoclay with the rate of 0.03 t ha-1 could decrease the runoff coefficient, soil loss and sediment concentration with the rate of 40.65, 88.38 and 82.19 percent, respectively. The average of soil loss in control treatment and conservation treatments of nanoclay with various rates was measured to be 3.76, 0.44, 1.33 and 3.16 g, respectively. Also, the results showed that the most sediment concentration was the control treatment with the rate of 5.84 g l-1 and the conservation treatments with nanoclay in the applied rates was 1.04, 3.47 and 2.96 g l-1, respectively. Also, the results showed that the nanoclay effect was significant on changing the soil loss and sediment concentration at the level of 99 percent. Finally, due to the effect, the use of this conditioner in natural conditions and investigation of the effects on environment and aggregates stability are recommended.
T. Dehgan, M. A. Gholami Sefidkouhi, M. Khoshravesh, N. Samadani Langroudi,
Volume 25, Issue 1 (5-2021)
Abstract
In this research, the nitrate removal by beech leaves was investigated in batch and column systems. The batch experiment was performed to address the effect of pH, contact time, adsorbent dosage and initial nitrate ion concentration on the nitrate removal. The results showed that with an increase in pH, the removal efficiency and adsorption capacity were decreased and nitrate removal by millimeter and nano adsorbent beech leaves reached equilibrium 120 and 90 minutes after experiment, respectively. With an increase in the nitrate concentration, the removal efficiency was decreased from 59.2% to 39.7% and 82.1% to 69.9% for millimeter and the nanoparticles of Beech leaves, respectively. In fixed-bed column adsorption experiments, the flow rates of 5, 8 and 11 ml/min and the nitrate concentration of 15, 50 and 120 mg/L were studied. The results showed with an increase in the nitrate concentration from 15 to 120 mg/L, the saturation time was decreased from 240 to 150 and 360 to 270 minutes for millimeter and nanoparticles of Beech leaves, respectively. Thomas, Dose-response and Yoon-Nelson models were fitted to the results of the continuous experiments. The Thomas model fitted the experimental data with high accuracy. Compared to the adsorbents, nano-adsorbent had more adsorption capacity in the batch and column systems.
H. Fazlolahi, R. Fatahi, K. Ebrahimi,
Volume 25, Issue 1 (5-2021)
Abstract
Water is the most crucial factor for agricultural development. Therefore, the economic evaluation of water resources is critical. The purpose of this paper was to determine the economic value of water resources, to evaluate the financial efficiency and to decide on the price of agricultural water in Arak plain. For this purpose, the economic value of water resources for wheat, barley, alfalfa and corn was identified in 2015- 2016, using the mathematical model developed in this research. The results showed that the financial efficiency was calculated for three alternatives: free-cost water, water cost equal to the 10% of the calculated price and water cost equal to the exact calculated price. The irrigation efficiency of 40% financial efficiency was 2.38%, 1.68% and 0.47% , respectively, for the aformentioned methods, and the irrigation efficiency of 70% financial efficiency was 2.07, 1.92 and 0.71, respectively. Also, the sensitivity analysis of the financial efficiency was performed, with 10% change in the farmers income and costs. The results also revealed that irrigation efficiency and financial efficiency were not aligned when farmers had free water; however, they were aligned when the farmer paid 10% of the calculated price. Financial efficiency was more sensitive to changes in the farmers income when compared to the changes in costs.