Research Article
nafise seyednezhad; Seied Hosein Sanaei-Nejad; B. Ghahraman; H. Rezaee Pazhand
Abstract
Regional analysis, estimating missing values, areal rainfall, estimating PMP and rainfall- runoff models in daily scale are essential in water resources and climatological researches. Modified inverse distance interpolation method based on Fuzzy Mathematics (MIDW-F) is a new, efficient method and independent ...
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Regional analysis, estimating missing values, areal rainfall, estimating PMP and rainfall- runoff models in daily scale are essential in water resources and climatological researches. Modified inverse distance interpolation method based on Fuzzy Mathematics (MIDW-F) is a new, efficient method and independent of complex preconceptions hypothesis. The purpose of this paper is applying the new interpolation equation for above essential needs by calibration the daily rainfall of Mashhad Plain catchment. Screening and normalizing distances and elevations were done, then effects of fuzzy operations (Max, Min, Sum, Multiplication and SQRT) are Checked out and optimizing the parameters of MIDW-F by Genetic algorithms. The 215 daily precipitations (49 rain gauge stations) were analyzed and were calibrated. The results showed that the best operators are Minimum (Share58%), multiplying (Share35%) and total contribution rate of others are 6%. The MIDW-F was compared with the three others conventional methods (the Arithmetic mean, Thiessen polygon and IDW) and results showed that the errors of MIDW-F method were reduced noticeably. Largest Regional Mean Square errors (RMSE) is for Arithmetic mean (Max. 90.45, Min. 5.76, variance 686.8 and 70% Cv) and smallest RMSE belong to MIDW-F (Max. 56.67, Min. 4.6, variance 340.92 and 57% Cv). Zoning of daily rainfall at 22/3/2009 and 23/2/2010 and with MIDW-F and IDW methods were conducted and evaluated. The results showed that the zoning by MIDW-F proposed more details. So this method\ is proposed for the interpolation of daily precipitation in a homogeneous region.
Research Article
J. Givi
Abstract
In addition to qualitative and quantitative land suitability evaluation, economical evaluation can be carried out as well, based on net or gross benefit per surface area unit. The present research was done to evaluate land suitability, qualitatively and economically,, by different methods for irrigated ...
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In addition to qualitative and quantitative land suitability evaluation, economical evaluation can be carried out as well, based on net or gross benefit per surface area unit. The present research was done to evaluate land suitability, qualitatively and economically,, by different methods for irrigated maize, wheat, potato and barley in Shahrekord area. In this regards, qualitative land suitability class was determined by matching land characteristics with the studied crops growth requirements, using simple limitation method and ALES program. Economical land suitability evaluation was carried out, using "internal rate of return", "gross profit", "net present value" and "benefit/cost ratio" methods which are included in the ALES program. The results showed that qualitative suitability class in all of the studied land units for irrigated maize, wheat and barley is S2 and for irrigated potato in 73% of the units is S2 and in 27% of them is S3. As the "net present value" method is used, % 73 and % 27 of the land units are classified as S2 and S1, respectively for all of the studied crops. For wheat and maize, all of the land units are classified as S1, as gross profit, benefit/cost ratio and internal rate of return methods are used. For potato and barley, using gross profit and internal rate of return methods, % 73 and % 27 of the land units are classified as S2 and S1, respectively and as the benefit/cost ratio method is used, economical land suitability class in all of the land units is S1.
Research Article
A. Moghaddam; A. Alizadeh; Alinaghi Ziaei; A. Farid Hosseini; D. Fallah Heravi
Abstract
Genetic Algorithm as a one of the main evolutionary algorithms has had a most successful role in the water distribution network optimization.This algorithmhas been undergoing many reforms and improved versions are published. A type of genetic algorithms is Fast Messy Genetic Algorithm (FMGA), that has ...
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Genetic Algorithm as a one of the main evolutionary algorithms has had a most successful role in the water distribution network optimization.This algorithmhas been undergoing many reforms and improved versions are published. A type of genetic algorithms is Fast Messy Genetic Algorithm (FMGA), that has the ability to increase the convergence rate in solving optimization problems with reducing the length of chromosomes and removing the inefficient genes, meanwhile studying the chromosomes which are not equal in terms of gene strings.In this paper, for evaluation of the FMGA performance in solving water distribution network optimization problems, after the sensitivity analysis and determining the best values of these parameters, two benchmark networks and a real network are analyzed, which are named Two-loop network, the Hanoi network and Jangal City network, respectively, and the results were compared with previous researches. Least-cost in two loop network was estimated after 2880 number of function evaluations that had significant improvements compared to the results of previous researches. In Hanoi network, the minimum cost obtained equal to 6.045×106 $ that is less than other researchers results are issued so far. After proving the efficiency of algorithm, its performance was shown in design of real Jangal city network according to increasing network size and design constraints.
Research Article
S. Pouresmaeil; M.F. Maghrebi
Abstract
Bottom intakes are hydraulic structures widely adopted for diverting water in steep rivers. The problems of vibration, corrosion, deformity, and clogging of the bottom racks by sediment, freezing and foliage inspire a new system of bottom intake in which a filled trench of porous media replaces the bottom ...
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Bottom intakes are hydraulic structures widely adopted for diverting water in steep rivers. The problems of vibration, corrosion, deformity, and clogging of the bottom racks by sediment, freezing and foliage inspire a new system of bottom intake in which a filled trench of porous media replaces the bottom racks. In the present paper we have analyzed the data obtained from a systematic series of experiments carried out in a laboratory two-story flume. Measurements of the diverted discharge were performed for different rates of flow, grain size distributions, surface slopes and dimensions of intake as well as important factors. Also the relationships presented in previous studies, are compared with the results of new experiments and the characteristics of the physical behavior of these equations are investigated. Due to lack of the validity in previous models, a new equation for estimating discharge coefficient and flow diversion in porous bottom intake is presented, by using dimensional analysis and multivariate regression with experimental observations. The robustness of the proposed relationship is confirmed by the principles of hydraulic behavior of this intake and the comparison between the calculated discharges through the proposed relationship and those measured in an extensive series of experiments, characterized by ranges of the relevant flow parameters much larger than those investigated in the present contribution.
Research Article
Sh. Shams; Mohammad Mousavi baygi
Abstract
Mashhad is Iran second most populous city, where in terms of tourism, economy and agriculture is very important. Regarding to the importance of the change of climatic factors and its effect on future policy, in this study the max and minimum temperature changes in the scale of yearly, seasonally, monthly ...
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Mashhad is Iran second most populous city, where in terms of tourism, economy and agriculture is very important. Regarding to the importance of the change of climatic factors and its effect on future policy, in this study the max and minimum temperature changes in the scale of yearly, seasonally, monthly and daily, was investigated by means of SNHT, Buishand, Pettitt, Von-neumann and kendall-tau. The results of this study indicate a temperature increase of Mashhad, comparison of the results showed that during the past 60 years (1951-2010), minimum temperature increased 2times more than maximum temperature (0.062 versus 0.031). Test results also showed temperature increasing in all seasons, but just winter maximum temperature increasing trend was not significant in 95% confidence level. Also the highest rate of temperature increasing was belonged to autumn minimum temperature, with the slope of 0.074. Like the difference between annual series, in all season minimum temperature increasing trend is higher than maximum trend, comparing trends in monthly maximum and minimum temperatures show similar results. It also was shown that the minimum temperature trend rose approximately near the year 1985, while maximum temperature break point is near 1995.
Research Article
N. Moosavian; M.R. Jaefarzadeh
Abstract
The gradient-based algorithms are widely used for hydraulic analysis of pipe networks. Solving system of linear equations has the most computational cost in the gradient-based methods particularly for large networks with more than hundreds of variables. The Jacobian matrix form in the gradient-based ...
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The gradient-based algorithms are widely used for hydraulic analysis of pipe networks. Solving system of linear equations has the most computational cost in the gradient-based methods particularly for large networks with more than hundreds of variables. The Jacobian matrix form in the gradient-based methods is square and banded. Elements of this matrix are function of flow rate and hydraulic resistance of pipe. The sparse Cholesky method with node reordering is commonly applied for solving system of linear equations in the EPANET and WATERGEMS softwares. As an alternative, the Jacobian matrix can be solved using the Multi-Grid method. This paper studies the application of pre-conditioner methods such as AMG-CG and AGMG for solving the Jacobian matrix and compares its results with other iterative and direct solvers. According to the results, AGMG demonstrates better performance than AMG-CG in all studied cases and it is the best method for solving system of linear equations in hydraulic analysis of huge pipe networks.
Research Article
seyed vahidodin rezvani
Abstract
Today, remote sensing is used in various sciences, such as: geography, biology, meteorology, agriculture, water resources management and etc. Easy and inexpensive data access and data precision, digital and extensive and comprehensive of images that having the frequency spectrum, are some advantages ...
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Today, remote sensing is used in various sciences, such as: geography, biology, meteorology, agriculture, water resources management and etc. Easy and inexpensive data access and data precision, digital and extensive and comprehensive of images that having the frequency spectrum, are some advantages of remote sensing, than other methods of providing information. Therefore, by using algorithms in remote sensing that having the evaporation and transpiration, you can have a big step in the management of water resources. Among of these algorithms, SEBAL is a remote sensing algorithm that calculating surface energy balance for each pixel of a satellite image at each moment. In this study, surface albedo, surface temperature and vegetation status index were calculated by using this algorithm and multi-spectral satellite data and meteorological information such as degree of temperature, hours of sunshine, wind, saturated vapor pressure, soil humidity and etc. Finally evapotranspiration of Miandarband plain (west of Iran) was determined and the evapotranspiration maps were prepared. Also, the actual evapotranspiration computed for wheat using FAO conventional method and was compared with SEBAL method. The results showed that there was a high correlation (0.84) between these two methods.
Research Article
Mahdi Delghandi; Saeid Boroomand Nasab
Abstract
Field experiments for quantifying optimal breeding strategies are time-consuming and expensive. Crop simulation models can provide an alternative, less time-consuming and inexpensive means of determining the optimum breeding strategies. These models consider the complex interactions between weather, ...
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Field experiments for quantifying optimal breeding strategies are time-consuming and expensive. Crop simulation models can provide an alternative, less time-consuming and inexpensive means of determining the optimum breeding strategies. These models consider the complex interactions between weather, soil properties and management factors. CERES-Wheat is one of best models which can simulate the growth and development of wheat. Therefore, in present paper DSSAT 4.5-CERES-Wheat was evaluated for predicting growth, phenology stages and yield of wheat (cultivar of Chamran) for Ahwaz region. For this purpose, one Experimental research was designed at the experimental farm of the Khuzestan Agriculture And Natural Resources Research Center (KANRC), located at Ahwaz in 2010-2011 growth season. Using results of this research and two another research, CERES-Wheat model was evaluated. Results of evaluation showed that most and less NRMSE were abtained for simulation of maximum Leaf Area Index (6%) and phenology stages (2%), respectively. Therefore, it can conclude that CERES-Wheat is a powerful model in order to simulation of growth, phenology stages and yield of wheat.
Research Article
samaneh ahmadi gheshlaghi
Abstract
Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and is a major component of soil organic matter, which plays an important role in soil aggregation and carbon sequestration. Glomalin is produced only by the AM fungi. On the other hand, stressful environments such as salinity ...
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Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and is a major component of soil organic matter, which plays an important role in soil aggregation and carbon sequestration. Glomalin is produced only by the AM fungi. On the other hand, stressful environments such as salinity can affect the AM fungi .The purpose of this study was to investigate the effect of NaCl salinity on glomalin production by Glomerales in symbiosis with corn plant. A factorial experiment was conducted in completely-randomized design (CRD) with four replications in a greenhouse. Factors were NaCl salinity with three levels (S0: 1.34, S1:4 and S2: 8 dS/m) and mycorrhizal fungi with four levels (non mycorrhizal, Glomus versiforme, G. intraradices, G. etunicatum). The results showed that the interaction of salinity and mycorrhizal fungi on plant dry weight, leaf proline, root colonization percentage, EEG and TG was significant at p
Research Article
Ali reza Karimi
Abstract
Loess deposits of Kopeh Dagh area usually occur patchy, with low thickness and should be identified and differentiated from other deposits for environmental planning and landscape evolution studies. The objective of this study was to identify distribution and determine the characteristics of loess deposits ...
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Loess deposits of Kopeh Dagh area usually occur patchy, with low thickness and should be identified and differentiated from other deposits for environmental planning and landscape evolution studies. The objective of this study was to identify distribution and determine the characteristics of loess deposits and investigate their formation in the Sarakhs area. Thirty surface samples were collected from the study area and analyzed for particle size distribution. Coarse silt and very fine sand are the dominant fraction of the sediments and overally exceed 70%. Dominance of coarse silt and very fine sand, lack of coarse fragments and abrupt boundary of these sediments with underlying materials are evidences of eolian origin. With decreasing very fine sand and increasing coarse silt, sand dunes in the east and center of the area gradually change to loess deposits from Sarakhs city towards Dousti dam (along Hariroud River) and Kopeh Dag heights in the south and west. The maximum thickness of loess sediment occurred around the Dousti dam. Dominance of coarse silt and very fine sand in the sediments and gradual boundary between sand dunes and loess deposits shows the local source of the particles. Kopeh Dagh heights in southern and western parts of the area, like a barrier have trapped eolian sediments and caused their formation.
Research Article
yaghoub dinpazhoh; sabereh darbandi
Abstract
Limited of water resources and the sustainable management, has made it impossible water supply of all needs, therefore, in order to supply water are required careful planning with high reliability. For this reason, is more than ever before the importance of water management in the catchment basin. In ...
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Limited of water resources and the sustainable management, has made it impossible water supply of all needs, therefore, in order to supply water are required careful planning with high reliability. For this reason, is more than ever before the importance of water management in the catchment basin. In this study used dynamics model (Vensim) and genetic programming to simulate the process of rainfall - runoff in Lighvan Watershd. The genetic programming model was tested to get the best combination of input model.The results show high accuracy Vensim model in the simulation of rainfall - runoff process than genetic programming.The results indicate that Vensim model for most events have a highly significant correlation of genetic programming, also is predicted peak flow and minimum absolute error.
Research Article
Abstract
The important step in using the soil particle size distribution (PSD) to predict soil moisture characteristic curve is the determination of accurate and continuous curve for PSD. Many models have been introduced to describe PSD curve and fitting to the experimental data, but their fitting capability ...
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The important step in using the soil particle size distribution (PSD) to predict soil moisture characteristic curve is the determination of accurate and continuous curve for PSD. Many models have been introduced to describe PSD curve and fitting to the experimental data, but their fitting capability in different textural groups have been rarely investigated. The aim of this study was to evaluate the ability of 15 models to fit the experimental data and determine the best model among them for the PSD of all soil samples and for each soil textural groups. In this study, 160 soil samples were collected from subsoil and top soils of Gilan, Hamadan and Kermanshah provinces, and after determining the PSD and soil texture, they were partitioned into three soil textural groups of sandy, loamy and clayey. Fifteen PSD models were fitted to the experimental data of all soil samples. The most accurate model was determined for the total data and for each of three groups based on error criteria. Results showed that the Weibull model was the most accurate model for all soil samples as well as for the clayey and loamy groups. After the Weibull model, the models of Rossini Ramlr, Fredland and van Genuchten were the most accurate ones; however, their differences were not significant at 95% level. The S-Curve model showed the better fit than the other models for the coarse texture group. The results indicated that the different models have higher accuracy in different textural groups.
Research Article
Mohammad Taleai
Abstract
According to predictions, due to population increase and income growth, demand for food will continue to rise by over 3% annually. Wheat with providing over 33% of global world foods is one of the main sources for food security and meeting the needs of increased population. Land suitability assessment ...
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According to predictions, due to population increase and income growth, demand for food will continue to rise by over 3% annually. Wheat with providing over 33% of global world foods is one of the main sources for food security and meeting the needs of increased population. Land suitability assessment (LSA) is one of the basic approaches for obtaining maximum profit while protecting environmental resources for future. In this context, the suitability of arable lands of Miyaneh County is assessed for rain-fed wheat based on the FAO model and Fuzzy-AHP-OWA technique in GIS environment. In this study, with considering regional conditions and previous scientific researches, 8 environmental parameters (depth and texture of soil, erosion, slope, elevation, rainfall, temperature and degree days), 3 economic parameters (cooperatives, distance to markets and communication lines) and a social parameter (force labor) are used for land evaluation. These parameters were aggregated in two-stage using OWA model. Resulted suitability maps based on environmental criteria and fuzzy linguistic quantifier (LQ) includes: at least one, few, some, half, many, most and all, illustrate an overall accuracy, 26.7, 61, 84.3, 57, 44 , 8, 38.5 and 22% respectively, in compared with ground truth map.The final suitability maps based on social and economical criteria present 21.5, 61.8, 88.2, 53.7, 39.6, 38 and 19.3% overall accuracy. Based on this research finding,the proposed approach based on Fuzzy-AHP-OWA has great potential to model land use suitability evaluation problem. In addition, from the used criteria climate, soil, slope, number of co-operatives, distance to markets and communication lines are most important in evaluating land suitability for rain-fed wheat
Research Article
Hemmatollah Pirdashti
Abstract
Soil pollution by heavy metals due to industrial activities, factories, fertilizers and pesticides is an environmental problem which threatens public health. Therefore, it is necessary to find some solutions to ameliorate the negative effects of heavy metals in soil. Accordingly, an experiment was designed ...
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Soil pollution by heavy metals due to industrial activities, factories, fertilizers and pesticides is an environmental problem which threatens public health. Therefore, it is necessary to find some solutions to ameliorate the negative effects of heavy metals in soil. Accordingly, an experiment was designed to evaluate the effect of Trichoderma harzianum fungi as a cadmium (Cd) biosorbent in barley (cv. Sahra) cultivated on a Cd contaminated soil. Treatments were arranged in factorial experiment based a completely randomized design and were replicated three times. Experimental factors consisted of T. harzianum fungi at two levels (inoculated and non-inoculated control) and four levels of cadmium nitrate (0, 50, 100 and 150 mg L-1). Results indicated that Trichoderma inoculation increased barley biological yield (by 36%) as compared to those in non-inoculated plants. Where Cd was added, both Cd amount in soil and Cd bioaccumulation in plants markedly increased. The Cd content in barley root varied from 0.02 mg kg-1 in non-contaminated soil to 688.2 mg kg-1 in 150 mg L-1 contaminated soil. Furthermore, the presence of the Trichoderma significantly increased the Cd uptake in plant roots (from 53 to 96%) in moderate to high levels of cadmium contamination when compared to those in non-inoculated plants. The maximum Cd phytoextraction (5.260 mg per pot) resulted in Trichoderma inoculated plants and at maximum rate of Cd which was 100% greater than untreated plants. In conclusion, it seems that inoculation of Trichoderma with barley plants could be an optimum option to remediate the Cd contaminated soils.
Research Article
Behrooz Azimzadeh; mohammad ali bahmanyar
Abstract
With rising urbanization and change in lifestyle and food habits, the amount of waste material has been increasing rapidly and its composition changing. Vermicomposting is the best method of converting waste material into a useable soil amendment with the use of earthworms and microorganisms. The study ...
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With rising urbanization and change in lifestyle and food habits, the amount of waste material has been increasing rapidly and its composition changing. Vermicomposting is the best method of converting waste material into a useable soil amendment with the use of earthworms and microorganisms. The study began with collecting restaurant waste (as organic waste) from restaurants. The selected wastes were mixed with cow-dung (as bulk material) in various bed combination ratios: 1:0 (100% cow dung), 2:1 (34% restaurant waste + 66% cow dung), and 1:1 (50% restaurant waste + 50% cow dung). For study of liming effect on vermicomposting process, two types of treatments were prepared by adding 1% (w/w) and without limestone in bed combinations. Vermicomposting step started by inoculation 10 fold earthworms Eisenia foetida with 4.46 ± 0.17 g total biomass, approximately. The investigation was conducted in a factorial complete randomized design with six treatments and three repetitions. In during of study, the sampling carried out 3 time per 1 month from each bioreactor and some chemical properties such as pH, electrical conductivity (EC), organic carbon (OC), total nitrogen (TN), exchangeable potassium (Kex) and available phosphorus (Pav) were measured. At the end of study total and immature biomasses of earthworms were determined. The results shown that with increasing in the proportion of waste restaurant and adding 1% lime have led to a rise in nutrients content (TN, Kex and Pav) of vermicompost, significantly. Respectively, vermicomposting has also led to 12%, 53%, 51%, and 19% increasing in EC, TN, P, and K and 5%, 19, and 46% decreasing in pH, OC, and C/N as compared to beginning of the process. Also, bed combination, liming treatment factors, and interaction of them have led to a growth in total and immature biomasses of earthworms. 2:1 vermibed with 1% lime has highest growth and reproductive rate (156% total biomass) between other treatments after 3 month.
Research Article
Mohammad Ghorbanian
Abstract
Many numerical and analytical models have been developed for estimation of soil water distribution in order to increase water use efficiency in drip irrigation. Accurate solution of well-known soil water equation, Richard’s equation, in these models cause more accurate estimation of soil wetting front. ...
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Many numerical and analytical models have been developed for estimation of soil water distribution in order to increase water use efficiency in drip irrigation. Accurate solution of well-known soil water equation, Richard’s equation, in these models cause more accurate estimation of soil wetting front. The purpose of this study was to evaluate finite difference and finite element methods to numerical solution of Richard’s equation for simulating soil water flow around dripper via comparing HYDRUS-2D and SEEP/W numerical models. Experiments were carried out to collect required data to investigate the advance of moisture front inside a Plexiglas box filled with a silt loam soil in central laboratory of water researches in University of Tehran. Wetting front advance at different time intervals were plotted on the transparent Plexiglas box walls. The wetting front around the emitters, for pressures 1.5 and 2.2 meters (equivalent to 4.5 and 6.3 liters per hour, respectively), were measured. Comparison of two simulation models, HYDRUS-2DandSEEP/W, showed that HYDRUS-2D model (finite difference solution method) with higher determination coefficient and lower root mean square error coefficient had better performance to simulate wetted area dimensions for both surface and subsurface drip irrigation.
Research Article
nargess hoseinzadeh; Mohammad hasan Salehi; jahangard mohammadi
Abstract
Now a day, performing soil surveys by minimum time and budget as well as enough accuracy is one of the soil scientists' interests. The present study was investigated to study the effect of sampling density on statistical and geostatistical accuracy of estimation for some of soil properties in Shahrekord ...
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Now a day, performing soil surveys by minimum time and budget as well as enough accuracy is one of the soil scientists' interests. The present study was investigated to study the effect of sampling density on statistical and geostatistical accuracy of estimation for some of soil properties in Shahrekord plain. For this purpose, 240 soil samples (horizon A) with 125 m interval were collected. Then, the physical and chemical analysis included bulk density, soil texture, volume percent gravel, percentage of calcium carbonate equivalent, organic matter, pH and electrical conductivity were determined. The second (120 samples) and third (60 samples) sampling densities were randomly selected the first samplings (240 samples) by considering uniform distribution throughout the region. Results showed that there are no significant differences among the studied soil properties for three sampling intervals. Also, by reducing the number of samples, no regular increase or decrease was observed for coefficient of variation, mean estimation error and root mean square error. The cross validation showed that mean estimation error was close to zero and the root mean square error was low which indicate the acceptable accuracy of estimations. Visual and quantitative interpretation of kriging maps showed high accordance for three sampling densities. Therefore, semi-detailed soil surveys can be replaced for detailed ones which allow saving time and budget.
Research Article
Seyed Hamidreza Sadeghi
Abstract
Awareness of the variety, quality and quantity of sediment transport rates in different time scales, is inevitable for monitoring the hydraulic behavior of channel and flow affected by the mining activities and proper management of sand removal. However, less comprehensive studies have been conducted ...
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Awareness of the variety, quality and quantity of sediment transport rates in different time scales, is inevitable for monitoring the hydraulic behavior of channel and flow affected by the mining activities and proper management of sand removal. However, less comprehensive studies have been conducted on fluvial behavior and characteristics of the bed load under different conditions. The present study therefore aimed to investigate the effect of sand mining with different harvesting and hydrological conditions on particle size distribution and morphometric characteristics of bed sediments for three sand and gravel mines viz. Vaze-e-Olia, Vaze-e-Sofla and Alesh-Roud in Mazandaran Province, Iran. In order to achieve the study purposes, different bed sediments characteristics were computed by GRADISTAT and GIAS softwares after extracting bed sediments morphometric specifications with the help of Gravelometer and Paint software for sampling sites located in the upstream and the downstream of the study mines. The samplings were taken place on monthly basis during a year from February 2012 to January 2013. The results of the study showed that the different natural and sand and gravel mining conditions and other anthropogenic activities affected the particle size distribution and morphometric characteristics of riverbed sediments. According to the statistical analyses, most of the variables were non-significantly (P>0.07) differed in the upstream and the downstream sites in the study mines.
Research Article
Mohammad ali Ghorbani
Abstract
Time series analysis methods have been detected as important tools for evaluating the issues related to water resources management. Spatial differences in streamflow trends can occur as a result of spatial differences in the changes in rainfall and temperature, spatial differences in the catchment characteristics ...
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Time series analysis methods have been detected as important tools for evaluating the issues related to water resources management. Spatial differences in streamflow trends can occur as a result of spatial differences in the changes in rainfall and temperature, spatial differences in the catchment characteristics and human activities and, trend analysis of this time series is necessary in causes of these differences. On the other hand, these series have a different structure, so that the successive values of them are interdependent. In this study has attempted to analyze of this time series for Aji Chai sub basin using of Seasonal Kendall method. In addition, Hurst exponent value, as an effective factor in trend and seasonality of time series, is also evaluated using Variance, R/S and DFA methods. The results showed a significant increasing trend for temperature and, both significant decreasing and increasing trend for precipitation at 10% significance level over sub basin. Also, for discharge, downstream stations showed significant decreasing trend. The analysis results of Hurst exponent estimation methods showed that precipitation and discharge time series have a relatively moderate long term persistence (H~0.65). The Hurst phenomenon existence has also been confirmed as a factor affecting on the seasonality and trend of precipitation and discharge time series using α > 0.5 exponent by DFA method.
Research Article
jalil kakeh; manoochehr gorji
Abstract
Biological soil crusts (BSCs( result from an intimate association between soil particles and cyanobacteria, algae, fungi, lichens and mosses in different proportions, which live on the surface, or immediately in the uppermost millimeters of soil. Biological soil crusts, are important from the ecological ...
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Biological soil crusts (BSCs( result from an intimate association between soil particles and cyanobacteria, algae, fungi, lichens and mosses in different proportions, which live on the surface, or immediately in the uppermost millimeters of soil. Biological soil crusts, are important from the ecological view point and their effects on the environment, especially in rangeland, and desert ecosystems. These effects have encouraged researchers to have a special attention to this components of the ecosystems. The present study carried out in Qara Qir rangeland of Golestan province, Iran, to investigate the effects of BSCs on Soil saline-sodic properties. In the study area, four sites were selected which included sections with and without BSCs. Soil sampling was carried out in each section for depths of 0-5 and 5-15 cm, with four replication. The gathered data from soil samples were analyzed by nested plot. Results showed that BSCs than non-BSCs, significantly decrease the amount of soil acidity, calcium carbonate and soil saline-sodic properties such as electrical conductivity, sodium, calcium and magnesium concentration, sodium adsorption ratio, and exchangeable sodium percentage at both depths. In general, it can be concluded that BSCs enhance soil infiltration rate and available water content, that together their bioaccumulation properties, leads to decreasing soil saline-sodic properties. Potassium concentration did not differ among areas covered by BSCs and without BSCs. But infiltration rate and available water content were increased significantly in two mentioned depths on sites covered with BSCs than without BSCs. In general, it can be concluded that BSCs enhance soil infiltration rate and available water content, that together their bioaccumulation properties, leads to decreasing soil saline-sodic properties.
Research Article
Abstract
تصویر جلد نشریه
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تصویر جلد نشریه
