Research Article
ghassem aghajani mazandarani
Abstract
Introduction: Better use of water and soil resources in paddy fields, increase in rice production and farmer's income, installation of subsurface drainage system is necessary. The main goalof these systems, are aeration conditions improvement prevention of water logging, yield increase, land use increase ...
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Introduction: Better use of water and soil resources in paddy fields, increase in rice production and farmer's income, installation of subsurface drainage system is necessary. The main goalof these systems, are aeration conditions improvement prevention of water logging, yield increase, land use increase and multiuse of the land. In different countries, installation of subsurface drainage cause yield increase and working condition on the land, but no research has been conducted in different depths and spacing. On the other hand, spacing and depth are the most important parameters in the installation of drainage systems, have a direct effect on incoming water into the drains. The aim of this research, is an investigation of the effect of subsurface drainage with different depths and spacing on discharge rate variation and water table fall, in order to analyze the improvement of water flow movement in the soil. Also, study the effect of different drainage systems on the increase of the canola yield as the second cultivation in these treatments have been compared.
Materials and Methods: To measure hydraulic conductivity in different depths, the auger holes have been dug (excavated). The saturated hydraulic conductivity in these holes wasdetermined using Ernst method (1950) before installation of drainage systems. In the drainage pilot plot of Sari Agricultural Sciences and Natural Resources University three subsurface drainage systems with mineral envelope have been installed. 1- The first one with the 0.9 m depth and 30 m spacing (D90 L30), 2- The second one with 0.65 m depth and 15 m spacing (D0.65 L15) and 3- The third one with 0.65 m depth and spacing (D0.65 L30) and one bi-level system with mineral envelope including four drains of 15 m spacing with 0.9 m and 0.65 m depths were installed alternatively. After auger hole equipment installations, in the middle spacing of two subsurface and water table reading possible, the water table fluctuation and drain outlet discharge rate from farm drains during canola growing season were measured on a daily basis. Also, canola yield during 4 years after drainage systems were monitored.
Results and Discution: The results showed that mean discharge rates of drainage systems have increased with time and in the fourth year it was better than first and second years. Duringthe second year, the highest discharge rate onthe first day was in the low depth treatment and after 3 days the discharge rates become the difference among less. In the third year, the discharge rates of high spacing drains (D0.65 L30) have become higher than of spacing drains (D0.65 L15) discharge rates. But, in the first day its discharge rate was less and one can conclude that it is due to horizontal flow. With passing time and soil structure improvement, one can observe better yield from drains with higher spacing (30 m) also. By performance of drainage and soil conditions improvement in the third and fourth year, the deeper drainage systems have becomes better and water table fall of deep drain discharge rate and soil condition improvement in these systems become higher. In bi-level drainage, by increasing deep percolation, the water table fall in this treatment increased with time. Also, based on monitoring water table, in the first and second years after 5th day and in the third and fourth years after 4th day the water tables of deep drains decreased to lower depth drains. Due to heavy soil in paddy fields and existence of hardpan, the performance of low depth drains in falling water table was better in the first years. With passing time and performance of drainage the conditions for water movement in the soil become better and performance of deep drainage systems improved and at the fourth year, deep drainage systems had better performance in draining water with respect to low depth drainage systems. Also, canola yield as second cultivation, has increased from first to fourth year and along with important of soil aeration conditions and performance of drainage systems, the grain yield hasincreased in different drainage treatments. The results showed a direct relationship between improvement of system performance and increase in grain yield. In the second year, grain yield increased in all treatments. On the other hand, the yield under drainage systems with deeper depth (D0.9 L30) even higher in the 2nd and 4th years than with low depth drain (D0.65 L30). This was because of more fall in water table levels during days after rainfall and also with next rainfall, saturation of soil up to surface layer in the plots with deeper drains were performed later and it may not reach up to thesoil surface.
Conclusion: Due to betterconditions of deep drains and with higher spacing in the improvement of paddy field use and also less environmental harm use of drains with higher spacing are recommended for these lands. On the other hand,a low increase in drain depth from 0.65 m to 0.9 m along with increase in spacing of30 m with respect to 15 m and even with 0.65 m depth, will have less cost. Due to decrease in the costs of drain installation with higher spacing, due to improvement of conditions, the performance of these systems in 2 to 3 years one can have cheaper drainage systems in the longest time and will improve the economic situation of farmers due to higher yield.
Research Article
Malihesadat Jafari; Seyed Ali Ayyoubzadeh; Mahdi Esmaeilivaraki; Mohammad Rostami
Abstract
Introduction: Bridges are certainly one of the most important structures but costly service elements in a transport system. The bridges are very required to access the damaged areas in emergency situations such as floods and earthquakes. Scour around the foundations of bridge piers exposed to the flowing ...
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Introduction: Bridges are certainly one of the most important structures but costly service elements in a transport system. The bridges are very required to access the damaged areas in emergency situations such as floods and earthquakes. Scour around the foundations of bridge piers exposed to the flowing water than can destroy the bridge itself is a subject of major concern. Flow pattern is known as responsible for all changes in stream bed. Any obstacle in the channel can form new flow patterns causing additional shear stress exerted on the bed than the equilibrium condition of the absence of the obstacle. Appropriate shaping of flow pattern and proper selecting of pier geometry and the location of bridge piers can be one of the proper methods in reduction of scour amount which is the main subject of the present study.
Materials and Methods: Inclined bridge group pier is a type of bridges with modern geometry based on development in building technology of structures. Many of these bridges have been built all around the world and the 8th bridge built crossing the Karun River in Ahvaz is a sample of the Iranian ones considered in this research. Hydrodynamic behavior of flow is investigated around the inclined bridge group pier settled on foundation using the FLOW-3D numerical model. Inclined bridge group pier investigated in this study, includes two rectangular piers which are 2.5 cm long and 3.5 cm wide and set in an angle of 28 degree on rectangular foundation which is 16 cm long and 10 cm wide and installed in three different foundation levels namely at, above and below the bed levels. The physical model of prototype pier considered in this study was constructed to the scale of 1:190 of the Ahvaz 8th bridge. In order to verify the accuracy of the numerical model, velocity data obtained from image processing technique were used.
Results and Discussion: Due to non- linearity and interactions between various phenomena involved, flow pattern around the piers group is entirely different than that for a single pier and consequently the outcomes of the flow pattern around single pier cannot be generalized to the pier group. At all levels of foundation setting, longitudinal component of flow velocity increases surrounding the first pier. The increase in the area and its extension towards downstream is caused by the constriction the flow due to the pier and area rotating of the wake vortex in downstream. When the pier foundation is set at the stream bed, the bed rotating flows extend to a distance between the two piers from near the bed up to the middle of flow depth while in upstream of the second pier and near water surface, the stream lines become parallel to the bed. The comparison of the results of the changes in bed shear stress in the situations of foundation setting in different levels showed that the maximum shear stress occurred when the foundation level is at the bed level and the maximum shear stress exerted on the bed decreases by factors of 17% and 53% in the cases of foundation level to be below and above bed levels, respectively. In addition, the results showed that, the amount of vortex flows increased in upstream piers group and near bed in the case of setting the foundation above the bed. This is because of the fact that the volume of piers group acted as obstacle against flow was more than other level settings. Furthermore, based on the obtained results, in the case of foundation level is set at the bed, the quantity and development zone of vortex flow are much higher than those observed when the setting foundation is below the bed level. This can be attributed to the higher effect of the second pier on the flow pattern being between the first and the second piers. Stream lines turn downward in the range between piers group, and after the collision to bed turn upward to water surface and cause to form rotating flow and hence high turbulence intensity in the area. In the near water surface and the center of group piers, stream lines were observed to be parallel to the bed and caused low turbulence intensity in this area.
Conclusions: The results showed that the levels of setting foundation have a significant effect on hydrodynamic characteristics and flow pattern around the piers. By increasing the dimensionless height of the setting foundation from -1 to 0.5 vortices formed in the downstream piers group is strengthen more and the results from the numerical model are consistent with the results of experimental scour around piers group in all three levels of setting foundations. When the foundation setting is at the bed level, the maximum bed shear stress is observed. The maximum bed shear stress is decreased by factors of 17 and 53 percent when the foundation to be set below and above bed levels, respectively.
Research Article
Zahra Abdollahi; Ataollah Kavian; kaka shahedi; neda Abdollahi; Mohammad Jafari
Abstract
Introduction: River discharge as one of the most important hydrology factors has a vital role in physical, ecological, social and economic processes. So, accurate and reliable prediction and estimation of river discharge have been widely considered by many researchers in different fields such as surface ...
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Introduction: River discharge as one of the most important hydrology factors has a vital role in physical, ecological, social and economic processes. So, accurate and reliable prediction and estimation of river discharge have been widely considered by many researchers in different fields such as surface water management, design of hydraulic structures, flood control and ecological studies in spetialand temporal scale. Therefore, in last decades different techniques for short-term and long-term estimation of hourly, daily, monthly and annual discharge have been developed for many years. However, short-term estimation models are less sophisticated and more accurate.Various global and local algorithms have been widely used to estimate hydrologic variables. The current study effort to use Lazy Learning approach to evaluate the adequacy of input data in order to follow the variation of discharge and also simulate next-day discharge in Talar River in KasilianBasinwhere is located in north of Iran with an area of 66.75 km2. Lazy learning is a local linear modelling approach in which generalization beyond the training data is delayed until a query is made to the system, as opposed to in eager learning, where the system tries to generalize the training data before receiving queries
Materials and Methods: The current study was conducted in Kasilian Basin, where is located in north of Iran with an area of 66.75 km2. The main river of this basin joins to Talar River near Valicbon village and then exit from the watershed. Hydrometric station located near Valicbon village is equipped with Parshall flume and Limnogragh which can record river discharge of about 20 cubic meters per second.In this study, daily data of discharge recorded in Valicbon station related to 2002 to 2012 was used to estimate the discharge of 19 September 2012. The mean annual discharge of considered river was also calculated by using available data about 0.441 cubic meters per second. To estimate the discharge of considered day, three methods of constant, linear and quadratic functionscontrollers based on the local linearization provided by the lazy learning algorithm were considered. Lazy learning is a memory-based linear technique for local modeling approach which is reported as a high-efficient algorithm for simulating variables with low input data.The series of input data was categorized into previous 6, 8, 10, 15 and 20 days, 1 and 2 months, 1, 2 and 3 seasons and also 1 and 2 years to evaluate which series is appropriately enough to predict next-day discharge inthe river. Then, mean absolute error and root-mean square error were calculated for all series and modelsin order to find the best estimator model and the most appropriate series of input data.
Results: Results showed that constant and linear model had the minimum root-mean square error of 0.001 and 0.057 respectivelywith previous 60 days’ data series. Whilethe quadratic model had its best estimation with previous 2 season data series with the minimum root-mean square error of 0.059. The result indicated that the more input data increase, the best quadratic model estimate until 60 days. But after 60 days, estimation error gradually increased. Consequently, not more data but adequate areneeded for accurate estimation. Also, RMSE in linear model had less fluctuation and therefore less sensitivity compared with other models. And quadratic model had less fluctuation and sensitivity to neighborhoods. Also, according to results, the more variation in each period increase, the better estimation is accrued by lazy learning algorithm. Hence, it was expected that next-day discharge prediction in low-water period needs longer data series than high-water period.
Conclusion: Regarding to thousands of prepared training models, constant model with previous 60 days’ data and minimum error of 0.0001 was selected as the most accurate estimatefor next-day river discharge in Talar River. Results showed that despite of some limitation and demerits, the local Lazy Learning algorithm has significant efficiency in time series simulating. Although the accuracy of simulation increase with more input data, but this algorithm can runby at least 5 training data. However we find lazy learning to be the best performing approach on average goodness indicators (such as mean absolute error and Root-mean square error). On the other hand, the lazy learning predictor can be quickly developed and easily kept up-to-date by adding new data to its database. Also, it does not face with overfitting problems which are common in global modeling approaches.According to some noteworthy features of lazy learning noticed in this regards, this approach will have good performance for time-series studies.
Research Article
sajjad razavi; kamran davary; Bijan Ghahraman; Ali Naghi Ziaei; azizallah izady; kazem esahgian; mehri shahedy; fatemeh taleby
Abstract
Limitation of water resources in Iran motivates sustaining and preserving of the resources in order to supply future water needs. Fulfilling these objectives will not be possible unless having accurate water balance of watersheds. The purpose of this study is to estimate the water balance parameters ...
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Limitation of water resources in Iran motivates sustaining and preserving of the resources in order to supply future water needs. Fulfilling these objectives will not be possible unless having accurate water balance of watersheds. The purpose of this study is to estimate the water balance parameters using a distributed method. The large number of distributed models and methods was studied and “Quasi Distributed Water Balance model” (QDWB) was written in the MATLAB programming environment. To conduct this model, it is needed that each data layer (precipitation, potential evapotranspiration, land use, soil data,..) to be converted into grid format. In this research the 500m * 500m cell size was used and water balance parameters for each cell was estimated. Runoff and deep percolation obtained from surface balance equation and irrigation needs were estimated based on soil moisture deficit. The study area of 9157 square kilometers is Neyshabour- Rokh watershed. The results showed there is a good correlation between water balance parameters such as precipitation-runoff, precipitation-evapotranspiration, and precipitation- deep percoulation and demonstrate that QDWB model is consistent with the basin hydrological process.Change in soil moisture at basin wide is 1 MCM in 1388-89 and 40 MCM in 1380-81. The evapotranspiration results from a distributed model” SWAT” and QDWB model were in good agreement.
Research Article
ELNAZ Rezaei abajelu; KAMRAN Zeinalzadeh
Abstract
Introduction: Soil Hydraulic conductivity is considered as one of the most important hydraulic properties in water and solutionmovement in porous media. In recent years, variousmodels as pedo-transfer functions, fractal models and scaling technique are used to estimate the soil saturated hydraulic conductivity ...
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Introduction: Soil Hydraulic conductivity is considered as one of the most important hydraulic properties in water and solutionmovement in porous media. In recent years, variousmodels as pedo-transfer functions, fractal models and scaling technique are used to estimate the soil saturated hydraulic conductivity (Ks). Fractal models with two subset of two (solid and pore) and three phases (solid, pore and soil fractal) (PSF) are used to estimate the fractal dimension of soil particles. The PSF represents a generalization of the solid and pore mass fractal models. The PSF characterizes both the solid and pore phases of the porous material. It also exhibits self-similarity to some degree, in the sense that where local structure seems to be similar to the whole structure.PSF models can estimate interface fractal dimension using soil pore size distribution data (PSD) and soil moisture retention curve (SWRC). The main objective of this study was to evaluate different fractal models to estimate the Ksparameter.
Materials and Methods: The Schaapetal data was used in this study. The complex consists of sixty soil samples. Soil texture, soil bulk density, soil saturated hydraulic conductivity and soil particle size distribution curve were measured by hydrometer method, undistributed soil sample, constant head method and wet sieve method, respectively for all soil samples.Soil water retention curve were determined by using pressure plates apparatus.The Ks parameter could be estimated by Ralws model as a function of fractal dimension by seven fractal models. Fractal models included Fuentes at al. (1996), Hunt and Gee (2002), Bird et al. (2000), Huang and Zhang (2005), Tyler and Wheatcraft (1990), Kutlu et al. (2008), Sepaskhah and Tafteh (2013).Therefore The Ks parameter can be estimated as a function of the DS (fractal dimension) by seven fractal models (Table 2).Sensitivity analysis of Rawls model was assessed by making changes)±10%, ±20% and±30%(in input parameters (porosity, fractal dimension and the intake air suction head).Some indices like RMSE, AIC and R2 were used to evaluate different fractal models.
Results and Discussion: The results of the sensitivity analysis of Rawls - Huang model, showed the least sensitivity to changes in porosity and suction entry air and the most sensitivity to changes in fractal dimension. The saturated hydraulic conductivity is underestimated by increasing the fractal dimension in Rawls - Huang model. The high sensitivity of the combined model to changes in fractal dimension, is considered as one of the model limitations.In other words, fractal dimension underestimation increased the error related to the hydraulic conductivity estimation. Sensitivity analysis of Ks regression model was done among parameters like bulk density, dry density, silt, sand, fractal dimension of particle size and porosity. Results showed less sensitivity to fractal dimension and porosity. The highest RMSE was 0.018 for fractal dimension and porosity (in the range of ±30% changes). The results showed that the amount of clay in the estimation of fractal dimension is of crucial importance. Statistical analyzes indicated the high accuracy of the PSF models based on soil texture data.Error indices showed the high accuracy of Rawls and three-phase fractal (pore- solid- fractal) models combination in estimating the Ks value. The results suggest that Huang and Zhang model, with the highest correlation, the least Root Mean Square Error and the least Akaike criteria among the studied fractal models for estimation of the Ks values. Fuentesand Hunt models, overestimated soil saturated hydraulic conductivity. Fuentes et al. (1996) as an experimental fractal model to estimate the saturated hydraulic conductivity indicatedvery poor results. Bird model had higher error values compared with the best model, (RMSE =0.73). This model fit well with the measured values compared to Sepaskhah and Taylor models particularly at low Ksvalues. Taylor's two-parameter model, which is similar to the Brooks - Corey and the Campbell model, was inserted in the fourth priority. The RMSE values of Sepaskhah and Taylor models were 0.62 (cm/h) and 0.55(cm/h) respectively. The fractal dimension is a function of soil texture. Heavy soils resulted in a larger fractal dimension and less hydraulic conductivity. Therefore, the Huang-Zhang model as a result of clay value using model (lower values for Ks), had a close fit with the measured data in probability distribution.
Conclusions: The results showed that the soil clay percent had a significant role in fractal dimension calculation.
Research Article
Parvaneh KazemiMeresht; Shahab Araghinejad
Abstract
Introduction: In spite of improving the water productivity due to development in water infrastructure systems, population increasing causing the water withdrawal is triple in the last fifty years. In this situation competition on water consumption especially in the agricultural sector which is the biggest ...
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Introduction: In spite of improving the water productivity due to development in water infrastructure systems, population increasing causing the water withdrawal is triple in the last fifty years. In this situation competition on water consumption especially in the agricultural sector which is the biggest consumer in the world and also in Iran is a severe problem. Water allocation has been assessed widely in the recent past. Additionally, several studies have explored methods to incorporate conflict resolution methods in water allocation. In a general classification, there are two types of methods. One is the method based on game theory, graph theory and general models based oncooperative game into a category that has the ability to consider the stakeholder preferences and assess the several scenarios under specified policy. Although this type of methods iseligible to cooperate the stakeholder in modeling but due to their weakness on considering the information on details and their limitations in adoption with changes caused from uncertainty, they are not popular in practical cases. Another type of conflict resolution method which is eligible to considering more detailed information of systems has the optimization approach basically, has the most interests between researchers. There is namely the Nash bargaining solution, the Kalai-Smorodinesky solution, the Equal loss solution and the area monotonic solution. There are several studies which areapplied these methods to investigate about groundwater (5, 6 and10). There are a few applications of water resource allocation models which is incorporated with conflict resolution methods in Transboundary Rivers nowadays and restricted to game theory related methods (1 and 2). The aim of this study is the assessment of the application of conflict resolution methods such as symmetric and non symmetric Nash solution, non symmetricKalai-Smorodinesky, non symmetric equal loss solution and finally the area monotonic solution in water allocation between beneficiary's provinces in Atrak basin. The performances of these methods are compared with each other and also with the common water allocation model.
Materials and Methods: In the last decades, Atrak river basin located at the eastern north of Iran, shared between three provinces; Razavi Khorasan, northern Khorasan and Golestan, has a tense conflict between upstream and downstream beneficiaries. It is predictable that this conflict will be more tense in the near future due to development of upstream and increasing the water withdrawal. Because of the venial role of the Razavi Khorasan province in the Atrak basin, this province is considered as a coalition with northern Khorasan. Related data for 41 years time series and other information were gathered. Due to Hydrology studies, wet and dry periods in the two regions have not differences. As a fact that the main problem of water allocation belongs to the agricultural sector and it is the biggest consumer in the region, supply of the municipal, industrial and environmental requirement is assumed.To begin, a linear programming model is developed to optimize the agricultural water resource allocation using the LINGO® which is a comprehensive tool designed to make building and solving Linear, Nonlinear (convex &nonconvex/Global), Quadratic, Quadratically Constrained, Second Order Cone, Stochastic, and Integer optimization models faster, easier and more efficient. In the second place, conflict resolution methods such as symmetric Nash, non symmetric Nash, Kalai-Smorodinsky, equal loss, uniform area solutions are applied as an object function of water allocation models one by one. In all of these methods the stakeholder preferences should be defined with their weights in the object function. Moreover, the mentioned models are assessed with performance criteria such as reliability in time and in volume and also the resiliency.
Results and Discussion: Comparison of the results of 4 water allocation models using conflict resolution methods besides the common water allocation model using LP is shown in the figure 3 which shows the differences between models in mean of Agricultural water deficit in both provinces separately.
Figure 3- Mean of long term of agricultural deficit in different models
As mentioned before water allocation models are evaluated with performance criteria and the result is revealed in the table3.
Table 3- Comparison of conflict resolution models using the performance criteria
Reliability in time
(%) Reliability in volume
(%) Resiliency
(%)
Golestan Khorasan Total Golestan Khorasan Total Golestan Khorasan Total
LP 100 20 26 100 31 55 100 18 23
Nash 41 34 36 57 54 55 38 33 42
Kalai 32 37 29 50 54 53 25 38 31
Loss 12 39 34 41 57 52 11 40 37
Area 59 12 8 64 17 34 41 14 9
It is clear that models which have the Nash, Kalai-Smorodinesky, Equal Loss, Area Monotonic solution as the object function produce an equitable allocation between two stakeholders in comparing with the LP.
Conclusion: Without better management in agricultural water in the future which is treated by increasing population and changing the climate, growing conflicts between stakeholders are expected. In this study application of conflict resolution methods in water allocation models in Atrak basin is considered. Comparison of models in terms of their performance to allocate water equitably between two beneficiary provinces is appraised. Results revealed that the conflict resolution methods have the same action in water allocation in general though; the Nash has desirable results than others. All the conflict resolution models have the better performance in general in comparison with the common water allocation model using the linear programming. To conclude, the dependencies of results to provinces weights are appraised. Application of conflict resolution methods are proposed instead of common water allocation models without stakeholder's preference consideration due to water allocation between several stakeholders equitably.
Research Article
elham kalbali; Mahmood Sabouhi; mahmoud ahmadpour
Abstract
Introduction: In the present study, dealing with water deficit challenges for Gorgan River Basin has been considered. Golestan province's economy is dependent on agriculture but the occurrence of drought periods reduced the agricultural production and consequently the region's economy is in crisis. Therefore, ...
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Introduction: In the present study, dealing with water deficit challenges for Gorgan River Basin has been considered. Golestan province's economy is dependent on agriculture but the occurrence of drought periods reduced the agricultural production and consequently the region's economy is in crisis. Therefore, performing studies for programming and management of the water resources of the province and the water allocation in the margin of Voshmgir dam in Gorganrood basin has a great deal of importance. The issue of the allocation of water resources is proposed in order to maximize the expected profit of the water system. According to the regional water organization policy, one of the main goals of Voshmgir dam water management is the allocation of water between the competing consumers. If the amount of promised water is released in the future, the expected net profit of the system will be realized and if it is not released, the system will experience losses.
Materials and Methods: In this studyWater supply is considered stochasticand objective function of the model is to maximize the system (Agriculture, Aquaculture and Environment) profit and optimal allocation of water during the programming period using a two-stage stochastic model as follows:
Constraint of the available land:
Constraint of the available water in each of the main canals:
Constraint of the available water:
Constraint of the amount of inflow water
Reservoir capacity constraint
Constraint on the maximum and minimum water demand for environmental sector
Constraint on the maximum and minimum water demand for crops
Constraint on the maximum and minimum water demand for warm-water fish
Constraint on non-negativity of the decision variables in the model
Results and Discussion: The length of the right main canal of this network is about 17.76 km and the length of the left main canal is about 21.338 km. In this study, is considered for the right main canal and is considered for left main canal. Lands under irrigation network are considered in three regions. Right bank regions and sample farm are covered by the network in the right part of the network and the left bank regions are covered by the network on the left. Thus, there is one region in the left side of the network and there are two regions on the right. The major crops cultivated in the agricultural lands of the network include wheat, barley, canola, cotton, alfalfa, sunflower, rice, cotton-melon, and maize. Due to the random nature of the river flow to the dam, fixed and determined data cannot be used to calculate the volume of water entering the irrigation system, for this reason, using simulation techniques, we can predict the future behavior of the system for each reservoir. The results of the study showed that only agriculturalsector suffers from water deficit and target water demand of the other sectors is supplied and there is no deficit of water for these sectors and target water demand, lack of water and the final allocation of water in the agricultural sector are declined under different efficiencies of irrigation. If other sectors are remained unchanged and irrigation efficiency did not affect them, it is because irrigation efficiency has a direct impact on the water use in agriculture and decreases by increasing the efficiency of the allocated water to this sector and the amount of water stored in the reservoir for the coming year is added. By increasing the efficiency of irrigation which has a direct impact on water use in agriculture sector, the amount of water deficit reduced as a result of the increased system profit.
Conclusion: The results showed that there is no water deficit for aquaculture and environmental sectors in the scenarios of dry, wet and normal years and the target water demand of these sectors is supplied. However, the amount of water deficit in agricultural sector in dry year with the probability of 18% and under the efficiencies of 37, 45 and 51 percent would be 40.98, 23.67 and 14.07, respectively. With the increase in efficiency, water demand in agriculture, water deficit and ultimate allocation of water to this sector are decreased and system profit under different efficiencies is increased. Based on the obtained results, highlighting the irrigation efficiency and allocating the minimum water demand of the sectors is recommended.
Research Article
Amir Parnian; Mostafa Chorom; Nematolah Jafarzade Haghighy Fard
Abstract
Introduction: With increasing of population and the valuable water resource pollutions, a demand has been felt for new and inexpensive methods in order to remediation and improving of water quality. Cadmium is a trace element. In low concentration, this heavy metal is harmful to life, and considered ...
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Introduction: With increasing of population and the valuable water resource pollutions, a demand has been felt for new and inexpensive methods in order to remediation and improving of water quality. Cadmium is a trace element. In low concentration, this heavy metal is harmful to life, and considered as a dangerous pollutant. Cadmium leads to pollution and reduction of water quality; sometimes even toxicity through contaminated sources such as wastewater (Agricultural, municipal and industrial). Phytoremediation with aquatic macrophytes is an effective and inexpensive method for improving water quality and wastewater. The aim of this study was to investigatethe cadmium phytoremediation by Ceratophyllumdemersum L. as a potential method for remediation of cadmium pollution in aquatic medium.
Materials and Methods: In this study, the remediation of cadmium pollution in aquatic medium monitored, within 14 days cultivation of coontail (Ceratophyllumdemersum L.). At first, for estimating the level of local wastewater cadmium pollutions, five-month cadmium concentration measurement of steel industrial wastewater and urban wastewater set. Then, plants collected from the irrigation channels of ShahidChamran University of Ahvaz. After finding the best pH of nutrient solution for Ceratophyllumdemersum L. growth by cultivating the plants in 2 liters pots filled by the solutions withthree different pH(5.5, 7 and 9.5) within three weeks; 12 grams of plants cultivated in 2 liters of Hoagland nutrient solution contaminated by cadmium(pH = 7). The initial contamination levels were setasfive different concentrations of cadmium (0, 1, 2, 4, and 6 mg l-1) with three replications. The cadmium concentrations of the pots were measured every day and on the last day of cultivation, plants wet weight, plants dry weight and Cd concentration in plants weremeasured. Then,biomass production, Cd bioconcentration factor (BCF), Cd uptake index, and Cd uptake percentage of plants were calculated. Standard deviations calculationand correlation and regression analysis were performed using Microsoft Office Excel2007 and SPSS 16. One-way ANOVA performed to identify significant differences in metal concentrations in the different treatments. Differences considered significant atp < 0.05.
Results and Discussion: Among three pH (5.5, 7 and 9.5) for plants cultivation, C. demersum L.grewbetter in pH = 7. In fact, the average amount of produced biomasses were 46.6 g (pH = 5.5), 79.6 g (pH = 7) and 68.4 g (pH = 9.5). Therefore, to investigate the Cd remediation, the pH of nutrient solution set equal to 7. The final Cd concentrations in nutrient solution for initial Cd concentrations of 1, 2, 4 and 6 mg l-1 were 0.30, 0.36, 2.76 and 3.85 mg l-11respectively. Moreover, the Cd uptake percentage after 14days cultivation of C. demersum L.in nutrient solution for initial Cd concentrations of 1, 2, 4 and 6 mg l-1 were 70.00, 82.01, 31.00 and 35.83 %respectively. Cd uptake percentage of plants for initial concentrations of 4 and 6 mg l-1weresignificantly lesser than those of 1and 2 mg l-1.The decreased uptake efficiency percentage maybe caused by the effect of Cd toxicity on plant cell membrane permeability and efficiency.The average of BCF in plants for initial Cd concentrations of 1, 2, 4 and 6 mg l-1 were 384.4, 707.9, 66.5 and 75.0respectively. High reduction ofBCF amounts with increasing the initial concentration of 2to 4 and 6mg l-1, maybe caused by cadmium physiological adverse effects on plants. The averages of uptake index in plants were 1.26, 2.95, 2.24 and 3.92 mg for initial Cd concentrations of 1, 2, 4 and 6 mg l-1respectively. The results showed a reduction between 2 and 4 mg l-1concentrations that probablycaused by Cd toxicity disruption on plants uptake mechanism and growth. Moreover, the increase of plants uptake index in initial concentration of 6 mg l-1 could be explain by partial losing of the selective permeability of the plants cell membrane. The maximum (3.60 g/day) and minimum (1.62 g/day) of biomass production related to pollutant concentrations of 0 and 6 mg l-1 respectively, and it shows a greatefect of the Cd on C. demersum L.growth.
Conclusion: The plant accumulated cadmium efficiently, and the remediation efficiency was near to 82%. However, the pollutant removal was not complete in a short time.In total, phytoremediation of cadmium and other pollutants from wastewater or other aqueoussolutions by Ceratophyllumdemersum, as a native aquatic plant of most of Iran’s rivers, could be anefficient and appropriatemethod.
Research Article
Ahmadreza Sheikhhosseini; H. Shariatmadari; M. Shirvani
Abstract
Introduction: Pollution of soil and water environment by release of heavy metals is of great concerns of the last decades. Sorption of heavy metals by low cost materials is considered as an inexpensive and efficient method used for removal of heavy metals from soil-water systems. The presence of different ...
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Introduction: Pollution of soil and water environment by release of heavy metals is of great concerns of the last decades. Sorption of heavy metals by low cost materials is considered as an inexpensive and efficient method used for removal of heavy metals from soil-water systems. The presence of different ligands with various complexing abilities can change the sorption properties of heavy metals and their fate in the environment as well. In order to assess the effect of citrate and arginine as natural organic ligands in soil environment, in a batch study we investigated the effects of these ligands on equilibrium sorption of nickel to sepiolite and calcite minerals and also kinetics of Ni sorption by these minerals.
Materials and Methods: Minerals used in this study included sepiolite from Yazd (Iran) and pure calcite (Analytical grade, Merck, Germany). Sepiolite was purified, saturated with Ca using 0.5 M CaCl2, powdered in a mortar and sieved by non-metal 230 mesh standard wire sieve. For equilibrium sorption study, in a 50-mL polyethylene centrifuge tube,0.3 g sample of each mineral was suspended in 30 mL of a 0.01 M CaCl2 solution containing 0, 5, 10, 20, 40, 60, 80 and 100 mg L-1 Ni (NiCl2) and containing zero (as control) or 0.1mmol L-1 citrate or arginine ligands. The applied concentrationsfor each ligand can naturally occur in soils. Preparedtubes were shaken (180±2 rpm, 25±1oC) for 24 h using an orbital shaker and centrifuged (4000×g for 10 min) and the supernatants were analyzed for Ni concentration using an atomic absorption spectrophotometer (AAnalyst 200 Perkin-Elmer) at a wavelength of 232 nm and a detection limit of 0.05 mg L-1. The quantity of Ni retained by each mineral at equilibrium was calculated using equation qe = (Ci - Ce)V/W where qe was the amount of nickel retained by mineral surface at equilibrium. Ci and Ce were the initial and the equilibrium concentrations (mg L-1) of Ni, respectively, V was the volume (L) of the solution, and W was the mass (g) of the sorbent. The Langmuir, Freundlich and linear isotherm models were fitted to sorption data using Graphpad prism 5.0. For kinetic study,30 mL of 0.01 M CaCl2 solution, with or without 0.1 mM citrate or arginine, containing Ni at a concentration corresponding to the maximum sorption capacity of each mineral (estimated from sorption isotherms) were transferred into 50-ml polyethylene centrifuge tubes containing 0.3 g of sepiolite or calcite. The suspensions were shaken (180±2 rpm, 25 °C) continuously and after 0.5, 1.5, 3, 6, 12, 18 and 24 hours, corresponding tubes were centrifuged (4000×g for 10 min) and supernatants were analyzed for Ni concentration by atomic absorption spectrophotometer. Using Graphpad prism 5.0, kinetic data were fitted to Pseudo-first order, pseudo-second order and power function kinetic models.
Results: With or without ligands, the Langmuir model was the best description of Ni sorption to sepiolite while the linear model was the best fit of calcite data showing the physical nature of Ni sorption by this mineral. Kinetics of Ni sorption to sepiolite and calcite were best described by power function model. In the presence of citrate, both capacity and rate of sorption of Ni to sepiolite decreased. There was no considerable change in sorption of Ni to calcite. In the presence of arginine, however, sorption capacity of minerals for Ni increased. Arginine enhanced the rate of Ni sorption on all three minerals. Citrate showed opposing effects on Ni sorption kinetics depending on the studied minerals. Totally, citrate and arginine had opposite effects on sorption of Ni to sepiolite and calcite.
Conclusion: Organic ligands can change sorption characteristics of the minerals. It seems that citrate decreases sorption of Ni to sepiolite but its effect on Ni sorption to calcite is negligible, while arginine increases Ni sorption to both minerals. Our results suggested that presence of citrate and arginine in soil influence Ni sorption by soil minerals. As in warmer seasons of year,microbial activities due to optimum temperature and moisture result in production of citrate and argininewhich facilitate and suppress uptake of Ni by plants respectively. Production of citrate in soil may increase risk of Ni contamination of underground and surface water sources while arginine can decrease soil solution Ni and in turn the risk of water contamination.
Research Article
morteza akbari; Ehsan ranaee; Hasan Mirzakhan; Alireza Dargahi; Mohammadreza Jargeh
Abstract
Introduction: Snowmelt runoff plays an important role in providing water and agricultural resources, especially in mountainous areas. There are different methods to simulate the process of snowmelt. Inter alia, degree-day model, based on temperature-index is more cited. Snowmelt Runoff Model is a conceptual ...
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Introduction: Snowmelt runoff plays an important role in providing water and agricultural resources, especially in mountainous areas. There are different methods to simulate the process of snowmelt. Inter alia, degree-day model, based on temperature-index is more cited. Snowmelt Runoff Model is a conceptual hydrological model to simulate and predict the daily flow of rivers in the mountainous basins on the basis of comparing the accuracy of AVHRR and TM satellite images to determine snow cover in Karun Basin. Additionally, overestimation of snow-covered area decreased with increasing spatial resolution of satellite data.Studies conducted in the Zayandehrood watershed dam, showed that in the calculation of the snow map cover, changes from MODIS satellite imagery, at the time that the image does not exist, using the digital elevation model and regression analysis can provide to estimate the appropriate data from satellites. In the study of snow cover in eastern Turkey, in the mountainous regions of the Euphrates River, data from five meteorological stations and MODIS images were used with a resolution of 500 m. The results showed that satellite images have a good accuracy in estimating snow cover. In a Watershed in northern Pakistan in the period from 2000 to 2006, SRM model was used to estimate the snow cover using MODIS images. The purpose of this study was to evaluate the snowmelt runoff using remote sensing data and SRM model for flow simulation, based on statistical parameters in the Kardeh dam basin.
Materials and Methods: Kardeh dam basin has an area of about 560 square kilometers and is located in the north of Mashhad. This area is in the East of Hezarmasjed – kopehdagh zone that is one of the main basins of Kashafrood. This basin is a mountainous area. About 261 km of the basin is located at above 2000 m. The lowest point of the basin is at the watershed outlet with1300 meters and the highest point in the basin, in the North West part of the basin with 2962 meters above sea level. Kardeh dam was primarily constructed on the Kardehriver for providing drinking and agriculture water demand with an annual volume rate of 21.23 million cubic meters.
Satellite image: To estimate the level of snow cover, the satellite Landsat ETM+ data at path 35-159, rows 34-159 over the period 2001-2002 were used. Surfaces covered with snow were separated bysnow distinction normalized index (NDSI), But due to the lack of training data for image classification (areas with snow and no snow), the k-means unsupervised classification algorithm was used.
Extracting the data from the meteorological and hydrological
Since only a gauging station exists at the Kardeh dam site, the daily discharge data recorded at these stations was used. To extract meteorological parameters such as precipitation and temperature data, the records of the three stations Golmakan, Mashhad and Ghouchan, as the stations closest to the dam basin Kardeh were used. The purpose of this study was to simulate snowmelt runoff using SRM hydrological models and to compare the results with the outputs of the neural network models such as the ANN and the ANFIS model. Flow simulation was carried out using SRM, ANN model with the Multilayer Perceptron with back-propagation algorithm, and Sugeno type ANFIS. To evaluate the performance of the models in addition to the standard statistics such as mean square error or mean absolute percentage error, the regression coefficient measures and the difference in volume were used. The results showed that all three models are almost similar in terms of statistical parameters MSE and R and the differences were negligible.
SRM model: SRM model is a daily hydrological model. This equation is composed of different components including 14 parameters. The input values were calculated based on the equations of degree-day factor. The evaluation of the model was performed with flow subside factor, coefficient and subtracting volume.
Results and Discussion: After determining the study area, the DEM in GIS software was produced and was divided into 4 height classes with 500 meterintervals based on the basin area. Thus, the hypsometric map of the region with slope and aspect maps wasobtained from DEM. The parameters that were entered into the SRM model included area, the average height of DEM and area of slope directions. Weighted average altitude was about 2007 m in the basin. Height classes of 2000-1500 comprise about 47 percent of the total area, with the highest frequency. The main slope happens in the southwestern region(SE). The results show that the model has properly simulated the daily flow hydrograph at the time of the study period. Factor subtracting volume was modeled based on daily discharge hydrograph at a 17-year period. The best x and y values of the simulated hydrograph for watershed dam Kardeh were respectively 0/79 and 0/084 and finally entered into the model. To evaluate the model for the period of 79-80, the subtracting volume was about 0.21 percent, the regression coefficient was 0.91, the calculated runoff volume was 4/876 million cubic meters and calculated discharge was estimated 0.212 cubic meters per seconds, that indicated a very good agreement with observed values. In addition, it was shown that between the parameters introduced into the model, change of the snow runoff coefficient and the coefficient of flow subsidence have the highest sensitivity, and then two parameters were accurately calibrated, to reach more conformity with ground truth. The results showed that the use of images with high spatial resolution, results in relatively good results in determination of snow-covered surfaces. These results were in agreement with other studies. SRM model is relatively successful so that changes in daily flow modeling provide a better quality. The comparison of the mean absolute percent error between the three models of ANFIS than the ANN model by 40 percent compared to15 percent SRM model has reduced the error of the simulation process and the difference in volume between ANN and ANFIS models were better than the SRM model and the value of this parameter for both models are low.
Research Article
Abolfazl Nasseri
Abstract
Introduction: Due to sensitiveness of flow to roughness coefficient (RC), selection of this coefficient is important in earth canals designing purposes. Precision selection of this coefficient is necessary for design and operation of earthen canals purposes. Overestimation of the actual amount of this ...
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Introduction: Due to sensitiveness of flow to roughness coefficient (RC), selection of this coefficient is important in earth canals designing purposes. Precision selection of this coefficient is necessary for design and operation of earthen canals purposes. Overestimation of the actual amount of this coefficient will cause an underestimation for flow velocity. Accordingly, sedimentation in the earth canals will reduce canals’ capacitances. Adversely, underestimation of this coefficient will cause an overestimation for flow velocity and water flux in the earth canals. It will also increase the risk of soil erosion in the channels. This coefficient is expressed by Manning, Chezy and Darcy Weisbach equations. While, hydraulic engineers have selected Manning equation to estimate the flow rate in open channels due to ease of use and acceptable precision in the application of this equation. Water for crop production in Moghan, as one of the most important agricultural centers in Iran, is supplied from Moghan-Meel diversion dam via main canal of irrigation and drainage network with a capacity of 80 m3 s-1 with a length of 116 km. All of the branched 63-channel from the main channel are earthen. Continual sedimentation in the earth canals reduced the capacity of them and re-estimation the capacity of this canals needs to the precise quantities of variables such as roughness coefficient. Because the overestimation of the actual value of the coefficient would reduce the canals’ capacity and underestimation of the coefficient increase the risk of erosion in earth canals. The analysis of the correlation among variables, regression, analysis of statistical distribution of variables, analysis of variance of variables and the analysis of the events probabilities for stochastic variables can be made by statistical methods. Therefore, these methods were applied to analysis of roughness coefficient in the earth canals. Also, due to the importance of roughness coefficient and significant sensitivity of the capacity to this coefficient, the current study was conducted to statistically analyze and to evaluate roughness coefficients in non-vegetated canals for irrigation and drainage network of Moghan (in North-west of Iran). The results of the research may be applied in the design, evaluation and utilization of networks, especially in the irrigation and drainage network of Moghan.
Materials and Methods: Experimental area was Moghan plain located at the north-west of Iran with latitude from 39º 22’ to 39º 45’ N, longitude from 47º 22’ to 47º 45’ E and sea level of 32.0 m. The annual averages air temperature, relative humidity and pan evaporation are 14.5º C, 72% and 111 mm month-1, respectively. Annual rainfall in this plain is 332 mm. In the network of Moghan, 50 sections were selected to measure water flow velocity (with a flow meter) and canals cross sections (with profilimetery devices). The selected sections were in earth canals located at the farms of Agro-Industrial Company of Moghan, farmers’ farms, Pirayvatlu’s farms, Iranabad, Hajhazar, Farms of Agricultural Education Center and Agricultural Research Center. A flowmeter (type AOTT) made by Iranian Water Resources Engineering Company was applied to measure flow velocity in different sections of the channel. Resistance coefficient were determined by the following equation according to the dimensions and the velocity of the water flow in the earth canals
(1)
Where R is the hydraulic radius (m), V is velocity (m/s) and S is channel slope (m/m).
In this study, the Reynolds number was applied to determine the flow regime in the channel. The partial correlation coefficient was used to determine the effective variables in the roughness coefficient in canals without vegetation. The application of the coefficient of correlation is that the dependent variable (multiple independent variables) and independent stay in the form of fixed values of other independent variables. The software’s of SPSS and Minitab were used in statistical analysis.
Results and Discussion: Roughness coefficients averaged 0.06. Results revealed that RC varied from 0.014 to 0.050 (and more than) for 90 to 40% probabilities in non-vegetated canals. Also, flow velocity, hydraulic radius, cross section area, wetted perimeter and roughness coefficient were lognormal in distributions.
Results also showed that flow regimes were turbulent and with increase in Reynolds numbers, roughness coefficients decrease. Sensitivity analysis of flow rate to roughness coefficient showed that with increase as 200 and 300 percent in roughness coefficients, flow rates were 0.50 and 0.33 of flow rate from average roughness coefficient. Moreover,
A simple regression model was developed based on effective variables (viz. flow velocity and canal slope) on roughness coefficient by omitting non-effective variables in non-vegetated canals. Developed model was as follows:
(2) R2=0.99
The variables of the model were previously introduced earlier. The coefficient of determination (R2) shows that more than 99% variations in RC could be explained by flow velocity and canal slope.
Conclusion: Roughness coefficient in the earth non-vegetated canals was successfully and precisely evaluated for irrigation and drainage network of Moghan (in North-west of Iran) by statistical methods. Roughness coefficients averaged 0.06. The sensitivity of canal discharge to roughness coefficient was significant. It is recommended to select and apply actual values of this coefficient in engineering or computing purposes. By omitting non-effective variables in roughness coefficient in non-vegetated canals, a simple regression model with R2 of 0.99 was developed based on effective variables. In this study, the role of vegetation in channel for roughness coefficient was not evaluated. Therefore, it is recommended that the effect of different vegetation on roughness coefficient tobe evaluated with models such as hydrodynamic and zero-inertia.
Research Article
F. rejali; A. Esmaelzad; K. Saghafi; V. hemati
Abstract
Introduction: Biofertilizers have been identified as alternative to chemical fertilizers to increase soil fertility and crop production in sustainable farming systems. One of the most useful kind of biofertilizers include plant growth promoting rhizobacteria (PGPR). Azospirillum is an associative rhizobacteria ...
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Introduction: Biofertilizers have been identified as alternative to chemical fertilizers to increase soil fertility and crop production in sustainable farming systems. One of the most useful kind of biofertilizers include plant growth promoting rhizobacteria (PGPR). Azospirillum is an associative rhizobacteria which can be very useful for plants such as wheat. It can help plant by fixing nitrogen through biological way, causing root development, plant strength improvement in primary phases, causing germination percent increment, improving plant tolerance in stress situations (drought, salinity, soil compaction and pathogens), secreting plant promoting hormones like cytokinin, Oxin and finally yield increment will be observable. Modern agriculture largely relies on the extensive application of agrochemicals, including inorganic fertilizers and pesticides. Although pesticides are important, their effects on nontarget organisms are of great concern because this poses a risk to the entire ecological system. The fungicides may also adversely affect the soil microflora, especially the types of microorganisms that can applied to seeds as bacterial inoculants. Considering useful effects of plant growth promoting rhizobacteria especially Azospirillum on Wheat, this study was done in order to survey interaction effects between fungicide and available biofertilizers in Iran market.
Materials and Methods: Effect of carboxin tiram in 2 levels (applied, non-applied) as fungicide, on efficacy of wheat plant (Chamran Cultivar) and final crop yields under association conditions with 5 Azospirillum species (A.brasilense, A.lipoferum, A.halopraeferense, A.irakense, A.sp) using powdery and liquid formulation were studied in a greenhouse test for four months in Soil and Water Research Institute.At first some properties of used soil, including soil texture, pH, EC,organic carbon and available soil K, P, Fe, Zn, Mn and Cu were measured by laboratory methods.Nutrient Broth medium were used for bacterial inoculum production with 108 bacterial cound per ml in final suspention. Using factorial experiment in a Completely Randomized Design (CRD), 2 bacterial inoculants factors (5 inoculation level and a non-inoculation level), CarboxinThiram fungicide levels (applied, non-applied) and two inoculants formulations (liquid and powdery) with four replicates per treatment and a total of 96 experimental units (pots), the most effective contribution of different species of Azospirillum bacteria with Chamran wheat varieties were evaluated in the presence of the fungicide. Studied Parameters included number of tillers, node interface, flag length, number of grains per spike, grain weight per spike, shoots wet weight, 1000 grain weight and shoot dry weight of wheat plant. Data were analyzed with SASS and Excel softwares. The comparison was done by Tukey test.
Results and Discussion: Regarding ANOVA table (table 2), liquid and powdery formulations of Azospirillum with different species had significant effect on 8 of 11 studied traits including number of tillers, plant hight, spike length, node interface, flag length, number of spikes per square meter , grain weight in spike, shoot wet weight, shoot dry weight. Fungicide had effect on 2 traits such as number of grain per spike and grain weight spike independently. Bacteria and fingicide interaction had significant effect on number of tillers, node interface, flag length, number of grain per spike, shoot dry weight (p< 0.01) and shoot wet weight (p< 0.05).
Numeric comparsion between similar treatments in presence and absence of fungicide, it can be concluded that although fungicide presence had no significant positive effectson studied traits, it did not have any negative effects eigther.Even it could increase traits quantity by affecting on bacteria. Also, regarding to Table 5, comparing fungicide effect on bacteria with studied trait in two formulations, it can be concluded that fungicide presence with bacteria was effective on quantity of some trait in powdery formulation and some in liquid formulation.These findinds may be the result of fungicide effects in controlling soil born pathogens in compatable treatments with used bacterial inoculums.
Conclusions: As final result, using A.lipoferum with both formulations and A.halopraeferense with powdery formulation, because of high compatibility with carboxin thiram fungicide can be advised in case of fungicide application. This advice can have good effects on functional traits such as number of tillers, grain weight in spike and shoot dry weight.To consider the effects of environmental conditions on the final results we propose to do this experiment in field scale in some Iranian provinces with different climatic conditions.The use of different concentrations of carboxin tiram and also different kinds of PGPR and other fungicides must be consider in future experiments.
Research Article
Mojtaba Moqbeli; Mohsen Farahbakhsh; Naser Boroumand
Abstract
Introduction: Boron (B) is an essential plant micronutrient whose soil availability is influenced by many soil factors.Understanding the processes controling activity of boron (B) in the soil solution is important for soil fertility management. The reaction of adsorption and desorption of boron in soil ...
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Introduction: Boron (B) is an essential plant micronutrient whose soil availability is influenced by many soil factors.Understanding the processes controling activity of boron (B) in the soil solution is important for soil fertility management. The reaction of adsorption and desorption of boron in soil determines the amount of boron that is available to plants. Adsorption–desorption processes play a major role on boron equilibrium concentration and therefore on its bio-availability. Ionic strength, pH and ionic composition in exchangeable phase are among themajor factors affecting B adsorption reactions.Reducedadsorption of boron at high pH is because of a surface potential decrease onminerals with pH-dependent charge. Ionic strength has also a considerable effect on B adsorption.Several studies have been performed inthe adsorption of boron and the effect of factors such as ionicstrength and cations has been understudied, however, the effect of sodium adsorption ratio and itsinteraction with the ionic strength on boron adsorption behavior has not been reported. In thisstudy, the adsorption isotherms of boron in the soils affected by the combined effects of ionic strengthand sodium adsorption ratio were investigated.
Materials and Methods: In order to assess the effects of ionic strength (IS) and Sodium Adsorption Ratio (SAR) on availability of B, the adsorption of B was investigated in a calcareous soil that hadlow levels of electrical conductivity, sodium adsorption ratio and available P. For this purpose, 5 g soil wasequilibrated with 20 mL of B solution (0, 2, 5, 8, 10, 15, 20 mg L-1) in 0.02, 0.06 and 0.12 M background solutions (prepared by NaC1,CaC12.2H2O, MgCl2.6H2O), at two SAR levels (20 and 100).The reaction temperature was 25◦C. The suspension was centrifuged, filtered, and a sample was removed and B was determined by Azomethine-H spectrophotometric method (at a wavelength of 420 nm). B adsorption in Soil was obtained by subtracting B in solution after filtration, from added boron.
Results and Discussion: The Langmuir isotherm waswell fitted to the adsorbtiondata based on the R2 and SEE.At different IS and SAR levels, the soil exhibited different adsorption behaviors. The effect of SAR on the boron adsorption was greater at high concentrations.The results showed the increase in sodium adsorption ratio,increased soil pH and Boron adsorption.An increase in sodium adsorption ratio up to 100 resulted in a small increase in Boron adsorption compared to SAR=20. With sodium adsorption ratio of 100, soil pHincreased from 8.3 to 8.7. At about PH=9.5, maximum adsorption occurs because boron dissociation is greater when pka = pH. Increasing ionic strength increased the boron adsorption; the absorption rate wasmuch higher at higher ionic strength.Model-predicted and experimental parameters obtained using the Langmuir equation pointed to the large effect of salt concentration on the boron adsorption which wasan increase of around 10% and 75% in q max as a result of an increase in salt concentration from 0.02 to 0.06 and 0.12 M respectively. We can ignore the effect ofsalt at very low equilibrium concentration; however, it increases gradually with increasing the equilibrium concentration of boron.
Conclusions: The results of the present study showed that sodium adsorption ratio was low, in low equilibrium concentration related to low boron concentration, but the equilibrium concentration of boron increased with increasing the sodium adsorption ratio.In sodium adsorptionratio of 100, increasing pH increased the adsorption of boron. Boron adsorption was increased with increasing ionic strength; the adsorption rate was muchhigher than the rate of increase in ionic strength.Increasing the ionic strength suppresses the DDL on planar surface and therefore more negative borate ions are able to move close enough to interact with the adsorption sites located on the edge surfaces. Assuming that this phenomenon affects the adsorption of boron, the effect of ionic strength on boron adsorption can be partly dependent on it. Due to the high variability of soil minerals and the differences in their chemical properties, interpretation of the effect of ionic strength on adsorption of boron is not easy, but we can say that it is the sum of the effects of the above-mentioned factors. The positive effect of ionic strength on boron adsorption may suggest that the formation of inner sphere complex is the dominant mechanism for boron adsorption.
Research Article
Leila Bakhshandehmehr; Mohammad Reza Yazdani; Ali-Asghar Zolfaghari
Abstract
Introduction: In recent years, due to the reduction in surface water, utilization of groundwater has been increased to meet the growing demand of irrigation water. The quality of these water resources is continually changing, due to the geological formations, the amount of utilization, and climatic parameters. ...
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Introduction: In recent years, due to the reduction in surface water, utilization of groundwater has been increased to meet the growing demand of irrigation water. The quality of these water resources is continually changing, due to the geological formations, the amount of utilization, and climatic parameters. In many developing countries, the irrigation water is obtained from poor quality groundwater resources, which in turn, creates unfavorable circumstances for plant growth and reduces the agricultural yield. Providing adequate water resources for agricultural utilization is one of the most important steps needed to achieve the developmental targets of sustainable agriculture. Thus, this necessitates the assessment and evaluation of the quality of irrigation water. There are many proposed methods to determine the suitability of water for different applications, such as Piper, Wilcox, and Schoeller diagrams. Zoning of quality and suitability of irrigation water could represent the prone and critical areas to groundwater exploitation. Garmsar alluvial fan is one of the most sensitive areas in the country where traditional agriculture practices had turned into modern techniques and excessive exploitation of groundwater has caused an intensepressure on aquifers and increased water salinity. The aim of this study is to evaluate the suitability of groundwater for irrigation in a 10-year period (2002-2012) and its changes in this basin.
Materials and Methods: Garmsar alluvial fan is located in the North-West of Semnan Province. Semnan is situated in the Southern hillside of the Alborz Mountains, in North of Iran. The study area includes the agricultural land on this alluvial fan and covers over 3750 hectares of this basin. In order to evaluate the quality of groundwater in this area, the electrical conductivity and sodium absorption ratio of 42 sample wells were calculated. The raster maps of these indicators were obtained using Geo-statistical techniques. The suitability of irrigation water was determined by Wilcox diagram. Upon evaluating the data distribution and testing the data from Klomogrov-Smirnov normality test, normalization of the data was performed in SPSS software. Spatial correlation and spatial structure of variables were analyzed by drawing their semi-variograms in GS+ software. The most accurate variogram model was selected according to the lowest Residual Sums of Squares (RSS) and the highest correlation coefficient (R2). Interpolation and zoning of the indicators were performed in ArcGIS software and the Quality classes were determined.
Results and Discussion: According to the results of Kolmogorov-Smirnov test, none of the data series had normal distribution. Therefore, they were normalized through calculating the logarithm of variables. Fitting and the selection of variograms were performed in GS+ software and after the calculation of errors, kriging method with Guassian model was determined as the best fitting model. The correlation coefficient was 0.896 for electrical conductivity and 0.99 for sodium absorption ratio. Interpolation of indicators in ArcGIS implied fewer measurements of these indicators in north of the study area (Hableh-Rood inlet). The maximum measurement of indicators was observed on the western edge of the alluvial fan. In total, the values of both electrical conductivity and a sodium absorption ratio indicators in the western half of the area, in the vicinity of the third period domes, were more than the eastern half. The result of the water classification using Wilcox diagram represented the unsuitability of groundwater for irrigation in all of the study area. The area with unusable groundwater for irrigation has increased over the 2005 – 2009 period.
Conclusion: In this study, relying on the use of GIS and Geo-statistical methods, the quality of Garmsar basin groundwater has been evaluated. The electrical conductivity was applied to monitor water salinity, and Sodium absorption ratio was used to monitor alkalinity. The interpolation of these indicators was performed by Kriging method and Guassian fitting model. Likewise, in other studies, the Kriging method was introduced as an appropriate method for the interpolation of chemical parameters of the groundwater. The accuracy of various fitting models in the prediction of interpolated values differed according to the number and the distribution of sample points. In the current study, the Guassian fitting model was determined as the best model to interpolate both of the indicators. According to the maps, it seems that the third period domes in the western margin of the study area have a great influence on the quality of Garmsar’s surface water and groundwater. In total, the groundwater of Garmsar basin didn’t poss high suitability for irrigation, and was classified into two unsuitable and unusable classes. Moreover, according to the maps, the maximum area of unusable groundwater for irrigation in the area was observed in 2008.
Research Article
borhan sohrabi
Abstract
Introduction: Iran is a vast country with limited water resources. Iran is located in arid areas and average precipitation is estimated to be 250 mm. In recent years, water shortage has created many problems for Iranian farmers. In these conditions, surface and ground water use is excessive. High consumption, ...
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Introduction: Iran is a vast country with limited water resources. Iran is located in arid areas and average precipitation is estimated to be 250 mm. In recent years, water shortage has created many problems for Iranian farmers. In these conditions, surface and ground water use is excessive. High consumption, low irrigation efficiency, bad time and geographical distribution of precipitation, population growth and increasing agricultural land are one of the main reasons for the irrigation water crisis. Therefore, the main problem of drought and water shortages still remains. The area of agricultural land in Golestan province is high, but most of them are rain-fed cultivation or left fallow. Due to the loss of irrigation water in traditional agriculture, development of pressurized irrigation as a solution to increase productivity and reduction of strain on water resources was raised. With government support, the use of pressurized irrigation systems is increasing.
Materials and Methods: To evaluate the effect of different amounts of water on new variety of cotton-Sepid, a two-year study was conducted using drip irrigation at Hashemabad Cotton Research Station, Gorgan, Iran.The Hashemabad Cotton Research Station is located in north of Iran at 36° 51' N latitude and 54° 16' E longitude at the south-east corner of Caspian Sea and its height from sea level is 13.3 meters. That station has a Mediterranean climate with relatively mild winters and relatively dry summers. The station's annual evaporation, precipitation and relative humidity are 1311mm, 525 mm and 71%, respectively. Soil texture of Hashem Abad station is silty clay loam. In this study, four levels of irrigation water: 0%, 40%, 70% and 100% evaporation of class A pan were studied in a randomized complete block design. Land was plowed in autumn last year and was ready for planting in April with the disc. During tillage, manure fertilizer on the soil surface was sprayed based on the soil test recommendations. At this stage, for combating weeds, herbicide trifluralin (2.5 liters per hectare) was used. Planting new varieties of cotton - Sepid was in the first decade of May. Each plot consists of 8 lines which was ten meters. After evaporation of 50 mm from Class A evaporation pan, irrigation is done. Irrigation tapes were placed just alternate between planting rows. Water consumption was measured using a volumetric water meter. To measure the product, cotton-seed of four rows of each plot were harvested. Yield components were measured in the same four rows. Product wastaken in October and early November during two harvesting.
Results and Discussion: Cotton as thermophilic plants, especially in humid areas, is strongly influenced by farm management. Among the controllable factors, irrigation management had very effective role in the balance between vegetative and reproductive growth. In other words, water stress control in cotton fields is essential for economic output. Through advanced techniques, drip irrigation despite high initial cost, will be the first choice. Because in addition to irrigation efficiency, with earliness management, mechanization harvesting is done better. According to the analysis of variance, the effect of different amounts of water on the total yield was significant at the level of one percent. The lack of statistical significant differences between treatments in terms of total yield of I100 and I70, the second treatment due to a 30% saving in water consumption and earliness as the best in the normal condition. One of the parameters that are usually affected by irrigation management is earliness. Average comparison shows in term of earliness, three treatments of I70، I40 and I0 in group A and treatment I100 are in the latter group. Thus, from this aspect I70 can be recommended. In terms of water use efficiency I40 and I70 with 1.44 and 1.17 kg per cubic meter had the highest WUE, respectively.
Conclusions: The results shown that irrigation water had significantly effects on first pic, second pic and total yield. But irrigation water treatments had no significant effect on earliness and boll weight. According to the combined analysis table (two years data), as much as % 70 of cumulative evaporation from class A pan, will be recommended for cotton farming in north of Iran in normal weather. In dry years, % 100 of cumulative evaporation from class Apan is suggested.
Research Article
Khadije Salarinik; Mohsen Nael; Ghasem Asadian; Ali Akbar Safari Sinegani
Abstract
Introduction: Soil organic matter is influenced strongly by vegetation cover and management, therefore it is proposed as the main indicator of soil quality and health. The changes in soil organic matter status occur much more rapidly in the labile pools than in organic C. Thus, labile pools can be used ...
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Introduction: Soil organic matter is influenced strongly by vegetation cover and management, therefore it is proposed as the main indicator of soil quality and health. The changes in soil organic matter status occur much more rapidly in the labile pools than in organic C. Thus, labile pools can be used as early indicators of changes in total organic matter that will become more obvious in the longer term here. In addition, the labile fraction has a disproportionately large effect on nutrient-supplying capacity and structural stability of soils. Land management as well as soil and environmental conditions lead to the deployment of different plant communities in rangeland ecosystems, which in turn may have different effects on soil quality indicators. The main objective of this research was to investigate the influence of different vegetation covers on the quantity and quality of soil organic carbon fractions in Gonbad experimental watershed, Hamadan. Moreover, the seasonal changes of selected soil carbon fractions were investigated.
Materials and Methods: Paired Gonbad watershed in Hamedan consists of two sub-basins: in control sub-basin no grazing management is applied, while in protected sub-basin, grazing has been restricted to a very short period in late autumn since 2002. Average annual precipitation and average annual temperature in the area are 304.4 mm and 9.5 °C, respectively (5). The soil cover of the watershed consists of TypicCalcixerepts, TypicHaploxerepts and Lithic Xerorthents (9). Five different vegetation typesof which, grasses (G), Astragalus-Bromus (A-B), Astragalus-Artemisia (A-A), Astragalus-Lactuca (A-L) in protected sub-basin, and Astragalus-Euphorbia (A-E) in control sub-basin, were selected. In addition, a formerly cultivated hilly land outside the watershed, now under rainfed wheat farming (RW) was selected as a non-pasture vegetation type. All of the six vegetation types were similar in terms of soil parent materials and slope aspect.. Soil and plant sampling were conducted in mid-autumn 2012 (a), and late spring 2013 (s). Three plots (1*1 m2) were studied in each vegetation type. Total organic carbon (TOC), carbon stock (CS), carbon stock normalized with sand(CS/Sa), active carbon (AC), normalized active carbon (AC/TOC), soil carbohydrates (Ch), normalized carbohydrates (Ch/TOC), basal respiration (BR) and normalized basal respiration (BR/TOC) were measured in surface soils (0-15 cm). A factorial experimental design with two factors, vegetation type (6 levels) and time (2 levels), was conducted. Prior to statistical analysis, data were normalized, if required.
Results and Discussion: TOC and CS contentswere significantly different between vegetation types. A-B and A-A had highest canopy cover, litter cover and species diversity. Species diversity in the rangeland ecosystems has direct effect on fodder production and soil organic carbon content. A-E site, despite its low TOC content, hadhigher CS/Sa (51.9 Mg/ha) due to higher amount of clay content, compared to A-A (43.1Mg/ha) with higher TOC content. The amount of AC andAC/TOC in different vegetation types is proportional to the amount of TOC, CS, total canopy, and the canopy and production of herbaceous species. AC content was significantly highest in A-B (711.7 mg/kg), and lowest in RW site(262.6 mg/kg). A-B site is rich in grass species with high amounts of readily decomposable root residues and exudates. The variation of carbohydrate contents in different vegetation types wasvery similar to that of total organic carbon, in that A-B and A-A exhibited the highest (5843 and 5258 mg/kg, respectively) and RW showed the lowest (1937 mg/kg) carbohydrate contents. The woody, not easily decomposible litters in A-A explainedthe high content of Ch/TOC (38.12%) in this site; low rate of humification entails increased soil carbohydrates. Ch/TOC was significantly lower in A-E than other covers. The highest BR andBR/TOC, were observed in A-B and A-A sites, mainly due to the high canopy cover, species richness,and soil organic matter. The lowest BR andBR/TOC were observed in A-E.Thesoil texture in this site was clay.The recirculation of organic matter in fine-textured soils is low because of organic materials protection from microbial decomposition. Total organic matter and labile organic carbon inputs werelower in A-L, A-E and G sites; this may explain the reduction of microbial activity in these vegetation types. Except for AC/TOC, Ch, and BR, seasonal changes of all other indicators were significant. Unlike other indicators, the content of Ch/TOC was significantly higher in autumn than spring.
Conclusion: Vegetation types had significant effects on selected soil quality indicators, so that A-A and A-B sites exhibited the highest soil quality, mainly because of higher vegetation cover, litter, and plant diversity. RW, followed by A-E site, demonstrated the lowest soil quality due to the tillage practices and low plant residue inputs in the first case, and overgrazing of vegetation cover and litter in the second. Total soil organic carbon and active carbon were significantly higher in spring compared to autumn. Seasonal changes of basal microbial respiration and carbohydrates were not statistically significant.
Research Article
Maryam Mohammad Ebrahimi; mohammad reza javadi; mehdi vafakhah
Abstract
Introduction: Soil erosion by water is one of the most important processes of land degradation, especially in semi-arid areas. Among different types of the soil erosion, gully erosion accounts as one of the most critical processes which can cause soil destruction, changes in landscape and water resources ...
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Introduction: Soil erosion by water is one of the most important processes of land degradation, especially in semi-arid areas. Among different types of the soil erosion, gully erosion accounts as one of the most critical processes which can cause soil destruction, changes in landscape and water resources filling of reservoir of dams,decrease in water transport capacity of rivers and agricultural lands destruction in the lowland areas. Based on the Posen definition, gully is a river with high slope walls and an erosive high slope and active head which occurs by erosion resulted from the surface flow (usually during or after high density rainfalls). Different factors play role in occurrence and development of gullies and sediment production resulted of this kind of erosion which includes slope, amount and distribution of rainfall intensity, construction operations, vegetable cover destruction, land-use change, unsuitable utilization, and susceptibility of bed materials to the erosion and flood. Considering the importance of gully erosion and the way of its occurrence and development and its control, more comprehensive studies are needed to be done. Although, some studies have done in this subject that some of them are depicted below:
Rinkez et al showed that gully erosion is further occurred in soils with high exchangeable sodium percentage and sodium absorption ratio and they depicted that these two factors are important indices for soil diffusion amount in gullies. Buma and imson investigated factors such as electricity conductivity, calcium carbonate percentage, and the type of clay mineral in white, brown, and gray samples of marl in the Peter area, Spain. According to their results, factors such as electrical conductivity and sodium absorption ratio had high correlation with erosivity of the Bad Lands.
Material and Methods: Agh Emam(2) watershed is located between 55º 42´ 53˝ to 55º 45´ 43˝ eastern longitudes and 37º 41´ 01˝ to 37º 46´ 19˝ northern latitudes in the east parts of the Golestan province with an area of 2,595 hectares. Arab gharehaji rural is considered as the most important area which is located at the outlet of the basin. In current study, at first, frame work and total surface of the area were investigated by field observations and 9 digitated gullies were observed during field observations. Then, spatial position of each gully was determined by using global positioning system and map of gully distribution was obtained for the study area. Then, by overlaying this map on lithology, slope degree and altitude maps of the study area, the mentioned characteristics were determined for the gullies. After sampling from the soil, they were carried to the lab and clay percentage, silt percentage, sand percentage, saturation humid percentage, electrical conductivity, acidity, organic matter percentage, exchangeable sodium percentage, sodium absorption ratio, percentage of neutrophil materials for two considered depths were measured. Then, two statistical tests were applied in order to determine the significance and or non- significance of different physical and chemical characteristics of the soil which are compare means of two statistical populations and t-Student tests. Also, a non- parametric (chi-square) test was used in order to determine the statistical analysis of the effect of non-soil factors of occurrence of digitated gullies including slope classes, altitude classes, lithology and land use.
Results: Initial investigations of the field observations, aerial photos and satellite images showed that different factors play role in the occurrence of digitated gully in the study area. So, physical and chemical characteristics of the soil, slope classes, altitude classes, lithology and land use were investigated in current study.
A: Results of the effective physical and chemical characteristics of the surface and sub- surface soil on the occurrence of digitated gully erosion
Results showed that, there wasn’t statistically significant difference between the percentages of sand, electrical conductivity, organic matter and lime, out of the digitated gully erosion (upland of the gully and beholder area) and their amounts in surface soils in the digitated gully, but, there was significant difference for silt, clay, saturated humidity percentage, cation- exchange capacity (CEC), exchangeable sodium percentage and sodium absorption ratio. Also, the results showed that there wasn’t statistically significant difference between the sand percentage, silt percentage, clay percentage, acidity, organic material and lime in sub- surface soils out of the digitated gully erosion (upland of the gully and beholder area) and their amounts in sub- surface soils in the digitated gully, but, there was significant difference for saturated humidity percentage, electrical conductivity, cation- exchange capacity, sodium absorption ratio and exchangeable sodium percentage.
B: Results of the role of non- soil effective factors on the occurrence of the digitated gully erosion
The results of the non- parametric Chi- Square test of the effect of slope classes, altitude classes, lithology and landuse on the occurrence of digitated gullies showed that only lithology affected the occurrence of the digitated gullies. The results of current study are compatible with the results of Ghoddusi and Davoodirad, ZareMehrjerdi et al, Servati et al, Shadfar et al, Khuje et al, Rahi et al, Bayati Khatibi et al, Sayadi and Tashakkori.
Conclusion: Totally, it can be said that saturated humidity percentage, cation- exchange capacity, sodium absorption ratio and exchangeable sodium percentage as soil factors had effective role on gully erosion occurrence in the study area, while, lithology was effective among the non- soil factors. Therefore, considering these factors is necessary in order to control the erosion.
Research Article
Hamid Reza Salemi; Ali Reza Tavakoli
Abstract
Introduction: Water crisis as a majorlimitation factor for agriculture, like other arid and semiarid regions exists in Isfahan province which is located in the central part of the Zayandehrud River Basin (ZRB). Rice appears to be the far-most profitable crop but at the same time it has a major impact ...
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Introduction: Water crisis as a majorlimitation factor for agriculture, like other arid and semiarid regions exists in Isfahan province which is located in the central part of the Zayandehrud River Basin (ZRB). Rice appears to be the far-most profitable crop but at the same time it has a major impact on basin scale water resources, especially affecting downstream farmers. In the study area (ShahidFozveh Research Station), the water resources for agricultural production face heightened competition from other sectors like industry and domestic use. This necessitates considering different crops, altered agricultural systems and innovative methods that can reduce the water requirements for the irrigation of rice. The Alternative Wetting and Drying (AWD) seems to be an effective method reducing water use for rice crops and possibly save the water for downstream users. There have been no qualitative evaluations of rice production under deficit irrigation practices in Isfahan area. This study sought to determine, under study area conditions, the quantities of water irrigation used with AWD practices, the resulting water productivity (WP) and the effects of alternative irrigation management on yield, quality indices and rice production performance.
Materials and Methods: The ZRB (41,500 km2) is a closed basin with no outlet to the sea. The research was conducted in the Qahderijan region of Isfahan province, which is located in the central part of the ZRB. The ShahidFozveh Agricultural Research Station (32°, 36’ N, 51°, 36’ E) is located at the altitude of 1612 m above the sea level. In order to improve WP and illustration of the impact of various levels of flooding depth on grain yield and quality indices at rice production, a field experiment (3000 m2) was conducted at ShahidFozveh Research Station for 2 years arranged in a split plot design with three replications. It will be necessary to use different scenario of water flooding depth management to achieve the highest irrigation application efficiency and WP. The treatments included: three levels of irrigation managements I1: permanentflooding under 3.5 cm water during growth period, I2: permanent flooding under2.2cm water during growth period and I3: 0-1.5cm. (AWD) were considered as main plots and eight advanced rice cultivars (Geredehmahali, Zayandeh-rud, Sazandegi , Hasani, 67-97, 67-113, 67-47 and 67-72) as sub plots. The treatments were compared based on grain yield and quality indices for irrigation management and rice varieties including: amylose content (AC), Gelatinization temperature (GT) and gel consistency (GC). Production (grain yield), quality indices, the consumption water, WP and cultivars reactions to different irrigation management were evaluated in different treatments. The soil of the experimental area, according to USDA Soil Taxonomy 1994 is of FINE CLAYEY. At the soil depth of 1m, soil salinity (6.2 dS.m-1), water salinity (3.9 dS.m-1), and soil moisture at saturated capacity (48 Vol. %) at the field site were measured or experimentally obtained in the Isfahan Soil and Water Laboratory. The results were subjected to an ANOVA to analyze the effects of the treatments and their interactions using PROC GLM (SAS 9.1, SAS institute Ltd., USA). Duncan’s multiple range tests at 0.05 probability level was used for paired mean comparison.
Results and Discussion: Results showed that water flooding depth treatments had significant effect on gel consistency, geletination degree and WP (P0.01). Significant differences (P0.01) were noticed in Gelenation degree, gel consistency, grain yield, WP among the cultivars. Also cultivars have significant effect (P0.05) on amylose contents. The highest magnitude of WP was calculated 0.91kg.m-3for (I3) followed by Zayandehrud, 67-113 and Sazandegi with 0.86 and 0.85, respectively. Maximum WP obtained from AWD irrigation management and Zayandehrud rice variety, its amount was 9.1kg.mm-1. At this treatment with 33.4 percent reduction of irrigation water, have resulted only 11.1 percent decreased of paddy grain yield. Results showed that it is not necessary to maintain the rice field submerged in whole growth period. Considering the importance of water flooding depth optimization as the main scope in arid and semi-arid lands of Iran, (I3) is recommended.
Conclusion: During the two years of conduction of an experiment in ZRB with clay texture and mild saline water with the three (3) irrigation treatments imposed on the rice crop. The highest WP was achieved for (I3) followed by Zayandehrud, 67-113 and Sazandegi, respectively. It was found that the AWD irrigation management, despite its lower yield than other irrigation treatments, increased water productivity. Thus, this treatment is desirable therefore highly recommended for agricultural rice production in arid region.
Research Article
foroogh abbasi teshnizi; M. Kouchakzadeh; F. Abbasi
Abstract
Water for agriculture is one of the most important factors in arid and semi-arid areas and municipal wastewater treatment is an important resource for this purpose. Therefore, potential of transfer contaminations is a serious problem regarding use of treated wastewater for agriculture. Due to the risk ...
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Water for agriculture is one of the most important factors in arid and semi-arid areas and municipal wastewater treatment is an important resource for this purpose. Therefore, potential of transfer contaminations is a serious problem regarding use of treated wastewater for agriculture. Due to the risk of transfer contaminations through the use of wastewater, the study of transfer microbes in soil in recent decades has been of interest to researchers. In the present study, the transfer of bacteria fecal coliform was investigated in a lysimeter and the HYDRUS-1D model was used to simulate water flow and the fecal coliform in the soil. For calibration of the model and estimating the model input parameters, soil hydraulic and transport parameters, were inversely estimated. Results represented that the HYDRUS-1D with reasonably accurately simulated the outlet flow. To simulate the transfer of the bacteria in the soil, one site sorption model, two kinetic sites model (particle transport using attachment/detachment) and one kinetic site model were used. In the simulation of bacterial transfer, one site sorption model was selected as the proper model for this study. One site sorption model estimated solid-phase growth coefficient ( ) about sextuple more than liquid-phase. It showed that deposited cells had a higher division rate compared with the cell in liquid-phase. The calibrated model was used for surveying the effect various irrigation intervals and irrigation times on bacterial transfer. The results showed that by increasing irrigation times, more bacteria leached out from the soil. Also by increasing irrigation intervals, more bacteria observed in the soil profile, due to favorable environmental conditions and food for the bacteria growth. According to the results, the best interval and irrigation times were one day and four hours, respectively.
Research Article
Parisa Farzamnia; Shahram Manafi; Hamidreza Momtaz
Abstract
Introduction: Minerals are one of the main components of soils which play different roles in the soils. Minerals make up about 50% of the volume of most soils. They provide physical support for plants, and create the water- and air-filled pores that make plant growth possible. Mineral weathering releases ...
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Introduction: Minerals are one of the main components of soils which play different roles in the soils. Minerals make up about 50% of the volume of most soils. They provide physical support for plants, and create the water- and air-filled pores that make plant growth possible. Mineral weathering releases plant nutrients which are retained by other minerals through adsorption, cation exchange, and precipitation. Minerals are indicators of the amount of weathering that has taken place, and the presence or absence of particular minerals gives clues to how soils have been formed. The physical and chemical characteristics of soil minerals are important consideration in planning, constructing, and maintaining of buildings, roads, and airports. Clay minerals can be used for understanding of soil formation, optimum management of dry and wet lands and interpretation of paleo environments. Moreover, clay minerals can provide some valuable information such as the origin of sediments, transportation and precipitation of sediments and also some information about intercontinental weathering regimes. Quaternary sediments have occupied most of the agricultural and natural resources of Urima plain and recognition of mineralogical of these soils is essential to optimum and stabile use of these soils. Additionally, caly mineralogical investigation can provide some information about the intensity of weathering processes and climate change in this area. Thus, in this study clay minerals of quaternary sediments in northeast of Urmia and the mechanisms of their formation and also tracing probable climate change in this area were investigated.
Materials and Methods: This study was performed in theUrmia plain in west Azerbaijan Province. The study area is located on quaternary sediments and physiographically, this area is a part of a river alluvial plain with the gentle slope toward Urmia Lake. The mean annual precipitation and temperature of this area are 345.37 mm and 10.83 °C respectively and the soil moisture and temperature regimes are dry xeric and mesic respectively. In this study, eight soil profiles in quaternary sediments were dug and sampled and the morphological, physical, chemical and mineralogical properties were determined using standard methods.
Results and Discussion: According to the results, Illite, smectite, Kaolinite, chlorite, vermiculite and hydroxy interlayer vermiculite (HIV) were the dominant clay minerals in these soils. The origin of illite, chlorite and kaolinite were related to inheritance from parent material. Regarding to the present of some smectite in the parent material of these soils, some of smectites have been inherited from parent material. Nevertheless it seems that, the most of smectites in these soils have pedogenic origin. Based on mineralogical results and trends variation of smectite and illite along studied profiles, we concluded that some of smectites in these soils have been formed from illite transformation. In profiles 4 and 6, regarding to low depth water table and consequently poor drainage, high pH and high values of calcium and magnesium cations, provide suitable conditions for the neoformation of smectit and so, some of smectites have been formed via neoformation from soil solution. In these soils, vermiculites were pedogenic and have been formed during transformation of illite to smectite. Small amounts of hydroxy interlayer vermiculites were present in buried horizons and regarding that they were not present in parent material, it might be because these minerals are pedogenic and have been formed in a past wetter climate. The transformation of illite to smectite in lower horizons needs high moisture and regarding to recent semiarid climate of study area, the suitable amount of moisture for this transformation, especially in lower depths and also in buried horizons, is not present. Thus, it seems the transformation of illite to smectite in lower depths and buried horizons has been taken place in a wetter past climate. So we concluded that smectite and hydroxy interlayer vermiculite are evidences of a wetter past climate in this area.
Conclusion: In this study the origin of smectite in buried horizons was related to transformation of illite. According to high moisture condition which is necessary for the weathering of illite, the occurrence of this process related to more humid climate of the past. Additionally, the presence of hydroxy interlayer vermiculites was related to previously wetter climate as well. So results of this study can be used for recognition of climatic change in the study area.
Research Article
Alireza Hosseinpur`; hamid reza motaghian
Abstract
Introduction: Application of organic fertilizers in agricultural soils with low organic matter content is one of the best ways of nutrientsaddition to these soils. Different organic fertilizers have different effects on nutrient availability in soil. Moreover study of the distribution of nutrients in ...
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Introduction: Application of organic fertilizers in agricultural soils with low organic matter content is one of the best ways of nutrientsaddition to these soils. Different organic fertilizers have different effects on nutrient availability in soil. Moreover study of the distribution of nutrients in the soil allows investigating their mobility and bioavailability. The nutrients availability and kinetics of nutrients desorption into the soil solution is often closely related to the distribution of nutrients to different fractions in the soil. It has been assumed that the factors influencing metal fractionation and availability in soil include rate of amendment application, amount of nutrients in amendment, root-induced pH changes, metal binding by root exudates, root-induced changes of microbial activities, and metal depletion because of plant uptake.
Materials and Methods: In this study, availability and fractionation of Zinc (Zn) and Copper (Cu) were compared in one calcareous soil amended with 0, 0.5, and 1% (w/w) of cow manure and vermicompost in a completely randomized design. Also, wheat was planted in treated and untreated soils in greenhouse condition.Available Zn and Cu were determined using different methods (DTPA-TEA, AB-DTPA, and Mehlich 3). For Zn and Cu fractionation, the soil samples were sequentially extracted using an operationally defined sequential fractionation procedure, based on that employed by Tessier et al. (1979) in which increasingly strong extractants were used to release Zn and Cu associated with different soil fractions. Five Zn and Cu -fractions were extracted in the following sequence: Step 1: exchangeable fraction (a 8 ml volume of 1.0 MNaOAc (pH= 8.2) for 120 min. at room temperature)., Step 2: carbonate-associated fraction (a 8 ml volume of 1.0 MNaOAc adjusted to pH 5.0 with acetic acid for 6 h at room temperature, Step 3: iron-manganese oxides-associated fraction (20 ml of 0.04 M NH2OH.HCl in 25% (v/v) HOAc for 6 h at 96 0C)., Step 4: organic matter-associated fraction (3 ml of 0.02 N HNO3 adjusted to pH 2 and 5 ml 30% H2O2 (adjusted to pH 2.0 with HNO3) and at 85 0C for 2 h in sequence, followed by 3 ml of 30% H2O2 (adjusted to pH 2.0 with HNO3) the sample was heated to 85 0C for 3 h with intermittent agitation. After cooling, 5 ml of 3.2 M NH4OAc in 20% (v/v) HNO3 was added and agitated continuously for 30 min. Finally step 5: residual fraction was determined using 4 M HNO3 (a 12.5 ml volume of 4 M HNO3, for 16 h at 80 0C). Concentrations of Zn and Cu in all extractants were determined by AAS.
Results and Discussion: The results showed that the effect of treatments on amount of extracted Zn by different methods were significant (P0.05). The minimum and maximum of extracted Zn by DTPA-TEA were in untreated soil (0.73 mg/kg) and treated soils with 1% manure (1.30 mg/kg) and treated soils with 1% manure (1.17 mg/kg), respectively. The results showed that the effect of treatments on Zn associated with Fe-Mn oxides and Zn associated with organic matter was significant (P0.05). The correlation between extracted Zn and Cu by DTPA-TEA and AB-DTPA with Fe-Mn oxides fraction were significant (P
Research Article
majid montaseri; sarvin zamanzad ghavidel
Abstract
Introduction: A total dissolved solid (TDS) is an important indicator for water quality assesment. Since the composition of mineral salts and discharge affects the TDS of water, it is important to understand the relationships of mineral salts composition with TDS.
Materials and Methods: In this study, ...
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Introduction: A total dissolved solid (TDS) is an important indicator for water quality assesment. Since the composition of mineral salts and discharge affects the TDS of water, it is important to understand the relationships of mineral salts composition with TDS.
Materials and Methods: In this study, methods of artificial neural networks with five different training algorithm,Levenberg-Marquardt (LM), Scaled Conjugate Gradient (SCG), Fletcher Conjugate Gradient (CGF), One Step Secant (OSS) and Gradient descent with adaptive learning rate backpropagation(GDA)algorithm and adaptive Neurofuzzy inference system based on Subtractive Clustering were used to model water quality properties of Zarrineh River Basin, to be developed in total dissolved solids prediction. ANN and ANFIS program code were written in MATLAB language. Here, the ANN with one hidden layer was used and the hidden nodes’ number was determined using trial and error. Different activation functions (logarithm sigmoid, tangent sigmoid and linear) were tried for the hidden and output nodes. Therefore, water quality data from seven hydrometer stationswere used during the statistical period of 18years (1993-2010).In this research, the study period was divided into two periods of dry and wet flow, and then in a preliminary statistical analysis, the main parameters affecting the estimation of the TDS are determined and isused for modeling. 75% of data are used for remaining and 25% of the data are used for evaluation of the model, randomly. In this paper, three statistical evaluation criteria, correlation coefficient (R), the root mean square error (RMSE) and mean absolute error (MAE) were used to assess models’ performances.
Results and Discussion: By applying correlation coefficients method between the parameters of water quality and discharge with total dissolved solid in two periods, wet and dry periods, the significant (at 95% level) variables entered into the model were Q, HCO3., Cl, So4, Ca, Na and Mg. The optimal ANN (LM) architecture used in this study consists of an input layer with seven inputs, one hidden and output layer with two and five neurons for dry and wet periods, respectively. Similar ANN(LM), ANFIS-SC model had the best performance. It is clear that the ANFIS with 0/72 and 0/58 radii value has the highest R and the lowest RMSE for dry and wet periods, respectively. Comparing the ANFIS-SC estimations with the measured data for the test stage demonstrates a high generalization capacity of the model, with relatively low error and high correlation. From the scatter plots it is obviously seen that the ANFIS-SC predictions are closer to the corresponding measured TDS than other models in two periods. As seen from the best straight line equations (assume the equation as y=ax) in the scatter plots that the coefficient for ANFIS-SC is closer to 1 than other models. In addition ANFIS-SC performancedwith the correlation coefficients in dry and wet periods, respectively 0.975 , 0.969 and with Root-mean-square errors, respectively 34.41 , 23.85 in order to predict dissolved solids (TDS) in the rivers of Zarrineh River Basin. The obtained results showed the efficiency of the applied models in simulating the nonlinear behavior of TDS variations in terms of performance indices. The results are also tested by using t test for verifying the robustness of the models at 99% significance level. Comparison results indicated that the poorest model in TDS simulation was ANN-GDAin dry and wet periods, especially in test period. The observed relationship between residuals and model computed TDS values shows complete independence and random distribution. It is further supported by the respective correlations for ANFIS-SC models (R2 = 0.0012 for dry period and R2 = 0.0214 for wet period) which are negligible small. Plots of the residuals versus model computed values can be more informative regarding model fitting to a data set. If the residuals appear to behave randomly it suggests that the model fits the data well. On the other hand, if non- random distribution is evident in the residuals, the model does not fit the data adequately. On the base of these results, we propose ANFIS-SC and ANN (LM) methods as effective tools for the computation of total dissolved solids in river water, respectively.
Conclusion: It can be concluded that the ANN with Levenberg-Marquardt training algorithm and ANFIS-SC models can be considered as promising tools for forecasting TDS values, based on water quality parameters. With attention to the aim of current research that is presenting the feasibility of artificial intelligence techniques for modeling TDS values, it is notable that the results presented in this paper are for research purpose and applying the abstained results for real-world needs some complicated steps and building artificial intelligences methods, based on complete data and parameters maybe affected the TDS values
Research Article
Ali Reza Vaezi; Mohammad Abbasi; Jalal Heidari
Abstract
Introduction Soil infiltration rate is the major soil hydraulic property which can be affected by the soil physical characteristics and management practices. The use of land can affect various soil properties such as physical and hydraulic properties. Differences of the hydraulic soil characteristics ...
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Introduction Soil infiltration rate is the major soil hydraulic property which can be affected by the soil physical characteristics and management practices. The use of land can affect various soil properties such as physical and hydraulic properties. Differences of the hydraulic soil characteristics such as infiltration rate in various land uses can affect their potential to runoff production as well as soil loss in the catchment. The knowledge of the physical and hydraulic characteristics of various land uses can help to better management of soil and water in the catchment. It is very essential in the semi-arid catchments where vegetation cover is generally poor, the soils are often instable against erosive factors especially when the rainfalls are consecutive and intensive. Therefore, this study was conducted to investigate the soil physical and hydraulic characteristics in the TahamChai catchment, in a semi-arid region, NW Zanjan. Various land uses consist of pastures, rainfed and irrigated lands can be observed in the catchment, which cover about 62%, 33%, and 5% of the catchment area, respectively. The pastures have been covered with poor vegetation and are intensively exhausted by over-grazing. Rainfed lands are mostly under winter wheat cultivation. Soil erosion and sedimentation were the major environmental problem in this catchment.
Materials and Methods The maps of land use and slope gradient were provided for study area. A total of 20 sites were selected based on the surface area of each land use in the catchment located between 34 46-36 53 N latitudes and 48 17-48 37 E longitudes. The study area consisted of ten sites in the pasture, seven sites in the rainfed and three sites in the irrigated lands. The geographical positions of study sites were determined by a global positing system (GPS). Soil infiltration rates were measured by double rings method at three replications in each site. Variation of soil infiltration rate was determined for each land use. Soil samples were collected at three replications from each site to determine other physicochemical soil properties. Particle size distribution, bulk density, saturation percentage, aggregate mean weight diameter, organic matter, and equivalent calcium carbonate were determined using standard methods in the lab. Mean comparisons of infiltration rate along with other physicochemical soil properties among the land uses were done using the Duncan's parametric method. The Pearson’s correlation coefficients were used to determine the relationships between soil properties and soil infiltration rate.
Results and Discussion Based on the results, no significant difference was observed between the land uses in particle size distribution. Soil infiltration rate showed different patterns among the land uses, so that significant difference was observed among them (p< 0.01). Pastures showed the lowest infiltration rate among the land uses (about 86 and 66 times lower than that of the rainfed and the irrigated lands, respectively). This result was associated with increasing soil compaction through the over-grazing in the pastures. Positive correlation was found between soil infiltration rate and aggregate mean weight diameter(r= 0.54, p< 0.05) while its correlation with bulk density was negative (r= -0.74, p< 0.01). Pastures showed the lowest organic matter content (1.35%) as well as aggregate mean weight diameter (1.12 mm) as compared with other land uses. Since the pastures are located on the steeper slopes, they have the highest intrinsic potential to runoff production and soil erosion as compared to other land uses. As a consequence, the over-grazing is the major factor of soil structure breakdown, soil compaction, and in consequence declining soil infiltration rate in the pasture lands.
Conclusion: Pastures with poor vegetation cover appeared the lowest soil infiltration capacity as compared to other land uses in the catchment. Decreasing soil infiltration rate was associated with increasing bulk density in the area. It seems that overgrazing in the pastures increases soil bulk density and leads to decline the soil organic matter content as well as soil aggregation and aggregate stability. According to the results, pastures have the highest potential to runoff production and soil erosion rather than the other land uses (rainfed lands and irrigated lands). Therefore, maintaining vegetation cover and preventing over-grazing in the catchment is recommended to increase soil organic matter content and decrease soil compaction. These practices improve the hydraulic soil characteristics especially infiltration rate and in consequence decrease the catchment potential to runoff production and soil erosion.
Research Article
seyed sajjad hosseini; Amir Lakzian; Akram Halajnia
Abstract
Introduction: Application of EDTA may increase the heavy metal availability and phytoextraction efficiency in contaminated soils. In spite of that, it might also have some adverse effects on soil biological properties. Metals as freeions are considered to be severely toxic, whereas the complexed form ...
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Introduction: Application of EDTA may increase the heavy metal availability and phytoextraction efficiency in contaminated soils. In spite of that, it might also have some adverse effects on soil biological properties. Metals as freeions are considered to be severely toxic, whereas the complexed form of these metalswith organic compounds or Fe/Mn oxides may be less available to soil microbes. However, apart from this fact, some of these compounds like EDTA and EDTA-metal complexes have low bio- chemo- and photo-degradablity and high solubility in their own characteristics andable to cause toxicity in soil environment. So more attentions have been paid to use of low molecular weight organic acids (LMWOAs) such as Citric acid because of having less unfavorable effects to the environment. Citric acid increases heavy metals solubility in soils and it also improves soil microbial activity indirectly. Soil enzymes activity is a good indicator of soil quality, and it is more suitable for monitoring the soil quality compared to physical or chemical indicators. The aims of this research were to evaluate the changes of dehydrogenase, urease and alkaline phosphomonoesterase activities, substrate-induced respiration (SIR) and Pb availability after EDTA and citric acid addition into a contaminated soil with PbCl2.
Materials and Methods: An experiment was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition. The soil samples collected from surface horizon (0-20 cm) of the Typic haplocalsids, located in Mashhad, Iran. Soil samples were artificially contaminated with PbCl2 (500 mg Pb per kg of soil) and incubated for one months in 70 % of water holding capacity at room temperature. The experimental treatments included control, 3 and 5 mmol EDTA (EDTA3 and EDTA5) and Citric acid (CA3 and CA5) per kg of soil. Soil enzymes activity, substrate-induced respiration and Pb availability of soil samples were determined by standard methods after 7, 14, 21 and 28 days of chelates addition.
Results and Discussion: The soil texture was loam and the indigenous Pb content was 25.55 mg kg-1. The soil pH was 7.4 and electrical conductivity of saturated extraction measured 2.5 dS m-1. The soil carbonate calcium was 14% and the content of organic carbon and essential nutrients were low. The results showed that EDTA3 and EDTA5 treatments increased Pb availability by 2.17% and 10% compared to control treatment but CA3 and CA5 treatments decreased it by 3.8% and 15.7% respectively. The Pb availability in control and EDTA5 treatments did not change during the incubation time. The available Pb concentration dropped sharply during the incubation time in EDTA3, CA3 and CA5 treatments. The reduction rates in CA3 and CA5 treatments were more than EDTA3 treatment. This may be due to the high stability and low biodegradability of EDTA than biodegradable chelators and low molecular weight organic acids. The results showed that urease and dehydrogenase activities were significantly reduced in EDTA3 and EDTA5 treatments compared to control treatment. Urease and dehydrogenase activities were decreased with the increase of EDTA concentration. Alkaline phosphomonoesterase activity was not affected by the EDTA3 and EDTA5 treatments. In CA3 and CA5 treatments, dehydrogenase and alkaline phosphomonoesterase activities significantly increased with increasing the concentration of citric acid. CA5 treatment showed a prominent effect on urease activity compare to CA3 treatment. The soil enzyme activities increased with incubation time. It seems that reduction in Pb availability causes an increase of soil enzymes activities. Significant negative relationships were found between soil enzymes activities and available Pb concentration (dehydrogenase activity (r=-0.906, P
Research Article
Mohammad Ghasemzadeh Ganjehie; Ali reza Karimi; Ali Zeinadini; Reza Khorasani
Abstract
Introduction: Playa is one of the most important landscapes in arid regions which covers about 1% of the world's total land area. Study of playas is important from different points of view especially pedology, sedimentology, mineralogy, environmental geology, groundwater and surface water chemistry. ...
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Introduction: Playa is one of the most important landscapes in arid regions which covers about 1% of the world's total land area. Study of playas is important from different points of view especially pedology, sedimentology, mineralogy, environmental geology, groundwater and surface water chemistry. More than 60 playas have been identified in Iran. Considering the fact that playas and surrounding landforms are important archive of landscape evolution and paleoenvironmental variations, it seems that less attention has been paid to them so far. Soils are known as indicators of the landscapes evolution. Previous studies in arid regions of Iran imply different periods of deposition and soil formation in playa and alluvial fans or pediments. Bajestan playa is one of the known playa in northeastern Iran, and the largest clay flat exists in this playa. There is no information on the soils and their evolution in Bajestan playa. The objective of this study were to 1) identify the soils in different landforms along a transect from alluvial fan to clay in Bajestan playa 2) determine the morphological, micromorphological and mineralogical characteristics of these soils 3) determine the periods of soil and landform evolution and 4) comparison of soils evolution of the study area to other arid regions of Iran.
Material and Methods: The study area of approximately 20000 hectares is located in southeastern of KhorasanRazavi province. The climate of the study area is hot and dry with mean annual temperature and rainfall of 17.3 °C and 193 mm, respectively. Soil moisture regime is aridic with subdivisions of weak aridic and soil temperature regime is thermic. Firstly, landforms and geomorphic surfaces of the study area were recognized based on Google Earth images interpretations and field observations. Four main landforms were recognized in the study area. The landforms from north to the south of the study area were alluvial fan, intermediate alluvial fan- clay flat, pediment and clay flat. Considering the diversity of geomorphic units, 11 soil profiles were described and diffrenet soil layers and horizons were sampled. Undisturbed soil samples were taken micromorphological studies. Some horizons were selected for clay mineralogy analysis. The mineralogy of clay fraction was determined using X-ray diffraction method.
Results and discution: All studied soils except the profiles in the pediment were classified in the Aridisols order. There were two geomorphic surfaces in alluvial fans. In the first geomorphic surface a soil with the Bk horizon buried a soil with red Btk horizon. In the second geomorphic surface, it seems that the erosion has been removed the overlying soil. The Bk horizon showed the maximum soil development in the clay flat and intermediate alluvial fan-clay flat landforms. Clay coating on sand in thin section was the evidence of clay illuviation in Btk horizon. Carbonate nodules associated with clay coating are the compound pedofeature in Btk horizon. These evidences reflect polygenetic nature of the soils and different period of climate change and soil formation. Smectite, mica, chlorite and palygorskite are the clay minerals in the studied soils. Similar to soils in arid regions of Iran, palygorskite was found in Bk, Bt and Bz horizons. The existence of Bk horizon in overlying soils, buried Btk horizon, removal of surface horizon in alluvial fan are the evidences of regressive and progressive of pedogenic processes in the study area. Btk horizon represents a warm and wetter and Bk horizon indicates a relatively wetter period in comparison to present time.
Conclusion: Btk was the most developed horizon in the study area that occurred as buried paleosol in alluvial fan. Bk, Bw, By and Bz were the common horizon in other landforms. Clay coating and red color of Btk horizon might seem as indicators of hot and humid conditions in the past, during the argillic horizon formation. Covered carbonate nodules with clay coating can also be mentioned as sign of a hot and wet period which is suitable for clay illuviation and weathering after a period of carbonate accumulation. The buried Btk horizon under alluvial layers in the alluvial fan indicates that after apedogenic period, alluvial processes have been responsible in burying this horizon. Bk horizon in overlying soil of all landforms represents a less intense period of soil formation. The dominant clay minerals in the study area were Illiite, cholorite, kaolinite, and palygorskite. The sequence of Bk and Btk horizons in this research and the occurrence of these soils in central, eastern and northeastern Iran imply the similar pedogenetic conditions in arid regions of Iran.
Research Article
Hossain Shohab Arkhazloo; H. Emami; Gholam Hosain Haghnian; Abazar Esmali
Abstract
Introduction: Gully erosion is an important type of soil erosion in Iran and Ardebil province (Moghimi and Salami, 2011; Khatibi, 2006). Increasing the cross section of gullies is an indicator for gully developing (Deng et al, 2015). Topography and soil properties are two important factors in gully developing ...
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Introduction: Gully erosion is an important type of soil erosion in Iran and Ardebil province (Moghimi and Salami, 2011; Khatibi, 2006). Increasing the cross section of gullies is an indicator for gully developing (Deng et al, 2015). Topography and soil properties are two important factors in gully developing in various regions of worldwide (Poesena et al, 2003). Despite the importance of soil properties in gully erosion, the direct effect of these agents was less investigated and few researches have been carried out to the effect of physical and mechanical soil properties on gully erosion. Therefore, the objectives of this research were to determine 1) the effect of topography on gully erosion, 2) effect of surface and subsurface soil physical and mechanical properties on increasing the cross section of gullies and 3) to select the most important soil properties affect developing the cross section of gullies in three regions of Ardebil province (Ortadagh, Molla Ahmad, and Sarcham). In addition, the relationship between the most soil properties and topographic agents was investigated
Materials and Methods: The effect of topography on gully erosion was investigated by using of two methods i.e. topographic threshold of gully forming (as , where A and S is gully watershed cross section and slop, respectively, a and b is local coefficients) and the relationship between slope classes with gullies density. In regard to catchment characteristics, a set of similar gullies was selected in each region and the changes of cross section area for gullies in four points along its length were measured as indicator of gully development during two years. 17 physical and mechanical of surface and subsurface soil properties in each point were measured and the most important properties that affect on gully development were selected based on principle component analysis (PCA) method. Finally, the stepwise regression model was fitted to the soil properties selecting from PCA for gully's development in each region.
Results: The relationship between Slope classes and gully density showed that in MollaAhmad region gully density was increased with increasing the slope. In OrtaDaghregion, similar trend was observed up to 20-30% slope, while in Sarcham region these was no relationship between slope classes and gully density. According to the topographic threshold it seems that runoff is the main agent for gully forming in MollaAhmad,but in Sarchamthe piping and tunnel erosion might have caused gully formation and in Ortadagh both surface and subsurface flows were recognized as effective agents for gully formation. Increasing values of the cross section for the selected gullies during 2 years was 0.9, 0.6, and 0.8 m2 for Ortadagh, MollaAhmad, and Sarcham regions respectively, which were 41, 44 and 61 percent more than their initial cross sections. Among mechanical soil properties, liquid limit (LL), plastic limit (PL) and shear strength (SS) had the negative and significant correlations with increasing the cross sections of gullies in 3 regions. Among the particle size fractions, Water dispersible clay had the most effect on increasing the gully’s cross sections and except for surface depth of Molla Ahmad, its correlation with gully’s cross section was significant. Principle component analysis (PCA) demonstarated that in MollaAhmad and Ortadagh mainly mechanical properties of soil and aggregate stability had the more effect on increasing the gully cross section, but in Sarcham soil particle size classes and aggregate stability indices had more effect on gully’s cross section.
Conclusion: According to topography threshold, it can be concluded that surface runoff is the main agent for gully forming in MollaAhmad and gully density increases by increasing the slope classes. In this region the effect of surface runoff on surface soil erosion was sever. In Sarcham there was no relationship between slope and gully density and it was found that the subsurface flow is predominant factor for gully forming. In OrtaDagh both surface and subsurface flows were the main factors for gully forming, so due to increasing the surface flow up to slope 20-30% class, maximum gully density was noted in this slope class and the effect of subsurface soil properties in developing gully cross section was higher than surface soil properties. In general, the relationship between gully density with slope classes, topographic threshold and soil physical and mechanical properties which were effective on gully development indicated the close consistency between the type of hydrologic flow in gully forming and the most important soil properties on increasing the gully’s cross section.
Research Article
Hanifeh khormai1; farshad kiani; Farhad khormali
Abstract
Introduction: Globally, Soil erosion is a principal degradation process resulting in negative impacts on different soil functions (food and other biomass production, water storing, filtering and transformation, habitat and gene pool, physical and cultural environment for mankind, and source of raw materials) ...
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Introduction: Globally, Soil erosion is a principal degradation process resulting in negative impacts on different soil functions (food and other biomass production, water storing, filtering and transformation, habitat and gene pool, physical and cultural environment for mankind, and source of raw materials) which ultimately causes irreversible effect on the poorly renewable soil resource. Determination of the soil erodibility factor (K-factor) is a cumbersome and expensive undertaking in the effort to predict the soil loss rates. Soil erodibility (K-value) is a key parameter in erosion prediction and is important for conservation planning in the face of a rising need for protecting the limited land resources. The technique proposed by Wischmeier& Smith for estimating the soil erodibility factor is among the most important methods in this regard.
Materials and Methods: Given the high amounts of silt and lime content in loess soils of eastern parts of Golestan province, the purpose of this study was to evaluate the ability of Wischmeier& Smith index to estimate the soil erodibility of this region. In this study, soil erodibility was obtained by Wischmeier’s nomograph and then was compared with the actual values obtained by selecting three plots and then performing physical and chemical tests on these samples. The Universal Soil Loss Equation (USLE) developed by Wischmeier and Smith (1978) is the most frequently used empirical soil erosion model worldwide. Soil erodibility is one of six factors affecting soil erosion in the USLE that reflects the ease with which soil is detached by splash during rainfall, surface flow or both. To check soil erosion,three plots of 15 meters long and three meters wide with a slope of 16 percentwere selected in the next sites of the station. The plots were separated by metal fences to a height of 30 cm,.To measure the soil profile parameters, the sampling was performedin one stage from depth of0-30 cm in the middle of July 2010 and the samples were transported to the laboratory. The erosion Wischmeier& Smith Index (A), as well as those obtained by SWAT model and two obvious erosion indices of (R) and Fournier was Carefully evaluate based on the half-hour rainfall intensity.
Results and Discussion: The analysis of soil profile parameters showed that the soilsweremostly silty loamwith 20.29%sand, 66.54% silt and 13.66% clay, with 2% organic matter and 16.6% CaCO3. The soil aggregate stability expressed as MWDwas about 0.8 mm. Overal, 74 rainfallsoccurredin 2010-2011. The minimum and maximum intensities of deposit-producing rainfalls were 2.98 and 73.589 mm h-1, respectively. Using the nomograph, Wischmeier index was calculated to 0.05-0.092 Mg h MJ−1 mm−1. The results showed that Wischmeier index was 182 times the actual value of erosion obtained from plots and half-hour rainfall intensity and 4.11 times that value while considering Fournier index (R); this parameter was also 6 times the value obtained by SWAT model and half-hour rainfall intensity and 0.35 times that value while considering Fournier index. According to the results,there was a negative correlation between clay and soil erodibility factor in USLE, so the rates of erosion in loess soils increases with the decrease in the clay content. Aggregate stability was affected by organic matter content and there was a negative correlation between aggregate stability and the K-factor. The results showed that the soil mostly contained silt and had a medium texture. This is due to the presence of loess parent materials in the soils of the study area. Based on the laboratory results, the actual soil erodibility was0.35 to 182 times smaller than the value estimated by USLE nomograph. The results showed that the parameters used in determining soil erodibility index have shortcomings for use in the soils of the study area. Therefore, corrections must be done according to soil characteristics or other indicators should be used. The particle size and the amount of lime in the soil are two factors that affect the index.
Conclusions: The obtained results showed that the erodibility estimated by Wischmeier& Smith index was higher than the actual measured value. Also,Wischmeier &Smith’snomographhas been proposed by assessing the erodibility of almost non- calcareous soils with limited amount of silt. While in arid and semiarid loess soils of Golestan province, limestone and siltstone have key roles in erodibilityand aggregate stability. On the other hand, the nomograph is based on rainfalls of semi-humid areas of Central America that are different from rain characteristics (intensity and duration) of the study area. Poor performance of this index in loess soils indicates the need for further research in this field.
Research Article
aliakbar sabziparvar; B. Khatar
Abstract
Introduction: Solar Net Radiation (Rn) is one of the most important component which influences soil heat flux, evapotranspiration rate and hydrological cycle. This parameter (Rn) is measured based on the difference between downward and upward shortwave (SW) and longwave (LW) irradiances reaching the ...
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Introduction: Solar Net Radiation (Rn) is one of the most important component which influences soil heat flux, evapotranspiration rate and hydrological cycle. This parameter (Rn) is measured based on the difference between downward and upward shortwave (SW) and longwave (LW) irradiances reaching the Earth’s surface. Field measurements of Rn are scarce, expensive and difficult due to the instrumental maintenance. As a result, in most research cases, Rn is estimated by the empirical, semi-empirical and physical radiation models. Almorox et al. (2008) suggested a net radiation model based on a linear regression model by using global solar radiation (Rs) and sunshine hours. Alados et al. (2003) evaluated the relation between Rn and Rs for Spain. They showed that the models based on shortwave radiation works perfect in estimating solar net radiation. In another work, Irmak et al. (2003) presented two empirical Rn models, which worked with the minimum numbers of weather parameters. They evaluated their models for humid, dry, inland and coastal regions of the United States. They concluded that both Rn models work better than FAO-56 Penman-Monteith model. Sabziparvar et al. (2016) estimated the daily Rn for four climate types in Iran. They examined various net radiation models namely: Wright, Basic Regression Model (BRM), Linacre, Berliand, Irmak, and Monteith. Their results highlighted that on regional averages, the linear BRM model has the superior performance in generating the most accurate daily ET0. They also showed that for 70% of the study sites, the linear Rn models can be reliable candidates instead of sophisticated nonlinear Rn models. Having considered the importance of Rn in determining crop water requirement, the aim of this study is to obtain the best performance Rn model for cold semi-arid climate of Hamedan.
Materials and Methods: We employed hourly and daily weather data and Rn data, which were measured during December 2011 to June 2013 in climatology station of Bu-Ali Sina University. This experiment was performed for the cold semi-arid site of Hamedan (Iran). The study site (Hamedan) is a mountainous research station (1860 meters above sea-level) which is located at the eastern side of central Zagros Mountain Range. The net radiation fluxes were measured by four SW (300-2800 nm) and LW (4500-42000 nm).Hukseflux Thermal Sensors mounted on an automatic logger system. The logger reported four upward and downward solar components in every 8-minute intervals. In this study, total daily net radiation was estimated by 12 empirical and semi-empirical Rn models including: Basic Regression Models (BRM), Extended Regression Models (ERM), Linacre, Berliand, Wright and FAO-56 Penman-Monteith. The model performances were evaluated by R2, RMSE, MBE and MPE criteria and the best model was selected accordingly.
Results and Discussion: In this research, the model calculations were done for seasonal and annual time scales. The results indicate that Basic Regression Model Rn(BRM-4) performs the best estimates in spring time. Further, for summer and autumn seasons, Rn (BRM-3) was superior for the cold semi-arid climate of Hamedan. Therefore, with the exception of winter, the BRM models performed the best estimates. Unlike the other seasons, for winter, Irmak presented the most accurate results. This is due to the fact that net radiation as estimates by Irmak Model is mainly dependent on daily maximum (Tmax) and minimum temperatures. For Irmak model, as the Tmax is increased, Rn will be reduced proportionally. For this reason, Irmak does not perform good estimates for warm months. In annual time scale, the Basic Regression Model of Rn (BRM-3) presented the most accurate estimates of net radiation. The study of Monteith and Szeicz (1961)and MirgaloyBayat (2011) also showed that Rn (BRM-3) model can generated the best Rn estimate in annual scale for mountain regions.
Conclusion: Unlike the recommendation of FAO for using Penman-Monteith and Wright approaches in evapotranspiration models, it was found that the aforesaid Rn models are not suitable for cold semi-arid regions such as Hamedan. This result is in good agreement with the findings of Izoimon et al. (2000) and MirgaloyBayat (2011). In general, for cold climate condition of Hamedan, the Basic Regression Models are more reliable than the other Rn models. This study was performed based on 18-month field data and 12-Rn models. To achieve more accurate results, using a longer term experimental data and examining more Rn models are suggested as the future works. To achieve a regional Rn zoning, inclusion of satellite-based dataset is also recommended.
Research Article
vajiheh mohammadi sabet; Mohammad Mousavi Baygi; Hojat Rezaee Pazhand
Abstract
Introduction: The Southern Oscillation is a large scale phenomenon that changes the Normal oscillating air pressure on both sides of the Pacific Ocean. It disrupted the normal conditions and the patterns of temperature and precipitation change in the nearby region and other regions of the world. This ...
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Introduction: The Southern Oscillation is a large scale phenomenon that changes the Normal oscillating air pressure on both sides of the Pacific Ocean. It disrupted the normal conditions and the patterns of temperature and precipitation change in the nearby region and other regions of the world. This phenomenon is caused by changing the water slope in the Pacific Ocean between Peru (northwestern South America) and Northern Australia (about Indonesia and Malaysia). ENSO phenomenon is formed of Elnino (warm state) and La Niña (cold state). There is high pressure system in the East and low pressure system in the West Pacific Ocean in normal conditions (Walker cycle). The trade winds blow from East to West with high intensity. ENSO start when the trade winds and temperature and pressure balance on both sides of the PacificOcean change. High pressure will form in the west and low pressure will form in the East. As a result, west will have high and east will have low rainfall. Temperature will change at these two locations. Enso longs about 6 to 18 months. This research investigated the impact of ENSO on monthly precipitation and temperature of Mashhad.The results showed that temperature and rainfall have a good relation with ENSO.This relation occurs in 0-5 month lag.
Materials and Methods: The severity of ENSO phenomenon is known by an index which is called ENSO index. The index is the anomaly of sea surface temperature in the Pacific. The long-term temperature and precipitation data of Mashhad selected and analyzed. The Rainfall has no trend but temperature has trend. The trend of temperature modeled by MARS regression and trend was removed.The rainfall data changed to standard and temperature changed to anomaly for comparison with ENSO index. The 2016 annual and monthly temperature of Mashhad is not available. The 2016 Annual temperature was forecasted by ARMA (1,1) model. Then this forecast disaggregated to monthly temperature. For each period of occurring high ENSO, these three indexes (ENSO index, standardized rainfall and anomalies temperature) were compared. The co-variation of these indexes was compared. Also, the correlation and cross correlation for each period of occurring ENSO, with rain and temperature of Mashhad was calculated.
Results and Discussion: Mashhad monthly temperature and precipitation were compared with the extreme values of ENSO index in periods of the occurrence this phenomenon (1950-2016). In addition, the correlation and cross-correlation between ENSO-Rainfall index and ENSO-temperature index for this period were calculated.Forecasted temperature for 2016 by ARMA (1,1) was 13.2 Degrees Celsius, which has 0.2 degree increase in comparison to last year. Results showed thatthere is no an obvious relation between ENSO-Temperature and ENSO-Rainfall in interval (-1, +1). But there are good relation between ENSO-Temperature and ENSO-Rainfall beyond of (-1,+1). The results of Elnino showed that the monthly precipitation and temperature increase with a lag of 2 to 5 months and 0 to 4 months, respectively. The results of Lanina showed that the monthly precipitation and temperature decrease with a lag of 3 to 5 months and 1 to 4 months, respectively. Also when ENSO index is located in the interval (-1, +1), there is no certain harmony with temperature and precipitation of Mashhad.
Conclusions: The aim of this study was evaluating the effect of the ENSO phenomenon on monthly temperature and precipitation of Mashhad.Mashhad monthly temperature and precipitation, respectively, for 132 and 124 years were available.Precipitation was static and has no trend, but temperature was not static and has two changed (jumped) point in 1976 and 2000. MARS regression was used for patterning the process. Removing the trend was done by MARS model and the data was obtained without trend. Monthly ENSO index since 1950 from reliable websites worldwide (NOAA) was obtained. Mashhad monthly temperature data was animalized and precipitation data was standardized. This was performed for comparing Temperature and Rain with ENSO index. The effect of the ENSO phenomenon on Mashhad precipitation and temperature in both graphical and cross-correlation was performed.As a final result, there is a good relation with latency zero up to 5 months for temperature and precipitation of Mashhad beyond the interval (-1, + 1). It cannot be claimed that after the phase of La Nina, El Nino must be entered and vice versa. This note is important for forecasting the temperature and precipitation of 2016coming months. If ENSO index in the coming months, especially in autumn and winter, decrease and inter in La Nina phase, the winter will be cold with low rainfall.
