Research Article
Z. Ahmadpoor; M. Khoramivafa; S. Jalali Honarmand; K. Cheghamirza; M. Khan Ahmadi
Abstract
Introduction: There is necessary to clean up the nitrate and phosphate from surface waters before effluence of them to environment and eutrophication formation because of water health importance and considering to nitrate and phosphate consequences. Nitrate and ammonium as the - forms of inorganic and ...
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Introduction: There is necessary to clean up the nitrate and phosphate from surface waters before effluence of them to environment and eutrophication formation because of water health importance and considering to nitrate and phosphate consequences. Nitrate and ammonium as the - forms of inorganic and nitrogen have been subjected to the center of issues related to environment pollutants and water resources in a long time. The nitrate is more important than other inorganic nitrogen forms such as ammonium because of various reasons such as high dynamics and causing diseases such as some of digestion system and lymph nodes cancers in adults and methemoglobinemia in infants. Therefore the maximum concentration of this ion in drinking water has been determined as 45 mg.Lit-1 by WHO. Regarding the importance of the water health and the complications due to existence of some compounds such as nitrate and phosphate, in this experiment, the possibility of elimination or decreasing excess nitrate and phosphate from water in hydroponic conditions using of two watercress and pennyroyal plants was evaluated. Watercress(Nasturtiumofficinale) and pennyroyal (Menthapulegium)were selected because of some properties such as adaptability with the most climates of Iranamd less requirements care.
Materials and Methods: Two RCD factorial experiments were carried out to evaluate the ability of watercress and pennyroyal to biosorption of nitrate and phosphate from polluted water in hydroponic conditions. First factor was plant species including watercress and pennyroyal. Second factor included nitrate (50, 100, 150 Mg/L) and phosphate (5, 10, 15 Mg/L) in first and second experiment respectively.The final concentrations of nitrate and phosphate in water was measured using spectrophotometer in wavelength of 410 nm and 690 nm by sulphatebrucine and chloride methods , respectively, which are mentioned in Standard Methods for the Examination of Water and Wastewater. At the end of the each experiment, watercress and pennyroyal plants were brought out from the pots carefully and their roots and shoots were separated. Roots and shoots were placed in aluminum foil separately and were dried by oven method (50°C and 48 h). The weights of dried samples were measured by a digital balance scale (0.001 gr accuracy). Three accumulation indices including Bio-concentration Factor, Translocation Factor and Tolerance Index were calculated by measuring of nitrate and phosphate accumulation in roots and shoots
Results and Discussion: According to the results, root phosphate accumulation in two plants was different significantly (p ≤ 0.05). Also, the level values of nitrate and phosphate were resulted to their root accumulation significantly. In this regard, the phosphate accumulation in watercress root changed to 10 mg. Lit-1 significantly and reached to 4.3 mg.Kg-1 dry weight in this concentration. While for pennyroyal, there was no significant increasing in roots phosphate accumulation when its concentration was increased in medium (p ≤ 0.05). Although phosphate accumulation was difference between the two plants in root and shoots, there was similar the alteration of phosphor bioconcentration trend. Because increasing of phosphate concentration resulted in significant decreasing of this index. Whilst both of watercress and pennyroyal accumulated high amount of nitrate and phosphate, quantity of accumulation in shoots was higher than of roots. Consequently, nitrate translocation factor was 1.3 in watercress and 1.07 in pennyroyal, and phosphor translocation factor was 1.07 and 0.94 in watercress and pennyroyal respectively.
Conclusions: Results indicated that two plants were pollutants purified of nitrate and phosphate (The nitrate translocation factors were 1.3 and 1.07 in watercress and pennyroyal and the phosphate translocation factors were 1.07 and 094 in watercress and pennyroyal, respectively). Generally, it was found that watercress and pennyroyal have extractive behavior completely about nitrate and phosphate. Because of the high ability of these plants in biosorption of phosphate and nitrate, with recovery of nitrogen and phosphorus cycle, they can be used as organic resources of nitrogen and phosphor supply in agricultural soil and prevent from entrancing them to seas. It is more important about phosphate, which has slowly cycle. Therefore two main roles for watercress and pennyroyal in aquatic ecosystems are expected. First, perform as bio-filter and returning the nitrogen and phosphor from surface water or wastewater for preventing the environmental pollution and second as secondary saleable or utilizable crop such as green manure and so on.
Research Article
B. Ghahraman
Abstract
Introduction: Actual crop evapotranspiration (Eta) is important in hydrologic modeling and irrigation water management issues. Actual ET depends on an estimation of a water stress index and average soil water at crop root zone, and so depends on a chosen numerical method and adapted time step. During ...
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Introduction: Actual crop evapotranspiration (Eta) is important in hydrologic modeling and irrigation water management issues. Actual ET depends on an estimation of a water stress index and average soil water at crop root zone, and so depends on a chosen numerical method and adapted time step. During periods with no rainfall and/or irrigation, actual ET can be computed analytically or by using different numerical methods. Overal, there are many factors that influence actual evapotranspiration. These factors are crop potential evapotranspiration, available root zone water content, time step, crop sensitivity, and soil. In this paper different numerical methods are compared for different soil textures and different crops sensitivities.
Materials and Methods: During a specific time step with no rainfall or irrigation, change in soil water content would be equal to evapotranspiration, ET. In this approach, however, deep percolation is generally ignored due to deep water table and negligible unsaturated hydraulic conductivity below rooting depth. This differential equation may be solved analytically or numerically considering different algorithms. We adapted four different numerical methods, as explicit, implicit, and modified Euler, midpoint method, and 3-rd order Heun method to approximate the differential equation. Three general soil types of sand, silt, and clay, and three different crop types of sensitive, moderate, and resistant under Nishaboor plain were used. Standard soil fraction depletion (corresponding to ETc=5 mm.d-1), pstd, below which crop faces water stress is adopted for crop sensitivity. Three values for pstd were considered in this study to cover the common crops in the area, including winter wheat and barley, cotton, alfalfa, sugar beet, saffron, among the others. Based on this parameter, three classes for crop sensitivity was considered, sensitive crops with pstd=0.2, moderate crops with pstd=0.5, and resistive crops with pstd=0.7. Therefore, nine different classes were formed by combination of three crop types and three soil class types. Then, the results of numerical methods were compared to the analytical solution of the soil moisture differential equation as a datum. Three factors (time step, initial soil water content, and maximum evaporation, ETc) were considered as influencing variables.
Results and Discussion: It was clearly shown that as the crops becomes more sensitive, the dependency of Eta to ETc increases. The same is true as the soil becomes fine textured. The results showed that as water stress progress during the time step, relative errors of computed ET by different numerical methods did not depend on initial soil moisture. On overall and irrespective to soil tpe, crop type, and numerical method, relative error increased by increasing time step and/or increasing ETc. On overall, the absolute errors were negative for implicit Euler and third order Heun, while for other methods were positive. There was a systematic trend for relative error, as it increased by sandier soil and/or crop sensitivity. Absolute errors of ET computations decreased with consecutive time steps, which ensures the stability of water balance predictions. It was not possible to prescribe a unique numerical method for considering all variables. For comparing the numerical methods, however, we took the largest relative error corresponding to 10-day time step and ETc equal to 12 mm.d-1, while considered soil and crop types as variable. Explicit Euler was unstable and varied between 40% and 150%. Implicit Euler was robust and its relative error was around 20% for all combinations of soil and crop types. Unstable pattern was governed for modified Euler. The relative error was as low as 10% only for two cases while on overall it ranged between 20% and 100%. Although the relative errors of third order Heun were the smallest among the all methods, its robustness was not as good as implicit Euler method. Excluding one large error of 50%, the average relative errors in this method was less than 10%. However, the ETc is time-dependent and varies from one day to another. So, averaging ETc over a larger time step brings about more error in computations. Accumulated relative error in Eta (ETp=5 mm.d-1, W0=Wj, t=1 d) under medium soil and crop type was decreased as the number of time steps increased, irrespective of the numerical method.
Conclusions: Based on practical considerations, we propose implicit Euler for its robustness, and 3-rd order Heun for its low maximum relative error for all combinations of soil and crop types.
Research Article
M.R. Khaledian; S.A. Moussavi; H. Asadi; M. Norouzi; M. Aligoli
Abstract
Introduction: With increasing awareness of human beings towards the environment, researchers pay more attention to process and redistribution of water flow and solute transport in the soil and groundwater. Moreover, determination of soil hydraulic conductivity is necessary to determine the runoff from ...
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Introduction: With increasing awareness of human beings towards the environment, researchers pay more attention to process and redistribution of water flow and solute transport in the soil and groundwater. Moreover, determination of soil hydraulic conductivity is necessary to determine the runoff from basins. Water movement within the unsaturated zone is often described by the formulae proposed by Richards. To solve this equation, initial and boundary conditions of the hydraulic conductivity and the soil water pressure should be determined as functions of soil water content. Beerkan method was developed to identify retention and hydraulic conductivity curves. In this method, van Gunechten with Burdine condition and Brooks and Corey equations were used to describe water retention and hydraulic conductivity curves. Recognition of the spatial pattern of studied parameter using semivariogram and then preparing zoning map with interpolation methods such as IDW and kriging can help us in relevant watershed management. The aim of this study was to spatial analyze of saturated hydraulic conductivity from 50 infiltration tests at watershed scale using Beerkan method and then preparing zoning map for the Navroud watershed.
Materials and Methods: Navroud-Assalem watershed with an area of about 307 km2 is located in the west part of Guilan province, within the city of Talesh. Of the total watershed area of Navroud, about 41 km2 is plains and the rest of it is about 266 km2, corresponding to the mountainous area. The study area includes an area with a height above 130 m. In order to complete the database of the studied watershed the present study was designed to assess soil saturated hydraulic conductivity. In this study, a 2×2 km network was designed in Navroud watershed with a surface area of 307 km2, and then infiltration tests were carried out in each node using single ring of Beerkan. Beerkan method derives shape parameters from particle-size distribution and normalization parameters from infiltration test with a near zero pressure head. Evaluation of spatial variation was done using GS+ and zoning map was prepared with ArcGIS software. Statistical evaluation of recorded data was done using SPSS software package.
Results and Discussion: Results showed that the soil bulk density was of 1.07 gr cm-3 in average. Furthermore, the results showed that the average of saturated hydraulic conductivity (Ks) in the watershed was of 3.96 cm hr-1 with a coefficient of variation of 151%. The watershed Ks is classified in the moderate class. Regarding the high value of Ks variation coefficient, using geostatistics is necessary to analyze Ks spatial variation. The results indicate the absence of the anisotropy. Using GS+ software, exponential model was fit on the empirical variation (r2=0.953 and RSS=0.0057 cm hr-1). The effective range was of 2280 m. The difference between the amounts reported by other studies and this study was because of the effect of the difference in the study area (307 km, in this study), scale (the field or watershed) and the distance between measured points. Two usual methods of interpolation including inverse distance weighting and ordinal kriging were verified. The results showed that ordinal kriging performed better than inverse distance weighting method (RMSEs for ordinal kriging and inverse distance weighting were 8.97 and 9.75, respectively). Zoning map of Ks was prepared according to the results of GS+ software using ArcGIS software. The correlation coefficients between Ks and sand, silt and clay percents were -0.04, 0.01 and 0.07, which demonstrate a weak effect of soil texture on the Ks as compared with soil structure. The correlation coefficient of the soil bulk density with Ks was of -0.45 which demonstrate a stronger effect as compared with the soil texture.
Conclusions: The results of this study can be used to proper management of watersheds. One of the main information needed to manage a watershed is Ks. Determining the spatial variability of soil saturated hydraulic conductivity at watershed scale in spite of its difficulty is one of the main prerequisite parameters to provide detailed maps of a watershed. The aim of this study was to analyze the spatial variability of Ks in Navroud-Assalem watershed, Guilan province. After analyzing spatial data, using ordinary kriging interpolation method, zoning map of Ks was prepared. This map can be used to find the optimal management of watershed, such as determining the amount of basin runoff and groundwater recharge.
Research Article
M.M. Heidari; S. Kouchakzadeh
Abstract
Introduction: Determination the hydraulic performance of an irrigation network requires adequate knowledge about the sensitivities of the network structures. Hydraulic sensitivity concept of structures and channel reaches aid network operators in identifying structures with higher sensitivities which ...
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Introduction: Determination the hydraulic performance of an irrigation network requires adequate knowledge about the sensitivities of the network structures. Hydraulic sensitivity concept of structures and channel reaches aid network operators in identifying structures with higher sensitivities which will attract more attention both during network operation and maintenance program. Sluice gates are frequently used as regulator and delivery structures in irrigation networks. Usually discharge coefficient of sluice gate is considered constant in the design and operation stage. Investigation of sensitivity of offtakes and cross-regulators has carried out by various researchers and some hydraulic sensitivity indicators have been developed. In the previous researches, these indexes were developed based on constant coefficient of discharge for free flow sluice gates. However, the coefficient of discharge for free flow sluice gates depend on gate opening and the upstream water depth. So, in this research, some hydraulic sensitivity indicators at structure based on variable coefficient of discharge for free flow sluice gates were developed and they were validated by using observed data.
Materials and Methods: An experimental setup was constructed to analyses the performance of the some hydraulic sensitivity. The flume was provided with storage reservoir, pumps, electromagnetic flowmeter, entrance tank, feeder canal, delivery canals, offtakes, cross-regulators, collector reservoir, piezometric boards. The flume is 60.5 m long and the depth of that is 0.25 m, of which only a small part close to offtake and Cross-regulators was needed for these tests. Offtakes and Cross-regulators are free-flowing sluice gates type. Offtakes were located at distances 20 m and 42.5 m downstream from the entrance tank, respectively. and, Cross-regulators were located 2 m downstream from each offtakes. The offtakes are 0.21 m and Cross-regulators are 0.29 m wide. The upstream and downstream water levels at gates were measured with piezometer taps. There is a collector reservoir downstream of each delivery canal that was equipped with a 135 V-notch weir as a measuring device. The flow was provided by a pump having maximum capacity 35 lit/s, and was measured by an electromagnetic flowmeter of 0.5% accuracy. The suction pipe of the upstream pump was connected to the storage reservoir and its discharge pipe delivered the water to an entrance tank located at the upstream side of the flume. The entrance take was equipped with a turbulence reduction system. Measured water entered to feeder canal and, after adjusting water depth by Cross-regulators, it moved to offtakes and the brink of the feeder canal. Underneath the downstream end of the feeder canal and delivery canals, a tank was installed to collect the water. Water accumulated at the collector tanks was pumped to the storage reservoir by using a pump to complete the water circulation cycle.
Results and Discussion: Discharge coefficient is the most important parameter that is effect on hydraulic indicators sensitivity. Therefore, coefficient of discharge for free flow sluice gates determined based on experimental data. Sluice-gate discharge coefficient is a function of geometric and hydraulic parameters. For free flow, it is related to upstream depth and gate opening. In this study, analytical relationships for various sensitivity indices for channel reach were developed, and the performance of the proposed relationships was verified with experimental data compiled during this research. It was shown that using constant discharge coefficient yields average error in the calculated sensitivity of the water depth upstream regulator to the inlet flow, and average error of calculated reach sensitivity indicator, as 16.6% and 5.8%, respectively. While those values for variable coefficient was 5.7% and 1.9%, respectively. Also, for 20% variation in reach inflow, the variable coefficient improved the calculated mean flow depth error upstream of a regulator drastically, i.e. the mentioned error using constant coefficient was 17% while that of variable one was 4.3%
Conclusion: In this research, Analytical relationships based on using variable discharge coefficient for Three sensitivity indicators for a canal reach, i.e. reach sensitivity indicator of water depth, reach sensitivity indicator for conveyance and delivery developed. Comparing reach canal sensitivity indicators and the structural sensitivities, i.e. sensitivity of delivery of offtake to absolute water depth deviation and water depth sensitivity to the discharge for regulator with experimental data, showed good agreement. Hence, the technique proved to be reliable in providing what is necessary for practical canal.
Research Article
P. Maleki; M.J. Ketabdari; hossein samadi; D. Maleki
Abstract
Introduction: Interactionbetweenwater flow characteristics andthe bed erodibilityplays an important role in sediment transport process. In order to reach stability, rivers with deposition or bottom erosion make a different bed form in the riverbed. One way to identify thebehavior of therivers is to study ...
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Introduction: Interactionbetweenwater flow characteristics andthe bed erodibilityplays an important role in sediment transport process. In order to reach stability, rivers with deposition or bottom erosion make a different bed form in the riverbed. One way to identify thebehavior of therivers is to study the structure and formation of bed forms within them. Ripples are the smallest of the bed forms. The longitudinal cross section of ripples are usually not symmetrical. The upstream face is long and has a gentle slope, and the downstream face is short and steep. The height of ripples is usually between 0.5 cm and 2 cm; the height ripple is not more than 5 cm. The wave lengths normally do not exceed 30cm, and they are usually within the range of 1 cm to 15 cm. Their occurrence is the result of the unstable viscous layer near the boundary. They can form in both shallow and deep water.With an increase of the flow velocity, the plan form of the ripples gradually develops form straight line to curves and then to a pattern like fish scales, symmetrical or unsymmetrical, as shown in Fig 1.
Figure1-The patterndevelopment oftheripple
Raudkivi (1966) was the first person that, the flow structure over ripples was investigated experimentally.Hethenestablishseveraldifferent conditionsonthemovingsandbedinanlaboratorychannelconsisted of a rectangular cross-section with base width of 70cm, wasable toform arow ofripples , he wassucceed toform arow ofripples.JafariMianaei and Keshavarzi(2008),studied the turbulentflow betweentwoartificialripples for investigate the change of kinetic energyandshearstress on overripples. The stage- discharge rating curve is one of the most important tools in the hydraulic studies. In alluvial rivers,bed rippled are formed and significantly affect the stage- discharge rating curve. In this research, the effects of two different type of ripples (parallel and flakeshape) onthe hydraulic characteristicsof flow were experimentally studied in a flume located at the hydraulic laboratory ofShahrekordUniversity, Iran.
Bass (1993) [reported in Joep (1999)], determined an empirical relation between median grain size, D50, and equilibrium ripple length, l:
L=75.4 (logD50)+197 Eq.(1)
Where l and D50 are both given in millimeters.
Raudkivi (1997) [reported in Joep (1999)], proposed another empirical relation to estimate the ripple length that D50 is given in millimeters:
L=245(D500.35) Eq. (2)
Flemming (1988) [reported in Joep (1999)], derived an empirical relation between mean ripple length and ripple height based on a large dataset:
hm= 0.0677l 0.8098 Eq.(3)
Where hm is the mean ripple height (m) and l is the mean ripple length (m).
Ikeda S. and Asaeda (1983) investigated the characteristics of flow over ripples. They found that there are separation areas and vortices at lee of ripples and maximum turbulent diffusion occurs in these areas.
Materials and Methods: In this research, the effects of two different type of ripples onthe hydraulic characteristics of flow were experimentally studied in a flume located at the hydraulic laboratory of ShahrekordUniversity, Iran. The flume has the dimensions of 0.4 m wide and depth and 12 m long. Generally 48 tests variety slopes of 0.0005 to 0.003 and discharges of 10 to 40 lit/s, were conducted. Velocity and the shear stress were measured by using an Acoustic Doppler Velocimeter (ADV). Two different types of ripples (parallel and flake ripples) were used. The stage- discharge rating curve was then estimated in different ways, such as Einstein - Barbarvsa, shen and White et al.
Results and Discussion: In order to investigateresult of the tests, were usedst atistical methods.White method as amaximum valueofα, RMSE, and average absolute error than other methods. Einstein method offitting the discharge under estimated. Evaluation of stage- discharge rating curve methods based on the obtained results from this research showed that Shen method had the highest accuracy for developing the stage- discharge rating curve than other methods. It also showed that theShenmethod was much accuracy by the parallel shape of ripplebed form compared with the flake shape.
Conclusion: Evaluation of stage- discharge rating curve methods based on the obtained results from this research showed that Shen method had the highest accuracy for developing the stage- discharge rating curve than other methods. It also showed that theShenmethod was much accuracy by the parallel shape of ripplebedform compared with theflakeshape. The results of the estimation of statistical parameters such as root mean square error (RMSE) and mean percent error for these cases indicated that the Shen method is associated with the lowest RMSE and error percentage. Therefore it estimates the stage- discharge rating curve more accurately than other methods. Furthermore in the case of parallel and flake ripple bed forms correlation coefficient was obtained as 0.87 and 0.43 respectively. This indicates that the Shen method is more accurate for the parallel shape of rippled bed forms than the flake shape ones.
Research Article
A. Shahnazari; M. Rezaiyan
Abstract
Introduction: Deficit irrigation (DI) is a suitable solution to gain acceptable and economic performance by using minimum amount of water. The partial root zone drying (PRD) method introduced in Australia for the first time and its goal was controlling the vine’s excessive growth. This goal gained ...
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Introduction: Deficit irrigation (DI) is a suitable solution to gain acceptable and economic performance by using minimum amount of water. The partial root zone drying (PRD) method introduced in Australia for the first time and its goal was controlling the vine’s excessive growth. This goal gained by alternative drying the rootzone. Basically the theory of PRD method, is expanding the plant’s roots by applying alternative stress on different sides of the roots. So the plants with PRD irrigation method can have different root system in comparison with other irrigation methods. At this method the plant’s condition would be OK by uptaking water from wet side, and the roots at the dry side can release abscisic acid hormone which decrease the stomatal conductance and consequently the water use efficiency would be increase.There had been studies on the effect of water tension on strawberry. The previous studies on strawberry indicated that the water stress can increase the plant’s brix concentration and some of plant acids.The awareness of the impact of water deficit stress on strawberry plant quantity and quality is essential for irrigation and product management, and at the current study, effect of different deficit irrigation methods on quantitative and qualitative traits of strawberry have been evaluated. The focus at the current study was on the qualitative traits.
Materials and Methods: The present study was conducted in one of strawberry farms of Babolsar city in 2012 to evaluate the effects of deficit irrigation and partial root zone drying on quantitative and qualitative traits of strawberry plants. Three Irrigation treatments were studied: Full Irrigation (FI), Regulated Deficit Irrigation (RDI75%) at 75% level of plants water requirementand Partial Root zone Drying (PRD75%) at 75% level of plants water requirement. The study was conducted in a randomized complete block design with three replications. Irrigation was continued until the soil moisture reached to field capacity. The field capacity point’s moisture was measured by using pressure plate equipment. By having the soil moisture curve and measuring the soil suction with tensiometer, the soil moisture situation determined. According to the point that the strawberry’s root is about 25 centimeters (cm), the tensiometers were installed at 2 depths next to the plant. The 1st depth was 8 cm and the 2nd one was 23 cm. The distance between tensiometers and the plant were 4 cm. 2 stochastic replication at the field were considered for the tensiometers positions. In order to deliver precise amount of water to irrigation treatments, the volume counters had been used. The water was applying by using drip tapes. The flow from the emitters on the drip tapes was 2.9 liters per hour. The harvest time was from May 5th to June 20th. To measure the performance, each shrub’s strawberries were weighted separately.Depth of irrigation water during the whole irrigation season for full and deficit irrigation treatments were 341 and 256 mm, respectively. Evaluating the effect of treatments was conducted by measuring the quantitative and qualitative traits of fruits at harvesting time.For analyzing the data, the SAS software and to plot the graphs, the Excel software were used. The SNK test (5% level) was used to comprise the treatments’ traits.
Results and Discussion: Quantitative traits consisted of fresh weight, dry weight, leaf area, leaf area index and yield in FI was higher significantly than deficit irrigation treatments. In comparison with the qualitative traits consisted of titratable acid, acidity and flavor of the fruit there was no significant difference between treatments. The leaf area index (LAI) at RDI and PRD were lower than the FI. Its reason could be the growth’ reducing as a result of abscisic acid (ABA) hormone’s release in the roots which can control the growth. The amount of total sugar (brix) and anthocyanin in RDI were significantly higher than the other two treatments.
Conclusion: The comparison between irrigation treatments indicated that the best quantitative results were at FI treatment. By considering the quantitative and qualitative traits, PRD had the nearest results to FI. At the water stress conditions, applying PRD method at 75% level would be a good management technic to have better performance and increasing the fruit quality. In Mazandaran Province condition, using this method would be a good way to minimize the quantitative losses and increasing the quality of fruits at stress condition.
Research Article
K. Shahverdi; M.J. Monem
Abstract
Introduction: Nowadays considering water shortage and weak management in agricultural water sector and for optimal uses of water, irrigation networks performance need to be improveed. Recently, intelligent management of water conveyance and delivery, and better control technologies have been considered ...
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Introduction: Nowadays considering water shortage and weak management in agricultural water sector and for optimal uses of water, irrigation networks performance need to be improveed. Recently, intelligent management of water conveyance and delivery, and better control technologies have been considered for improving the performance of irrigation networks and their operation. For this affair, providing of mathematical model of automatic control system and related structures, which connected with hydrodynamic models, is necessary. The main objective of this research, is development of mathematical model of RL upstream control algorithm inside ICSS hydrodynamic model as a subroutine.
Materials and Methods: In the learning systems, a set of state-action rules called classifiers compete to control the system based on the system's receipt from the environment. One could be identified five main elements of the RL: an agent, an environment, a policy, a reward function, and a simulator. The learner (decision-maker) is called the agent. The thing it interacts with, comprising everything outside the agent, is called the environment. The agent selects an action based on existing state in the environment. When the agent takes an action and performs on environment, the environment goes new state and reward is assigned based on it. The agent and the environment continually interact to maximize the reward. The policy is a set of state-action pair, which have higher rewards. It defines the agent's behavior and says which action must be taken in which state. The reward function defines the goal in a RL problem. The reward function defines what the good and bad events are for the agent. The higher the reward, the better the action. The simulator provides environment information. In irrigation canals, the agent is the check structures. The action and state are the check structures adjustment and the water depth, respectively. The environment comprises the hydraulic information existing in the canal. Policy is a map of water depth-check structure pairs. Reward function is defined based on the difference between water depth and target depth, and the simulator is a hydrodynamic model which, in the present study, was Irrigation Conveyance System Simulation (ICSS). In the developed RL, the RL begins with required initializations, and then the canal structures are operated. While the maximum reward is reached at the time step of t, the agent receives some representation of the state of the environment and, on that basis, selects an action. The simulator performs the action and provides information on the state of the new environment by simulating the canal system. Finally, the reward is assigned. Maximizing the reward, the RL goes on to the next time step. This process is continued until the final simulation time step is reached. The learning process is similar for all operations. The ICSS hydrodynamic model was used to simulate the canal system and provide the environmental information. Input to the ICSS was the new selected action. The ICSS performed the action and simulated the canal system. The output from the ICSS was information on the new environment for use in the next time step. Two scenarios of flow increase and decrease with initial flow of 25 l/s were simulated. MAE (Maximum Absolute Error), IAE (Integral of Absolute magnitude of Error) and SRT (System Response Time) indicators have been used to assess developed model. For flow decrease scenario, the indicators value are obtained zero.
Results and Discussion: Results were obtained from the performed scenarios. In the flow increase scenario, water depth variations were inside the dead band, therefore, SRT indicator was obtained zero. The MAE and IAE indicators were obtained 3.5% and 2.57%, respectively, which showed the water depth deviations from target depth was very low. In the flow decrease scenario, the all indicators values were obtained zero. At time zero in two scenarios, 1000 populations were generated and tested. As the RL controlled the water depth, it generated new populations, too. The reason for this is that the RL generates a new population if there is no classifier with maximum reward in the population. There are no new generation after 0.03 hr and 0.16 hr in flow increase and flow decrease scenarios, respectively. Considering the results, it could be concluded that the developed control system is a powerful technique in terms of accuracy and response time for water depth control.
Conclusion: In this research, the RL upstream control system was developed and connected with ICSS hydrodynamic model and evaluated in two scenarios of flow increase and flow decrease. The results showed an ability to control of deviations, short response time and accurate performance of the developed RL control system, which could be used for further study in irrigation canals.
Research Article
N. Seyyednezhad Golkhatm; H. Rezaee Pazhand
Abstract
Introduction: The analysis of extreme events such as last frost dates are detrimental phenomena which influence in various branches of engineering, such as agriculture. The analysis and probability predicting of these events can be decrease damage of agriculture, horticulture and the others. Furthermore, ...
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Introduction: The analysis of extreme events such as last frost dates are detrimental phenomena which influence in various branches of engineering, such as agriculture. The analysis and probability predicting of these events can be decrease damage of agriculture, horticulture and the others. Furthermore, this phenomenon can have a relation with other thermal indexes. The analyzing of last frost dates of all synoptic stations of Khorasan Razavi province is subject of this article. The frequency analysis applied to eight distributions. Then the relationship between last frost dates and termal index were studied. Best relation was between minimum temperature and return periods of last frost dates.
Materials and Methods: The analyzing of last frost dates (origin is 23th september) of all synoptic stations of Khorasan Razavi province is subject of this article. First data of each station were screening. The basic properties such as homogeneity, randomness, stationary, independence and outliers must be test. The eight distribution distribution Normal, Gumbel type 1, Gamma 2-parameter, Log normal 2 or 3 parameters, Generalized Pareto, Generalized extreme values and Pearson Type 3 fitted to data and the parameters estimated with 7 methods by the name of the several types of Moments (5 methods), maximum likelihood and the maximum Entropy. The Kolmogorov – Smirnov goodness of fit test can compared the best distribution. The return periods of last frost dates are major application in frequency analysis. There is maybe a relationship between periods and termal index such as min., max. and mean temperature. This relationship can be adapted by regression methods.
Results and Discussion: The statistical analysis for prediction probabilities and return periods of the last frost dates for all synoptic stations in Khorasan Razavi province and the relationship between annual temperature indicators and this phenomenon is the aim of this article. The origin dates of this phenomenon are 23th September. First, data were screened. Then basic hypothesis test were applied which including the Runtest (randomness), the Mann-Whitney test (homogeneity and jump), the Wald-Wolfowitz test (independence and stationary), the Grubbs and Beck test (detection Outliers) and the three sigma methods (Outlier). The results were: 1-The Golmakan, Kashmar and Torbatejam had lower Outliers that will not cause any problem in data analysis by their skewness. 2- The independence of all stations was accepted at the 10% level. 3-The Gonabad data was not homogeneous and removed. Eight probability distributions (Normal, Gumbel type 1, 2-parameter gamma, 2 and 3 parameters log-normal, the generalized Pareto, the generalized extreme values and the Pearson type 3) were applied. The skewness coefficients for all stations were more than 0.1 so Normal distribution was rejected. Also the7 methods of estimation (five different methods of moments, maximum likelihood and maximum entropy methods) were used. The ks fit test was applied. The ks for some stations were closed together at several estimations methods. The results are as follows: GPA (4 times), PT3 (4 times), LN2 (4 times), GA2 (3 times). The obtained results were: 1- The shortest duration of frost date was belonged to the Sarakhs station, but the longest return periods were not same. 3- The interior station ranges were 32 to 50 days for all return periods, with a mean of 41, standard deviation 9.3 and the coefficient of variation 5.9%, which represents the damping of the phenomenon within the station. 4-Pearson type 3, which has been recommended by some researchers, can not be generalized. 5- The major method of estimation was MOM (8 cases). The relationship between the last frost days and other meteorological factors such as, minimum, average and maximum temperature were investigated in this paper. The linear relationship between last frost days and the average annual minimum temperature were the best-fit.
Conclusion: The last frost dates analyzing of all Khorasan Razavi province synoptic stations is subject of this article. The data screening and basic tests were applied and data accepted as random samples. The 8 distributions with 7 methods of estimation were fitted to data. The best fitted distribution at all stations mainly included GPA, PT3, LN2. The major estimation method was MOM. The relationship between last frost periods and minimum temperature was the best linear models. So, we can predict the return period from this temperature as well.
Research Article
S. M. Seyedmousavi; A. parvaresh Rizi; S. Isapour
Abstract
Introduction: The use of automatic control system for managing the conveyance and distribution of water in surface irrigation systems, as a means of improving the management and performance of these systems is essential. Automating networks using the programmable controller provide the implementation ...
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Introduction: The use of automatic control system for managing the conveyance and distribution of water in surface irrigation systems, as a means of improving the management and performance of these systems is essential. Automating networks using the programmable controller provide the implementation of a number of control ways according to different water delivery scenarios. Also the implementation of these systems using sensors and recording water levels by hydraulic devices can supply an accurate data collection of water distribution networks in the long term and can influence the decisions to manage the network. Control systems in irrigation canals include two parts: calculation for adjustment the structures (algorithms or control system software) and application the calculated settings on structures (hardware of control systems). The success of these parts is depending on the ability of control algorithm to determine the control parameters.
Materials and Methods: Doosti irrigation network in the plains of Sarakhs is located in the northeast of Iran. In the end of the main canal, two canals has branched which named EPC and WPC2. This study was performed on the EPC canal with the discharge and length of 4.43 m3/s and 18.7 km respectively. There are 15 duck-bill check structures along the EPC. Also 14 intake structures and secondary canals are responsible for water distribution between local water users. In this study, the performance of system identification process, SI, in estimation of coefficients of proportional-integral controller and improvement of adjusting the control algorithm was compared with trial and error process. This proportional-integral control algorithm was designed for EPC canal. The efficiency of algorithm was evaluated using the simulation results of several different choices of operating systems with SOBEK hydrodynamic model and computing evaluation indices of control systems. This model can simulate all kinds of structures in water conveyance and distribution networks. In addition to the integrity of this software, two proprietary approach of the model are ability to design the control algorithms for smart irrigation systems and the ability to integrate each of its modules with each other and increase compliance with real systems. Evaluation of designed control algorithm was done using the pattern of the one-month operation, with extreme daily variation to cover the most intense perturbations in canal. To evaluate the performance of the designed control algorithm for investigated scenarios in the canal, the performance evaluation indices of control systems were used.
Results and Discussion: The results of SI process show that the delay time for the longest reach is greater than the other. Also the values of delay time show that the smaller discharges produce more delay time. By comparing the storage area for applied discharges for SI process, it was concluded that the amount of storage area for low flows is higher. Because for low flows with fixed target level in upstream the check structures, the length of backwater curve is more and consequently the amount of storage area would be higher. By comparing the amount of resonance frequency and maximum resonance for the potential of 10%, 50% and 80% of the design flow for various scenarios, it is indicated that in low flows the resonant behavior has significant effects on canal reach. The results show that the adjusted control algorithm using identification process, rather than trial and error, has considerable accuracy and high potential to flow control and to damp the perturbation of hydraulic disturbances. Also this algorithm provides the on-demand distribution and promotes the efficiency of water control and distribution systems.
Conclusion: Although using automated control systems faced with the problem of high initial investment but as an effective tool, it improves the performance of water delivery and provides the optimal usage of irrigation network capacity. For this reason, it is recommended to custodians of irrigation networks to design and employment of these controllers in irrigation networks with more attention. In present control system IP controller was used. This controller requires the calculation of adjustment coefficients of control algorithm. For comparison between the calculation of these coefficients by trial and error and the identification system, the IP controller for EPC canal of Doosti Irrigation was designed. Then its performance was studied based on the method of canal operation and standard indices. The results indicated that the tuned algorithm control using SI has considerable accuracy and potential to control the flow and to damp the perturbations concluding from structural and hydraulic disturbances. Also this algorithm provides demand oriented distribution and performance promotion of water distribution system. Since in this study a relatively long canal includes multiple reaches and structures such as inverted siphon was studied, the capability of PI and SI process is also confirmed in these situations.
Research Article
S.N. Mousavi; Davoud Farsadi; H. Arvanaghi; A. Abbaspour
Abstract
Introduction: The compound sharp-crested weirs are composed from several notches and those are designedin different shapes. One of the hydraulic advantagesof compound weirs is that atlowflow rate, the bottomnotchacts assimpleweir andwith the creation of morehydraulicheadonits upstream, due to theshape ...
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Introduction: The compound sharp-crested weirs are composed from several notches and those are designedin different shapes. One of the hydraulic advantagesof compound weirs is that atlowflow rate, the bottomnotchacts assimpleweir andwith the creation of morehydraulicheadonits upstream, due to theshape of thenotch, make dischargemeasurement withappropriatesensitivity. In high flow rates, the upper notch prevents of increasing upstream water level and backwater and discharge measurement is possible with acceptable accuracy. The compound sharp-crested weirs can be used as an appropriate solution for discharge measurement with reasonable accuracy and sensitivity of the extensive range of flows. Relations are derived from this kind of weirs hassufficientaccuracy withobservation of design criteriaandconstructionstandards. The purposeofthisresearch was a laboratory investigation of geometricandhydraulic effective parameterson discharge coefficient of compound arched circular- rectangular sharp-crested weirs in two cases of full width of channel and partially contracted weirs and compare the values of the discharge coefficient of compound and simple rectangular weirs.
Materials and Methods:Considering the geometric, kinematic and dynamic variables affecting the free flow of sharp-crested weirs, there are 11independent variableswiththree main quantities (length, massandtime). Usingdimensional analysis with π-Buckinghammethod,it can bederived thedimansionlessrelationship. In order to assess theeffect of various parametersonthe coefficient ofCd,thedimansionlessdiagramsare used. Inthe state of(h≤h0), discharge relationship usedinsimplecircular weir. In thestate of(h>h0), discharge of compound weir is computeted from the linear combination of discharge relationships in circular and rectangular weirs. Experimentsare conducted inthe hydraulic engineering models laboratory, Department of Water Engineering, University of Tabriz, in a rectangular glass-metal flume of 9 m length, 25 cm width and 50 cm height. Aftersetting up the weirs in a relevant place of flume andestablish thesteady flow,experiments were performedinthefree flowon36 models of weirs.
Results and Discussion:In this research, theeffects ofrectangularnotch width, the height of weir crest, the height ofcirculararch notch were investigated forchanges of headwithdimensionless ratios of h/P,h/R,h/h_0 ,h/Bon discharge coefficient. The results showthat fora known headover the weir, discharge coefficient increase about 2 to 10percent with the development of the rectangular notch width of compound and simple rectangular sharp-crested weirs. For a given head over the weir, discharge coefficient decrease approximately 1 to 5percent by increasing the height of the weir crest of compound and simple sharp-crested weirs. Fora given head over weir in low head values, discharge coefficient increase approximately 35percent by reducing the height of circulararch notch in the compound weirs than simple rectangular weirs. Based on statistical indicators, computational and observation discharge coefficient values in most compound and simple weirs, acceptable coincidence with each other. The meanvalues of thecoefficient of determination (R2) androot mean square error(RMSE) are 0.630and0.061,respectively. Among the effective factors that indicate the difference, it can be referred to the theoretical equation in the compound state that is obtained by assuming a linear combination of simple weirs. The effect of the lateral walls of the flume, the measurement accuracy of hydraulic head and discharge, the conditions of flow entrance, the extension of the range of empirical equations proposed in literature for discharge coefficient of simple weirs, Other factors contributing to the difference between the estimated and observed values of discharge coefficient. Inthistypeofweirs,the least amount ofdiscontinuityin thetransition region of simple to compound state in head-discharge relationship can be seenin thewide rangeofdischargescomparedwithother kinds ofcompound weirswithhorizontalorslopingcrests.
Conclusion:In this research, a seri of experiments conducted to investigate Cd of the compound arched circular-rectangular sharp-crested weirs in both full width of the channel and partially contracted. The advantage of these weirsisdischarge measurement ina wide range. According to the parametersaffecting theweir, Cd has changed from 0.54 to 0.89 range in the compound weirs and 0.55 to 0.66 range in the simple rectangular weirs. Bychanging the weir specifications, Cd increase about 35 percentthan thesimplerectangular weir. Forchanges of the head by usingthe experimental data, the discharge continuityofthistypeofweir is far more thanthecompound weirs withhorizontal orinclined crests. Based on theevaluation criteria, using alinear combinationofthe discharge relationshipof circularandrectangularsharp-crested weirs, be able to estimate Cd of the compound weirs withacceptable accuracy.
Research Article
T. Eshrati; R. Fazloula; M. Sanei; A. Emadi
Abstract
Introduction: Weirs are one of the common structures for discharge and flow measurement. Therefore,these types of hydraulic structures depending on the purposeofuse havedifferent shapes. In some cases, due to practical constraints, spillways with curvature in plan are designed. In such situations study ...
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Introduction: Weirs are one of the common structures for discharge and flow measurement. Therefore,these types of hydraulic structures depending on the purposeofuse havedifferent shapes. In some cases, due to practical constraints, spillways with curvature in plan are designed. In such situations study of flow distribution over the spillway and other related parameters, will be important. In this study, a physical model of dam spillway, which is type of ogee-crested weir with curvature in plan, were tested. Also in order to investigate the effects of curvature on the performance of the flow, the second model of spillway in normal shape, with similar geometric and hydraulic conditions, were compared.
Materials and Methods: First physical model of prototype is built at the scale of 1:75 and the second model was constructed in straight form (without curvature in plan) with similar geometric conditions to the first model. Spillways have been designed according to USBR standard for design head at value of 4 cm in model and vertical upstream face. Experiments were performed in Soil Conservation and Watershed Management Research Institute at reservoir with dimensions 1.2 m length, 0.70 m width and 0.5 m height walls of Plexiglas. To measure the flow discharge, a sharp triangular weir with apex angle of 90˚ in the output of channle was used. Measurements in first model were conducted with five discharges and five values of h/Hd (0.53, 0.74, 0.90, 1.08 and 1.44) and for six sectors on spillway body. To evaluate the effect of curvature, flow performance and discharge coefficient changes were compared for five early discharges (ratio of critical depth to design head at value of 0.28, 0.44, 0.58, 0.72 and 0.81) and six other discharge (mentioned ratio at value of 0.36, 0.51, 0.66, 0.76 and 0.83) in both models.
Results and Discussion: The results related to the first model showed that by increasing the ratio of head to design head (h/Hd), rate of spillway discharge coefficient increases to the value of 1.72 and decreases to 1.23, when the weir was submerged. It also observed that with increase in flow rate of each discharge and reducing the pressure along the spillway, possibility of vacuum-creation and corrosion of structure increased and the corrosion rate witch introduced by Cavitation Index decreased. The minimum value for Cavitation Index that has been calculated was 1.45 that is greater than the critical value of it. The results of the pressure distribution and changes of Cavitation Index in first model showed, the minimum height of the pressure for each discharge occurred at the end of ogee profile and the minimum value of the Cavitation Index occurred at the last section of spillway in downstream for the value of h/Hd=0.53.As well as for all test cases in this study, the maximum velocity and minimum of Cavitation Index were calculated at the same section of spillway where hydraulic jump was observed. On the other hand, it was observed that with increasing flow rate, the critical section moves upward on the spillway body. The results related to the spillway efficiency generally indicated that by increasing the ratio of critical depth to design head (yc/Hd) discharge coefficient increases. In fact, by increasing the ratio of h/Hd and increase the discharge rate up to design discharge, the amount of evacuation and efficiency of both models goes up. For larger discharges, the flow is blocked by the spillway forehead and model efficiency will decrease due to submersion and flow rejection. Results obtained from comparison of two models indicated for the spillway in normal shape submergence of the weir occurred faster and discharge coefficient of each test achieved in lesser value per test, So that the discharge coefficient increasing in curved spillway continued until the value of 0.81 yc/Hd (at 10.3 lit/s of discharge) and in normal shape until the value of 0.72 yc/Hd (at 9.2 lit/s of discharge). Therefore it seems that the upward central arch factor will increase the discharge coefficient and efficiency of spillway.
Conclusion: In the present research the hydraulic performance of ogee spillway with curved plan to investigate the pressure distribution and the vacuum-creation and in particular to compare the results related to flow performance and the effect of spillway curvature on its performance were studied using two experimental models. The impact of increasing the discharge coefficient for the weir with upward central arch compared to weir with straight crest, in terms of similar geometric and hydraulic conditions, was calculated to the value of 21 percent, in this study.
Research Article
A. Pourhaghi; F. Radmanesh; A. Maleki
Abstract
Introduction : Sustainable development of groundwater resourcesrequires a proper assessment of available resources, understanding of system behavior and interaction between groundwater and surface water.In recent years, a Delfan plain (in Iran) is facing a sharp decline in groundwater levels due to increasing ...
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Introduction : Sustainable development of groundwater resourcesrequires a proper assessment of available resources, understanding of system behavior and interaction between groundwater and surface water.In recent years, a Delfan plain (in Iran) is facing a sharp decline in groundwater levels due to increasing in population and exploitation of groundwater resources.In this study, using modflow model effect of drought and wet conditions on water table fluctuations of Delfan plain aquifer was evaluated.
Materials and Methods: Delfan plain is one of the Lorestan Plains (in Iran Country) and located in the north of the Lorestan Province, around the city ofNurabad (Delfan).Precipitation survey of the region shows that the average annual rainfall in the plains is 480 mm and aquifers of the region has 10 piezometric wells. Drawing of the groundwater hydrograph from 2004 to 2013 shows that the general trend of the groundwater level is downward, which represent decreasing in groundwater resources of the region. At the beginning of the modeling process using Modflow model, after gathering all the required information, conceptual model of the plain was generated. To preparing this model, various data such as topographic maps, geophysical data, logs of wells, pumping tests and observation wells data and flow data taken from exploitation wells was used. Water level data of October 2007 which has the lowest fluctuation was used for the calibration of steady state.In this step with model successive run, hydraulic conductivity is optimized. After model calibration in the steady state, do same in the unsteady state.Specific discharge was optimized at this step.After calibration in the unsteady state, model needs verification to be trusted.For this purpose, verification was done in November 2012 to November 2014.After calibration and validation of the model, the model was carried out under drought and wet conditions.Drought is one of the environmental disasters that its occurrence could bring the water challenges in the field of quality and quantity. Because of drought and lack of rainfall affect groundwater resources, soil moisture and river flow, used index called Standard Precipitation Index (SPI) to quantify the impact of rainfall in of 3, 6, 12, 24-month period.This index is calculated based on long-term statistics.
Results Discussion :In steady state, the model's sensitivity is studied according to changes in hydraulic conductivity value and discharge of pumping wells and in the unsteady state according to specific yield and other parameters was investigated. Based on this analysis in steady state, generally it can be said that the model is more sensitive to the exploitation wells. In unsteady state, the model is more sensitive to specific yield and hydraulic conductivity and other parameters are in the next level.With SPI reviewing of 120-months, it was seen that the plain in 1984 and 1993 has the lowest 120-month SPI with the value of -1.08 (with average precipitation value of 423 mm).For applying virtual wet period with 30-years precipitation reviewing, it was observed that years of 2001 and 2010 have the most 120-month SPI value with value of 1.86 (with average precipitation value of 587 mm).For applying the virtual wet conditions in the next step, the model was simulated with the rainfall data of 2001 and 2010.To decrease the water table drop, considering the amount of drop and water needs of the region, several runs were performed which ultimately results showed to offset the drop in these three exploitation areas, the discharge of exploitation wells must be reduce 20% that This strategy is able to reduce the average annual rate of water table drop for the next 10 years. Finally, after model’s run and piezometers drop, plain model was used to obtain groundwater balance.
Conclusion: The model implementation in drought and wet conditions shows that in these conditions the groundwater level decreases with the average of (-7.80m) and (-5.83m), respectively. which with the 20 % decrease of the discharge of the exploitation wells in these conditions, the level groundwater and aquifer balance improves.For the next ten years in the normal condition or present situation of exploitation, plain balance is -83.20 million cubic meters which by 20% reduction in wells exploitation, this water balance is predicted -41.20 million cubic meters for next 10 years.In the drought conditions Delfan aquifer water balance is predicted as -91.20 million cubic meters during ten years which by 20% reduction of wells exploitation this water balance increases to -49.20 million cubic meters.
Research Article
D. Baharlooi; S. Ghorbani Dashtaki; B. Khalil Moghadam; Mahdi Naderi; P. Tahmasebi
Abstract
Introduction: The detachment process can be conceptually divided in two sub-processes included aggregate breakdown (Le Bissonnais, 1996) and movement initiation of breakdown products(Kinnell, 2005). soil detachment depends on raindrop size and mass(Elison, 1944; Bisal, 1960), drop velocity(Elison, 1944; ...
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Introduction: The detachment process can be conceptually divided in two sub-processes included aggregate breakdown (Le Bissonnais, 1996) and movement initiation of breakdown products(Kinnell, 2005). soil detachment depends on raindrop size and mass(Elison, 1944; Bisal, 1960), drop velocity(Elison, 1944; Bisal, 1960), intensity rainfall (Ting et al, 2008), kinetic energy (Kinnell, 2003; Fernandez- Raga et al, 2010), runoff depth(Torri et al, 1987; Kinnell,1991 and 2005), crop covers(Bancy, 1994; Ghahremani et al, 2011), wind speed( Erpul et al, 2000) and experimental area (cup size) (Leguedois et al, 2005; Luk, 1979; Torri and poesen, 1988). Many of studies have been conducted to evaluate the relationship between splash and slope (Bryan, 1979; Torri and Poesen, 1992; Wan et al, 1996).Torri and Poesen (1992) expressed that in steep slope the gravity force adds to the drop detaching force and decreases of soil resistance, consequently increases splash erosion rate with increasing slope. Soil splash erosion is also strongly influenced by soil properties including soil particles size distribution (Mazurak and Mosher, 1968; Legout et al, 2005; fan and li, 1993), soil shear strength(Cruse and Larson, 1977; Al-Durrah and Bradford,1981; Ekwue and ohi; 1990 ), soil cohesion(Torri et al, 1987), soil organic matter content and aggregate size (Ekwue and Maiduguri, 1991; Qinjuan et al, 2008), soil aggregates stability(Qinjuan et al, 2008), surface crust (Qinjuan et al, 2008).
Fire, play an important role in splash erosion. The absence of vegetation cover in disturbed lands accelerates splash erosion rates by as much as several folds compared to undisturbed sites (Lal, 2001; Thomaz and luiz, 2012).The detachment of soil particles by splash depends on several raindrop characteristics, including raindrop size and mass, drop velocity, kinetic energy, and water drop impact angle (Sharma et al., 1993; Singer and Le Bissonnais, 1998; Cruse et al., 2000, Bhattacharyya et al., 2010). Detachment rate is strongly influenced by soil properties, including soil texture and thickness of the water layer at the soil surface (De Ploey and Savat, 1968; Moss and Green, 1983; Sharma et al., 1991; Kinnell, 1991, Jomaa et al., 2010), soil strength, bulk density, cohesion, soil organic matter content, moisture content, infiltration capacity (Nearing et al., 1988; Owoputi, 1994; Morgan et al., 1998, Planchon et al., 2000, Ghahramani et al., 2011), soil initial water content, surface compaction and roughness (Planchon et al., 2000), the nature of soil aggregates and crust, porosity, capacity of ionic interchange, and clay content (Poesen and Torri, 1988). Several studies have shown that splash detachment rate is mainly related to surface rock fragments in soils with sparse vegetation cover (Jomaa et al., 2012). The present study was conducted to investigate the effects of fire on splash erosion and some erosion depended properties in semi-steppe rangeland of Karsanak region in Chaharmahal and Bakhtiari province which affected by man-made fire during 2008, 2009, 2010 and 2011.
Materials and Methods: Soil samples were obtained on 2012 from the mentioned regions (8 samplesfrom the burned area and 8 samples as a control (unburned) in the adjacent burned area) from 0-7 cm depth. Splash erosion under simulated rainfall intensity of 2 mm per minute was measured using multivariate splash cup apparatus considering the slope of 5 and 25 degree. Soil pH, soil electrical conductivity, equivalent calcium carbonate, soil organic matter, sand size fraction particulate organic matter (SSF POM), mean weight diameter and, geometric mean diameter of aggregates, percent of macro and micro-aggregates, percent of clay, silt, sand, water dispersible clay and soil bulk density were measured. Statistical data analysis was performed by t-test at 5% level.
Results Discussion: The results showed that soil splashing increased significantly in treatment 1 year after the fire in both slope 5 and 25 degree and in treatment 2 year after the fire in slope 25 degree. The amounts of increase in soil splashing compared to control treatment were 22, 24 and 15 percent in treatment 1 year after fire in slope 5 and 25 degree and in treatment 2 years after the fire in slope of 25 degree respectively. Comparison of the total soil splash on slopes of 25 degree at 1, 2, 3 and 4 years after the fire, showed a significant increase in the level of five percent relative to the slope of 5 degree at 1, 2, 3 and 4 years after the fire. The other measured soil properties (except equivalent calcium carbonate) was affected by fire. Also, the differences between many of the mentioned properties in the first 2 years after the fire was significant compared with the control area, but they have been reached to the initial values in the third and fourth years after the fire.
Conclusion: Time was shown to be effective factor inrecovering soil propertiesin Karsanak region of Chaharmahal and Bakhtiari province which affected by man-made fire during 2008, 2009, 2010 and 2011. Fire accelerates splash erosion rates by as much as several folds compared to control in this area.
Research Article
M. Moradi Tayyebi; E. Amiri Tokaldany
Abstract
Introduction: Study of flow characteristics in rock porous media is one the most interesting issues for scientists and engineering dealing with river engineering works. So, there is no surprise that many models to describe the relationship between the flow velocity of clear water with hydraulic gradient, ...
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Introduction: Study of flow characteristics in rock porous media is one the most interesting issues for scientists and engineering dealing with river engineering works. So, there is no surprise that many models to describe the relationship between the flow velocity of clear water with hydraulic gradient, rock size, porosity, Reynolds number, and kinematic viscosity, have been introduced. Due to the large spaces between the coarse materials, flow velocity passing through the materials is high which in turn results in higher amounts of Reynolds number of flow. This type of flow classified as turbulent flow. Although Darcy law rules the flow in porous media, it is used for laminar flow in fine porous media and its application is not recommended for turbulent flows. Moreover, as the flow parameters in turbulent flows vary against time, the state of the flow is not steady. The equations describing the turbulent flows are obtained using equations defining basic concepts of hydrodynamics and turbulence effects. Due to complexity of the turbulent flow, these equations are described in the form of the partial differential equations. In order to introduce the specifications of this type of flow, various relationships have been provided by many researchers. However, their applications are confined to the limited conditions of porosity and size materials. In this study, we aim to provide a relationship which can be applied for a wide range of porosity and material size of porous media.
Materials and Methods: To describe the relation between effective hydraulic parameters in coarse porous media, we used dimensional analysis theorem of Buckingham. In this regard six dimensionless parameters have been provided from which a relationship including four constant parameters has been obtained. We used a part of (70 percent) several available sets of data, provided from Soil Conservation and Watershed Management Research Institute, Irrigation and Reclamation Engineering Department of the University of Tehran, and mostly from published results, to find the magnitude of the constant parameters. So, we introduced a new equation which expresses a relationship between hydraulic gradient, porosity, and Froud number. Finally, using the remained part of (30 percent) available data, we compared the results of the new equation with those obtained from available models.
Results and Discussion: To evaluate the new introduced equation and comparing the results obtained from the new equation and those obtained from available equations, we computed the magnitude of relative errors as well as the mean relative errors of the hydraulic gradient estimated from all equations versus the hydraulic gradients provided from field and laboratory observations. It is found that the new equation has the least mean of relative error (15.3 percent) among all equations. Moreover, for various magnitudes of rock size as well as porosity, we computed the mean relative error of estimated hydraulic gradients according to observed data. We found that the new equation has the second largest accuracy (with the mean error of 11.64%) among all evaluated models in this research. Finally, we developed two relationships between hydraulic gradient and Froud number using actual as well as apparent velocities. Again, it is found that the new relationship has the least mean of relative error (14.03 percent) among all equations.
Conclusion: Since all available equations introduced to express the flow characteristics in coarse porous media, can be used in a defined limits of porosity, rock size, etc., in this research we aimed to provide a new relationship which can be used for a wider range of porous media specifications. So, based on dimensional analysis and using several sets of available field and laboratory data, a new equation has been introduced in this research which can be used for a wide range of rock size, Reynolds number, and porosity; i.e. rock diameter of 0.5 to 20 cm, Reynolds number greater than 100, and porosity of 0.35 to 0.55. Moreover, we introduced two equations to demonstrate the relationship between hydraulic gradient and actual velocity as well as apparent velocity. When we evaluated the results obtained from the new relationship with those obtained from some available equations, we found that the relative error of the new equation is 14 percent, which illustrates that the error of the results produced by the new equation is less than those produced by the available equations.
Research Article
H. Sanikhani; yaghoub dinpazhoh; M. A. Ghorbani; M. Zarghami
Abstract
Introduction: In the recent years, researchers interested on probabilistic forecasting of hydrologic variables such river flow.A probabilistic approach aims at quantifying the prediction reliability through a probability distribution function or a prediction interval for the unknown future value. The ...
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Introduction: In the recent years, researchers interested on probabilistic forecasting of hydrologic variables such river flow.A probabilistic approach aims at quantifying the prediction reliability through a probability distribution function or a prediction interval for the unknown future value. The evaluation of the uncertainty associated to the forecast is seen as a fundamental information, not only to correctly assess the prediction, but also to compare forecasts from different methods and to evaluate actions and decisions conditionally on the expected values. Several probabilistic approaches have been proposed in the literature, including (1) methods that use resampling techniques to assess parameter and model uncertainty, such as the Metropolis algorithm or the Generalized Likelihood Uncertainty Estimation (GLUE) methodology for an application to runoff prediction), (2) methods based on processing the forecast errors of past data to produce the probability distributions of future values and (3) methods that evaluate how the uncertainty propagates from the rainfall forecast to the river discharge prediction, as the Bayesian forecasting system.
Materials and Methods: In this study, two different probabilistic methods are used for river flow prediction.Then the uncertainty related to the forecast is quantified. One approach is based on linear predictors and in the other, nearest neighbor was used. The nonlinear probabilistic ensemble can be used for nonlinear time series analysis using locally linear predictors, while NNPE utilize a method adapted for one step ahead nearest neighbor methods. In this regard, daily river discharge (twelve years) of Dizaj and Mashin Stations on Baranduz-Chay basin in west Azerbijan and Zard-River basin in Khouzestan provinces were used, respectively. The first six years of data was applied for fitting the model. The next three years was used to calibration and the remained three yeas utilized for testing the models. Different combinations of recorded data were used as the input pattern to streamflow forecasting.
Results and Discussion: Application of the used approaches in ensemble form (in order to choice the optimized parameters) improved the model accuracy and robustness in prediction. Different statistical criteria including correlation coefficient (R), root mean squared error (RMSE) and Nash–Sutcliffe efficiency coefficient (E) were used for evaluating the performance of models. The ranges of parameter values to be covered in the ensemble prediction have been identified by some preliminary tests on the calibration set. Since very small values of k have been found to produce unacceptable results due to the presence of noise, the minimum value is fixed at 100 and trial values are taken up to 10000 (k = 100, 200, 300,500, 1000, 2000, 5000, 10000). The values of mare chosen between 1 and 20 and delay time values γ are tested in the range [1,5]. With increasing the discharge values, the width of confidence band increased and the maximum confidence band is related to maximum river flows. In Dizaj station, for ensemble numbers in the range of 50-100, the variation of RMSE is linear. The variation of RMSE in Mashin station is linear for ensemble members in the range of 100-150. It seems the numbers of ensemble members equals to 100 is suitable for pattern construction. The performance of NNPE model was acceptable for two stations. The number of points excluded 95% confidence interval were equal to 108 and 96 for Dizaj and Mashin stations, respectively. The results showed that the performance of model was better in prediction of minimum and median discharge in comparing maximum values.
Conclusion: The results confirmed the performance and reliability of applied methods. The results indicated the better performance and lower uncertainty of ensemble method based on nearest neighbor in comparison with probabilistic nonlinear ensemble method. Nash–Sutcliffe model efficiency coefficient (E) for nearest neighbor probabilistic ensemble method in Dizaj and Mashin Stations during test period of model obtained 0.91 and 0.93, respectively.The investigation on the performance of models in different basins showed that the models have better performance in Zard river basin compared to Baranduz-Chaybasin. Furthermore the variation of discharge values during test period in Zard basin was lower in comparison of Baranduz-Chay basin. The real advantage of including streamflow forecasts requires detailed and specific investigations, but the preliminary results suggest the good potentiality of probabilistic NLP method. Using ensemble prediction method can help to decision makers in order to determine the uncertainty of prediction in water resources field.
Research Article
F. Abbasi; A.; N. Salamati
Abstract
Introduction: Application of simultaneous nitrogen fertilizer and water as fertigation in surface irrigation systems is developing. In fertigation is possible to increase water and fertilizer use efficiency and it allows growers to apply nutrients in split and small amounts throughout the season in response ...
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Introduction: Application of simultaneous nitrogen fertilizer and water as fertigation in surface irrigation systems is developing. In fertigation is possible to increase water and fertilizer use efficiency and it allows growers to apply nutrients in split and small amounts throughout the season in response to crop needs. In this study, sugarcane furrow fertigation experiments is carried out in Dehkhoda agro-industry company to improve fertilizer management, water and nitrogen use efficiency, and reduce urea fertilizer consumption.
Materials and Methods: Large scale furrow experiments were conducted on a plant field. Field experiments were carried out as split plot with a complete randomized block design. Experimental treatments consisted of three fertilizer splits (2, 3, and 4 splits) in main plots and three levels of urea fertilizer (60, 80 and 100% of required urea fertilizer) in subplots and compared with the common method (control) used in the agro-industry fields. Experiments were conducted on a 25 hectare field in 250 meter long and blocked end furrows. Irrigation water during the crop season was applied the same for different fertigation treatments and measured using the WSC flumes in each irrigation events. Irrigation interval varied from 8 to 15 days during the crop season. Qualitative and quantitative traits (e.i., stalk height, cane yield, purity, brix, white sugar yield, and water, fertilizer, and sugar use efficiency) at harvest were measured and analyzed using the MSTATC software.
Results and Discussions: A total of 21 irrigation events during the growing season were measured. Average water consumption in each irrigation event was 865 cubic meters per hectare. Total applied irrigation water during the growing season was 18,155 cubic meters per hectare. Results showed that fertilizer split factor significantly affected the qualitative and quantitative traits at a 5% level of significance. So that, all qualitative and quantitative traits in four split treatments were significantly (P
Research Article
S. Babaei Hessar; R. Ghazavi
Abstract
Introduction: Precipitation is one of the most important and sensitive parameters of the tropical climate that influence the catchments hydrological regime. The prediction of rainfall is vital for strategic planning and water resources management. Despite its importance, statistical rainfall forecasting, ...
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Introduction: Precipitation is one of the most important and sensitive parameters of the tropical climate that influence the catchments hydrological regime. The prediction of rainfall is vital for strategic planning and water resources management. Despite its importance, statistical rainfall forecasting, especially for long-term, has been proven to be a great challenge due to the dynamic nature of climate phenomena and random fluctuations involved in the process. Various methods, such as time series and artificial neural network models, have been proposed to predict the level of rainfall. But there is not enough attention to global warming and climate change issues. The main aim of this study is to investigate the conformity of artificial neural network and time series models with climate scenarios.
Materials and Methods: For this study, 50 years of daily rainfall data (1961 to 2010) of the synoptic station of Urmia, Tabriz and Khoy was investigated. Data was obtained from Meteorological Organization of Iran. In the present study, the results of two Artificial Neural Network (ANN) and Time Seri (TS) methods were compared with the result of the Emission Scenarios (A2 & B1). HadCM3 model in LARS-WG software was used to generate rainfall for the next 18 years (2011-2029). The results of models were compared with climate scenarios over the next 18 years in the three synoptic stations located in the basin of the Lake Urmia. At the first stage, the best model of time series method was selected. The precipitation was estimated for the next 18 years using these models. For the same period, precipitation was forecast using artificial neural networks. Finally, the results of two models were compared with data generated under two scenarios (B1 and A2) in LARS-WG.
Results and Discussion: Different order of AR, MA and ARMA was examined to select the best model of TS The results show that AR(1) was suitable for Tabriz and Khoy stations .In the Urmia station MA(1) was the best performance. Multiple Layer Perceptron with a 10 neurons in hidden layer and the output layer consists of five neurons had the lowest MSE and the highest correlation coefficient in modeling the values of annual precipitation. So MLP was determined as the best structure of neural network for rainfall prediction. According to results, precipitation predicted by the ANN model was very close to the results of A2 and B1 scenario, whereas TS has a significant difference with these scenarios. Average rainfall predicted by two A2 and B1 scenarios in Urmia station has more difference than other stations. Based on the B1 scenario, precipitation will increase 11 percent over the next two decades. It will decrease 10.7 percent according to A2 emissions scenario. According to ANN models and two A2 and B1 scenarios, the rates of rainfall will increase in Tabriz and Khoy stations. However, according to TS model, rainfall will decline 5.94 and 3.63 percent for these two stations, respectively.
Conclusion: Global warming and climate change should have adverse effects on groundwater and surface water resources. Different models are used for simulating of thes effects. But, conformity of these models with the results of climate scenarios is an issue that has not been addressed. In the present research coincidence of TS model, ANN model and climate change scenarios was investigated. Results show under emissions scenarios, during the next two decades in Tabriz and Khoy stations, precipitation will increase. In Urmia station B1 and A2 scenario percent increase by 11 percent and 10.5 percent decline predicted, respectively. The results of Roshan and et al (4) and Golmohammad and et al, (7) investigations show increasing trend in the rainfall rate and confirming the results of this study According to results, the performance of ANN model is better than TS model for rainfall prediction and its result is similar to climate change scenarios. Similar results have been reported by Wang et al (29) and the Norani et al (20). Due to the significant difference between the TS and climate scenarios used in the study area, is not recommended, though it can be used as a plausible climate scenario to predict the precipitation of stations in the future studied. At the end, it is suggested that the similar studies carried out in a larger number of stations in the country with respect to global warming and climate change, to determine the validity of the methods used to the predicted rainfall.
Research Article
ali asghar ghaemi; B. Zamani
Abstract
Introduction: Barley is very important to feed humans, livestock, medical, industrial uses, especially in fermentation industries. In Iran, barley crop cultivation was nearly 1.4 million hectares withits production of 1.3 million tons in 2003 (2). Barelyis the oldest crops to environmental stresses such ...
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Introduction: Barley is very important to feed humans, livestock, medical, industrial uses, especially in fermentation industries. In Iran, barley crop cultivation was nearly 1.4 million hectares withits production of 1.3 million tons in 2003 (2). Barelyis the oldest crops to environmental stresses such as drought and salinity resistance (3).The different barely growth stages with extreme water requirement can benoted in germination stage, stem elongation, heading the production stage, the stage of flowering and seed production. Typically, for spring and autumn barely respectively 3 and 4 to 5 times irrigation is done during the growing season. The barley water requirement over its life is between 4 and 7 thousand cubic meters and 518 liters of water is needed to produce one kilogram of dry matter. Due to limited water resources and low rainfall in Iran, efficient use of water is absolutely essential and the maximum water utilization must be achieved by applying a minimum amount of water in agriculture. One of the ways to increase productivity in agricultural water is deficit irrigation.Deficit irrigation is an optimization strategy for water use efficiency in irrigation.The purpose of this study was to evaluate the simultaneous effect of fertilizer treatments (150, 225 and 75 kg/ ha) and water at three different levels (100%, 75% and 50% of crop water requirement) at different growth stages on leaf area index, weight fresh and dried herb and plant nitrogen concentration and the effect of irrigation and nitrogen fertilizer on yield, yield components and productivity of water use.
Materials and Method: This research was conducted in Shiraz University in fall 2012 to study the effect of interaction of deficit irrigation and nitrogen fertilizer on yield, yield component and water use efficiency and nitrogen concentration in different stages of barley (Bahman species) growth. This experiment were evaluated using a randomized complete block design with s plit-plot layout with three deficit irrigation treatments ( consisted of irrigation with 100% ,75% and 50% of crop water consumption use) and three nitrogen fertilizer treatments (included 75 kg/ha, 150 kg/ha and 225 kg/ha) with three replication. A total of 27 experimental plots were carried out. In each plot, 11-row barley with 30 cm spacing apart and 5 cm depth were planted by hand. Barley seeding rates on the basis of 200 kg per hectare were planted in each experimental plots in the first half of November.Nitrogen requirement was applied in three stages of the growth: 30% before cultivation, 40% in shooting stage and 30% in barleyclusterstage.Irrigation treatments included 100% = W1, in this treatment 100% treatment crop water requirement was estimated by neutron meter (this was the control treatment which received muchwater as neededand no water stress in all growth stages),75% = W2: in this treatment 75% of the crop water requirement was applied, and 50% = W3: the 50% of the crop water requirement plant was applied. During differentgrowth stages plant required data were collected and the parametersinclude: grain yield, biological yield, straw yield, number of grains per spike, spike per unit area, grain protein, harvest index, 1000 grain weight, number of unfilled and filled grain per spike and efficiency of water use were determined . Tests to determine the percentage of leaf nitrogen and protein was measured by kjeldahldevice(6405UV / VIS). The software SAS (version.9.1) was used to analyze data and graphs were drawn in Excel.
Results and Discussion: results showed that the highest yield,yield component was obtained on 100% irrigation and 225 kg/ha fertilizer treatments. Also it was observed that at the certain level of irrigation treatment by increasing the amount of nitrogen fertilizer the amount of this parameters will be increased.Result also showed that at the certain level of nitrogen fertilizer by decreasing water, the maximum plant response to the nitrogen fertilizer consumption will be decreased gradually in most cases, 225 kg/ha nitrogen fertilizer treatment caused most of crop yield parametersbut the differences of crop yield at this treatment with 150kg/ha nitrogen fertilizer treatment wasnot significant. Water use efficiency for 50% deficit irrigation treatment was 0.77 and for 100% irrigation treatment was 0.55. Regarding the results obtained from this study andexisting water crisis problem in Iran, it can be noted that the irrigation ofbarley should not be exceeded more than the 100% of crop water consumption use but using 75% of water requirement is suggestive. Also using 150kg/ha nitrogen fertilizer treatment is more suitable for the area.
Conclusion: This study was conducted in order to determinethe yield performance of barley (Bahmanspecies)inBadjgah (Fars Provience)using three different irrigation treatments of 100, 75 and 50 percent of crop water requirement (based on the total available water plant) and three nitrogen treatments include 225, 150 and 75 kg/ ha in the spring and autumn cultivation. In terms of deficit irrigation, during the growing season crop will interface with different intensities and durations of water stress. This tension changes in response to nitrogen fertilizer by plant that creates unpredictable and in some cases is not always the same.Statistical analysis showed that there are significant differencesbetweenthe different treatments of irrigation, nitrogen fertilizer and their interaction.Applying 75% of barley water requirement is suggestive. Also using 150kg/ha nitrogen fertilizer treatment is more suitable for the study area.
Research Article
M. Hosseini; S.A.R. Movahedi Naeini; A. Bameri
Abstract
Introduction: The effects of any tillage method on soil properties, depends on location (soil, water and air) and the number of (years) their implementation. Soil compaction reduces yield through increased soil mechanical resistance against root growth and lower water and nutrient use efficiency (Gamda ...
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Introduction: The effects of any tillage method on soil properties, depends on location (soil, water and air) and the number of (years) their implementation. Soil compaction reduces yield through increased soil mechanical resistance against root growth and lower water and nutrient use efficiency (Gamda et al. 18 & Ishagh et al 23). Soil surface and sub surface compaction both reduce yield due to limited root growth and plant potassium uptake (Doulan et al. 14). Sabt et al. (50) reported that in the study area, which the lands are mostly illite clay (high specific surface area) with sufficient nitrogen, soil potassium is the most important limiting factor for the growth of wheat.Considering the point that loess soils in Golestan Province have a high specific surface area,they can provide potassium for plants to produce crop, but for a higher production, potassium fertilizers should be used. Previous studies indicated that production of wheat is limited due to potassium deficiency (4, 49, 54 and 57). In these soils with a high specific surface area, the speed of movement of potassium from the soil solution is low, and doing solimits wheat yield.In loess soils containing high illite and high specific surface area (eg, soilsin the series of Rahmat Abad of Gorgan), ammonium acetate measured potassium on exchange and solution surfaces, which is highly correlated with grain yield (54) . There is a high correlation between grain yield with overload of potassium and Na TPB extraction (57). The aim of this study was to absorb potassium (limiting factor for plant growth) with different tillage systemsat different depths. International recommendations towards reducing the depth and intensity of tillage (from minimum tillage to no-tillage) in order to reduce erosion and oxidation of organic substances plays an important role in determining the amount of greenhouse gases. If potassium absorption does not reduceafter reducing tillage intensity,low or no-tillage methods are preferred. Otherwise no choice but to continue conventional tillage. The second objective is to assess the effects of the treatments (different tillage systems) on the growth and size of the roots and to predict nutrient uptake by plants.
Materials and Methods: This research was a field experiment during 2009-2010 in estates of Gorgan University of Agricultural Sciences and Natural Resources (Seyed Miran Area) with 5 treatments and 4 replications which used completely randomized block design. Treatments were 5 tillage methods including moldboard-ploughing (20-25 cm depth) followed by disking, rotivator (12-17 cm depth), disking (8-10 cm depth), chisel (25- 30 cm depth) and no-tillage. Row spacing, distance between seeds in a rowand the amount of seeding was 20 cm 1.5 cm and 268.5 kg ha respectively (planting was done by hands). The consumption of fertilizers based on soil test results and the results reported by other researchers were added to the soil surface before planting (54). In all treatments, 350 kg per hectare of ammonium phosphate and 200 kg of potassium sulfate before planting and by hands were added. For treated moldboard,rotary cultivator, disc and chisel were used, and for no-tillage system by disc plow and sweep were used.Main parameters measured were soil mechanical resistance at 6 stages during wheat growth using a cone penetrometer (0-8 cm soil depth), soil potassium at two stages during plant growth (before heading and harvest) using sodium tetraphenyl boron(12), ammonium acetate(28) and ammonium nitrate as extractents and using potassium surface excess(8) determination method and also bulk soil solution potassium concentration(2). Yield of wheat and its components were also determined at harvest. Data analysis include the analysis of variance and mean comparisons using LSD and correlations which carried out using SAS software.
Results and Discussion: Results show there was a significant difference between treatments with respect to extractible soil potassium using sodium tetraphenyl boron at 5 percent level and ammonium acetate at 1 percent level, both before wheat heading. Soil potassium content did not differ significantly in this stage when potassium excess method was used. With all methods of soil potassium determination, soil potassium did not differ significantly at harvest. Soil potassium with moldboard-ploughing was less than all other tillage methods at before plant heading. Thomas et al. (55) and Martin Rhoda et al.(40) also stated that soil potassium was greater with no-tillage method. Lopez Phando & Pardo. (34) similarly stated that soil potassium with no-tillage method was greater than moldboard ploughing. According to results of the current experiment, soil mechanical resistance was further reduced as tillage intensity was increased. Soil mechanical resistance with moldboard ploughing was less than other tillage methods between early heading stage and harvest. Lower mechanical resistance with increased tillage intensity increased root growth and soil potassium uptake by wheat grain and straw, leading to greater yield production in accordance with results by Fakori (16).
Conclusions Soil tillage with moldboard ploughing reduced mechanical resistance, increased root density (and possibly soil-root contact surface area) and soil potassium uptake which results a greater wheat head density and yield and also a lower soil potassium with different methods (potassium excess determination and bulk soil solution potassium concentration methods and also using soidium tetraphenyl boron, ammonium acetate extractants) at before heading which is the stage for maximal growth and nutrient accumulation rate. Soil extractants maybe used for plant nutrient uptake and yield predictions in a plant canopy, when plant nutrient uptake has a positive significant correlation with soil potassium and treatments do not affect root growth and the mentioned correlation.
Research Article
A. Mehnatkesh; S. Ayoubi; A. Jalalian
Abstract
Introduction: Soil depth is defined as the depth from the surface to more-or-less consolidated material and can be considered as the most crucial soil indicator, affecting desertification and degradation in disturbed ecosystems. Soil depth varies as a function of many different factors, including slope, ...
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Introduction: Soil depth is defined as the depth from the surface to more-or-less consolidated material and can be considered as the most crucial soil indicator, affecting desertification and degradation in disturbed ecosystems. Soil depth varies as a function of many different factors, including slope, land use, curvature, parent material, weathering rate, climate, vegetation cover, upslope contributing area, and lithology. Topography, one of the major soil forming factors, controls various soil properties. Thus, quantitative information on the topographic attributes has been applied in the form of digital terrain models (DTMs). The prediction of soil depth by topographic attributes depends mainly on: i) the spatial scale of topographic variation in the area, ii) the nature of the processes that are responsible for spatial variation in soil depth, and iii) the degree to which terrain-soil relationships have been disturbed by human activities. This study was conducted to explore the relationships of soil depth with topographic attributes in a hilly region of western Iran.
Materials and Methods: The study area is located at Koohrang district between 32°20′ to 32°30′ N latitudes and 50°14′ to 50°24′ E longitudes, in Charmahal and Bakhtiari province, western Iran. The field sites with an area of 30,000 ha are located on the hillslopes at about 20% transversal slope. The soils at the site are classified as Typic Calcixerepts, Typic Xerorthents and Calcic Haploxerepts for the representative excavated profiles in summit, shoulder and backslope, respectively. The soils located at footslope and toeslope were classified as Chromic Calcixererts. Measurements were made in twenty representative hillslopes of the studied area. At the selected site, one hundred points were selected using randomly stratified methodology, considering all geomorphic surfaces including summit, shoulder, backslope, footslope and toeslope during sampling. Overall, 100 profiles were dug and described; and the solum thickness was measured for each profile. DEM data were created by using a 1:2,5000 topographic map. Topographical indices were generated from the DEM using TAS software. Terrain attributes in two categories, primary and secondary (compound) attributes; primary attributes are included elevation, slope, aspect, catchment area, dispersal area, plan curvature, profile curvature, tangential curvature, shaded relief. Secondary or compound attributes such as soil water content or the potential for sheet erosion, stream power index, wetness index, and sediment transport index. Correlation coefficients to define relationships between soil depth and terrain attributes, and analysis of variance by Duncan test were done using the SPSS software. The statistical software SPSS was used for developing multiple linear regression models. Terrain attributes were selected as the independent variables and soil depth was employed as dependent variable in the model. Thirty sampling sites were used to validate the developed soil-landscape model. In testing soil-landscape model, we calculated two indices from the observed and predicted values included mean error (ME) and root mean square error (RMSE).
Results and Discussion: The soil depth in the studied profiles varied from 30 cm to 150 cm with an average of 108.6 cm. Relatively high variability (CV = 76%) was obtained for soil depth in the study area. The linear correlation analysis of the 12 topographic attributes and one soil property (soil depth), showed that there was a significant correlation among 36 of the 77 attribute pairs. Soil depth showed high positive significant correlations with catchment area, plan curvature, and wetness index, and showed high negative correlation with sediment transport index, sediment power index and slope. Low positive significant correlations of soil depth were identified with tangential curvature, and profile curvature. Moreover, soil depth was negatively correlated with elevation. The rest of the topographic attributes including aspect, shaded relief, and dispersal area were not significantly correlated with soil depth. Many of these relationships are similar to those found in other landscapes. The results of analysis of variance showed that there are significant differences for soil depth among the selected slope positions in the studied area. The highest values of soil depth were observed in the downslope positions including footslope and toeslope. The lowest soil depth was observed in shoulder position with the highest rate of soil erosion.
Conclusions: It seems that the high variability for soil depth depends on topography of the field, and the landscape position, causing differential accumulation of water at different positions on the landscape; and moreover the soil erosion and deposition processes, resulting in high variability in the soil depth. We found relatively high correlation coefficients of soil depth with two groups of topographic attributes (erosional processes and water accumulation). Empirical model (MLR) using selected terrain attributes explains 76% of the variation of soil depth in the studied area. The terrain attributes that best predicted soil depth variability in the selected site were mainly the attributes that had significant relationships with soil depth. The dominant attributes in the MLR model included slope, wetness index, catchment area and sediment transport index.
Research Article
S. Nikmehr; A. Akhgar
Abstract
Introduction: Phosphorus (P) is considered to be one of the most essential macro elements required for growth and development of plants, but, due to low solubility and fixation in soils, only a small fraction of phosphorus in soil (1 ppm or 0.1%) is readily available to plants. chemical fertilizers are ...
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Introduction: Phosphorus (P) is considered to be one of the most essential macro elements required for growth and development of plants, but, due to low solubility and fixation in soils, only a small fraction of phosphorus in soil (1 ppm or 0.1%) is readily available to plants. chemical fertilizers are widely used in meeting the phosphorous need of crops. However, as the fertilizer production is dependent upon fossil energy sources, continuous use of chemical fertilizers has become a matter of great concern, not only because of the diminishing availability of costly inputs but environmental concerns also. Under this background, it has obviously brought the subject of mineral phosphate solubilization in the forefront. A group of soil microorganisms is recognized to be involved in microbial phosphate solubilization mechanisms through which insoluble forms of inorganic and organic phosphates convert into soluble forms (HPO4-2 or H2PO4-). Acidification of the medium, chelating, exchange reactions and production of various acids has been discussed as the key processes attributed to the conversion. Phosphate solubilizing bacteria (PSB) are a group of plant growth promoting rhizobacteria (PGPR) that convert unavailable forms of phosphorus to available forms and it helps to the growth and yield of plant. The use of plant growth promoting rhizobacteria (PGPR) is considered one of the most important factors increasing sesame yields. Therefore, the aim of the present study was to investigate the interactive effects of PGPR and phosphorus fertilizer on some growth parameters and components of yield and also phosphorus and Zinc uptake in sesame.
Materials and Methods: In order to investigation of the effect of combined application of phosphate solubilizing bacteria and phosphorus fertilizer on growth and yield of Sesame, a greenhouse experiment was conducted as factorial based on completely randomized design with three replications including five levels of phosphorous fertilizer (0, 100, 200 and 400 kg ha-1 of triple superphosphate and 1200 kg ha-1 of rock phosphate) and three bacterial levels (inoculation with two phosphate solubilizing fluorescent pseudomonad, isolates of P3 and P5 that known in this study as B1 and B2 and non-inoculated). It should be noted that rock phosphate used in this study has contained 4% of zinc oxide. The bacteria selected from microbial bank of Vali-E-Asr University were able to dissolve the insoluble phosphate and produce siderophore and IAA. Four months after planting, plants were cut at the soil surface, and shoot dry weight, stem height, number of Seeds in pot, seed dry weight and seed oil percentage were recorded. Also phosphorus and Zinc contents in shoot were determined.
Results and Discussion: Results indicated that both bacteria (B1 and B2) significantly increased shoot dry weight and B1 increased seed dry weight. Also application of phosphorus fertilizer significantly increased shoot dry weight and plant height. 200 kg ha-1 of triple superphosphate had highest shoot dry weight and was similar with rock phosphate. Combined application of Phosphorous fertilizer and phosphate solubilizing bacteria increased shoot dry weight. Results also showed that seed oil was increased by application of Phosphate rock. Phosphorus concentration in seed was increased with Using B1 and B2 isolates. Application of B2 significantly increased phosphorus concentration in seed (11.5%) and Phosphorous fertilizer levels increased concentration of P and Zn in seed. Application of 200 and 400 kg ha-1 triple superphosphate had the highest concentration of P and Zn in seed. Phosphorus fertilizer levels significantly enhanced uptake of P and Zn in shoot. Application of 200 and 400 kg ha-1 triple superphosphate led to increased uptake of phosphorous in shoot. Also rock phosphate significantly increased uptake of Zn in shoot. Combined application of Rock phosphate and bacteria of B1 and B2 had more significant effects on uptake of Zn in shoot.
Conclusion: this study showed that Phosphate solubilizing bacteria (B1 and B2) had significant effects on the growth and nutrient uptake especially phosphorus and zinc in sesame. The simultaneous application of Phosphate rock and Phosphate solubilizing bacteria increased most of the measured parameters similar to the highest levels of triple superphosphate. Therefore, because of high cost of chemical fertilizers production and its environmental problems, application of less levels of phosphorus fertilizers or rock phosphate along with Phosphate solubilizing bacteria could be an appropriate option to avoid wasteful consumption of phosphorus fertilizers.
Research Article
F. Mahmoodi; R. Jafari; H. Karimzadeh; N. Ramezani
Abstract
Introduction: Use of remote sensing for soil assessment and monitoring started with the launch of the first Landsat satellite. Since then many other polar orbiting Earth-observation satellites such as the Landsat series, have been launched and their imagery have been used for a wide range of soil mapping. ...
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Introduction: Use of remote sensing for soil assessment and monitoring started with the launch of the first Landsat satellite. Since then many other polar orbiting Earth-observation satellites such as the Landsat series, have been launched and their imagery have been used for a wide range of soil mapping. The broad swaths and regular revisit frequencies of these multispectral satellites mean that they can be used to rapidly detect changes in soil properties. Arid and semi-arid lands cover more than 70 percent of Iran and are very prone to desertification. Due to the broadness, remoteness, and harsh condition of these lands, soil studies using ground-based techniques appear to be limited. Remote sensing imagery with its cost and time-effectiveness has been suggested and used as an alternative approach for more than four decades. Flood irrigation is one of the most common techniques in Isfahan province in which 70% of water is lost through evaporation. This system has increased soil salinization and desert-like conditions in the region. For principled decision making on agricultural product management, combating desertification and its consequences and better use of production resources to achieve sustainable development; understanding and knowledge of the origin, amount and area of salinity, the percentage of calcite, gypsum and other mineral of soil in each region is essential. Therefore, this study aimed to map the physical and chemical characteristics of soils in Vazaneh region of Isfahan province, Iran.
Materials and Methods : Varzaneh region with 75000 ha located in central Iran and lies between latitudes 3550234 N and 3594309 N and longitudes 626530 E to 658338 E. The climate in the study area is characterized by hot summers and cold winters. The mean daily maximum temperature ranges from 35°C in summer to approximately 17°C in winter and mean daily minimum temperature ranges from 5°C in summer to about -24.5°C in winter. The mean annual evaporation rate is 3265 mm. In this study, image processing techniquess including band combinations, Principal Component Analysis (PC1, PC2 and PC3), and classification were applied to a TM image to map different soil properties. In order to prepare the satellite image, geometric correction was performed. A 1:25,000 map (UTM 39) was used as a base to georegister the Landsat image. 40 Ground Control Points (GCPs) were selected throughout the map and image. Road intersections or other man-made features were appropriate targets for this purpose. The raw image was transformed to the georectified image using a first order polynomial, and then resampled using the nearest neighbour method to preserve radiometry. The final Root Mean Square (RMS) error for the selected points was 0.3 pixels. To establish relationships between image and field data, stratified random sampling techniques were used to collect 53 soil samples at the GPS (Global Positioning System) points. The continuous map of soil properties was achieved using simple and multiple linear regression models by averaging 9 image pixels around sampling sites. Different image spectral indices were used as independent variables and the dependent variables were field- based data.
Results and Discussion: The results of multiple regression analysis showed that the strongest relationships was between sandy soil and TM bands 1, 2, 3, 4, and 5, explaining up to 83% of variation in this component. The weakest relationship was found between CaCo3 and 3, 5, and 7 TM bands. In some cases, the multiple regressions was not an appropriate predicting model of soil properties, therefore, the TM and PC bands that had the highest relationship with field data (confidence level, 99%) based on simple regression were classified by the maximum likelihood algorithm. According to error matrix, the overall accuracy of classified maps was between 85 and 93% for chlorine (Cl) and silt componets, repectively.
Conclusions: The results indicated that the discretely classified maps had higher accuracy than regression models. Therefore, to have an overview of soil properties in the region, classification techniques appears to be more applicable than regression models. The findings of this study shows that the extracted maps of the physical and chemical characteristics of soils can be used as a suitable tool for field operations, cambating desertification and rehabilitation purposes and compared to maps that are created by traditional methods, our final maps have more economically and time saving advantages. Therefore, they can be used as an adjunct to field methods to aid the assessment and monitoring of soil condition in the arid regions of Isfahan province.
Research Article
F. Nooralivand; A. Farrokhian Firouzi; A. Kiasat; M. Chorom; A. Akbar Babaei
Abstract
Introduction: During the recent decades, the use of N fertilizers has undeniable development regardless of their effects on the soil and environment. Increasing nitrate ion concentration in soil solution and then, leaching it into groundwater causes increase nitrate concentration in the water and raise ...
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Introduction: During the recent decades, the use of N fertilizers has undeniable development regardless of their effects on the soil and environment. Increasing nitrate ion concentration in soil solution and then, leaching it into groundwater causes increase nitrate concentration in the water and raise the risk suffering from the people to some diseases. World health organization recommended maximum concentration level for nitrate and nitrite in the drinking water 50 and 3 mg/l, respectively. There are different technologies for the removal of nitrate ions from aqueous solution. The conventional methods are ion exchange, biological denitrification, reverse osmosis and chemical reduction. Using nanoscale Fe0 particles compared to other methods of nitrate omission was preferred because of; its high surface area, more reactive, lower cost and higher efficiency. More studies on the reduction of nitrate by zero-valent iron nanoparticles have been in aqueous solutions or in the soil in batch scale. Nanoparticles surface modified with poly-electrolytes, surfactants and polymers cause colloidal stability of the particles against the forces of attraction between particles and increases nanoparticle transport in porous media. The objectives of this study were to synthesize carboxymethyl cellulose stabilized zero-valent iron nanoparticles and consideration of their application for nitrate removal from sandy soil.
Materials and Methods: The nanoparticles were synthesized in a lab using borohydride reduction method and their morphological characteristics were examined via scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier Transmission Infrared Spectroscopy (FTIR). Experiments were conducted on packed sand column (40 cm length and 2.5 cm inner diameter) under conditions of different nanoparticle concentration (1, 2, and 3 g1-1)and high initial NO3- concentration (150, 250, and 350 mgl-1). Homogeneous soil column was filled with the wet packed method. CMC-NZVI suspensions of nanoparticle in aqueous solution (0.01 M CaCl2 and 0.001MKCl) were pumped into the sand column during the injection of nitrate solution. During transport experiment, the flask containing CMC-ZVIN suspension was sonicated using a 50 KH ultrasonicator (DSA100-SK2) to prevent particle agglomeration and ensure homogeneity of the suspensions. In these experiments pore water velocity was 0.16 mms-1. Nitrate and Nitrite concentrations in the samples were measured using UV-VIS.HACH DR 5000 spectrophotometer at wavelengths 220 and 530nm, respectively, and ammonium concentration was measured by Kjeldahl method. All chemicals used in this research were of chemical grades and all solutions were prepared using deionized water (DI).
Results and Discussion: Effect of nanoparticles and nitrate concentration on nitrate reduction by stabilized nanoparticle in sand column was investigated. The Results of study indicating at the first of reaction in both cases rate and amount of nitrate reduction was increased gradually. But over time, due to saturation capacity of nanoparticles at higher concentrations of nitrate, reduction speed and amount of reduction was constant approximately. The result showed that increasing dosage of nanoparticles and decreasing the influent nitrate concentration would increase percentage of nitrate reduction. Maximum percentage of reduction (82.56%) were observed at nanoparticles concentration=3 gl-1 and high initial nitrate concentration=150 mgl-1 and minimum percentage of reduction (63.94%) were observed at nanoparticles concentration=1 gl-1 and high initial nitrate concentration=150 mgl-1. After the end of experiment time, amount of observed ammonium and nitrite was a few in the drainage water of sand column. During the reaction nitrate reduction by nano-particles, H + was used and OH- was produced therefore through reaction, environment pH increased continuously. In conditions of alkaline, ammonium release in the form of N2. Therefore reduction of the amount of ammonium may due to high pH of environment reaction or fixation of ammonium in the surface colloidal of particles in porous medium. Nitrite is an intermediate product and due to the reaction conditions can be converted to ammonia or nitrogen gas. The final product of reduction would be nitrogen gas, and produced nitrite and ammonium was less than 2%.
Conclusion: The results indicate that, in all experiments (effect of nanoparticle and nitrate concentration on nitrate reduction), amount of observed ammonium and nitrite was a few in the drainage water of sand column and most of the nitrate converted to nitrogen gas. Since maximum concentration level of ammonium in drinking water is 50 times less than nitrate concentration, nitrogen gas is an ideal product in water treatment process. Carboxymethyl cellulose prevents agglomeration ZVI nanoparticles and enhanced the reactivity and transport of nanoparticle in the porous media. The findings of this research demonstrated that carboxymethyl cellulose-stabilized zero-valent iron nanoparticles have a high potential for reduction of nitrate in aqueous solutions and porous media. Therefore, it can be used as an effective method for removing nitrate from water.
Research Article
T. Raiesi; A. Hosseinpur; F. Raiesi
Abstract
Introduction: The biological and chemical conditions of the rhizosphere are known to considerably differ from those of the bulk soil, as a consequence of a range of processes that are induced either directly by the activity of plant roots or by the activity of rhizosphere microflora (16). Municipal sewage ...
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Introduction: The biological and chemical conditions of the rhizosphere are known to considerably differ from those of the bulk soil, as a consequence of a range of processes that are induced either directly by the activity of plant roots or by the activity of rhizosphere microflora (16). Municipal sewage sludge (MSS) applied to agricultural soils is a well known reusable source of phosphorus (P), nitrogen (N) and other macro- and micro-nutrients (33). Sludge provides a short-term input of plant-available nutrients and stimulation of microbial activity, and it contributes to long term maintenance of nutrient and organic matter pools (33). Availability of P following application of MSS can be influenced by microbial and chemical properties of the soil, MSS composition, and rhizosphere processes. The specific interrelationships between these components have proven to be complex and, despite continued study, a thorough understanding of the interactions among plant roots, manure P, and P solubility has yet to be achieved (42). Little quantitative information is available about the chemical and biological properties in the rhizosphere of bean plant growing in soils un-amended and amended with MSS. Therefore, the objectives of this research were to evaluate the rhizospheric effects of bean on chemical and biological properties in 10 calcareous soils as amended with municipal sewage sludge (MSS) or unamended (control) under rhizobox conditions.
Materials and Methods: Ten surface soil samples (0–30 cm) were collected from Chaharmahal-Va-Bakhtiari province, in the central Iran. Municipal sewage sludge was used from the refinery of Shahrekord city, central Iran. Air dried and sieved (
