WATER AND SOIL SCIENCE (AGRICULTURAL SCIENCE)
Year:2018 | Volume:28 | Issue:2 |Papers Count:18

While investigating the stability of slopes at the rivers, uncertainty of soil shear strength parameters and their spatial variations affect the accuracy of results. Nowadays, probabilistic analyses are adopted to understand the probability of slope stability as the complementary methods. Throughout the current research on the meanders in Shalmanrood river of Guilan, the probabilistic analysis using Monte-Carlo method was carried out after field and laboratory studies on the soil. Accordingly, the pore pressure and strain under unsteady condition were modeled using finite element method. Then the slope stability was evaluated combining Monte-Carlo and limit equilibrium methods and compared with other researches’ results. The results showed that at meandering section 2 (the highest curvature), pore water pressure was dissipated in low rate after decline of the water level at the river. Additionally, results of strain analysis demonstrated that at the water elevations lower than normal level, swelling and compression occurred in meanders with slight and high curvatures, respectively. The probabilistic analysis with Monte-Carlo method applying Ordinary Slice method approximated the probability of slope failure within a bigger time span, as compared to Morgenstern-Price method. Meanwhile by decrease of the water level in river, the probability density function (PDF) of the safety factor showed a descending trend within 9. 6 hours. In meander with the maximum curvature (section 2), a bigger temporal variations were observed in the position of PDF of safety factor, as compared to the minimum curvature (section 4).

In order to evaluate the effect of various levels of drought stress on some growth and bio-chemical parameters of marigold (Calendula officinalis L. ) and application of salicylic acid for mitigating drought impacts under greenhouse conditions, an experiment was conducted with a factorial arrangement based on completely randomized design with three replications at Research Greenhouse of Agricultural Faculty of Bardsir, Shahid Bahonar University of Kerman in 2015. The experimental treatments were different levels of drought stress at four levels (irrigation for fulfill of 100%, 75%, 50% and 25% of the field capacity) and foliar-application of salicylic acidat at five levels (0, 0. 5, 1, 1. 5 and 2 mM). The results showed that the irrigation levels had significant effect on all studied traits. The traits of dry weight, carotenoid contents, proline contents and soluble sugars were significantly affected by the salicylic acid treatment. Interaction of the irrigation and salicylic acid had significant effect on dry weight, proline contents and soluble sugars. The results showed that increase in drought stress caused to significant decreasing in growth parameters and also chlorophyll a and b contents. Contents of carotenoid, soluble sugars, proline and phenol were significantly increased by decreasing amount of irrigation water. Increase of salicylic acid to 1. 5 mM increased the plant dry weight, carotenoid contents and soluble sugars relative to the control conditions. 2 mM salicylic acid decreased the traits compared to non-foliar application. Generally, the results showed that application of salicylic acid specially in 1. 5 mM had a positive role in mitigation of negative effects of drought stress.

Numerous studies in optimization of water supply networks have been allocated to cost reduction of these infrastructures. In general optimization methods, minimizing the costs is the unique purpose, but applying this view point for the case of water supply systems may lead to reduction of the utility and efficiency of the system. Therefore, some multi-objective optimization models have been used to decrease the large amount of costs in these systems and to increase their operation efficiency. The present study has attempted to illustrate a case study for a town of Kerman in order to decrease the costs of rebuilding pipe network using the Imperialistic Competition Optimization Algorithm. So, the network simulation was performed with Water GEMS software. Firstly, the water supply network of the study area was simulated in the Water GEMS model. Next, the properties of water supply network were inserted. Then, using the standard pressure and speed constraints, the optimal options of the algorithm were obtained. By re-running the results of this optimized model in the Water GEMS model and the limits’ checkup, the total costs were estimated and compared. Analysis of the optimal model results showed that in comparison with the state prior to the network optimization, the Imperialistic Competition Algorithm has significantly reduced the cost function of the network.

Pressurized flushing is one of the common methods in hydraulic flushing of dam reservoirs. In this method, sediments settled in the reservoir are released out together with water flow using the bottom outlet of the dam. In this research, by employing the submerged vanes with radial arrangement in front of the bottom outlet, effect of this arrangement in enhancement of the vortex flow and pressurized flushing efficiency were investigated. The effect of different parameters of radial arrangement including cross distance of the main vanes (Lm), distance between the main and side vanes (Ls) and the distance of vanes from the side wall (Lv) on this phenomenon were investigated in three different water depths of the reservoir (20, 30 and 40 cm). Based on the results, the optimal non-dimensional lengths values of the radial arrangement parameters were obtained as Lm/D=0. 5, Ls/D= 0. 25 and Lv/D=0. 2 (D, diameter of bottom outlet). In the best radial arrangement parameters of the vanes in the different hydraulic condition, flushing efficiency increased about 11. 33 times compared to the control model. In radial arrangement, with increasing the water depth of reservoir, the flushing performance increased. This condition, more flushing in high water depth, is a comparative advantage for flushing. In other words, the flushing operation has more efficiency in the full condition of the reservoir and it is not necessary to empty the reservoir.

One of the important purposes of the river engineering is to protect the river banks from erosion phenomenon and to prevent the shifting of the main channel path. Spur dike is a hydraulic structure which has a lot of applications for stabilizing river banks and increasing water depth. Owing to the widespread use of this structure, it is important to understand the flow pattern around it. Since flow pattern around a spur dike is complex and fully 3D, hence a 3D simulation has been done in this study. FLOW-3D software was employed to simulate the flow around a submerged spur dike. VOF method was used for free surface simulation and RNG k-ε model was used for turbulence modeling. Based on comparison of the numerical and experimental results for stream wise velocity components and flow depths, it was concluded that the numerical model could simulate the flow passing the submerged spur dike. Then the effect of the spur dike length on the velocity profiles, free surface and flow pattern was studied. Based on the results, the maximum stream wise velocity in the nose of the spur dike increased with increase of spur dike length. This velocity showed about 24% and 59% increase in case of the spur dike with 0. 1m and 0. 4m length, respectively. Also, the flow depth increased with increase of the spur dike length.

Reduction of rivers inflow which discharge to reservoirs of the country such as Lake Urmia is the most important present problem of water industry. so the role of runoff coefficient to determine the runoff arising from precipitation in order to anticipate and manage the stream flow is of great importance. Soil moisture, especially surface soil moisture, plays an important role in the natural water cycle in nature particularly in the distribution of rainfall and its turn into runoff and infiltration. On the other hand, stream flow always affects the level of the groundwater table. Therefore, the relationship between the runoff coefficient with surface soil moisture and water table level in order to determine the volume of runoff arising from precipitation can be one of the most important issues in the field of water resources management. In this study, MODIS satellite images were used to estimate the spatial and temporal variations of soil moisture and relationship between instantaneous runoff coefficient (events) and daily groundwater table level, as well as its relation with daily surface soil moisture extracted from the atellite images for the two hydrometric stations located at the beginning and end of the Ghaleh_Chay river discharging into the Lake Urmia were investigate Results of this research confirmed the existence of a direct relationship between the runoff coefficients and water table at the Shishavan and Yengejeh stations with a correlation coefficient 0. 9 and 0. 84 respectively. Also direct connection between the runoff coefficient and daily surface soil moisture was registered with correlation coefficient of 0. 792 and 0. 815 at the stations of Shishavan and Yengejeh, respectively.

Sand and gravel mining from the rivers bed in the country has been increased in the recent years which causes changes in the rivers systems. Irregular excavation of sand and gravel regardless of the river sedimentation capacity causes changes in river sediment balance and morphology. In this study to investigate the impacts of the sand and gravel mining on the bedload amount and gradation in Zaremrood river, the bedload was sampled by placing pit sampler in the river bed. Granulometric analysis of sediment was carried out for each sample separately using ASTM method. Their weights were measured in the laboratory, too. Then, the sizes of diameters D10, D50, D90, mean grain size and the values of sorting, skewness and kurtosis were obtained in micron and Φ scale using GRADISTAT software. Finally, a significant difference between the sediment statistics of the upstream and downstream cross sections of sand and gravel mining in SPSS22 software was investigated. The results showed that the sizes of diameters D10, D50, D90, and mean grain size, sorting showed a significant difference in the bedload samples of the upstream and downstream cross section of the mining place. However, skewness and kurtosis of bedload sediment particles size did not show significant difference in the mentioned samples. Also, sand and gravel mining from river bed in the study reach caused the bed erosion, dislocation of sedimentary layers and changes in the sediment balance.

Hydraulic structures in some cases, cause to produce obstacles in path of the flow that create oscillating vortices in downstream of the obstacles. Vortices produce oscillating forces to the obstacle that are harmful for the stability of structure. In recent years this phenomenon is used to create clean energy. In this study, oscillation of an obstacle in the presence of a fixed obstacle at the upstream was examined. The experiments on triangular block were carried out under varying discharge and different upstream distances. The main objective of this study was to investigate the effect of parameters of velocity and upstream obstacle distance on the oscillation frequency. Using dimensional analysis, the dimensionless parameters of Strouhal number, Reynolds number and ratio of distance to diameter were obtained. The charts of the relationship of the Reynolds number and also the ratio of distance to diameter vs. the Strouhal numbers were plotted. Finally, a new relationship was presented using data analysis and spss20 software to estimate the Strouhal number. Verifying the proposed relation, confirmed a fairly good prediction of this relation.

The drought phenomenon is one of the natural disasters, which may occur in all climatic zones and cause serious damages to the environment and human life. So, forecasting this phenomenon may have significant impact on the water resources management and reduce its destructive effects as much as possible. In this study, the multivariate standardized precipitation index (MSPI) was utilized to compute the drought characteristics in the Lighvanchai basin and then the artificial neural network (ANN) was used to forecast the MSPI values. In order to train the ANN and estimate its optimized weights, the particle swarm optimization (PSO) algorithm was applied and its performance was compared with the backpropagation (BP) algorithm. In this context, different scenarios and structures were considered and then the goodness-of-fit tests were utilized for evaluating the accuracy of them. The results demonstrated that the ANN-PSO model had a better performance than the ANN-BP model for drought forecasting.

Determination of land suitability to achive sustainable agriculture and environmental protection is very important and essential, because of arable land decrease in the last decade. In this research, parametric approaches including Storie and Square Root and ELECTRE TRI multiple criteria method have been used for suitability evaluation of the maize cultivation under sprinkler irrigation in 12000 ha area of Dasht-e-Moghan via consideration of 167 soil profiles. After soil sampling, analysis, classification and extraction of soil properties values by weighted coefficients, finally eight properties including soil depth, lime, gypsum, pH, EC, ESP, slope and climate were selected using principal component analysis and Euclidean distance methods for calculations of the land suitability evaluation. Criteria weights via pair-wise comparison matrix method and ELECTRE TRI profiles and thresholds limits were determined using requirements table, soil and land properties data. Statistical comparison of the allocated grades, mean values to the suitability classes in the region and soil great groups showed that the results of the three methods were significantly different and ELECTRE TRI method had the best grade. Hotelling and Wilks tests of multivariate variance analysis distinguished a suitable separation accuracy of suitability classes by their P-values in ELECTRE TRI method. Also comparing the mean values of the soil and land properties via LSD test showed a significant difference among the ELECTRE TRI suitability classes that implie the high accuracy of this method due to determination of the transition suitable limits (classes between limit), appropriate values of thresholds and criteria weights as well as usage of the fuzzy logic relations and principles for performance of the calculation processes.

Due to low rainfall and high evaporation in climatic conditions of Iran, improper management of irrigation practices has resulted in salinity and waterlogging of many lands. By attention to importance of the research on drainage issue and drainage problems of 20, 000 ha agricultural lands in Moghan region, this research was conducted to identify the appropriate equation for determining subsurface drains’ spacing (s. d. s. ) in an experimental field with the area of 18 ha, located in section 807, branch 3, of Agro-Industry of Moghan. Three drainage systems with spacings of 50, 100 and 150 meters between the drainage pipes having 200 meters’ lengths, were constructed in the experimental field. After beginning the irrigation, the measurements of water levels and drainage out-flows were performed. Comparison of the methods for determining the suitable distances between the subsurface drains had that the Hammad, Bouwer & van schilfgard and vanschilfgard equations showed the most accurate results with 3, 6 and 7 average deviation percentages from subsurface drains’ actual spacings, respectively. Among the conventional equations for determining the s. d. s., the Bouwer & Vanschilfgard, Dumm, Glover and Vanschilfgard equations were recommended, respectively. The accuracy of these equations did not have a considerable difference with each other. Although, the efficiencies of the established drainage systems with 50 and 150 meters’ distances between drains were approximately identical, a system with 100 meters’ distance for drains was recommended to increase the degree of reliability.

Nitrate reductase enzyme activity can be a good indicator for nitrate uptake in the presence of chloride and plant tolerance to salinity. Gene expression programming is a mathematical model between input and output variables and has the ability of choosing the effective parameters in the model. In this study, ions contents of root (chloride, sodium, nitrate and potassium) in two grape genotypes (Gharashani and GhezelUzum) as the effective parameters in the nitrate reductase activity were used in genetic programming model. The results showed that the nitrate absorption was decreased under salinity, also at higher nitrate concentration this reduction was higher in the salt sensitive genotype. It means that in grape the low affinity transport system (LATS) was more sensitive to salinity compared to the high affinity transport system (HATS). In both genotypes, the nitrate reductase activity increased with increasing the nitrate concentration in root medium. Comparing the results obtained using three function set showed that the highest correlation and lowest root mean square error were achieved for training phase by using the default function set, while for the testing phase, the main operators along with the squared root and power gave the better performance accuracy. Also, according to the suggested model, nitrate, chloride, sodium and potassium as the selected effective variables contribute with a decreasing order in the nitrate reductase activity respectively.

Responses of olive self-rooted cuttings of Zard cultivar (Olea europaea L. cv. Zard) to different levels of soil compaction and irrigation water salinity at the field capacity under greenhouse condition were studied. A loamy sand soil passed through a 4. 76mm sieve, was poured into the PVC cylinders with diameter of 15cm and then they were compacted to be achieved the desired compaction levels. One-year-old rooted olive cuttings were transplanted into the PVC cylinders. After stabilization of cuttings, cylinders were irrigated by waters having different electrical conductivities at three days’ intervals, for five months. Some morphological and physiological properties of the olive plants were measured. As the salinity levels of irrigation water increased transpiration, stomatal conductance, photosynthetic rate, relative water content, water potential of stem, temperature difference between leaf and the environment and chlorophyll index decreased, for preserving plant internal water balance. Instantaneous WUE, electrolyte leakage and Na concentration of leaves increased as the salinity levels of irrigation water increased because of the decrease in transpiration and due to the plant’ s salinity tolerance mechanisms. The relative water content of leaf, water potential of stem and temperature difference between leaf and environment decreased as the soil compaction increased due to decrease in water uptake. Photosynthetic indices of olive cuttings of Zard cultivar significantly decreased beyond the EC of 8 dS m-1.

Land utilization has tremendously been increased as a result of growing the population. Therefor it’ s necessary to utilized the lands in accordance with their potential to increase their productivity and sustainability. As assessing the land suitability is a multifactorial issue, it’ s needed a special technique to assess all the factors simultaneously. In this way, multi-criteria decision making methods (such as the Analytical hierarchical process) are widely used. The purpose of the present study is the land suitability assessment of rainfed barley in a part of kuhin area with 500 ha land using Analytical Hierarchical Process (AHP) and GIS. According to the study of 23 soil profiles, region aerial photos interpretation (1/40000), soil morphological characteristics in 16 different units (land units) the land evaluation was carried out. For this, 9 criteria including CaCo3%, OC%, Surface gravel%, depth, texture, apparent CEC, pH, slope% and climate condition were selected as the effective factors on barley growth. The weight for each factor was calculated using 30 questionnaires which were completed by the experts and software of Expert Choice, then the overall weight for each criterion on was obtained by multiplying the normalized attributes and relative weights. The results showed that among 16 land units the maximum and minimum calculated indices were 64. 25 (unit 11) and 37. 12 (unit 4), respectively. Also in all units the maximum and minimum weight related to slope and climate, respectively.

Sewage sludge is an important source of organic matter, nitrogen, phosphorus and other nutrients. This sludge can be used as an organic fertilizer to improve the soil and it’ s fertility by a correct management. In present study an investigation was carried out in order to checking the effects of sewage sludge on yield of two types of wheat species (Sivand and Roshan) and some physical and chemical properties of the soil. The investigation was done in the form of a factorial experiment as a completely randomized design with three replications and three levels of sludge(zero, 60 and120 g kg-1soil) in research greenhouse of the Yazd University. The results showed that application of sewage sludge comparing control treatment caused a significant increase in the leaf surface, dry weight of aerial parts, seed number and total seed weight in the Sivand and Roshanas the two studied varieties, although the Roshan wheat height in control treatment was more than that is sewage sludge treatments. With increasing the level of sewage sludge, soil electrical conductivity increased too. While, soil pH and soil bulk dencity at treatment with 60 and 120g kg-1 of sludge showed a significant decrease as compared to the control treatment. Furthermore, the treatments of sewage sludge in comparison with control treatment increased the organic carbon, total nitrogen, phosphorus and absorbable potassium of the soil. According to the results, sewage sludge could increase soil fertility and plant yield by improving some physical and chemical properties of the soil.

There are different methods for evaluation of the biological nitrogen fixation, which they are mainly included acetylene reduction assay, labeled nitrogen and nitrogen difference methods. Accuracy and sensitivity of these methods are different, but applying of some of these methods isn’ t possible in all laboratories, so it cause the use of less accurate methods for evaluation of the nitrogen fixing content. Therefore, this article was aimed to investigate the content of nitrogen fixation (NF) of some bacteria isolates including Azotobacter using the Kjeldahl method. A total of 22 bacteria isolates were used and evaluated. The isolates were cultured in solid and liquid LG media and the content of the nitrogen fixation was measured in solid and pellet of liquid culture. According to the results of digestion, distillation and titration (Kjeldahl) of the cultured sample in the solid medium, the maximum nitrogen-fixation content 261. 10 and 258. 64 μ g/g were found in 14SP-Ш and 14SP2-1, respectively. The highest nitrogen-fixation content in liquid culture medium was obtained in 14SP-I (80 μ g/ml). The results of liquid and solid culture media indicated that the maximum nitrogen in14SP-I and 14SP2-1 isolates belonged to the Azotobacter chroococcum, Pseudomonas 35SP-2, and Achromobacter 14SP-Ш . The results of NF in both solid and liquid cultures showed a good correlation (r=0. 69**). It seems that the method can be used for screening the efficient nitrogen fixing bacteria, although this is not so a precise method. 14SP-Ι , 14SP-Ш , 14SP2-1, 35SP-2 and 44SP-2 strains can be suggested among the isolates for the greenhouse and farm experiments.

This research work carried out to investigate the effects of land use type on soil porosity by image analysis of soil thin sections in Karkaj Agriculture Research Station. Experiments were conducted by studying five soil profiles with different covers of apple and coniferous trees, alfalfa, rapeseed and bare land (no cultivation) and 450 TIFF format images from soil thin sections, were prepared by connected camera to microscope and pores were separated from minerals with the compensator Lambda plate. As a factorial trial with completely randomized design (CRD), undisturbed soil blocks were prepared with three replications from horizons of A or Ap, Bw and C and then soil thin sections were prepared and studied with a polarizing microscope. Obtained results indicated that total area of soil pores in apple and coniferous lands were greater than those in the utilized lands for alfalfa, rapeseed and bare one, that it can be related to root system and organic matter. Also maximum frequency of shape characteristics such as pores roundness and solidity observed in coniferous covered land were greater than those in alfalfa, rapeseed and bare lands. In alfalfa, rapeseed and bare lands the fractal dimension of the pore component (Dmp) and solid component (Dms) were significantly decreased and increased respectively. Therefore, the quantitative and statistical results revealed significant effects of the land use types on soil porosity and microstructure.

Determination of flow roughness coefficient in the channels and river hydraulics is necessary for calculating of the discharge, the velocity and the depth of flow. Calculating the exact values of this coefficient is complex and difficult due to the influence of various parameters on it. In this study, using support vector regression as one of the machine learning approaches, the flow roughness coefficient in alluvial channel with dune bedform is predicted for four experimental data series under three scenarios (modeling based on flow characteristics, flow and bedform characteristics and flow and sediment characteristics) and the rate of input parameters is investigated using different performance criteria. The obtained results show that the support vector regression approach has desired accuracy in predicting the roughness coefficient. Also, the flow Reynolds number parameter with the most impact was recognized as the most significant parameter in estimating the roughness coefficient in the erodible beds with dune bedforms.