WATER AND SOIL SCIENCE (AGRICULTURAL SCIENCE)
Year:2019 | Volume:29 | Issue:2 |Papers Count:15

In this study, by use of the daily rainfalls of Tabriz weather station the normalized rainfall curves (NRC) were investigated. For this purpose, the cumulative amount of daily rainfalls with the cumulative number of rainy days were considered and shown by k x and k y, respectively. Then, the NRCs were extracted according to the equations of exp( ) k k k x = ay by and exp[ (1 ) ] c k k k x = y − b − y. This approach was applied to all days and every months of the data recording time period, separately. The parameters of models were estimated using the solver option in Excel software by the optimization method. Moreover, some of the other mathematical models (including the n-th degree polynomial, power, modified power, exponential, continuous exponential, etc. ) were derived for k x and k y data by the Curve Expert 1. 3 software. Among the all extracted models, a model having the lowest RMSE and highest 2 R was introduced as the most appropriate one. The results showed that, approximately, in the all cases the RMSEmodel with the lowest exp[ (1 ) ] c k k k x = y − b − y value (0. 4858 mm) and the largest amount of 2 R (0. 9996) was known as the most appropriate model to derive the NRCs of Tabriz station. Furthermore, in monthly time scale the amount of RMSE varied from 0. 22 mm (in September) up to 0. 67 mm (in April). The 2 R values for these two months obtained as 0. 9999 and 0. 9993, respectively.

In this study the effectiveness of phosphatic microbial fertilizers produced from seven bacteria (Pantoea agglomerans P5, Pseudomonas fluorescens Tabriz, P. putida Tabriz, Pseudomonas sp. C16-2O, Enterobacter sp. S16-3, Bacillus megaterium JK6 and B. firmus) in the basal formulation of rock phosphate (45 g), bagasse (30 g) and sulfur (15 g) were evaluated. In this experiment, Pantoea agglomerans P5 which used in Barvar2 biofertilizer was applied as a positive control. The results obtained from the greenhouse experiments showed that the wet and dry weight of roots and shoots, uptake of potassium, iron and zinc in the root and shoot of corn S. C. 704 were significantly influenced by the PMFs. In most measured parameters, the effects of Enterobacter sp. S16-3 and Pseudomonas sp. C16-2O were similar to the P. agglomerans P5 and all the three treatments in most cases had higher performance than TSP. P. fluorescens and P. putida treatments showed similar effects on corn growth. It should be noted that B. firmus in some cases and B. megaterium treatment in most parameters had lower performance compared to the treatment bed without bacteria (negative control) and even lower than the treatment without fertilizer bed (No Carrier). It should be emphasized that the effect of different levels of fertilizer consumption (0. 6 and 1. 2 g pot-1 equal to 100% and 200% of recommended dose of phosphorus) were significant and the level of 1. 2 g pot-1 compared to 0. 6 g pot-1 caused an increase more than two-fold in plant performance.

In order to evaluate the effects of phosphorus (P), contamination of lead (Pb) and zinc (Zn) and soil waterlogging on extraction kinetics of the available P, Zn and Pb in a calcareous soil, an experiment was conducted as factorial on the basis of completely randomized design with two replications under laboratory conditions with four factors consisting waterlogging duration at six levels (0. 1, 2, 6, 12, 36 and 72 days), Zn at two levels (0 and 250 mg kg− 1 soil), P at two levels (0 and 500 mg kg− 1 soil) and Pb at two levels (0 and 800 mg kg− 1 soil). The extractable-P, Zn and Pb contents were measured at the end of each time by Soltanpour and Schwab method. The results showed that application of P, Zn and Pb increased the extractable-P, Zn and Pb, respectively. The extractable-P was significantly increased with increasing duration of waterlogging under no P fertilizer application whereas P application (500 mg kg− 1 soil) resulted in reducing the average extractable-P by 23%. The extractable-Zn and Pb significantly decreased with increasing duration of waterlogging and application of P fertilizer, regardless of Zn and Pb applications. The results showed that in Pb and Zn contaminated soils, application of P fertilizer and soil waterlogging could decrease mobility and bioavailability of these heavy metals, leading to restrict their entrance in waters and plants.

Investigation of the unsteady flow has an important role in water conveyance systems. In the present study water conveyance system including the storage tank, pumping station and pipeline was studied to investigate the maximum pressure due to occurrence of transient flow conditions. The transient condition was started by cutting the power of pumps and in a short time period, the change of flow condition was investigated in the supply collector. The friction losses in transient condition were calculated using Bentley Hammer software. In this process, four methods including steady, quasi steady, unsteady and unsteady Vitkovsky states were used. The pressure was measured by using a fast and sensitive pressure gauge and the observed results were compared with the simulation results and in this process the statistical methods were used. The results showed that there was not time correspondent between the period of cycles. The least amount of error for pressure, gained by method of unsteady Vitkovsky, is equal to 7. 07m water at initial times and 11. 79 m water in data logging period. For the maximum pressure values, maximum difference was obtained by use of unsteady method and the minimum difference by the two methods of steady and quasi steady methods. The maximum difference for the minimum pressure value was obtained for steady and unsteady Vitkovsky methods at initial and ulterior, respectively and its minimum difference was calculated for unsteady method. Increasing wave velocity had a direct effect on the maximum pressures and an inverse impact on the minimum pressures.

Forecasting rainfall depth is very important in water resources management. ARIMA family time series models have a widespread application in this context. The main objective of this study was to predict monthly rainfall using the best time series stationary method and the most suitable ARIMA family model. In this study, Ardabil synoptic station’ s data was used. In the first step, the trend and seasonality terms of monthly rainfall data from 1990 to 2016 were removed using different methods and in the second step the efficiency of different ARIMA models for predicting monthly rainfall was investigated. Results showed that the stationary method using 12 period centered moving average and seasonal average in order to remove trend and seasonal variation, respectively, is the best stationary method with the highest correlation coefficient (r=0. 8). Also, the SARIMA (1, 0, 1) (0, 0, 1)12 model with the highest correlation coefficient (r=0. 8) and the lowest Akaike criterion (AIC=191. 74) is the best prediction model for monthly rainfall at the studied station. Finally, the monthly rainfall of the next 3 years (2017-2019) forecasted using the optimized stationary method and the selected model. Results showed that the rainfall trends of Ardabil synoptic station will be decreased in the next three years.

The main aim of the present study was to use different Hydro-Ecological methods to determine the environmental flow requirements in a typical perennial river, the Gadar River, in the Urmia Lake Basin, Iran. The ecological needs of the Gadar River were investigated in two different reaches along the river. Eight Eco-Hydrological methods (1-Tennant, 2-Tessman, 3-Flow Duration Curve Analysis (FDCA), 4-Smakhtin, 5-FDC shifting, 6-DRM, 7-RVA, 8-Q Equation) were used for the assessment of the minimum river environmental flow requirements. In order to maintain the Gadar River at minimum acceptable environmental status (i. e. Class C of the environmental management of rivers), average annual flows of 3. 28 and 3. 25 m3/s are to be allocated along the river in Naqadeh Bridge and Bahramlu Bridge Stations (located 40 and 18 km upstream from the Urmia Lake), respectively. Also, the prescribed monthly distribution of environmental flow requirements has been considered and proposed for the Gadar riverine life. Restoration of Urmia Lake needs the evaluation of the potential flows from the in-basin rivers and the revision of agricultural water rights. Monitoring the minimum environmental flow regime is necessary along the rivers to make sure the delivery of the water into the Urmia Lake.

Explicit finite-difference along with the combination of Lax and Leap-Frog schemes have been used to solve the 2D shallow water equations (SWE) to describe the free surface dam break flow in open channels. Discretization of SWE were carried out on a staggered grid. The model assessment was carried out by comparing the model results with the results of the analytical solution of a one-dimensional instantaneous dam break over a flat bed without friction and also with some researcher’ s numerical data for two-dimensional break of a circular column of water. Then the model results were compared with the present experimental data of a symmetry partial dam break. In all cases, the model could simulate the dam break flow with an appropriate accuracy.

Evaluation of groundwater resources vulnerability to pollution can be considered as an effective tool for management decisions. In this study, vulnerability of Salmas plain aquifer to pollution was assessed using SINTACS model and geographic information system (GIS). The SINTACS model consists of seven parameters including: Depth of water table, Infiltration, Unsaturated zone, Soil media, Aquifer media, Hydraulic conductivity and Topography. The vulnerability mapping showed three main zones; low groundwater vulnerability risk zone (risk indexes: 114-82), moderate groundwater vulnerability risk zone (risk indexes: 146-114) and high groundwater vulnerability risk zone (risk indexes: 178-146). The results showed that about 31. 47%, 53. 42% and 15. 11% of the studied area had low, moderate and high vulnerability, respectively. Two tests of sensitivity analyses were carried out: map removal method and single-parameter method, for evaluating the influence of each parameter to pollute the aquifer. The results of both analyses indicated that parameters with most significant impact on the vulnerability risk zones in Salmas area were unsaturated zone and depth of water table.

Soil salinity is one of the most important limiting factors in crop production and more than 50% of the world irrigated lands have different levels of salinity. Also, one of the most important agricultural problems in Iran is soil salinty where West Azerbaijan province is no exception from this problem. The aim of present study was investigating the possibility of surface soil salinity mapping in an area of 68000 ha in the south of West Azarbaijan province using remote sensing. A systematic random sampling method was used to prepare a ground truth map of surface soil salinity (including 147 soil samples from a depth of 0-15 cm). In this research, IRS-P6 satellite data (multispectral and panchromatic bands) were used. Geometric correction of images was done using digital elevation model and road and river maps. Various indices were generated, using ratioing and principal component analysis methods, and were used in the classifications. After selection of suitable training samples, classification was performed with different number of classes by a supervised method and different algorithms. The results of the accuracy assessment showed that the highest overall accuracy percentage and Kappa coefficient (87. 96% and 0. 77) were related to the classification of the two classes with 4-band combination and the maximum likelihood algorithm. Also, the results revealed high potential of remote sensing and IRS-P6 data for surface soil salinity mapping on a local scale.

In recent decades, soil pollution with heavy metals in world countries (such as Iran) has been one of the most challenging issues. Stabilization of heavy metals by using absorbent in remediation of heavy-metal-contaminated soils is one of the low-cost and fastest methods. In order to study the effect of diatomite on chemical forms of Cd in calcareous soils, a factorial experiment was conducted in a completely randomized design (CRD) with 3 levels of diatomite application in soil (0, 2 and 5 %), 4 levels of incubation time (1, 2, 4 and 8 weeks) and two contaminated soils in three replications. Chemical distribution of Cd in soils were determined using Tessier sequential extraction method at the above-mentioned incubation time and reduced partition index (IR) and mobility factor (MF) of metal were calculated as a Cd mobility index in soils. Results showed that application of diatomite significantly (p ≤ 0. 01) decreased the exchangeable and carbonate fractions and increased iron and manganese oxide bound organic and residual fractions in comparison to the control treatment. In 5% diatomite treatment after 8 weeks’ incubation the IR (42-71%) and pH (5-8%) values increased but the amounts of MF (30-33%) and DTPA-extractable Cd (33-28%) decreased, demonstrating a decrease in the mobility of metal in soils. It was concluded that addition of diatomite in soil lead decreasing the mobility of Cd and Pb in soils. According to the results, diatomite due to greater efficiency for immobilization of Cd in contaminated soils as a low-cost amendment can be used for immobilization of the high amount of Cd ions from contaminated soils.

In this study, 8 drip irrigation systems were evaluated. In every system, an operating manifold was selected and its four laterals including the first, a third, two-thirds and the last one was evaluated. Discharge of 8 emitters per lateral, the first and the last pressure, and the minimum inlet pressure of the lateral were measured. The results showed that the discharge of 87. 5% emitters were significantly lower than their nominal discharge, due to low pressure, and physical, chemical and algal blocking. In 12. 5% of the emitters, the average discharge rates were 10% higher than the nominal discharge. Uniformity of water application, the potential efficiency of low quarter and application efficiency of low quarter of all systems were poor. The average of emission uniformity, the efficiency reduction factor, potential efficiency of low quarter and the application efficiency of low quarter of the systems were calculated as 38. 6, 71. 5, 34. 73 and 38. 6%, respectively. Assessments showed that the major problems of most drip irrigation systems were manipulation of emitters, the blockage of pipes and emitters, heterogeneity of pressure and non-uniform distribution of water, and the user’ s lack of knowledge and skills due to traditional attitudes of gardeners, designers and executers. Despite the importance of different filtrations in drip irrigation and the use of new accessories, gardeners usually don't care about the completeness and proportionality of filters with the discharge and the loss and leakage due to the improper maintenance of systems.

The temperature changes have shown increasing trend in recent decades and these changes are much more significant in regions like Iran, which is located in the arid and semi-arid belt of the world. Intensive heat waves are of the most important climatic disasters, which have devastating environmental implications in the nature every year. In this study, the simple probability, stationary probability and consecutive probability of 2-5 days were calculated, after identifying the heat waves. For this purpose, the 30 years data of daily maximum temperature from 16 stations with different climates (cold and dry to moderate humid climates) and were used for application of the first order Markov chain. Results indicated that the maximum and minimum values of the simple probability with of the heat wave days were observed at Bandar-Abbas and Khorram Abad stations with amount 6. 1% and 0. 2%, respectively. Also, Bandar-Abbas station had the maximum percentage of the average consecutive probability of 2-5 days with the heat wave amounts of 2. 91, 1. 40, 0. 67 and 0. 31%, respectively.

Extraordinary withdrawal of groundwater resources has caused severe damages to aquifers, and the country's plains are facing subsidence due to this situation. In this regard, following the encouragement of the government by offering financial supports, many of farmers have volunteered to run pressurized irrigation systems. Therefore, gathering proper quantitative and qualitative data of water resources is necessary for sustainable agriculture. In this study, water quality of 103 agricultural wells in Sarab plain, which owners are applying for the operation of pressurized irrigation system, was investigated. To determine the water quality conditions of these wells, the magnesium absorption ratio (MAR), permeability index (PI), salinity potential (PS), Kelley's Ratio (KR), sodium absorption ratio (SAR) and soluble sodium percentage (SSP) indices were evaluated along with some other chemical parameters in the studied plain. The EC, SAR, MAR, PS and chloride indices indicated a decline in water quality from east to west and from south to north of plain. Approximately, water in 50% of wells were in the C3S1 class and the average KR of all wells were in a suitable condition with the value of 0. 46. Except for one case with the value of 15. 52, the remaining wells water had non-alkaline water with the SAR values less than 15. Only 17% of wells water had SSP values over 40% and they were not suitable based on this indicator. Most of the samples were located below the standard limit of 50% for MAR. Finally, in this study condition the application of sprinkler and tape irrigation systems for 90% of wells is recommended and for 10% of the rest of wells gated the pipes irrigation system may be adapted.

Today, as a result of the uncertainty and spatial variations of soil consolidation parameters and their effects on the pore-water pressure during the foundation settlement, it is common to apply the uncertainty-based probabilistic methods in such problems. In current study, the role of uncertainty of soil volumetric compressibility, as one of the effective factors on temporal variations of pore-water pressure during consolidation was investigated in Shaft region of Guilan province. In this respect, soil sampling was carried out in 9 bore holes (at the foundation of a steel structure and its yard located in Shaft town). Following the consolidation experiments, the log-normal distribution of soil volumetric compressibility was derived. Then, a computer code was developed in MATLAB to probabilistically analyze the partial differential equation of consolidation using Monte-Carlo simulation method. According to the results, increasing the number of random samples (of compressibility coefficient) from 100 to 1000 caused negligible effects. Whereas, the widening of probability density curves with time implies the dramatic effect of time on increasing the uncertainty of pore-water pressure. Meanwhile, for a given depth, the increased thickness of investigated soil layer caused greater uncertainty of pore-water pressure. Doubling the soil depth and investigated thickness of soil layer led to the increase of probability density by more than 20 times. Finally, during 100 days, the greatest temporal increase in coefficient of variation of pore-water pressure was obtained equal to 2. 15 and 0. 25 percent for 4-and 16-meters thick layers of soil, respectively.

This study tries to analyze the consecutive frost-free and freeze day’ s occurance probabilities, in Hamedan and Malayer Synoptic stations using first-order two-state Markov Chain method. The analysis was performed for the minimum daily temperature data during the October to March in the period of 2000-2014. The data were arranged according to frequency matrix of the freeze and frost-free days mode change and the elements of probability matrix were calculated by the maximum likelihood method. In addition, the initial and consecutive probabilities of the frost-free and freeze periods were also calculated. Based on the results, the number of observed periods with 2 consecutive frost-free days at Hamedan and Malayer synoptic stations were 860 and 1199, respectively. In the same order the occurrences numbers of frost-free days after freezing days at the same stations were also 235 and 246, respectively. Accordingly, 235 and 246 freezing days were occurred after frost-free event and also, 1400 and 1039 periods of 2 consecutive freeze days were detected at Hamedan and Malayer stations, respectively. The average probability percentages of the consecutive freeze periods were 81. 06 and 76. 73 for the Hamedan and Malayer stations, respectively. The average probability percent of freeze days were 60. 11 and 46. 99 in the studied stations, respectively. Also, probability percentages for freezing duration of 2-5 days showed that the average probability percentages of the consecutive days were equal to 50. 9, 43. 73, 37. 67 and 32. 78 in Hamadan station and 37. 82, 30. 72, 25. 25 and 20. 99 in Malayer station, respectively. So the results can be used to predict and prevent potential damage, since the low temperatures have a detrimental effect on agricultural production.