مجله تحقیقات آب و خاک ایران
سال چهل و نهم شماره 6 (پیاپی 38، بهمن و اسفند 1397)

In order to investigate the effects of different levels of gypsum (0, 50 and 100% gypsum requirement), organic matter (1.5 and 3% w/w organic carbon) from different sources (alfalfa residue, corn residue, date waste and saw dust) and leaching on the physico-chemical properties of a sodic soil, a factorial experiment was conducted in a greenhouse using a completely randomized design with three replicates. The results showed that the application of gypsum improved the sodic soil properties, before and after the leaching. However, the application of organic matter slightly increased sodium adsorption ratio, exchangeable sodium percentage and the percentage of dispersible clay measured before leaching. But after leaching, these characteristics were decreased significantly as compared to the control. The application of organic matter together with gypsum, especially the application of 3% date waste with gypsum, improved the properties of the sodic soil after the leaching more effectively than the application of gypsum and organic matter separately.

In recent years, decreasing water resources stimulated researchers to consider dry drainage in dry area due to less cost and water requirement. Understanding mechanism and the amount of different salts transportation from the irrigated area to the non-irrigated area is necessary to evaluate the performance of this system and the pre-implementation of purification and recovery projects of the salt collected from the non-planted surface area. In this study, the effect of dry drainage on the transportation of important cations and salinity changes (EC) in a loamy soil were investigated using a physical model under barley cultivation in 2017. The physical model was made of galvanize and had useful length, width and height of 2, 0.5 and 1 meter respectively. On the basis of the results, changes in sodium and calcium concentration profiles were similar and they were different from changes in potassium and magnesium concentration profiles. Sodium, potassium and calcium ions were accumulated in the upper soil layer, but magnesium was accumulated in the lower soil layer of the non-planted area. At the end of experiment, sodium, calcium, potassium, magnesium concentrations and SAR at the soil surface of non-irrigated area were 210, 410, 125, 115 and 126 percent of their initial values respectively. At the end of experiment, the soil surface salinity of the planted and non-planted areas was increased up to 145 and 270% of their initial values, respectively.

One of the important issues in rivers planning is the stabilization of erosive reaches. For this purpose, grade control structures that can be made of stone and masonry or concrete materials are used. Stepped weirs are among the grade control structures for modification of rivers bed slopes. Paying attention to the geometry of scour depth at the downstream of these structures is important in order to design structures safely and stably. In the present study, the effects of labyrinths with different geometries on the scour depth variation at downstream of the stepped weirs with slopes of 1:1, 1:2 and 1:3 were investigated experimentally. The experiments were performed for various conditions of discharge, geometry of labyrinths and tail water depths. Analyses of the results showed at the best case of labyrinth geometry for the 1:1 stepped slope, the maximum scour depth corresponding to the minimum and maximum tail water depths reduced 30.1% and 65%, respectively as compared to the flat step. By reducing the steps slopeto 1:2, considered geometries of labyrinth did not have significant effect on reduction of the maximum scour depth. Further reduction of the steps slope to 1:3 at the best case of geometry reduced the maximum scour depth corresponding to the minimum and maximum tail water depths, 25.2% and 24.5% respectively, as compared to the flat step.

Subsurface drainage system is required to eliminate water logging and establish planting condition for the second crops in the autumn and winter seasons in the large part of paddy fields in northern Iran. Proper depth and distance in a drainage system minimizes the negative effects of drainage effluents on the environment. This research was carried out in a physical model scale of paddy fields in agricultural faculty of Gillan University during 1396 to evaluate the qualitative and quantitative performance of the subsurface drainage in the second crop cultivation. The phaseolus vulgaris l. crop was planted in the physical model after filling the box with the soil of paddy fields and creating the hard pan layer at the depth of 15 cm. Drainage water and soil solution samples were collected during the occurrence of precipitation and their electrical conductivity, acidity, sodium, calcium, magnesium, nitrate and orthophosphate parameters were measured. The pressure head and drainage discharge were measured before and after precipitation events. The trend of electrical conductivity of the drainage water was decreased 60% as compared to the initial value and the amounts of sodium adsorption ratio (SAR) were oscillated due to precipitation and calcium and magnesium adsorption in the soil. The maximum amount of nitrate in the drainage water was 46.9 mg/l at the beginning of the crop growth period, which exceeded the permissible level of drainage discharge into the environment and indicates the importance of fertilizer management. The concentration of nitrate in the soil was affected by the distance from the drain, while the concentration of orthophosphate was not affected. The mean values of pressure head (7-17 cm) with respect to the root depth, showed an efficient drainage performance regarding to the drainage discharge and no water logging at the root depth during the growth period.

One of the common problems in arid and semi-arid regions of the country is the presence of saline and sodic soils. Therefore, water and soil management is one of the key issues in supplying the food for growing population of the country. In this study, the effect of different treatments on chemical properties of the soil was investigated to reclaminate the saline and sodic soils in Azaranegin, Tabriz. Treatments included sulfuric acid, iron sulfate, sulfur and irrigation water as a control. Also, the amount of amendment materials was investigated. The amendment materials were added to the soil with the rate of 10% and 20%, separately. The results showed that the application of sulfuric acid reduced the amount of Exchangeable Sodium Percentage (ESP) and the Sodium Adsorption Ratio (SAR) to less than 60% and 45%, respectively. On the other hand, the results showed that the application of sulfuric acid and iron sulfate reduced the ESP, SAR and ECe values significantly. However, in the case of sulfur application, the mean parameters did not indicate any significant differences with control treatment. Finally, the findings showed that there was a significant difference between 10% and 20% levels of amendment materials, so that the most reduction of these parameters were related to the sulfuric acid with application of 20% level.

In this study, kinetic and thermodynamic of Cd and Pb sorption from aqueous solutions were studied using diatomite. Kinetic sorption of heavy metals was analyzed by pseudo-first-order, pseudo-second-order, Elovich and power function equation in terms of their fitness. Freundlich, Langmuir, Temkin, Dubinin-Radushkevich (D-R) isotherm models have also been used for fitness of adsorption data in different temperatures (283, 293, 303 and 313 K). The results showed that the sorption of Cd and Pb by diatomite is intensified by increasing contact time and temperature. Kinetic sorption of heavy metals data showed the best fitness with the pseudo-second-order equation (R2=0.99) and a good fitness with Langmuir and D-R equations. The thermodynamic parameters such as Gibb's Free Energey (ΔG), Enthalpy (ΔH) and Entropy (ΔS) indicated that the adsorption of Cd and Pb ions were spontaneous and endothermic at 283–313 °K. Regarding to the adsorption energy of D–R model, Cd adsorption by diatomite (E< 8 kJ mol− 1) is probably followed by a physical process, but Pb adsorption by diatomite (E> 8 kJ mol− 1) is probably followed by a chemical process Diatomite has a greater efficiency for removal of Pb (RE=99%) than that of Cd (RE=86%) from aqueous solutions. Therefore, diatomite could be used as an efficient sorbent for the sorption of Pb and Cd (II) from polluted water resources.

In this research, laboratory studies were carried out to improve a clay soil by adding calcium ion through Electrokinetic method Experiments were performed in a special device using distilled water firstly, as the reference test and calcium chloride solution with the concentration of 0.25, 0.5, 1 and 1.5 molar secondly, as an anode reservoir fluid under the influence of 52-volt voltage during 7 days. During the experiment, the pH value was measured for electrolyte at the anode and cathode reservoir. Also, volume of water discharged from the cathode reservoir was measured at a given time interval. After the tests, shear strength of the soil was measured at different distances from the anode. The results showed that the calcium injection into the soil increases shear strength of the soil, and its amount depends on the concentration of calcium chloride solution, so shear strength increases by increasing concentration of the calcium chloride solution.

In this study, a numerical 3D model for simulation of lateral intake from the main channel with trapezoidal section has been developed. This model has solved the 3D Reynolds equations using finite volume method and k-ω turbulent model for solution of turbulent equations. The equations discretized at non-orthogonal and non-staggered curvilinear mesh. Given the lack of mesh orthogonally, it is necessary to enter a new item for modification of pressure equations. Also, power-law scheme and the SIMPLE algorithm have been used for parameter’s discretization and pressure-velocity coupling respectively. Developed model verified by simulating of complex flow pattern at lateral intake from a straight channel and a proper fitness between laboratory data and the model results was obtained. After that, the effect of side slope of the main channel wall on the flow pattern and division zone width was examined and showed by increasing slope from the vertical mode, the ratio of intake flow from the surface is more than the bed and this can be effective in reducing sediment entry to the intake. In this situation and in contrast to the intake from channel with vertical wall, the variation of division’s width, from the floor to the surface of the water is initially decreased and then increased.

Normalized water productivity is one of the AquaCrop model inputs, which simulates the performance of the biomass. This parameter has been considered to be constant for each crop in Aquacrop model. As the planting date affects the crop yield, this question is raised whether the planting date affects the normalized water productivity parameter or no? The proposed crop was Basil which was planted in summer 2017 in the Field of Abourihan University of Tehran in Pakdasht area at three different times (three treatments T1, T2 and T3) with 10 days intervalsThe biomass and normalized water productivity were measured 24 times during the growth period of each treatment. Normalized water productivity for T1, T2 and T3 treatments were estimated 11.2, 13.7 and 13.9 g/m2, respectively. The coefficient of determination and the root mean square error were determined to be 0.99 and less than 14% respectively, using validation data. The difference among the above numbers indicates that the planting date is effective on the amount of normalized water productivity.

Reservoirs are among the most important sources of water supply that can affect the quality of water by changing the temperature. Conditions affected by climate change could affect the thermal regime of reservoirs water. This study investigates the temperature variation of water in Aidoghmoush reservoir depths under climatic conditions in the 10-year period of climate change (2030-2039). Temperature and precipitation are extracted by the CGCM2 model (IPCC’s Third Assessment Report) under a B2 emission scenario in the 10-year period of time (1991-2000) and then they were estimated for future conditions. In the following, thermal stratification simulation is performed by the CE-QUAL-W2 qualitative model. The results show that the temperature at the water surface and the floor of the reservoir will increase in conditions of climate change relative to the baseline conditions. The water temperature will increase by an average of 1.5 oC. The findings of this study will help managers and planners to optimize water resources management.

Soil improvement with plant residues incorporation influences many soil properties. This study was conducted to investigate the effect of apricot and winter olive leaves (0, 1 and 3 g residue 100g-1 soil) on the soil structural stability using high energy moisture curve (HEMC) method in different soil salinity levels (1, 5 and 10 dS m-1). Apricot residues increased the soil organic carbon content and diluted acid carbohydrates and decreased the soil basal respiration more than the winter olive leaves. Increasing residues and salinity levels have also increased the soil organic carbon and the carbohydrates concentration in the soil. Also, the soil basal respiration has been reduced by increasing salinity. There were no significant differences between the apricot and winter olive residues in terms of their effectiveness on the soil drainable porosity (VDP), the soil suction in inflection point (τd) and the stability index (SI) in slow wetting method. However, the apricot leaves increased the soil drainable porosity and the stability index more than the winter olive in fast wetting method. This finding shows the different response and the structural instability of the soil for the two proposed organic matters. Plant residues increment by improving soil carbon and carbohydrates concentration, and salinity increment by improving divalent cation concentration have enhanced the soil stability ratio and the soil VDP ratio in both; fast and slow wetting methods. The results of this study showed that the application of native crop residues in the soils with low organic matter could improve the soil physical characteristics and these changes probably recover the soil physical fertility in the long term application.

Freezing Level Height (FLH), Permafrost Edge Altitude (PEA), Equilibrium Line Altitude (ELA) and Snow-Cover Percentage (SC) are considered as important components of assessing and investigating the status of water resources. Environmental Lapse-Rate (ELR) was used to calculate these parameters. Regarding to the problem of using Land-Based climatological stations data, gridded radiosonde data were used as a replacement. This database has a higher and proper spatial and temporal resolution. In the first stage, raw data were processed in the Python programming environment, and then the ELR ratios on the lower part of troposphere were estimated up to 6000m in order to be used in FLH calculation during 2008 to 2016 time period, FLH and ELR were together used to calculate PEA at Sabalan mountainous area. The results are presented in the form of diagrams, maps and tables. Snow-Cover status at the Sabalan heights was obtained from Terra and Aqua Modis images, during the same period and they were analyzed and presented on the basis of monthly, seasonaly and annually time interval. The SC levels and the FLH altitudes were analyzed and compared. The FLH position, and hypsometrical distribution interactions, can be used for investigation of water resources future, and the establishment of appropriate water management scenarios. The comparison of SC percentage and the FLH level pointed out more differences during warm-months and the less during cold and wet months of the year. Winterly FLH level of Sabalan mountain lies at the elevation classes of 1200-1700, 1700-2200 and 2200-2700m which shows a normal, semi-critical and critical state of water resources respectively that could affect water resources management policies.

Soil quality as "the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation. Soil quality cannot be directly measured, but it can be inference from the integration of soil physical, chemical and biological properties. This study was conducted to compare the effects of conservative, reduced, and conventional tillage on soil quality indices. Tillage treatments were no tillage, disc plow tillage, combination tillage, and conventional tillage, which have been performed for five years. The results showed that no tillage, disc plow tillage and combination tillage improved the integrated quality index of the soil (IQI) respectively as 32.79%, 21.78% and 16.82%, for the depth of 0-10 cm, 18.94%, 15.74%, 14.76% for the depth of 10-20 cm, and 17.32%, 11.62%, 16.82% for the depth of 20-30 cm as compared to conventional tillage. Also, nemero quality index (NQI) of the soil was improved in all conservation treatments as compared to conventional tillage. Also, it was revealed that the soil quality decreased as the soil depth increases. Regarding to the research findings, the no tillage system, due to improvement of the soil quality, is recommended as a beneficial practice for farmers to manage the soil in the proposed and similar areas.

If the soil does not have natural drainage for removal of excess of water, irrigation would lead to waterlogging and stopping the growth or even damaging the crop root. Controlling water table level is one of the subsurface drainage goals to proper ventilize the plants root zone. High construction cost and negative environmental impacts, resulting from the effluent disposal are the main problems of drainage projects. Since, reducing the environmental affects leads to increasing construction cost, the aim of this study was to developed a model for determination of drainage design parameters, including diameter, depth and drainage distance, in a way that construction costs and environmental affects would be minimized. In this study, the multi-objective optimization algorithm AMOSA, a simulated annealing (SA) algorithm, has been used. Since the multi-objective optimization models output is consisted of several optimal points, conflict resolution models such as Kalai-Smorodinsky, Area Monotonic and Nash were employed to select a final competent result among the optimal points. The proposed model was run for the Salman Farsi agro-industry data, one of the Sugarcane Development Company projects. Results showed that the optimal depths were between 1.2m to 1.8m. The final favorable results were 1.25-1.65m for installation depth, 0.1m for pipe diameter and 30-50m for pipe spacing depending on the taken conflict resolution method.

Recently, the Geomorphologic Instantaneous Unit Hydrograph (GIUH) model has been widely employed for estimation of watershed response to rainfall. This model is based on the convolution integral of the effective rainfall by the ordinates of IUH product. In this study, the effective rainfall has been estimated using morphometric characteristics of Kashkan watershed, simulation of daily rainfall-runoff by GIUH model and four modified Soil Conservation Service-Curve Number (SCS-CN) models. The effect of temporal variations of and initial abstraction ratio () have been also investigated as a function of rainfall depth (P) in the SCS-CN models. The results of the proposed integrated models (GIUH and the modified SCS-CN models) were investigated using the percentages of errors correspond to; peak flow estimation (%), arrival time to the peak flow () and the runoff volume (%) for three periods of drought, normal, and wet for the fixed- and varied-parameter conditions. The results showed that the variations of CN and λ parameters proportion to the rainfall depth in SCS-CN model are more effective than the fixed-parametes of the SCS-CN model, . Additionally, the odified forms of SCS-CN models are more efficient that original form (i.e. keeping constant of equal to 0.2). The results of this study indicates the necessity of employing the modified forms of SCS-CN model and considering the temporal variations of CN and λ parameters for calculation of effective rainfall as an input parameter of rainfall-runoff models, especially in watersheds undergoing human impacts.

In this study, by introducing a novel approach and developing the required programs and codes, the standard FAOPenman-Monteith method is applied on the output of WRF (Weather Research and Forecasting) model, and the daily potential evapotranspiration has been calculated for a month of the study period, from 23th June to 23th July of the year 2017. The calculated values have been validated by the measured station data. The results showed that despite of the underestimation of the model outputs for the reference evapotranspiration, WRF model generally had a good performance with rational outputs on the locations of the stations as well as the whole simulation domain. Hence, model WRF could be considered as a precious tool in operational forecasting for agro-meteorological needs. Errors are expected due to various reasons; such as stationary land surface data which are not updated and the effect of spatial resolution in atmospheric simulations of the model. The results of this research could manage the agricultural water consumption by predicting the future values of daily potential evapotranspiration which is important in estimation of crop water requirement.

Determination of water productivity gap is very important for planning and accomplishing water productivity improvement and strategies. This study has been carried out in Qazvin province based on GYGA protocols, which is an international methodology in yield gap analysis. Water and crop data gathering, climate and soil classification with GIS and crop modeling with Aqua Crop model version 5 were used for this purpose. Yield gap of wheat, barley and maize were determined to be 5.4, 5.5 and 6.7 ton/ha, respectively. Also, water productivity gap of wheat, barley and maize was 0.82, 0.47 and 1.22 kg/m3, respectively. The Yield gap and water productivity gap were varied in different climate zones and water productivity was varied in different years. The mean relative water productivity index (the ratio of current to potential water productivity) for wheat, barley and maize were estimated 0.38, 0.54 and 0.39%, respectively. From this viewpoint, barely crop has had better status among the proposed crops. The high water productivity gaps between the current and potential water productivity show that there are considerable weak points in agricultural production and irrigation management. In addition, there are high opportunities for enhancing water productivity and food security and decreasing pressure on water resources.

Optimal management of water, as one of the main factors of production has an important role in the supply of essential nutrients, increasing yield and reducing leaching. Nowadays, application of magnetic water in many fields including agriculture has been payed attention by many researchers. In order to investigate the effect of magnetic water on plant nutrient uptake, this research was conducted in the controlled environmental conditions in greenhouse of Tarbiat Modares University. Magnetic water was produced using a magnetic device with a magnetic field intensity of 8 to 10 mT. The objective of this study was to investigate the effect of magnetic water on the essential nutrient uptake by bean (Phaseolus vulgaris) in saline conditions. The experimental design was two factors factorial (2x3) arranged in a completely randomized design. The combinations of the treatments were two levels of water; non-magnetic (Normal) and magnetic and three levels of salinity; 800, 1300 and 2100 ppm NaCl, with three replicates. The results showed that with increasing salinity, macronutrient uptake and protein percentage reduced, while micronutrient and sodium uptake increased. Moreover, comparisons of treatments means showed that the magnetic water increased all the nutrients uptake and protein percentage in the leaves and seeds, but no significant changes were observed in the roots and shoots of bean plants. Despite these findings, more researches are needed to be done in the field to prove the obvious beneficial effects of magnetic water.

Considering the casualties and economic damage of flood, the study and analysis of this phenomenon is of great importance. Many studies demonstrated the effect of climate signals on the intensity, duration and timing of meteorological variables. In this paper the effects of positive phase (El Niño) of the South fluctuations of Pacific Ocean on the occurrence of floods in the Gorgan-Rood Gharesu basin (as a Wet and Mediterranean Climate) and also Tashk Bakhtegan Maharloo (as a Dry and Semiarid Climate) are investigated, using the Oceanic Niño (ONI) index. For this purpose, the “extreme value distributions of the Gumbel” and the “Time Variation Analysis” in two phases “neutral” and “the occurrence of El Niño” were employed. Results of Gumbel distribution and Maximum instantaneous discharge showed that there are influences of El Niño with 23 and 8 events in the Gorganrud-Gharesu basin and the Tashk-Bakhtegan-Maharlo basin, respectively. The results also showed that the effect of El Niño on time variation in the Gorganrud-Gharesu basin is greater than of Tashk-Bakhtegan-Maharlo basin. Moreover, the ONI positive phase in the maximum instantaneous flood of the Gorganrud-Gharesu basin is more effective than the Tashk-Bakhtegan-Maharlo Basin.

The limitations of water resources and recent droughts have dictated to use modern crop production systems for reducing water application and increasing water productivity. This research was carried out in the integrated greenhouse of agricultural faculty of Shahid Chamran University of Ahvaz in 2016. This study has investigated the effects of regulated deficit irrigation (RDI) and partial root zone drying (PRD) on tomato under hydroponic culture conditions. This experiment was conducted in a completely randomized design with four replicates and five treatments, consisted of RDI at 85 and 70% of plant water requirement, PRD irrigation at 85 and 70% of the plant water requirement, and control. The results showed that the different methods and levels of deficit irrigation did not have a significant effect on calcium, magnesium, sodium, potassium, pH, TSS, organic matter and fruit diameter, while they have significant effect on the number of fruits, fruit weight, fruit height, and water productivity. The highest fruit weights per plant and water productivity were observed in PRD85 treatment and the least fruit weight per plant and water productivity were observed in PRD70 treatment. Also, deficit irrigation through PRD85 was selected as the best treatment for hydroponic cultivation of tomato.