Iranian Water Research Journal

Abstract In many irrigated areas, shallow water table causes water logging and salinity of the soils, thus usually subsurface drainage systems are used to control this situation. In most cases, subsurface drainage systems discharge a large amount of water and salt to the environment, hence drainage water management is necessary to prevent this situation. Drainage is an action that ensures the sustainable use of land, in addition to increasing the performance. The traditional view in the drainage systems’ design, has known the drainage aim, unique to increase the yield and improve the grown environment and does not examined the environmental impacts of drainage projects. Today, this attitude has lost its position in the new approaches, in addition to agricultural and industrial purposes, environmental goals of the drainage projects are also examined. In this study the quantity and quality of output drained water from the drainpipes as compared to the time were simulated using the method system dynamics analysis, and were compared to in vitro model data. The effect of changing the depth of drainage pipes, distances between drainage on the drained water volume, and the amount of output salt were investigated. For the experiments in this study, the physical laboratory model of Water Resources, in the Faculty of Agriculture, University of Tabriz was used. Physical model is a rectangle cube-shaped container, metal-glass, with 2 m length, 1 m width and 0.5 m height. In order to determine the position of water table in the soil, 20 piezometers were put at the bottom of the model. Four reticulated metal pipes with a diameter of 2 cm were embedded as drainage pipes in the model. Tests were performed with depths of 0.4, 0.3 and 0.2 m from the soil surface, and three distances of 1.4, 1 and 0.6 m between the drains. In the upper part of the model, a sprinkler irrigation system consisted of four lateral and eight water sprayers, were placed at the height of 0.6 m above the soil surface: they were used to produce precipitation and irrigation practices. In this research, the VENSIM programming software, which is one of the most appropriate programs for dynamic evaluation of systems was used for modeling. This software shows the performance of the system during the simulation, with repeated solving of various equations in the system, by limited different methods. In order to evaluate the performance of the systems, various tests on water table level, drainage water quantity, salinity of drained water and groundwater salinity were done. The water table level increases through time and remains constant at a steady state. The output discharge from drains also increases during time and reaches to a steady state by fixing the water table and reducing its fluctuations. The salinity of drained and  groundwater decreased during the experiment and approached to the amount of irrigation water salinity (0.45 dS/m), due to the mixing of irrigation water with low salinity groundwater with the higher salinity. The salinity of output drainage also decreases causing reduction of the groundwater salinity. Drainage volume, and the amount of drainage water EC, were measured in order to investigate the effect of changing the depth and distance between drainage pipes on the quality and quantity of the drainage water in each establishment. By increasing the depth and distance between drainage tubes, the length and depth of the water lines, towards drain pipes, increases and the share of groundwater participating in the output drainage increases, which leads to the increase of output’s salinity. This increase in depth and distance, also increases the soil storage volume in the drainage pipes, and increases the discharge of drainage water. The simulation data were compared with the measured values and correlation coefficients for output discharge, salinity of drainage water, water table level and groundwater salinity in trial mode (drain spacing: 1.4 m, depth: 0.4 m), which were 0.75, 0.92, 0.98 and 0.97, respectively. In addition, the values of the RMSE statistical indicator for these parameters were obtained as 0.1875 mm/min, 0.1684 dS/m, 0.0081 m and 0.0825 dS/m, respectively, indicating that the simulation results have the higher accuracy. The evaluation of quantity and quality of drains’ discharge cumulatively shows that the increase in drains’ depth and spacing causes the increase of the volume of drainage water and salt.  

Abstract The use of wastewater for irrigation has become more important due to water shrotage. The wastewater contains nutrients that, if properly managed, increase soil nutrients. Due to the low efficiency of fertilizer consumption, nitrogen fertilizers result in environmental problems such as groundwater pollution and surface contamination with nitrate and ammonium. Nitrogen loss, especially in irrigated lands and sandy soils, significantly leads to an increase in nitrate concentration in surface- and ground-waters. On the other hand, nitrogen is the most important nutrient for wheat, and its optimum consumption management is of utmost important for success in increasing grain and wheat protein production. The increasing demands for environmental protection and sustainable food production causes an increase in the use of natural and non-toxic materials in agriculture. Therefore, the use of soil amendments such as zeolite becomes important. Zeolites are natural, non-toxic and inexpensive materials which due to their unique physical and chemical properties, including specific surface area and high cation exchange, are considered as suitable soil modifier or carrier for plant foods. The aims of this study were to investigate the influence of size (mm and μm) and usage (20 and 60 grams per kilogram of soil) of natural zeolite of clinoptilolite (Cp) and surfactant-modified zeolite (SMZ) on the soil’s nitrate and ammonium leaching, and on wheat plant performance using soil columns and applying wastewater for irrigation at Greenhouse of Isfahan University of Technology in 2015-2016. The experimental soils were placed in Polyethylene columns with 11 cm inner diameter and 65 cm height. The experiment was factorial with completely randomized design with three replications for each treatment. The treatments under study from factorial were: two types of soil modifier (natural zeolite and surfactant-modified zeolite), soil modifier with two particle sizes (1 to 1.68 mm and 53 to 63 microns), and two modifier consumption levels (20 and 68 g/kg soil). This study evaluates the grain yield, dry weight, root dry weight, root volume, leaf area index, stem height, stem diameter, stem and leaf nitrogen, grain nitrogen, nitrogen harvested by the plant and nitrogen leaching. According to the results obtained from the current study, the use of Cp and SMZ modifiers had a significant effect on wheat growth, so that the amount of dry matter of the plant, grain yield, root dry weight, root volume, grain nitrogen and nitrogen harvested by the plants in Cp were significantly (P <0.05) higher in comparison with the SMZ treatments (at the level of 1%), so that the grain yield (2.3 and 0.8%) and dry weight (10.84 and 9.8%), root dry weight (6.61 and 5.37%) and root volume (5.68% and 4.8%), increased in Cp and SMZ treatments, respectively. Also, the concentration of the grain nitrogen and nitrogen harvested by the plant in Cp receptor columns were significantly (1.45 and 2.49%, respectively) higher than SMZ receptor columns. These results could be due to the difference in absorption and desorption of the NH₄⁺ and NO3-N of Cp and SMZ during the study period, respectively. Absorption and desorption of NH₄⁺ in Cp are due to the cation exchange and diffusion, while absorption and desorption of NO₃-N in SMZ are because of surface anion exchange. This means that SMZ would probably act slightly weaker than Cp in the timely release of nitrogen needed for the plant growth. However, Cp and SMZ modifiers did not affect the leaf area index, plant height, stem diameter, and stem nitrogen, leaf nitrogen and nitrogen leaching significantly. However, higher modifier application significantly (at 1% level) created better growth conditions for wheat plant than less modifer application, ie, application of Cp and SMZ at 60 g/kg soil was effective on nitrate leaching and growth of the wheat plant. This means that the use of Cp and SMZ as soil modifier significantly reduces the nitrate leaching and, consequently, increases the amount of nitrogen in the first layer of the soil. As a result, with increasing providing nitrogen in the root environment, pollution not only does not decrease, but the yield of the product increases and it helps to improve the growth of the plant. The size of the modifier particles has a significant effect on the nitrate leaching, but was not effective on the  growth of wheat plant. The use of modifiers at the level of 20 g/kg soil was not effective in reducing nitrate leaching and wheat growth. In general, according to the results, the Cp and SMZ modifiers as environmentally friendly materials, are effective in controlling soil nitrogen leaching and improving nitrogen removal efficiency by the plant.

Abstract The study of moisture patterns characteristics under a single dropper is necessary for the design, management, and implementation of drip irrigation systems. The proper design of these systems should be a desirable combination of dropper discharge, soil characteristics, application time, and type of used water that affect the water dynamics in the soil under surface dropper. However, less attention has been paid to the effect of water type, especially magnetic water, on the dynamics of water in the soil. Magnetic fields, while changing the physical and chemical properties of water, lead to changes in the characteristics of water movement in the porous medium. The purpose of this study was a laboratory investigation of the combined and separate effects of magnetism and organic matter on the distribution of moisture in layered soils. The experiments were carried out in two laboratories of Urmia University, Iran. A 50*50*50 cm box of transparent plexiglass was applied to observe the movement of the moisture front in the soil. Also, the experimental model of the present study included water resource, plastic pipe, magnets set for applying a magnetic field to water and a dropper with the constant discharge rate of 4 liters per hour. In this study, four permanent pairs of magnets were applied with two specific magnets (three couples of magnets with 0.2 T, and a couple of magnet of 0.3 T magnitudes). The porous media treatments of this research included two samples of sandy loam soil (74% sand, 11% clay and 15% silt) and clayey soil (15.5% sand, 52.5% clay and 32% silt) and hydroponics porous media (peat moss organic matter). Soil and hydroponic treatments were prepared in the form of a homogeneous mixture of soil (80%) with organic matter (20%). Also, the total thickness of the soil layer was considered 35 cm (25 cm for the width of the coarse-textured layer (SL) and 10 cm for the fine-textured layer (C)).The top of the box with 15 cm was kept empty. For this purpose, the effect of plain and magnetic water on the moisture movement was evaluated in the form of eight treatments: coarse-textured, fine-textured, coarse-textured mixed with peat moss, fine-textured mixed with peat moss. Finally, the chemical properties of drainage water extracted from soil samples and samples of soil mixed with peat moss were measured by pH (pH meter) and electrical conductivity meter (EC meter). The results of this study “referral to results and discussions after re-verification at international, national level is permitted” showed that due to the application of magnetism on irrigation water, the electrical conductivity of drainage water was decreased in all treatments, with the greatest decrease to 0.875 mmho/cm in the fine-textured soil, except the fine-textured soil mixed with peat moss. Also, pH of drainage water was increased in all four soil treatments, with the greatest increase in the fine-textured soil to 7.6. Furthermore, investigation about moisture dynamics showed that the significant effect of magnetic water application on certain treatments and the patterns of moisture distribution with their progressive radii were tangible. Also, based on the infiltration depth factor, the most general variability of magnetic water treatment was observed in T1 (increment), T7 (decrease), T3 (decrease) and T5 (increment) treatments. Contrariwise, the strongest influence of forwarding width was obtained in T7 (increment), T1 (decrease), T5 (increment) and T3 (increment) treatments. Besides, the analysis of forwarding curves-soil moisture distribution showed that due to the application of magnetic water the horizontal progression radius increased; for example, the maximum extend in the horizontal direction was reaching to 38.9 cm by 19.81% increase. Also, T7 (the fine-textured soil on the coarse-textured soil with magnetic water) can be described as a treatment that has the most beneficial result of magnetic water in the present study. As a result, even without using organic matter treatment and application of its fertilizers, it is possible to use the existing condition of agricultural soils with desired results, which have the same status as the present treatment and even the same treatments. In general, the results of this study were indicated that the magnetism was effective on the chemical properties of soil water and especially the dynamic characteristics of water in the soil, including the pattern of moisture distribution and forward velocity.

Abstract To cope with the current water resources issues in Iran which are going to pose a real threat on a national scale, taking into consideration of all determining factors causing these formidable water resources challenges is of paramount importance. Computer modelling has been increasingly developed over the last few decades for water resources management and planning. In the present study, climate variables included precipitation, relative humidity and temperature were predicted for the period of 2020-2049, using SDSM model. Then, impacts of climate change on hydrological conditions were evaluated via Soil and Water Assessment Tool (SWAT) in the Talvar river watershed located in the Kurdistan province, Iran. The Talvar river watershed with an area of 2490 km² is situated in longitudes of 47° 06' 09" E to 47° 45' 58" E and latitudes of 35° 03' 26" N to 35° 35' 26" N, located in Kurdistan province. Land use in this basin is mostly cropland and pasture. Cropland has accounted as approximately 85% of the total area, among which paddy fields and dry land farming account for 10% and 75%, respectively. Pasture cover has appraised as 14% of the study area. All other land use types (rural area, urban area, water) have made only 1% of the total study area. Mean elevation of the watershed is 1927 m above mean sea level. The SWAT model requires input on topography, soils, land use and meteorological data. Therefore, recently available GIS maps for the model inputs of the study area were used. The Talvar river watershed was discretized into 50 sub-basins and also, based on the land use, slope and soil classes the watershed was subdivided into 1151 HRUs. The climatic data were derived from 7 meteorological stations located in and out of the basin under study. Climatic data refer to daily precipitation, maximum and minimum temperature, relative humidity data. The calibration of the SWAT model was done manually based on physical catchment understanding and sensitive parameters and calibration techniques from the SWAT user manual. Sensitivity analysis has been performed using OAT (One Factor at a Time) method to evaluate and demonstrate the influences of the model parameters on water budget components included surface runoff, lateral flow, groundwater and evapotranspiration. Data from Qorveh synoptic station (1990-1999) were used for calibration of SDSM model. Climate variable include precipitation, relative humidity and temperature were predicted for the period of 2020-2049 using SDSM model. Simulated values due to considered scenarios (RCP26, RCP45 and RCP85) were compared with baseline period (1990-2005). The performance of the SWAT model was evaluated via coefficient of determination (R²) and Nash–Sutcliffe efficiency (E_NS), also the performance of the SDSM model was evaluated via coefficient of determination (R²), Nash–Sutcliffe efficiency (E_NS), Mean Absolute Error (MAE) and Percent Bias (PBIAS). Based on the results of sensitivity analysis, the parameters of initial SCS runoff curve number for moisture condition, the parameters that hadthe greatest influence on water budget components (including surface runoff, lateral flow, groundwater and evapotranspiration) can be listed as :.Π (CN2), soil available water capacity (SOL_AWC), soil bulk density (SOL_BD), saturated hydraulic conductivity (SOL_K), maximum canopy storage (CANMX), soil evaporation compensation factor (ESCO), minimum melt rate for snow during the year (SMFMN), maximum melt rate for snow during the year (SMFMX), snowfall temperature (SFTMP) and snow melt base temperature (SMTMP) According to the results, a satisfactory agreement was observed between monthly simulated and measurement discharge (R² and E_NS were 0.65 and 0.44 for calibration and 0.77 and 0.59 for validation periods). The results of the SDSM model showed that the monthly mean of minimum and maximum temperatures would increase compared to the baseline period except for the months of September, October, November and December. Also monthly average of precipitation would decrease in winter and spring seasons but it would increase in the summer and autumn seasons. The results of runoff simulation showed that monthly average of runoff would increase in the months of January, February and December, compared with the baseline period. The weakness of the model to simulate flow for some months was probably due to poor characterization of snowmelt processes in the basin under study. Also, the model overestimats surface water in the beginig of summer, due to its defaults for transfer in layers.

Abstract Many factors affect runoff and erosion. However, rainfall and soil characteristics are the two main factors affecting runoff and soil erosion. Among the rainfall characteristics, intensity and duration of precipitation are the two dominant factors that control the hydrological responses. Changes in rainfall intensity have major effects on soil erosion. In this study, the rainfall intensity of 30 minutes(I30) was considered as a rain erodible index based on the kinetic energy of rainfall intensity, which is a well-known indicator in different parts of Iran. Soil Water Repellency (SWR) is a soil feature that affects the hydraulics and hydrologic features of soils. When soil particles are coated with hydrophobic materials, water penetration is severely delayed, which reduces soil moisture capability. Studies have shown that under conditions of soil hydrophobicity, infiltration and runoff production time will be shorter. In the case of high rainfall, the effect of SWR will also be intensified. According to the studies, it cannot be concluded that there is less or more sediment in hydrophobic soils. Iran is located in arid and semi-arid climates and studying the hydrological phenomena in this climate is important. Therefore, the aim of this study was to simulate the effect of different probabilities of precipitation intensity on the volume and coefficient of runoff and sedimentation directly using physical model and also effect. These probabilities on hydrophilic agricultural soils and different degrees of hydrophobic soils are essential both in research and practical projects. To create the homogeneous hydrophobic conditions in the soil with definite physical specifications, the soil is made hydrophobic artificially by the use of stearic acid. The texture of the tested soil was sandy loam. The soil hydrophobicity is categorized in 5 degrees (hydrophilic as the control sample, slight repellency, strong repellency, severe repellency, and extreme repellency). The amount of the required stearic acid estimated for different hydrophobic levels was determined by WPDT empirical test, together with trial and error considerations. Using a physical model, the amount of sediment and runoff was simulated in five soil treatments under five rainfall intensities with a occurrence probability of 0 (probability of occurrence), ± 10% and ± 20% relative to the 30-minute rainfall with a return period of 1000 year of Shahr-e-Kord rain gauge station (base rainfall intensity: 1.41 mm/min). The physical model of a special equipment is named “Advanced Hydrological Investigations”. The driving force of the equipment includes an electric pump with the power of 0.55 KW. There are eight nozzles that provide sprinkler irrigation with square spraying pattern. The spraying flow was adjusted up to maximum of 1500 L/h, by a rotameter underneath the equipment. The required water for spraying was stored in a 220-Litre tank. The equipment was consisted of a soil tray with 2 m length, 1.2 m width, and 20 cm depth. Due to the 20-cm depth of the tray, the upper 5 cm was considered as the free board space. Five cm at the bottom of the tray was filled by sand in order to facilitate and accelerate the water drainage. A galvanized mesh was placed on the sand. The upper 5 cm of the 10 cm soil was considered as the surface soil. The runoff was volumetrically measured and sampled continuously for sediment concentration. The sediment concentration was determined as the ratio of the dry sediment mass to the sampled runoff volume. In the control treatment, the rainfall duration depends only on the rainfall intensity, and the maximum and minimum rainfall times were 53 (related to the lowest rainfall level, -20% probability of the base rainfall) and 47 minutes (related to the highest rainfall level, +20% probability of the base rainfall), respectively. In the hydrophilic soil treatments in addition to rainfall intensity, the soil hydrophobicity degree also affects the rainfall time. Since the water absorption is negligible, the rainfall duration is shorter than the control sample. The higher the water hydrophobicity was, the less the rainfall duration became. The less the hydrophobicity degree was, the less runoff was generated. In hydrophobic treatment, due to the water repellency, the runoff occurs rapidly. The highest observed runoff was 7000 cc in severe repellency treatment and the rainfall with +20% probability, means 120 L/h. However, the minimum volume of runoff observed in the control sample in probability level of -20%, was 720 cc. On the other hand, with the higher hydrophobicity level, the higher runoff coefficient was observed. Runoff coefficient has been observed in hydrophilic and hydrophobic soil treatments from 0.000 to 0.0011, and 0.05 to 0.94, respectively. Severe and extreme hydrophobic treatments worked quite imperviously. The rate of sedimentation exited along with runoff was decreased by increasing the hydrophobic level. The highest observed sedimentation was 12 gr in the hydrophilic treatment and the rainfall with +20% probability. However, the minimum volume of sedimentation was 2 gr which was observed in the extreme soil repellency treatment with probability level of -20%. The observed deep percolation in the control treatment (hydrophilic soil) was 17.5 to 23.8 L. The deep percolation amount was observed only in low and moderate hydrophilic levels (380 to 950 cm³). No significant deep percolation was observed in severe and extreme severe hydrophobic treatments.

Abstract In this study, two optimization models for cross-sectional design of trapezoidal open channel have been investigated. In one of the optimization models, the lined free board was not considered while it was regarded in the other.. In fact in this study, for the first time in the field of the optimization of open channels, the lined free board was considered as a design variable in addition to the total free board. In the two optimization models mentioned above, the first objective function was determined as a cost. The discharge, Manning's roughness coefficient and the longitudinal bed slope of the channel were random variables, because in real situations, the actual flow may exceed the design flow due to probable fault in the control of flow at the off take point, and the uncertain lateral inflow. The actual Manning roughness values may exceed the assumed design values according to imperfections in fabrication. The physical bed slope which was achieved may differ from the design values because of fabrication faults. These variations can cause the occasional flooding of man-made open channels. To maintain provisions for these possible variations within the designed cross-sectional dimensions, a flooding probability constraint must be incorporated in the optimal design model. The Manning flow equation is also considered as a constraint. Overall in the two models of optimization, the first objective was to minimize the cost of excavation and the lining channel cost and the second objective was to minimize the probability of overflow from the cross section. These models  were solved with Wolfram Mathematica software. Due to the probability of the second objective function, the model is classified into random optimization models and this is a two-objective optimization problem. To obtain the answers of the two-objective optimization problem, the multi-objective constrained programming method was used, which converts the vector optimization into a numerical one. This conversion from vector to numerical formulas was accomplished with regard to the first objective was to minimize the total cost of the channel (as the single objective in this problem) and the second objective which was sought to minimize the overflow (as an additional constraint). In this study, the flooding probability constraint was developed by using the first order analysis that essentially uses the calculus based differentiation of the Manning uniform flow. The numerical and deterministic forms of the previous modeling were solved with Wolfram Mathematica software for a numerical example. The results of solving models with the Wolfram Mathematica software for a numerical example showed that in both optimization models (with and without lined free board), for the probability of overflow, the total cost was greater and with increasing probability of overflow from 0.225 to 0.3, the total cost, the bottom width of the channel, the total free board and the lined free board were decreased; While,, the depth of flow in the channel and side slope was increased. But in general, the total cost for the construction of a channel in a model with a lined free board is lowered in compare with that in which the lined free board was not considered. In other words, considering the lined free board in the open channel, the optimal section has been created at a lower total cost. These results are presented in the form of tables and probability overflow–cost diagrams. According to the results of this study, the cost of channel construction had increase for both models with decreasing the possibility of overflow. Also, for low values of overflow, it is necessary to increase the total free board (and lined) and make the channel wider. Comparison of the free board model with the model that did not include the free board showed that considering the lined free board or somehow the unlined part reduced the total cost.  Besides, in general, the best choice among all the optimized responses obtained with different overflow probabilities in each model is up to the design engineer, who can determine the budget, importance, and usability of the channel and many other factors. Consequently, It is suggested that land acquisition and water loss costs (evaporation, transpiration) included in the objective function to develop the current design in future research; it is also possible to compare the results with current design standards.

Abstract Water deficit is known as the most important limiting factor in agricultural products, especially in arid and semi-arid regions. Agriculture has been negatively influenced by low obtainable water and because of climate change, making water stress conditions for economic crucial plants. As Iran's major region consists of the arid and semi-arid areas with limited water resources, the minimum of plants water-need may not be maintained; so, the plants would experience drought stress and the products would suffer irreparable losses. One of the approaches for optimal use and preservation of the water resources is applying of superabsorbent polymers which not only provide conditions for improved products quality, but also result in increase of water consumption efficiency, in the arid and semi-arid areas. Superabsorbent polymers can absorb and retain water up to several times of their weight. Due to the drying up of the environment, the water retained in the superabsorbent gradually discharges; and thus the soil remains moist for a long time, without needing further irrigation. This property is of the great importance to confront water shortage and reduce the negative effects of drought stress in plantations. Superabsorbent polymers cause water retention in soil and reduce the number of irrigation frequency up to 50%. In this study, the effect of water stress and different levels of superabsorbent on cucumber crop (variety of super dominus hybrid) was evaluated in a farm with sandy soil, in Seymareh region, Ilam Province, Iran. This experimental farm was located at 33° 09′ N and 47° 24′ E, with elevation of 982 m. Seymareh region has Mediterranean summer and winter. The average annual precipitation is about 350 mm and the average temperature is about -2° C in the winter and about 45° Celsius degrees in the summer. The hydrophilic polymer used in this study was Super-AB-A-300. This polymer is a granular type and a terpolymer of acrylamide, acrylic acid, and acrylate potassium. The experimental design was according to a split-plot method in a randomized complete block that was done with 12 treatments and 3 replications. In this study, 3 different depths of irrigation were considered as the main treatment including: I₁, I₂, I₃ for 100, 80, and 60 percent of water requirement of plant, respectively. Different levels of superabsorbent were used as secondary treatment including: S₀, S₁, S₂ and S₃, due to 0 (control), 15, 30, and 45 g m^-2, respectively. The size of each plot was 4×1.2 m², including 6 lines. The Superabsorbent for each line in each plot was distributed in the depth of 30 cm from the soil surface. The cucumber variety of this plan was planted manually in April (as spring planting) and August (as summer planting). The space between planting rows was 20 cm, and between each plant in each line was 40 cm; so, the total density of planting was 60 plants per each plot. Three grains were planted at each point which after germination, they were thinned out to one plant. The deficit irrigation treatment was applied from the 3 to 4-leaf stage (after the complete establishment of the seedling). For planning and determining the irrigation interval, by adopting the no water stress treatment as the criterion, the soil moisture index and the soil matric potential were incorporated. The percentage of soil moisture content was measured through sampling to the depth of plant root in the days before irrigation. When the weighted mean of the volumetric soil moisture reached the allowable depletion for the cucumber plant, the next irrigation was performed. Therefore, the irrigation interval was determined concerning the treatment with no water stress (control); simultaneously, all the treatment plans with equal irrigation intervals and with different water depths were irrigated. According to the results, the independent effect of irrigation and superabsorbent treatments at 1 percent level on cucumber crop yield was significant. The maximum and the minimum of cucumber fruit weight and crop yields were 72.86 and 56.90 g, and 3.7 and 1.97 kg m^-2 related to the complete irrigation (I₁) and severe drought stress (I₃), respectively. Results revealed that in the drought conditions, superabsorbent application increased cucumber fruit weight and crop yield, compared with control treatment. Also, the independent effect of irrigation and superabsorbent treatments at 1 percent level on water use efficiency of cucumber crop was significant. The maximum and the minimum of water use efficiency were 8.11 and 6.15 kg m^-3 related to the complete irrigation (I₁) and severe drought stress (I₃), respectively. In addition, a quadratic function was introduced as the optimum water-yield production function of cucumber crop (variety of super dominus hybrid) in the presence of superabsorbent in sandy soil. Finally according to the results, superabsorbent could prevent the significant reduction of cucumber crop yield in sandy soil and under drought stress conditions.

Abstract Due to the declining of the water resources in the alluvial aquifers, karst resources are used as the main sources of domestic water in the entire world, spatially in the arid and semiarid regions. Existence of large carbonate formations in many parts of Iran and the withdrawal from these sources for drinking and agriculture purposes by springs and wells are the indication of the significant importance of these resources. Proper management of these aquifers requires an understanding of the current situation and its variations in different conditions. Hydrogeological (quantitative) and hydrogeochemical-isotope (qualitative) researches of groundwater are essential as practical and scientific solutions for management actions. Precipitation is an important source of groundwater supply in karst and alluvial aquifers. Therefore, temporal and spatial evaluation of the isotopic behavior of precipitation is important. Because isotopic characteristics of water slightly change along paths and keep its origin characteristics, it can be useful in identification probable flow paths and different sources. In the northeast of Iran, The karstic aquifers are important sources for drinking and agricultural purposes. The first step to better management of these aquifers is to determine the water origin and catchment area, as well as the hydrogeochemical processes that govern them. The studied aquifer located in Northern Khorasan province, which has a wide outcrop of Tirgan limestone. This large and borderline aquifer, despite its high recharging, discharge by small number of karstic springs (Arnave, Rezghane, Asiazoo, Ghordanlou, Ayoub and Sarani) with a discharge between 15 and 500 L/s. Springs and precipitation water samples were collected for a one-year period and the main ions and stable isotopes (δ¹⁸O and δD) were analyzed to determine the meteoric water line, water origin and geochemical processes governing the karstic resources of the area. The EC value varies between 250 and 800 in cold water springs and about 1020 µS/cm in the Ayoub hot Spring. The isotopic samples of the study area were measured at the IAEA Laboratory in Vienna and Utrecht University, and expressed per mile (‰). In this research, the piper diagram, ions ratios, hydrochemical diagrams, physicochemical parameters and, Isotope characteristics were used for determining springs water origin in the study area. In the Arnaveh, Rezghaneh and Ayoub, increasing in the sodium and potassium concentrations can be related to existence of epikarst and shale-marl layers in the catchment area of these springs or deep regional flows and passing through shale-marl layers (Shuriyeh Formation) due to the high difference of the elevation between recharge area and springs. Increasing the concentration of sulfate in the Ayuob spring can be due to the dissolution of gypsum and anhydrite minerals or pyrite oxidation and the influence of deep regional flows also. According to the results and ionic ratios, the dominant facies in this karstic aquifer are calcium-magnesic bicarbonate facies, due to the dissolution of carbonate rocks and sulfate-calcium resulting from the dissolution of gypsum and pyrite. The discharged value has reverse relation with both EC and temperature values some springs due to the larger catchment area and the further development of Karst. In Arnaveh, Sarani, Estarkhi, Ghordanlu, electrical conductivity decrease slightly with increasing of the discharge in rainy months. In Estarkhi spring, Electrical conductivity is tangible from other springs because of more karst development and wide catchment area. The first time, the isotopic meteoric water line of the area is calculated based on the data taken as δ²H = 7 δ¹⁸O + 6.32, so that the slope and d-excess are less than GMWL due to the effect of secondary evaporation from rain during precipitation. All springs are located on the LMWL and close to the Mediterranean line, which suggests that the rainfall of the area is mainly originates from the Mediterranean air masses. The enrichment of the isotope composition of the Arnave spring is due to less evaporation during water flowing through the marl limestone and the high thickness of epikarst in its catchment basin, due to the influence of winter rainfall at elevations on Ayoub, Rezghaneh, have lower and lighter isotope values than other springs. Using data from various rainfall stations around the springs, the value of δ18O varies between 0.32 to 1.6 ‰ per 100 meters, and the elevation of the catchment area of the springs varies from 2200 to 2700 meters.

Abstract One of the most common reasons for the bridge failures is local scour around bridge piers. Finding an accurate method to predict the formation, development and final shape of the scour hole is of great importance in designing hydraulic structures. Most of previous researches have focused on finding a method to estimate the depth of local scouring. Despite the fact that the importance of scour depth is inevitable, the length and width of the holes are also of a great important. One of the reasons for its importance is the possibility of overlapping of the scour holes of two piers, which increases the scour depth, and the need to determine the extent to create a reinforce layer around the piers. Regardless of the scour hole’s dimension importance, the length and the width of the hole at a complex pier have not been investigated. In this research the effect of pile cap's shape on the scour hole dimensions was investigated using physical simulation. To provide safe design and minimize scouring problem and economic and geotechnical reasons, bridge piers on deep alluvial streambed are commonly constructed with complex geometries. A typical composite bridge pier has consisted of the column, pile cap, and pile group. After the construction of a bridge, pile cap is typically embedded in the streambed. Over time, the pile cap location in respect to the undisturbed streambed changes due to a combination of long term bed degradation, local scour, lateral shifting of the stream, and contraction scour. These issues change the pile cap role in scouring at composite piers through a flood. Since the number of effective parameter on local scour around bridge piers is considerably high, the implication of all the parameters in the estimation of scouring seems to be impossible. Therefore, the method of dimensional analysis using non-dimensional variables was implemented to evaluate how the scour hole formed. The data of the complex bridge piers in clear water conditions, extracted from the National Hydrological Research Institute of Malaysia, NAHRIM. Experiments were performed in a laboratory flume with a length of 46 m, a width of 1.52 m and a depth of 1.9 m that made of block and glass walls. The flume’s length of 15 m was filled with uniform sediment of 0.55 m thickness at a distance of 10.3 m downstream of the entrance. To conduct experiments in this research, three different models with different shapes were made from wood and PVC. In choosing models, various shapes and dimensions were sought. Three square, rectangular and chamfered shapes were selected in models 1, 2 and 3, respectively. In the next stage, the dimensions of the scour hole (depth, length, and width) were measured by a point gage in a Vernier scale with a precision of 0.1 mm. These dimensions were measured relative to the initial level of the streambed and the position of the hole in the three directions of X, Y and Z was extracted. Data analysis was performed using the Civil3D software. The 3D coordinates of the points can be imported to the software by various formats. The data was inputted into the software in PENZD format where P is number, E is value of x, N is value of y, Z is value of height and D is code or point description. In this format, the coordinates of the different points are separated, and the software distinct between the dimensions, longitudinal, transverse, or depth of the coordinates by a whitespace character. Changes in the scour dimensions of hole were investigated in the models by drawing diagrams for the models. In these diagrams, changes in the length and width of the scour hole were studied in relation to the elevation of the pile cap. In this research, the physical simulation of the scour hole dimension changes in the complex bridge pier was performed in the laboratory and effective variables were identified and their effect was investigated. Three models were tested in different shapes and at different heights of the initial bed. The results of this research can be summarized as follows. Among the entire complex pier components (pile cap, column and pile), the geometric shape of the pile cap plays an important role in the shape of the scour holes. Similar to the depth, the process of changing the length and width of the scour hole depends on the height of the cavity relative to the initial bed. The greatest length and width of the scour hole occurs at a negative height (above the top of the bed). The maximum length and width of the hole in a model with a chamfered shape pile cap occurs at the time of the pile cap undercutting, in the rectangular and square pile cape’s shape models, after the pile cap is undercut. The largest dimensions of scour hole’s length and width were respectively 11Lpc and 8.5bpc, respectively, and the depth of scour hole was equal to 9T.

Abstract Water shortage and drought are two phenomena that are unavoidable due to the high variations in soil moisture in time and place during the entire growing season. Generally, the irrigation water depth varies under different conditions of land shortage, drought and salinity stress, or a combination of these conditions. When irrigation with this depth can be maximized, net income can be maximized. In order to determine the optimum depth, various tools such as the production function of the yield, irrigation water and its derivatives, initial and current costs, yield prices and information on the water and land are needed. The turnip (Brassica rapa L.), as a strong source of nutritional supplementation, contains a variety of antioxidants such as vitamins and schucosinolates (Norin et al., 2010). Turnips are used in fresh and dried forms for human feed. Since there has been no research in the field of determining the optimal production function of water-salinity-turnip yield in the country, the aim of this study is to find the optimal function of turnip production in combination with salinity and drought so that the water consumption can be minimized by using saline water. This experiment was conducted as a factorial based on completely randomized design with three replications including two factors of salinity and irrigation water. Four levels of irrigation water salinity including two factors of salinity and irrigation water were applied, with three replications. The four levels of saline irrigation water include: S₁: 0.7 (as a control), S₂: 4, S₃: 8 and S₄: 12 ds/m and three irrigation water levels were considered as W₁: 100% of crop water requirement, W₂: 75% of W₁, and W₃: 50%W₁. The statistical data of the performance of the project implementation were fitted with the SPSS software and various forms of production functions were determined. For this purpose, the optimal production function, a statistical sensitivity analysis, was performed and then the relevant statistics determined the role of each entity in generating functions quantitatively. To evaluate the validity of the obtained functions, the analysis of the remaining errors and the differences between the measurement and prediction values were used. The statistics required for this study were the maximum error (ME), root means square error (RMSE), the coefficient of determination (R²), modelling efficiency (EF), and residual coefficient of variation (CRM). The results showed that the highest yield was obtained in control treatment (W₁S₁) and 75% W₁ (W₂S₁) treatments at the rate of 6.66 and 7.42 kg/m³, respectively. In addition, by increasing the drought and salinity stress, the water use efficiency decreased. The Ky values at the same conditions of salinity and drought stress were more than Ky in drought stress and less than Ky in salinity stress conditions. Therefore, it can be concluded that the effect of salinity stress on reducing yield is more than drought stress. Subsequently, Ks values showed that by increasing salinity and drought stress, the crop evapotranspiration was decreased. In order to adapt to the water shortage, it can use the optimal production function for the turnip yield in Kashmar. It can be stated that in drought stress conditions, evaporation and transpiration reduction is due to the water deficiency, and in salt stress conditions is due to the decreased water absorption because of decreasing osmotic potential of root zone. The results of the product curves showed that by increasing the amount of irrigation water, the water with higher salinity can be used.

Abstract Salinity is the most important factor in reducing the quality of groundwater resources, especially in arid and semi-arid regions. Due to droughts, water shortage and over-exploitation of aquifers, salinity has become a growing problem in Iran. Shahrood aquifer, is one of the aquifers that needs exact monitoring and management to control and prevent the spreading of salinity in its water resources. Groundwater in the northern part of the Shahrood aquifer is a bicarbonate type and has good quality, but in the southeast suddenly, its quality declines and eventually turns into saline water with sodium chloride type. The groundwater salinity in Shahroud plain has caused many problems for farmers, including crop reduction and land degradation. The present study is conducted to investigate and identify the origin of groundwater salinity in the southeastern part of the aquifer. In order to determine the source of groundwater salinity in Shahroud aquifer, 120 wells were sampled. The electrical conductivity (EC), pH and temperature were measured in the field. Samples were analyzed for determining the major ions and rare elements (Br and I) at the Geochemistry Lab of university of Ottawa. Also, 34 samples were analyzed for determination of ¹⁸O and ²H isotopes in GGHagh lab and 3 samples were analyzed for measurement of tritium isotope in AMS laboratory of university of Ottawa. The EC in the Shahrood aquifer ranges from 671 to 11210 microseisms per cm. The amount of this parameter is highest in the eastern and southeastern parts of the aquifer that indicates the existence of salinity sources in these parts. Despite the high salinity of samples in the eastern region and the generally flow direction of the groundwater (which is from east to the west of aquifer), western samples have a desirable quality and lower EC. In the central part of the aquifer, there are samples with different amounts of EC that are the result of mixing of the eastern and southeastern saline waters with freshwater. The suddenly changes of EC in the Shahrood aquifer represent a geochemical discontinuity that could have occurred for various reasons, including the performance of an impermeable barrier, such as a fault, presence of an impermeable layer, or a change in the flow direction. According to the geology and lithology situation of Shahrood aquifer, the most probable hypothesis for the groundwater salinity in this aquifer is the dissolution of evaporative formations whose dispersion in the eastern and southern parts of the aquifer is consistent with the high salinity areas in the aquifer. But despite the fact that there are also evaporative formations in the southwest parts of the aquifer, the salinity of samples taken from these parts, is low. Different hydrochemistry diagrams and ion ratios such as Na and Cl ratios, and relationship between Cl and I with Br, as well as the amount of saturation index of different minerals showed that the most important source of groundwater salinity in Shahrood aquifer is dissolution of evaporative minerals such as gypsiferous marl. These results were confirmed by the linear relationship between Cl and ¹⁸O. The location of fresh water samples on the Shahrood meteoric water line indicates that the source of these samples is meteoric water and present precipitation. However, saline water samples, despite the similarity in δ¹⁸O isotopic amounts, show a depletion in δ²H relative to fresh water and present precipitation. The amounts of tritium in the saline water samples of Shahrood aquifer is less than 0.8 TU and in freshwater sample is 2.8 TU. Considering the age distribution of water based on the concentration of tritium and the different results based on tritium in saline and fresh samples, at least two water resources with different ages can be identified in Shahrood aquifer. Since the fresh water has a higher tritium content than saline samples, it can be represented that the freshwater is younger than saline water in this aquifer. The southern saline water with tritium content less than 0.8 TU represents a mixture of relatively old water that fed before 1952 and newer meteoric waters. In order to determine the source of the saline water in the southeast part of the aquifer, the average isotope content of saline waters was plotted with a horizontal straight line on the SMWL. The position of the intersection point on SMWL showed that the source of saline waters is the past meteoric water, which has a lighter isotopic content than the current precipitation. Regarding the lower dexess content of saline samples, the past meteoric conditions are wetter and therefore, the depletion of old precipitation and consequently saline samples is justifiable. The movement of water in the aquifer and water-rock reactions, such as the dissolution of gypsum, cause the change in the water type and enrichment of ¹⁸O (δ¹⁸O-Shift), then the saline samples shifted to right in SMWL. Due to the difference in the age of saline and fresh waters, and the difference in the stable isotopes’ content, as well as the hydrochemical characteristics, it is necessary to study the hydrogeological factors that are effective in the occurrence of these conditions. Based on the hydrogeological map of Shahroud aquifer, in the central part, a water divide line has been created due to the concentration of productive wells and aquifer over exploitation. Due to the operation of this water divide line, a part of the input flows that flow from the northern, eastern and southeastern boundaries are diverted to the east. In other words, this dividing line decreases the flow rate of groundwater, which reduces the hydraulic connection of input flows from the east and south with the western parts of the aquifer. Reducing the flow rate of groundwater, while increasing the age of water by increasing its resident time, provides conditions for more mineral dissolution, thereby increasing the salinity and variations in the groundwater type. The gypsum dissolution, in addition to changing the type of water to sulfate water, results in water enrichment of oxygen-18 (Shift-¹⁸O) and therefore, the shift of saline samples to the right of the SMEL.

Abstract Iran is one of the arid and semi-arid countries which face with many problems in water supply. Membrane process such as reverse osmosis (RO) is one of the advanced methods of water treatment which are widely used in arid and semi-arid regions. Reverse osmosis system produces two types of waters, one purified water and the other concentrated wastewater. To reuse the concentrated wastewater in reverse osmosis, it is necessary to remove some critical elements that cause problems for the membrane. In this research ZLD processes were used for removing the critical elements of reverse osmosis wastewater of Lar city in Fars Province, Iran. The purpose of this study was to evaluate ZLD processes and determine the optimal process for recycling of reverse osmosis wastewater. In this research different scenarios were selected for reverse osmosis wastewater treatment including the processes of absorption, chemical precipitation and combination of these processes. Fluidized bed crystallization (calcium carbonate particles) was used for absorption process and sodium hydroxide, lime, sodium aluminate and aluminum sulfate were used for chemical precipitation processes. These chemicals were combined with wastewater in concentrations of 100, 200, 300, 400, 500 and 600 mg/L and some parameters including calcium, magnesium, chloride, sodium, potassium, pH, salinity, silica and turbidity were measured and optimum chemical concentration was determined. Optimal concentration was chosen based on maximum removal efficiency of harmful elements for reverse osmosis membrane. Optimum removal efficiency of sodium hydroxide, lime, sodium aluminate and aluminum sulfate, were in concentration of 500, 400, 200 and 100 mg.L^-1, respectively. To improve removal efficiency, the chemicals were combined together based on the optimal concentration of each chemical which was determined in the previous step. Therefore, aluminum sulfate with sodium hydroxide, aluminum sulfate with lime, sodium aluminate with sodium hydroxide and sodium aluminate with lime was mixed together. At this step the best removal efficiency was obtained in combination of optimal concentration of sodium aluminate and sodium hydroxide. Absorption process in fluidized bed crystallization was investigated for difference fluxes and the results showed that the optimum flux was 1.94 m³.h^{- 1}.m^-2. The maximum removal efficiency of harmful elements for reverse osmosis membrane was observed in the combination processes of chemical deposition and absorption which occurred in fluidized bed crystallization with flux of 1.94 m³.h^-1.m^-2 with adding optimized values of sodium aluminate (200 mg.L^-1) with hydroxide sodium (500 mg.L^-1). In combination of chemical precipitation with solute adsorption process using only one chemical, the fluidized bed crystallization process with the addition of sodium hydroxide (500 mg.L^-1) can be used as a desirable option because the removal efficiency of calcium and silica were 82.2 and 97.2%, respectively. Of course, magnesium removal was 31.1%, which is not appropriate. So this option is only suitable for removing calcium and silica. The removal of magnesium was 31.1% and not suitable, respectively. So this option is only suitable for removing calcium and silica. In the process of chemical precipitation in the form of combination of chemicals optimum concentrations, the combination of optimum concentrations of sodium hydroxide (500 mg.L^-1) and sodium aluminate (200 mg.L^-1) was suitable process for silica removal because calcium, magnesium and silica reduced 68.8, 54.2 and 93.3%, respectively. In the combination of Sodium hydroxide (500 mg.L^-1) and aluminum sulfate (100 mg.L^-1), the removal efficiency for calcium and magnesium was 88.2% and 100%, respectively. Therefore, to remove silica, combination of sodium hydroxide and sodium aluminate and to remove calcium and magnesium, combination of sodium hydroxide and aluminum sulfate were appropriate. But finally, by combining the process of solute adsorption and chemical precipitation, the mode of combining the optimum concentrations of sodium hydroxide (500 mg.L^-1) and sodium aluminate (200 mg.L^-1) and adding them to the fluidized bed crystallization, the highest removal efficiency for calcium, magnesium and silica (95.8, 97.9 and 94.4%, respectively) and maximum flux (1.94 m³.h^-1.m^-2) were obtained. Therefore, this is optimum ZLD process.

Abstract Considering the role of water in agricultural activities in low-water plain of the country, appropriate use of water is the best choice to have constant agricultural activities in the future. Generally, in logical pricing of water, total cost of water and purchasing power of group of consumers should be considered because a correct and proper pricing shows the consumers the exact cost of water and the way it should be consumed. As the water supplies are limited in most parts of the country (especially the area which is under study), the important role of water pricing in agriculture and its expansion seems to be necessary.  Irrigation network in agriculture section is one of the most important irrigation networks of the Khouzestan Province. The company of utilizing irrigation networks in Khouzestan was established in 1991 to utilize a huge irrigation network. It started working in 1993. One of the purposes of this company is improvement in the structure of manpower and economizing the activities. On one hand performing the irrigation and drainage plans in different regions of Karkhe and Shavour, which the most of their members are local and poor farmers, does not only have economical profits, but also includes economical advantages such as job creation, prevention from immigration to other professions, per-capita income increase and finally improvement in local people’s living standards. After pricing and determining economical value of agricultural water in the irrigation network of North Khouzestan, an appropriate economical management of water supply can be planned efficiently to prepare a background for saving this important resource and to prevent from wasting and polluting it. The most important role of water price can be its proper distribution among applicants based on different utilizations. In fact, one of the best policies and methods to protect water supplies is making appropriate pricing policy in different parts in order to apply an optimum model in water consumption. As a result, looking at water as an economical material, it should have proper pricing, just like other materials. This study calculates the total cost of agricultural water based on the cost of funding, utilization and maintaining installations. In addition, it determines the economical value of  consumed water in production of main crops such as wheat, corn and cucurbits, in 2017 in Dezful, via production function, determines agricultural water’s production elasticity using results of estimated demand function in each group and region, and determines water price using Gardner method. Water production elasticity shows farmers’ sensitivity to the water’s price changes. Any change in the form of production function that influences the calculated parameters also affects the calculated economical value. Due to the importance of proper form of function, after estimating various functions, the best function form was identified using tests and econometric criteria.  Moreover, to compute provision cost of 1 m³ agricultural water the following relation is used, In this study, the upper limit of water price is the shadow price or value of final output of water and the lower limit of water price is utilization price and preservation of water installations in different regions. In this path, the final cost is combination of water final output for agricultural products’ production and costs of water preservation behind the dam and other costs which are related to the organization. To make a connection between two sections (final output of water, and preservation and transformation costs) the Gardner method was used. In order to show the effect and importance of choosing models on the amount of economical value of water in production of wheat, corn and cucurbits, five types of production function were selected, including Cobb-Douglas, generalized quadratic Translog, Transcendental, and generalized Leo Leaf to explain the relation between the production elements and the amount of crops and then, they were computed using collected data statistics. The results of the surveys in the Transcendental function for wheat production, economical value of water and water production elasticity were calculated as 1957/33 Rials and 0/1263, respectively. And the generalized Leo Leaf function for corn production’s economical value of water and water production elasticity were calculated 2128/05 Rials and 0/4777, respectively. In the transcendental function for cucurbit production, economic value of water was calculated to be 1485/14 Rials and water production elasticity was equal to 0/3533. The guarantied price of wheat and corn, and the average price of cucurbits in 2017 were reported to be 14300, 11502 and 7003 Rials, respectively. At the end, the shadow price of water or in other words, the economical value of water for wheat, corn and cucurbit production was determined as 1957/33, 2128/05 and 1485/14 Rials for each cubic meter water, respectively. While paid prices by farmers of each product (wheat, corn and cucurbits) are 142/1, 201/3 and 457 Rials, respectively. In the method of calculating the entire price of agricultural water (considering funding costs, the cost of dams utilization, maintaining installations and amortization, without considering the fact that what products the farms are producing) the provision cost of 1 m³ agricultural water was calculated to be 1026 Rials, which is the minimum price of water. If 20% gross profit is expected compared with the final price, water price (based on costs of water organization of Khuzestan Province) will be 1231 Rials. In the Gardner method, if we consider equal water payments for farmers and the organization (that is X= 50), the final prices of water for each product, wheat, corn and cucurbits, are 1594/2, 1697/5, 1358/07 Rials, respectively. The study results show that the paid price by farmers has a great difference with the real water cost in production process of the main crops of the region. Therefore, water’s low price is one of the factors causing nonoptimized consumption of water in the studied area. Price increase of this input can lead to its consumption reduction for producing products. As a result function of product reduces per unit area. In addition, farmers may invest on new irrigation techniques that enhance the irrigation efficiency.  Following the low price of water, traditional irrigation systems are still being used and a huge amount of water is wasting. Therefore, it is recommended for water price to be adjusted based on its economical value. In addition, conditions for water proper utilization should be prepared so that agriculture production systems can improve and stabilize. This policy in a short term might dissatisfy farmers and has negative effects on their production, but as a long term policy it can result in consumption of water saving.

Abstract Dams have many essential benefits to serve the increasing demand of human population in making world a better place for living. Dams are purposely built for irrigation, power generation, flood mitigation, water supply and even for recreation and fishing activities. However, substantially huge amount of water body stored behind the standing dam structure could seriously pose severe risks to many. Great level of energy stored in the impounded reservoir will cause unbearable impacts if it be released suddenly to the downstream area. Therefore, it is important to conduct a dam break study to determine the outflow resulted from break event. The art of dam break modeling lies primarily in the prediction of the outflow hydrograph as a result of dam failure. This can be done via physical models and laboratory experiments and numerical modeling techniques. Physical models are not always financially viable therefore, the numerical modeling is often taken as a better alternative. Numerical modeling techniques estimate the outflow hydrograph via four methods; physically based methods; parametric models; predictor equations and comparative analysis This study has used the MIKE modeling software to simulate the dam break event, determine the outflow hydrograph to be routed to the downstream area, and to obtain the flood maps.   Furthermore, animation tools available in MIKE software offer better appreciation of the dam break event, added with enhanced graphics of inundation maps to visualize the flood wave movement in variation of time and space.  In the present study, the simulation of the dam break in Golpayegan and Kucherei earth dams in Isfahan Province was investigated using MikeFlood software. The MikeFlood is a software that creates a relationship between the one-dimensional model Mike11 and two-dimensional model Mike21. The way it operates is when the Mike11 is activated at times before the flow section fills in the main river and conducts flood routing in the main waterway. As the discharge increases and the cross-section fills in the main river and the stream enters the floodplain, the Mike21 model is activated and begins to simulate a two-dimensional flow in the floodplain. Due to different boundary conditions, different scenarios occur, which need to be introduced into the model. In this research, there are three possible scenarios including: 1) break of the both Golpayegan and Kucherei dams due to the overpass; 2) the break of the Golpayegan dam due to the piping, and the Kucherei dam due to the overpass, 3) no break in the Golpayegan dam, and the Kucherei dam break due to the piping, have been tested and compared. In the first scenario, 53 minutes after the Kucherei dam breakdown, the maximum flow rate of 118727 m³/s was perdicted.  In the second scenario, the maximum flow rate of 110717 m³/s, 51 minutes after the Kucherei dam breakdown was perdicted, and in the third scenario, the maximum discharge of 50208 m³/s was perdicted, 43 minutes after the Kocherei dam breakdown. The flood alert time and zone division have also been compared in different scenarios. In the first scenario, the floodplain has more area and the advance rate was faster. In the third scenario, the flow rate was lower than the others. Also, the Alvand town will not be flooded due to its location in a higher area than Golpayegan city, and also, Saeed Abad industrial town will not be flooded. The alert, peak arrival and flood recession times in the sections increase and are directly related to the increase ofthe distance from the sections to the dam. The results showed that due to the dam breakdown in all three different scenarios, Alvand town and Saeed Abad industrial town, which are among the important areas below the dam will not be flooded.

Abstract Introduction: Freshwater resources are fundamental for agriculture and food production. The increasing demands for water and climate changes cause shortage of freshwater on the planet. The water shortage can also limit the agricultural production, which can endanger the human food security. Due to the restriction of freshwater resources in the recent decades, many researchers have focused on the use of new methods for sweetening saline water. The sweetening saline water needs energy and this causes restriction use of these processes. Use of renewable energy sources is one of the best solutions for this problem. Solar energy is an environmentally responsible method of generating power, and also makes financially sense. In addition to being renewable, solar energy is typically labeled as a green source of energy due to the lack of harmful environmental side effects associated with its use. Iran has a high solar energy potential, because it is located in mid-latitude and also arid region of the earth. Sweetening saline water by using solar energy is one of the methods in which saline water first evaporates and then converts to fresh water by condensation. It is called condensation irrigation when it is used for irrigation purposes. Condensation Irrigation (CI) is a combined system for solar desalination and irrigation. The CI system presented in this research uses solar thermal energy to evaporate saline water. At the first, the saline water converts to vapor by solar energy and then, the vapor is being cooled and precipitates as freshwater on the distillation container walls. Methods: In this study, CI method was used for irrigating chili pepper in Shahrekord. This experiment was arranged as factorial experiment based on completely randomized design with four types of water (distilled water, drinking water and water with salinity of 4 and 6.5 dS/m) and three types of distillation container including transparent and dark plastic hemisphere, and pyramidal glass, as distillation areas. Two types of saline water used in this research were obtained from two regions of Naein in Isfahan province. The regions are desertic regions located on the margin of the desert areas of Iran and their groundwaters  are generally salty. After preparing the culture medium, the chili pepper seedlings were transferred to the field. Some growth related characteristics and physiological parameters such as, total fresh and dry weight of the Shoots, total fresh weight of fruit, plant height, number of fruits, leaf relative water content and chemical indices including chlorophyll a, b and total chlorophyll, ion leakage, carotenoids, and water use efficiency and the volume of consumed water were measured and evaluated. In order to analyze the results, SAS software (version 1/9) was used. Mean comparison was also performed by LSD test. Results: The results showed that, with increasing the salinity of water, the fruit’s fresh and dry weight, shoot weight, relative water content, carotenoids, water volume and water use efficiency decrease in comparison with distilled and drinking water, so that the water with salinity of 6.5 dS/m showed the most decrease in the studied indices. By increasing the salinity of the water inside the containers, the amount of evaporation decreases, resulting in decreased amount of fresh water produced on the distillation containers. In other words, the amount of available water to the plant decreases. Indices such as ion leakage, which indicates plant damage due to water stress, was also higher in the two saline water treatments (water with salinity of 4 and 6.5 dS/m). Also, the amount of carotenoids in the two saline water treatments was lower. By reducing available water for the plant (in other words, the more water stress for the plant) these indices become lower. Among the distillation containers, the highest values of the mentioned indices were observed in the pyramidal glass. The highest amount of water use efficiency was obtained in the two types of fresh water with an average of 4.4 kg/m3, and the lowest value of 1.6 kg/m3 was obtained in the water treatment with salinity of 6.5 dS/m. Finally, the results showed that if the distilled irrigation with water treatment with salinity of 4 and 6.5 dS/m and glass pyramid distillation was used, this method can supplies 24 to 27% of water requirement and the rest of the water has to be provided by supplemental irrigation.

Abstract Chlorine disinfection (chlorination) is one of the common methods in the water purification process. Chlorine is used as the most common disinfectant in water supply systems due to its residual preservation, effective performance as well as economic advantages. Chlorine decay occurs as it moves along a pipe or settles in storage reservoirs due to reaction with inorganic and organic matter in the volume of water (bulk decay) and biofilms and materials on the wall of the pipe (wall decay). Due to the lack of chlorine concentration, the risk of microbial contamination increased. On the other hand, increasing chlorine concentration during the treatment process can cause pipe corrosion, taste and odor problems and disinfection by-products formation. In the field of quality assessment of drinking water distribution and conveying lines, the study of decay and chlorine reactions is of particular importance. The reaction of chlorine and organic matter is one of the problems that many water supply lines are facing. In this article, the residual chlorine concentration in the Isfahan water supply line from Baba Sheikhali water treatment plant to Naeem is simulated by applying the first-order model, parallel first order model as well as second order single-reactor model in the EPANET-MSX software. The line’s total length is 259 Km and supplies drinking water for more than 4 million consumers. The nominal discharge of the line is 11.7 m³/s. EPANET is a widely used software for modeling the hydraulic and water quality of drinking water in distribution systems. While the water quality component in the original version of EPANET is limited to tracking the transport and value of just a single chemical species, the MSX extension provides qualitative simulation with a multi-species approach. The newly developed multi-species extension (EPANET MSX) brought enhanced capabilities for the simulation of chlorine residuals in water supply systems that allow the modeling of chemical reactions with any level of complexity. First, the hydraulics simulation of the model was performed and the results were compared with the measured pressures along the line. The model is calibrated and validated with the available pressure data. Then the quality simulation is applied. To determine the bulk coefficient, the bottle tests were performed at 6, 13 and 18 ° C. In order to extend the results of the experiment to different temperatures, the temperature coefficient is calculated based on Arrhenius law. Two methods of integrated and bisection are applied for numerical modeling in spring, summer and winter. In the first method, chlorine simulation was performed taking into account the whole Isfahan water conveyance line as one section (integrated) and determining a bulk decay and wall decay coefficient for the entire conveyance line. In the second method, the line was divided into two sections (bisection) and decay coefficients of chlorine for each section separately were dedicated. The model’s results were compared with the measured data at different nodes at the conveyance line. The results indicated that by separating the line into two parts and applying independent coefficients and decay parameters to each part, the RMSE value has been reduced for the measured and simulated chlorine concentrations, from 0.09 to 0.03 mg/L in summer and from 0.064 to 0.025 mg/L in winter. Comparison of the root-mean-square error (RMSE) value in different models between the measured data shows that if in simulation, the line is divided into two or more parts and the different coefficient is considered for each, the results are considerably improved and models show no significant advantages. The results indicated that the chlorine concentration is high at the beginning and lower than the minimum at the end of the conveyance line. In order to comply with the standard range, re-chlorination was investigated through two approaches. In the first approach, in order to meet the required minimum concentration at the end of the conveyance line, re-chlorination was performed at an intermediate node. The chlorine injection remained constant at the same rate as it is. In the second approach, the injection rate was reduced at the beginning of the line and three nodes were selected for re-chlorination. A comparison of the results showed that chlorine injection along the line results in maintaining the minimum chlorine level in the whole line and reducing the concentration of chlorine in the leading regions. Moreover, by application of the new method, the consumption of chlorine is reduced up to 50%.