مجله پژوهش آب ایران
پیاپی 37 (تابستان 1399)

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.

Due to low efficiency of fertilizer use, nitrogen fertilizers result in environmental problems. Therefore, use of soil amendments such as zeolite becomes important. 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 soil 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 experiment was factorial with completely randomized design with three replications for each treatment. The results showed that these amendments simultaneously improved wheat plant growth and increased the amount of nitrogen uptake by plants. So that, the concentration of nitrogen of the grain and nitrogen harvested by the plant in Cp receptor columns were significantly (1.45 and 2.49%) higher than SMZ receptor columns. Also, with the increasing level of modifier usage, the amount of nitrate-nitrogen in the output decreased significantly (at 5% level). Still, the type of modifier had no significant effect on the amount of leached nitrogen.

The study of moisture patterns 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 laboratory investigation of combined and separate effect of magnetism and organic matter on the distribution of moisture in layered soils.

The experiments were carried out in a 50*50*50 cm box of transparent plexiglass to observe the movement of the moisture front in the soil. Also, the experimental model of the present study includes water resource, plastic pipe, magnets set for applying magnetic field to water and dropper with a constant discharge rate of 4 liters per hour. In this study, four permanent pairs of magnets were applied with two specific magnets (three pairs of magnets with 0.2 T, and a pair of magnet of 0.3 T magnitude). The Porous media treatments of this study includes 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 homogeneous mixture of soil (80%) with organic matter (20%). Also, the total thickness of the soil layer was considered 35 cm (the thickness of the coarse textured layer (SL) 25 cm and the fine textured layer (C) 10 cm) that 15 cm was kept empty from the top of box. For this purpose, the effect of plain and magnetic water in the form of eight treatments, on the moisture movement in coarse-textured, fine-textured, coarse textured mixed with peat moss, fine-textured mixed with peat moss were evaluated. Also this tests in the irrigation and drainage and Soil Laboratories were designed and implemented. Finally, the chemical properties of drainage water extracted from soil samples and samples of soil mixed with peat moss were measured by pH meter (pH meter) and electrical conductivity meter (EC meter).

The results of this study showed that due to the application of magnetism on irrigation water, electrical conductivity of drainage water was decreased in all treatments with the highest decrease to 0.875 mmho/cm in the fine-textured soil, except the fine-textured soil mixed with peat moss. Also, drainage water pH was increased in all four soil treatments, with the highest 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, for infiltration depth factor, the most general variability of magnetic water treatment was observed in T1 (increment), T7 (decrease), T3 (decrease) and T5 (increment) treatments. On the other hand, the highest influence of forward width was obtained in T7 (increment), T1 (decrease), T5 (increment) and T3 (increment) treatments. In addition, the analysis of forward curves-soil moisture distribution showed that due to the application of magnetic water for example in the horizontal direction, the maximum horizontal progression radius increased by 19.81% to 38.9 cm. 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 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 was effective.

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 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 include 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.

The Talvar river watershed with an area of 2490 km2 is situated between longitudes of 47° 06' 09" E and 47° 45' 58" E and latitudes 35° 03' 26" N and 35° 35' 26" N, located in the Kurdistan province. Land use in this basin is mostly cropland and pasture. Cropland accounts for approximately 85% of the total area, among which paddy fields account for 10% and dry land farming accounts for 75%. Pasture cover 14% of the study area. All other land use types (rural area, urban area, water) make up only 1% of the 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. Recently available GIS maps for topography, land use, and soils 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 including 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 in RCP26, RCP45 and RCP85 scenarios and simulated values were compared with baseline period (1990-2005). The performance of the SWAT model was evaluated via coefficient of determination (R2) and Nash–Sutcliffe efficiency (ENS) and the performance of the SDSM model was evaluated via coefficient of determination (R2), Nash–Sutcliffe efficiency (ENS), 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 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) have the greatest influence on water budget components including surface runoff, lateral flow, groundwater and evapotranspiration. According to the results, a satisfactory agreement was observed between monthly simulated and measurement discharge (R2 and ENS 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 will increase compared to the baseline period except for September, October, November and December months. Also monthly average of precipitation will decrease in winter and spring seasons but it will increase in the summer and autumn seasons. The results of runoff simulation showed that monthly average of runoff will increase in January, February and December months compared to the baseline period. The weakness of the model to simulate flow for some months was probably due to poor characterization of snowmelt processes in basin under study.

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, thirty minute rainfall intensity (I30) is 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 hydrophobicity (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 sediment or more sediment in hydrophobic soils. Considering Iran's location in arid and semi-arid climates and the importance of studying hydrological phenomena in this climate, simulating the effect of different probability of precipitation intensity on 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 done 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 on five soil treatments under five rainfall intensities with a probability of occurrence 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 equal to 0.55 KW. There are eight nozzles that provide sprinkler irrigation with square spraying pattern. The spraying flow is adjusted up to max. 1500 l. /hr., by a rotameter underneath the equipment. The required water for spraying is stored in a 220-Litre tank. Working with the equipment is easy. The equipment consists 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 is considered as the free board space. Five cm of the bottom of the tray was filled by sand in order to facilitate and accelerate the drainage of water. A galvanized mesh is placed on the sand. The upper 5 cm of the 10-cm of soil was considered as the surface soil. 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 control treatment, the rainfall duration depends only on the rainfall intensity and the maximum rainfall time is 53 minutes (related to the lowest rainfall level (-20% Probability of the base rainfall) and the minimum rainfall time is also 47 minutes (related to the highest rainfall level (+ 20% Probability of the base rainfall). In the hydrophilic soil treatments in addition to rainfall intensity, the degree of soil hydrophobicity affects also the rainfall time. Since the water absorption is negligible, the rainfall duration is shorter than the control sample. The higher the water hydrophobicity, the less rainfall duration. The less hydrophobicity degree, the less runoff generated. In hydrophobic treatment, due to water repellency, the runoff occurs rapidly, and (hydrophilic soil). The highest observed runoff was 7000cc in severe repellency treatment and the rainfall with +20% Probability, means 120lph. However, the minimum volume of runoff observed in control sample in probability level of -20%, 720 cc. On the other hand, the higher hydrophobicity level, the higher runoff coefficient was observed. Runoff coefficient has been observed in hydrophilic soil from 0.000 to 0.0011 and in hydrophobic treatments 0.05 to 0.94. Severe and extremely severe hydrophobic treatments worked quite imperviously. The rate of sedimentation exited along with runoff is decreases by increasing the hydrophobic level. The highest observed sedimentation was 12gr in hydrophilic treatment and the rainfall with +20% Probability. However, the minimum volume of sedimentation is 2 gr which is observed in extreme soil repellency treatment in probability level of -20%. The observed deep percolation in the control treatment (hydrophilic soil) is 17.5 to 23.8 liters. The deep percolation amount was observed only in low and moderate hydrophilic levels (380 to 950 cubic centimeters). No significant deep percolation, was observed in severe and extreme severe hydrophobic treatments.

In this study, two optimization models for trapezoidal open channel cross-sectional design have been investigated. In one optimization model the lined free board is not considered and in the other the lined free board is considered. In fact, in this study, for the first time in the field of the optimization of open channels, in addition to the total free board, the lined free board is also considered as a design variable. In the two optimization models mentioned above, the first objective function is considered as a cost function. The discharge, Manning's roughness coefficient and the longitudinal bed slope of the channel were random variables, because in real life situation, the actual flow may exceed the design flow because of 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 because of imperfections in fabrication. The physical bed slope 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 is to minimize the cost of excavation and the lining channel cost and the second objective is to minimize the probability of overflow from its cross section. The Manning flow equation is also considered as a constraint. These models have 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 to the two-objective optimization problem, the multi-objective constrained programming method is used, which converts the vector optimization into a numerical one. This conversion from vector to numerical formulas with regard to the first objective is to minimize the total cost of the channel as the single objective in this problem and the second objective which seeks to minimize the overflow, as an additional constraint. In this study, the flooding probability constraint is developed by using the first order analysis that essentially uses the calculus based differentiation of the Manning uniform flow. The numerical and deterministic form of the previous modeling are 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 lined free board and no 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 have decreased. On the other hand, the depth of flow in the channel and side slopes have increased. But in general, the total cost for the construction of a channel in a model with a lined free board is lowered compared to that in which the lined free board is 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 has increased 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 a model that did not include the free board showed that considering the lined free board or somehow the unlined part, reduced the total cost. On the other hand, 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. It should be noted that it is suggested that land acquisition and water loss costs (evaporation, transpiration) be included in the objective function to develop the current design in future research and it is also possible to compare the results with current design standards.

Water deficit is known as the most important limiting factor in agricultural products, especially in the 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 is consisting of the arid and semi-arid areas with limited water resources, in case of the minimum plant water use is not maintained, the plant would experience drought stress and the products would suffer irreparable losses. One way for optimal use of the water resources and their preservation is the use of superabsorbent polymers which not only provide conditions for improved products quality but also results in increased water consumption efficiency in the arid and semi-arid areas. Superabsorbent polymers could 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 will gradually discharge, and thus the soil would remain moist for a long time, without needing further irrigation. This property is the great importance to confront water shortage and reduce the harmful effects of drought stress in plantations. Superabsorbent polymers cause water retention in the 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) in a farm with sandy soil, in Seymareh region, Ilam province, Iran was evaluated. This experimental farm was conducted at 33° 09′ N and 47° 24′ E, and with an elevation of 982 m. Seymareh region has a 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: Super-AB-A-300 used in this study. This polymer is a granular type and produced by Rahab Resin Co. with product license holding of Iran Polymer and Petrochemical Institute. This hydrophilic polymer is a terpolymer of acrylamide, acrylic acid, and acrylate potassium. The experimental design was according to a split-plot method in a randomized complete block design 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 as 100, 80 and 60 percent of water requirement of plant respectively and different levels of superabsorbent were used as secondary treatment including S0, S1, S2 and S3, equal 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 a depth of 30 cm from the soil surface. The cucumber variety of this plan was planted manually in April as spring planting and in August as summer planting. The space between planting rows was 20 cm, and between each plant in each line was 40 cm, so a 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. From the 3 to 4 leaf stage (after the complete establishment of the seedling) the deficit irrigation treatment was applied. 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 and 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) and 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 showed that in the drought conditions, superabsorbent application increased cucumber fruit weight and crop yield compared to 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, the results showed that superabsorbent could prevent the significant reduction of cucumber crop yield in sandy soil and under drought stress conditions.

Karstic water resources, especially in dry areas, are considered to be the most important source of drinking water in the world. The first step to better management of these aquifers is to determine the water origin and catchment area and the hydrogeochemical processes that govern them. The studied karstic aquifer located in North Khorasan province, which has a wide outcrop of Tirgan limestone. This large and borderline aquifer, despite its high recharging, is discharge by a 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 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. According to the Hydrochemical 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 physicochemical parameters display that the discharged value has reverse relation with both EC and temperature valuessome springs due to the larger catchment area and the further development of Karst. For 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 dexcess 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 enrichtment 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. The isotope results confirm hydrological and hydrochemical results also. The chatchment area of these springs is in its adjacent anticlines. 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 that confirms the chatchment areas.

Local scour around bridge piers is the most common reason for bridge failures. many bridges have fractured because the lack of attention to the importance of hydraulic factors every year. Despite extensive researches on local scour, there is no precise method for predicting scouring because of the complexity of the scour mechanism, especially in bridges with complex piers. In this research the effect of pile cap's shape on the scour hole dimensions was investigated by using physical simulation. Laboratory data were extracted of three scaled down models of complex piers with different pile cape's shape. The experiments were conducted in clear water conditions with uniform sediment and constant discharge. The models were made with an appropriate scale from real piers of bridges. During experiments water depth was kept constant and it provided shallow water depth condition. The variation of scour hole's length, width and depth was recorded. A 3D illustration of the model for each experiment was drawn. The length, width and depth of the scour hole coordinates were measured in three directions. The results illustrated that the length and width of the scour hole, the same as depth, are also significantly dependent on the shape of the pile cap and its elevation. Results showed that The maximum length, width and depth of the scour hole were,11lpc, 8.5bpc and 9T respectively. These results can be used by engineers and researchers in order to attain at a pattern for predicting the dimensions of the scour hole in the complex bridge piers.

In order to adapt to water scarcity, various strategies can be proposed and implemented including; the adoption of appropriate policies for optimizing water use through the determination of optimal production functions. Water scarcity and a decreasing in the quality of water and soil resources in the country are among the main causes of production decline. Hence, this study was conducted to determine the sensitivity coefficients of plant and optimum water-salinity-yield function for turnip in Kashmar. A factorial experiment was conducted in a completely randomized design with three replications including two factors salinity and irrigation water. Four levels of irrigation water salinity were, drinking water: S1 = 0.7, S2 = 4, S3 = 8 and S4 = 12 dS/m3, and three levels of irrigation water, including: full irrigation (100% water requirement) = W1, W2= 75 % W1 and W3 = 50% W1, applied to a sandy-loam soil texture. Functional data were fitted to different forms of production functions (linear, logarithmic, quadratic and exponential), and after sensitivity analysis, the optimum production function of turnip was determined. Then the water use efficiency and the sensitivity coefficients of the plant were determined. The results of the sensitivity analysis indicated that the quadratic production function for turnips as the optimal production function is recommended. The study of maximum error (ME) showed that the most error is related to simple logarithmic and linear functions. The Control treatment (W1S1) and W2S1 treatment (75% water requirement) were the highest yield with 6.66 and 7.24 kg/m3, respectively, but the water productivity decreased with increasing water stress and salinity. The average amount of crop yield response factor (Ky) was estimated at the rate of 1.73 in the salinity and water stress combination. Also, the sensitivity coefficient (Ks) decreased with increasing salinity and water stress and the lowest value of (Ks) belonged to W3S4 treatment at the rate of 0.5. The same product curves demonstrate that with an increasing amount of irrigation water, higher saline irrigation water can be used for turnip, which the yield does not change.

Salinity is the most important factors 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 has bicarbonate type and 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, which includes reduction of crop 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 electrical conductivity (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 part of the aquifer, that indicates the existence of salinity sources in these parts of aquifers. Despite the high salinity of samples in the east of the region and the generally flow direction of the groundwater (which is from the east to the west of the 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, these samples are the result of mixing of 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, the 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 that is consistent with the high salinity areas in the aquifer. But despite the fact that there are evaporative formations in the southwest parts of the aquifer too, the salinity of samples that taken from these parts, is low. Different hydrochemistry diagrams and ion ratios such as the Na and Cl ratio, 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 similarity in δ18O isotopic amounts, show a depletion in δ2H relative to fresh water and present precipitation. The amount of tritium in 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 of tritium in saline and fresh samples, at least two water sources with different ages can be identified in Shahrood aquifer. Since the fresh water has a higher tritium content than saline samples, it can be said that freshwater is younger than saline water in this aquifer. Southern saline water with tritium content less than 0.8 TU represent a mixture of relatively old water that fed before 1952 and newer meteoric waters. To determine the source of the saline water in the southeast of the aquifer, the mean 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 type of water and enrichment of 18O (δ18O-Shift), then the saline samples shifted to right of SMWL. Due to the difference in the age of saline and fresh waters, also, difference in the content of stable isotopes as well as the hydrochemical characteristics, it is necessary to study the hydrogeological factor that is affective in the occurrence of these conditions. Based on the hydrogeological map of Shahroud aquifer, in the central part of the this aquifer, a water divide line has been created due to the concentration of the productive wells and over exploitation from the aquifer. Due to the operation of this water divide line, a part of the input flows that inter from the northern and 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 the south with the western parts of the aquifer. Reducing the flow rate of groundwater, while increasing the age of water due to increasing its resident time, provides conditions for more dissolution of minerals, thereby increasing the salinity and variations in the groundwater type. The dissolution of gypsum, in addition to changing the type of water to sulfate water, results in water enrichment relative to oxygen-18 (Shift-18O) and therefore the shift of saline samples to the right of the SMEL.

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 areas. Reverse osmosis system produces two types of water, one purified water and the other concentrated wastewater. To reuse the concentrated wastewater in reverse osmosis, it is necessary to remove some of the 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 and sodium hydroxide, aluminum sulfate and lime, sodium aluminate and sodium hydroxide and sodium aluminate and lime were 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 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) and hydroxide sodium (500 mg.L-1).

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 correct and proper pricing shows the consumers exact cost of water and how it should be consumed. As the water supplies are limited in most parts of the country (specially 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 and its development 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 structure of manpower and economizing the activities that has been continued with effort of managers and employees of the company. On one hand performing the irrigation and drainage plans in different regions of Karkhe and Shavour that 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 standard of living. After pricing and determining economical value of agriculture water in 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 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 cost of funding, utilization and maintaining installations. In addition, it determines the economical value of consuming water in production of main crops such as wheat, corn and, cucurbits in 2017 in Dezful via production function and also demining production elasticity of agriculture water using results of estimated demand function in each group and region and determining water price by Gardner method. Water production elasticity shows farmers sensitivity to water price variation and it can be used in policy making. Any change in the form of production function that influences the calculated parameters also affects the calculated economical value. In this case, it is essential to choose a proper form to determine real cost of each input such as water input. Thus, after estimating various functions, the best form of the function is identified using tests and econometric criteria. Moreover, to compute provision cost of one cubic meter agricultural water following relation is used, Total consumed irrigation water/ ( depreciation cost of yearly profit of fund+ depreciation cost if installations and networks + depreciation cost of dams + utilization and protection cost) = provision cost of one cubic meter irrigation water. In parallel with the method mentioned above, Gardner method is applied to calculate irrigation water price, in the following relation: (F-Cᵤ)/(Lᵤ-Cᵤ)=X (1) In this equation Cu is the entire water cost in each cubic meter irrigation water, Lu is the final output of irrigation water,(upper bound of water price), X is the difference between upper bound of water cost in each cubic meter water and F is water price. In fact, water price is calculated with Gardner method. It should be mentioned that total water rent that farmers receive is equal to: (Lu -F)/ (Lu -Ctr) (2) In this equation (Lu-Ctr) shows water rent and difference between lower and upper limit of water price and water rate, (Lu-F) is extra water that devoted to farmers. In this study, upper limit of water price is the shadow price or value of final output of water and lower limit of water price is utilization price and preservation of water installations in different regions. In this path, final cost is combination of final output of water for production of agriculture products 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) Gardner method is used.

To show the effect of choosing different models on 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 production elements and 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 1957/33 Rials and 0/1263 respectively. And the generalized Leo Leaf function for corn production economical value of water and water production elasticity were calculated 2128/05 Rials and 0/4777 respectively. In transcendental function for cucurbit production, economic value of water was calculated to be 1485/14 rials and water production elasticity was equal to0/3533. The guarantied price of wheat, corn and average price of cucurbits in 2017 was reported to be 14300,11502 and 7003 Rials respectively. At the end shadow price of water or on the other words economical value of water on average of other consumed reserving of wheat corn and cucurbit production for each cubic meter water was determined 1957/33, 2128/05 and 1485/14 Rials 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 entire price of agriculture water- considering funding costs and cost of dams utilization, maintaining installations and amortization, without considering the fact that what products the farms are producing - provision cost of one cubic meter agriculture water was calculated to be 1026 Rials. This is the minimum price of water. If 20% gross profit is expected compared with final price, water price (based on costs of water organization of Khuzestan Province) will be 1231 Rials. In Gardner method, if we consider equal water payments for farmers and the organization (that is X= 50), final prices of water for each product, wheat, corn and cucurbits are 1594/2, 1697/5, 1358/07 Rials respectively. The results of this study shows 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. This means that the matter of low price of water is one of the most important factors in non optimized use of water sources in the understudied area. As water price increase, farmers show different reactions. 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 enhances irrigation efficiency and the important fact is that each unit of water will be used efficiently. The results of the study shows that real price of farming water is considerably more than its common water price. The difference between final water price and paid price by farmers cause loss of motivation among farmers for investment in order to increase irrigation output and using new irrigation technologies. Consequently, traditional irrigation systems are still used and a huge amount of water is lost in the farms. Therefore, it is recommended that not only water cost should be adjusted based on economical value of water but also conditions for proper utilization of water should be prepared so that agriculture production system improved and stabilized. This policy in a short term might dissatisfy farmers and has negative effects on their production because there is a big difference between real water price and paid water price by farmers, but as a long term policy in can creates motivation to use water saving technologies and eliminate low efficiency methods for irrigation and water transfer that lose considerable amount of water. In conclusion it is suggested that this policy applies in a way that first, it does not unmotivated farmers from farming and second, improves farmers cooperation for accomplishment. Considering the results of price calculation of each cubic meter water, price difference of each cubic meter stored water can paid to compensate profit reduction due to water consumption reduction. To enhance irrigation efficiency, motivation for beneficiaries is created and direct them through economization.

Dams have many essential benefits to serve the ever 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 activity. 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 should it be released suddenly to the downstream area. It is therefore important to conduct a dam break study to determine the outflow resulted from such unwanted dam 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 model and laboratory experiment and numerical modeling technique. Physical model is not always financially viable hence the numerical modeling is often taken as a better alternative. Numerical modeling techniques estimate the outflow hydrograph via four methods; 1) physically based methods 2) parametric models 3) predictor equations 4) comparative analysis With the rapid development of computer hardware and computing techniques, numerical study on dam break flows has been a popular research subject. This study had therefore used the MIKE modeling package to simulate the dam break event and to determine the outflow hydrograph to be routed to the downstream area and eventually to obtain the flood maps. Furthermore, animation tool available in MIKE software offers better appreciation of the dam break event, added with enhanced graphics of inundation maps to visualize the movement of flood wave in variation of time and space.

In the present study, simulation of dam failure in Golpayegan and Kucherei earth dams in Isfahan province was investigated using MikeFlood software. The MikeFlood is software that integrates 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 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, three possible scenarios are: 1) failure of both Golpayegan dam and Kucherei dam due to overpass; 2) Golpayegan dam due to piping and Kucherei dam overpass, 3) non-failure Golpayegan dam, and failure of Kucherei dam by piping has been tested and compared.

In the first scenario, after 53 minutes of Kucherei dam failure, the maximum flow rate is reach 118727 m3/s. In the second scenario, the maximum flow rate is achieved 110717 m3/s after 51 minutes of the Kocherei dam breakdown, and in the third scenario, the maximum discharge occurs about 50208 m3/s, 43 minutes after the Kocherei dam breaks. Flood alert time and zoning division have also been compared in different scenarios. When the first scenario is in place, the floodplain has more area and the rate of advance is faster. In third scenario, the flow rate is lower than in the first and second scenarios. Also, Alvand town will not be flooded due to its location in a higher area than Golpayegan city, and Saeed Abad industrial town will not be flooded. The alert time, the peak arrival time, and the flood recession time in the sections are directly related to the increase in the distance from the sections to the dam and increases. The results showed that due to dam failure 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.

Freshwater resources are fundamental for agriculture and food production. The increasing demands for water and climate changes cause shortage of fresh water on the planet. The water shortages can also limit the agricultural production which can endanger human food security. Due to the restriction of freshwater resources in the recent decades, many researchers have focused on the use of the new methods for sweetening saline water. The sweetening saline water need to energy and this cause restriction use of these processes. Use of renewable energy is one of the best solutions for this problem. Solar energy is an environmentally responsible method of generating power, and also makes financial sense. In addition to being renewable, solar energy is typically labeled 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 if located in mid latitude and also arid areas 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. When this method used for irrigation, it is called condensation irrigation. Condensation Irrigation (CI) is a combined system for solar desalination and irrigation. The Condensation Irrigation system presented in this research uses solar thermal energy to evaporate saline water. At the first the saline water convert to vapor by solar energy and then the vapor become cooled and precipitates as freshwater on the distillation container walls.

In this study, condensation irrigation 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 of 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 region is a desert region located on the margin of the desert areas of Iran and its water grounds are generally salty. After preparing the culture medium, the chili pepper seedlings were transferred to the field. Some growth related characteristics and also some 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 also 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.

The results showed that, with increasing the salinity of water, the fresh and dry weight of the fruit, shoot weight, relative water content, carotenoids, water volume and water use efficiency decrease compared 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 the 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 that indicating plant damage due to water stress was also higher in two saline waters (water with salinity of 4 and 6.5 dS/m). Also, the amount of carotenoids in the two saline waters 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 above 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 (1.6 kg/ m3) in 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 is used, this method can supplies 38% and 36% of water requirement and the rest of the water have to provide by supplemental irrigation.