Water and Soil

Abstract Introduction: The analysis of extreme events such as first frost dates are detrimental phenomena which influence in various branches of engineering, such as agriculture. The analysis and probability predicting of these events can decrease damage of agriculture, horticulture and the others. Furthermore, this phenomenon can have a relation with other thermal indexes. The analyzing of first frost dates of all synoptic stations of Khorasan Razavi province is subject of this article. The frequency analysis applied to eight distributions. Then the relationship between first frost dates and thermal index were studied. Best relation was between minimum temperature and return periods of first frost dates. Materials and Methods: The analyzing of first frost dates (origin is March 21) of all synoptic stations of Khorasan Razavi province is subject of this article. At first data of each station were screening. The basic properties such as homogeneity, randomness, stationary, independence and outliers must be tested. The eight distribution Normal, Gumbel type 1, Gamma 2-parameter, Log normal 2 or 3 parameters, Generalized Pareto, Generalized extreme values and Pearson Type 3 fitted to data and the parameters estimated with 7 methods by the name of the several types of Moments (5 methods), maximum likelihood and the maximum Entropy. The Kolmogorov – Smirnov goodness of fit test can be used to compare the best distribution. The return periods of first frost dates are major application in frequency analysis. There is maybe a relationship between periods and thermal index such as min, max and mean temperature. This relationship can be adapted by regression methods. Results and Discussion: The statistical analysis for prediction probabilities and return periods of the first frost dates for all synoptic stations in Khorasan Razavi province and the relationship between annual temperature indicators and this phenomenon is the aim of this article. The origin date of this phenomenon is March 21. First, data were screened. Then basic hypothesis test were applied which including the Runtest (randomness), the Mann-Whitney test (homogeneity and jump), the Wald-Wolfowitz test (independence and stationary), the Grubbs and Beck test (detection Outliers) and the three sigma methods (Outlier). The results were: 1-The Sabzevar, Mashhad and Gonabad had lower Outliers that will not cause any problem in data analysis by their skewness. The first frost data of all station were without upper outlier. 2- The independence of all stations was accepted at the 10% level. 3-All stations were Randomness, Independence and homogeneous and lack of jump. Eight probability distributions (Normal, Gumbel type 1, 2-parameter gamma, 2 and 3 parameters log-normal, the generalized Pareto, the generalized extreme values and the Pearson type 3) were applied. The skewness coefficients for all stations were more than 0.1 so Normal distribution was rejected. Also the7 methods of estimation (five different methods of moments, maximum likelihood and maximum entropy methods) were used. The ks fit test was applied. The ks for some stations were closed together at several estimations methods. The results are as follows: GPA (4 times), PT3 (4 times), LN2 (4 times), GA2 (3 times). Generalized Pareto distribution had the best fitted to data (60% of cases compared to the other functions). The results significantly indicated that the occurrence of first frost on the first day of process is in place. The first frost in the period of 2 years at all stations, not occur earlier than Aban(October 28). The 100-year return period event does not occur earlier than first of Mehr(September 22). There is no significant relationship between first frost in the period of 2 years with other factors such as altitude, latitude, longitude, temperature and precipitation as well. Conclusion: Date of the first fall frost is one of the unfavorite climate influences that cause reduction in crop products. The purpose of this paper is to analysis the frequency occurrence of first frost day in several Khorasan’s synoptic stations as study area. Screening and initial basic tests such as randomness homogenity, independence, etc. were done. Eight distribution function, namely Normal, Gumbel type 1, Gamma 2 parameters, Log normal 2 and 3 parameters, Generalized Pareto and Pearson type III were fitted to data with five probability distributions methods (Ordinary Moments, Maximum Likelihood method, Modified Moments, Probability Weighted Moment and Maximum Entropy). Goodness of fit test was Kolmogorove-Smirnov test. PWM and ModM methods revealed relatively superior results compared to the rest of methods. Generalized Pareto distribution had the best fitted to data (60% of cases compared to the other functions). The results significantly indicated that the occurrence of first frost on the first day of process is in place. The first frost in the period of 2 years at all stations, not occur earlier than Aban. The 100-year return period event does not occur earlier than first of Mehr. There is no significant relationship between first frost in the period of 2 years with other factors such as altitude, latitude, longitude, temperature and precipitation as well.

Abstract Introduction    Quinoa (Chenopodium quinoa) is native plant in Bolivia, Chile and Peru, which is widely adapted to different climatic conditions and can grow in all soils. This plant has shown adequate adaptation to arid and semi-arid areas conditions and is planted from areas with low elevation (sea level) to areas with an altitude of 4000 meters above sea level. Quinoa is often cultivated in areas with limited water resources, and it is rare to find quinoa cultivation under full irrigation conditions. Some studies have shown that quinoa yields slightly better under full irrigation (without water restriction) than quinoa under deficit irrigation. Crop growth models are very important tools in the study of agricultural systems and they can be used to simulate the yield of crop in different conditions. Given that the study of performance limiting factors requires numerous and costly research and experiments in different areas, so finding a way to reduce the number, time and cost of these experiments is worthwhile. Aquacrop model is one of the applied models that are used to simulate yield variations in different water and soil management. Materials and Methods    This investigation was carried out in two growing seasons of 2019 and 2020 to determine the efficiency of Aquacrop model for simulating Quinoa grain yield and biomass under imposing three stress treatments of 30, 50 and 70% of water consumption in development and mid-growth stages. Plant spacing was 40 cm between rows and 7 cm between plants within rows. Seeds of quinoa (Titicaca cultivar) were cultivated in the first decade of August 2019 and in the third decade of July 2020. The experiment was a randomized complete block design with three replications. Three deficit irrigation treatments including 30, 50 and 70% of available water were considered in two growth stages (development and mid-growth) in 18 experimental plots (3 × 4 m). Soil moisture in rooting depth (about 40 cm) was measured by TDR and after the soil moisture of the treatments reached the desired values, plots were irrigated until the soil moisture reached the field capacity. The results of grain and biomass yield in the first year were used to calibrate the Aquacrop model and the results of the second year were used to validate the model. Root mean square error (RMSE), normalized root mean square error (NRMSE), Willmott index (D), model efficiency (EF) and mean error deviation (MBE) were used to compare the simulated and observed values. Results and Discussion    The results of the first and second year were used to calibrate and validate the model, respectively. The results of the first year showed that irrigation with 50 and 70% of available water in the development stage reduced quinoa grain yield by 17 and 33%, respectively, compared to the control treatment. The application of these two deficit irrigation treatments in the middle stage reduced the yield by about 12 and 28%, respectively. The results of comparing the statistical indices of grain yield, biomass and water use efficiency showed that the NRMSE for grain, biomass and water use efficiency were 9, 8 and 14% in the first year and 9, 6 and 9% in the second years. Furthermore, the EF for these traits were 0.81, 0.77 and 0.64 in the first year and 0.68, 0.71 and 0.62, in the second year, respectively. Conclusion The results of calibration and validation of the model showed the accuracy and efficiency of the Aquacrop model in simulating grain yield, biomass and water use efficiency of quinoa. This model can be used to provide the most appropriate scenario and irrigation management for different levels of deficit irrigation managements.

Abstract Introduction
Accurate knowledge of water balance components is necessary to optimize water consumption in agriculture. On the other hand, measuring water balance components is expensive and difficult. Therefore, the use of models that can simulate water balance values is important for water management in agriculture and water used by plants. Crop simulation models have been turned into essential tools for studying plant production systems. In the SSM-iCrop2 models, it is presumed that diseases and weeds are optimally managed and will not affect growth and yield. Additionally, except in cases where the model accounts for specific nutrients such as nitrogen, it is generally assumed that nutrient deficiencies are eliminated through fertilization. Therefore, parameterized and evaluated models are designed to fit these conditions. These factors are present in the field and affect crop growth and yield as well as water use. However, in several cases it is required to estimate yield and water balance components and irrigation water volume under grower conditions. Naturally, models parameterized using experiments are unable to simulate these conditions. Therefore, a model must be prepared so that it can simulate the real conditions of farmers. In this study, the SSM-iCrop2 model has been calibrated for the real conditions of farmers, and the purpose of this study is to use the SSM-iCrop2 model in simulating water performance and water balance for farmers.
 
Materials and Methods
In this study, the SSM-iCrop2 model was calibrated for farmers conditions using variables such as yield and harvest index, which are available for farmers’fields or are cheap to measure. The effect of factors such as pests and diseases, weeds and unsuitable nutrients, density and sowing date entered the model along with the calibration of three parameters of radiation use efficiency, maximum leaf area and maximum harvest index for farmers’ fields. Calibration was done by comparing the performance of farmers against the performance simulated by the model and by changing the parameters of radiation use efficiency (IRUE), maximum leaf area (LAIMX) and maximum harvest index (HIMAX). This calibration was done at Hashem Abad station in Gorgan for irrigated rice (paddy) and wheat. The simulated actual yield was calibrated with the actual yield. Due to the acceptable simulation of actual yields after calibration, it was presumed that other estimates made by the model are also reliable.
 
Results and Discussion
Measurement of water balance and other estimates of the model from growth and yield formation in the grower fields is expensive, but a calibrated model can estimate them at a low cost. In this study, it was shown that with the model calibrated for farmers' conditions, not other easily measured information (such as the irrigation water volume) can be obtained, with the assumption that the model accurately captures this information as well as performance. To evaluate the simulated real performance model, it was compared with the actual performance of farmers (Agricultural Jihad Report) after calibration. In addition to phenology, the SSM model simulates traits related to growth and yield, evapotranspiration values, irrigation water volume, runoff, available soil water during planting and harvesting, cumulative drainage, etc. The output of the model shows the amount of irrigation water is needed for a certain amount of performance in a given place (with specified rainfall and transpiration). The irrigation water volume calculated by the model was compared with the results of field tests from previous studies conducted by researchers at agricultural research centers. It was found that the model's output and the observed values were in good agreement. The root mean square error for rice and wheat was 216.6 and 157.6 kg per hectare, respectively, and the coefficient of variation and correlation coefficient were 4 and 85% for rice and 3 and 94% for wheat, respectively. Then, the irrigation water volume estimated by the model was evaluated and validated with the measured irrigation water volume in different crops (in Golestan province for different years). Based on the results of the evaluation, the coefficient of variation and the correlation coefficient for the simulated irrigation water volume were 8.9 and 98%, respectively, compared with the observed value. This calibration was done for rice (paddy) and irrigated wheat in the fields of Gorgan town, and the simulation and running were done using the meteorological statistics recorded in Hashem Abad weather station, Gorgan. Noting the fact that the actual yield has been simulated with good accuracy after the calibration, it was assumed that the other estimates of the model are also reliable. Thus, the calibrated model estimates them with low cost and appropriate accuracy and can complement field experiments.
 
Conclusion
This study discovered that the SSM_iCrop2 model, when calibrated for the conditions of farmers' fields, can accurately simulate both growth and yield traits as well as water balance characteristics. Notably, the model provides reliable estimates of irrigation water volume in farming scenarios, a crucial factor for agricultural planning and drought adaptation.

Abstract Introduction: Solar radiation on the earth surface has a wide range of applications in hydrology, agriculture and meteorology. Solar radiation is an important parameter of estimated models of reference crop potential evapotranspiration such as the Penman–Monteith equation. Also, total sunshine hours are one of the most important factors affecting climate and environment, and its long-term variation is of much concern in climate studies. Reference crop potential evapotranspiration is one of the most important parts of water cycle in the nature but, direct measurement of this crop parameter is so difficult and not practical. Therefore, equations that can estimate the value of evapotranspiration only by using meteorological data are necessary. As mentioned before, the Penman–Monteith equation can be used for estimating reference crop potential evapotranspiration, however this equation needs solar radiation data, and the measurement of solar radiation is done in a limited numbers of weather stations in Iran, and also in Fars province, south of Iran. Since, the measurement of solar radiation is expensive, therefore many models have been derived for its estimation in different climates of the world., Many investigators also have been tried to estimate solar radiation for different locations of the world based on more simple measured weather data such as air temperature (minimum, maximum or mean) and sunshine hours. Hence, the derived equations for estimating solar radiation based on other weather data can be used for estimating reference crop potential evapotranspiration with the Penman–Monteith equation. Materials and Methods: In this study, solar radiation was estimated in Shiraz, central part of the Fars province in south of Iran. For this purpose, the daily measured of solar radiation data in Shiraz synoptic station were used. Also, other needed weather data were used. All available data was for the years 2006 to 2010. Measured data of years 2006 to 2008 were used for calibrating fourteen estimated models of solar radiation in seasonally and annual time steps and the measured data of years 2009 and 2010 were used for evaluating the obtained results. The equations were used in this study divided into three groups contains: 1) The equations based on only sunshine hours. 2) The equations based on only air temperature. 3) The equations based on sunshine hours and air temperature together. On the other hand, statistical comparison must be done to select the best equation for estimating solar radiation in seasonally and annual time steps. For this purpose, in validation stage the combination of statistical equations and linear correlation was used, and then the value of mean square deviation (MSD) was calculated to evaluate the different models for estimating solar radiation in mentioned time steps. Results and Discussion: The mean values of mean square deviation (MSD) of fourteen models for estimating solar radiation were equal to 24.16, 20.42, 4.08 and 16.19 for spring to winter respectively, and 15.40 in annual time step. Therefore, the results showed that using the equations for autumn enjoyed high accuracy, however for other seasons had low accuracy. So, using the equations for annual time step were appropriate more than the equations for seasonally time steps. Also, the mean values of mean square deviation (MSD) of the equations based on only sunshine hours, the equations based on only air temperature, and the equations based on the combination of sunshine hours and air temperature for estimating solar radiation were equal to 14.82, 17.40 and 14.88, respectively. Therefore, the results indicated that the models based on only air temperature were the worst conditions for estimating solar radiation in Shiraz region, and therefore, using the sunshine hours for estimating solar radiation is necessary. Conclusions: In this study for estimating solar radiation in seasonally and annual time steps in Shiraz region, three groups of equations were used (1: based on only sunshine hours. 2: based on only air temperature, and 3: based on sunshine hours and air temperature). Final results of this study for estimating solar radiation in Shiraz region were: 1) For autumn season the best equation was based on the extraterrestrial radiation, the ratio of daily actual sunshine hours to daily maximum sunshine hours, and minimum and maximum air temperatures. 2) For annual time step the best equation was based on the extraterrestrial radiation and the ratio of daily actual sunshine hours to daily maximum sunshine hours.

Abstract Introduction: The range of meteorological parameters, such as temperature, are different at different scales. Fractal geometry is a branch of mathematics that has many applications in the field of discrete and continuous domains. Downscaling may be done by different methods, including univariate, multivariate regression functions, splined function and fractal function. Finding the best model for fractal downscaling, is needed to implement the distance between measured and modeled data sets. This distance may be estimated by different methods, including Euclidian. For temporal downscaling, the data are two-dimensional, i.e. time and that of principal variable (e.g. temperatures).In such a case, the dimensionality problem arises in Euclidean space. In these cases, data are usually changed to non-dimensional forms which are referred to standardization, normalization, scaling, or non-dimensionalizing. So, in addition to imbalance of data calculating distance between two sets, we are also considering the impact of standardized data on the number of interpolation points, run time, and accuracy of downscaling the temperature of Mashhad synoptic station. Materials and Methods: In this paper, fractal model was used for modeling and downscaling temperature datasets for the period of 2007- 2009 at Mashhad Synoptic stations with two approaches of Hasdurf distance to determine the interpolation points (first approach: in first approach original data was used. Second approach: in second approach the data were standardized). We adopted some criteria, such as root mean squared error, correlation, and Akaike information criteria to assess the accuracy of fractal downscaling. Mashhad is the second most populous city in Iran and capital of Razavi Khorasan Province. It is located in the northeast of the country, close to the borders of Turkmenistan and Afghanistan. It is built-up (or metro) area was home to 2,782,976 inhabitants including Mashhad Taman and Torqabeh cities. It was a major oasis along the ancientSilk Road connecting with Merv in the East. The city is located at 36.20º North latitude and 59.35º East longitude, Mashhad features a steppe climate with hot summers and cool winters. The city only receives about 250 mm of precipitation per year, summers are typically hot and dry, with high temperatures sometimes exceeds 35 °C (95 °F). Winters are typically cool to cold and somewhat humid, with overnight lows routinely dropping below freezing. At first, fractal method was used to produce daily temperature from daily datasets with two attitude and different interval interpolation (5, 10, 15days). Then the same process was applied to produce 3-hours temperature. Results and Discussion: 1. Downscaling for daily temperature: In this part, we considered that which standardizing approach and which interval interpolation, will carry the best accuracy for the fractal modeling. Although RMSE, R2, AIC, show that standardized approach is not better, but the difference is not substantial. Results from fractal modeling from 5-day interval interpolation and 10-day interval interpolation with daily measured temperature in Mashhad compared based on 1:1 line of perfect agreement, and showed acceptable (=5%) behavior. In both approaches and two interval interpolation with both 5 and 10 days, predicted temperatures imitate the behavior of the measured temperatures. However, simulation with no standardization approach show better results for both distance interpolation compared to the second approach with standardization. 2. Downscaling daily temperature to 3-hour interval: We compared downscaled 3-hour temperature from two standardizing approaches and two timesinterpolation based on daily temperature with 3-hour measured temperature and compared the results with respect to 1:1 line of perfect agreement. It is clear that the results of the three-hour downscaling show the same results with daily downscaling, because temperature shows the fractal behavior. Although both approaches perform well but un-standardizing is better, yet the difference is not pronounced. Conclusion: Overall, in both approaches, three-hour and daily downscaling is done precisely and with high quality. The number of interpolation points was reduced by 30% under the second standardizing approach, which followed by considerable computer runtime. However, the result shows that the first approach had better modeling. The comparison results of the modeling with 5 intervals interpolation and with 10, the 10 intervals interpolation were more acceptable, such that correlation coefficient was between (first approach: 0.98 and 0.7, second approach: 0.98 and 0.65) while RMSE was between (first approach: 1.33 and 3.27 ° C and second approach: 1.44 and 6.02 ° C), and AICc was between (first approach: 0.55-3.27 and second approach: 2.87-3.51).The intercepts and slopes of regression lines between measured and predicted temperatures were not statistically (5% level of significant) different from 0 and 1, respectively.

Abstract Introduction Water is a primary and fundamental need for survival, industrial development, and economic prosperity. In other words, the key to development depends on the expansion of water resources and their optimal use. To achieve this, the correct allocation of water resources to different uses based on priorities is of great importance (Loucks and Van Beek, 2017). Any management planning to control water consumption in the agricultural sector requires a correct understanding of the mutual influence of variables controlling water resources and consumption on each other in order to ensure optimal provision of agricultural water needs and also to ensure the improvement of the economic situation of farmers (Veysel, 2024). The purpose of this study is to examine and compare available water resources and uses, including agricultural, drinking, industrial, and environmental needs, for the Tajan River basin, including the two parts of the Tajan Plain and the river basin up to the entrance to the plain during the exploitation season, in order to determine the possible shortage of water supply in different months. It is worth mentioning that the results presented in the report on the study of water resources and needs of the Tajan River Basin (Pandam Company, 1402) were used to prepare this article.   Materials and Methods The Tajan River is one of the important rivers of Mazandaran Province, which originates from the Hezar Jarib Mountains and flows into the Caspian Sea after passing through the city of Sari in Farahabad. The enJulye catchment area of this river up to the entrance to the plain with an area of about 4050 square kilometers and the Tajan Plain with an area of about 800 square kilometers, has been considered as the study area to investigate water resources and uses. In this study, long-term statistical data from hydrometric stations of the Zaremroud (Garm Rud Station), Lajim (Vastan Station), Chahardangeh (Varand Station), and Tajan (Kordkheil Station) rivers, as well as the inflow and outflow statistics of Shahid Rajaee Dam (during the ten-year operation period of 1390-1400) as the main source of water supply for the Tajan basin, have been used. For groundwater resources (wells), information obtained from the Mazandaran Regional Water Company in 1400 and basic water resource studies have been used. Regarding water ponds, the results of the interpretation of new satellite images in the form of a land use map have been used.   Results The results of the surveys show that in the entire study area, including the Tajan River basin to the entrance to the plain and the lands of the Tajan Plain, there are about 119,800 hectares of pure agricultural land in the form of irrigated and dry-land cultivation, of which 74,500 hectares are irrigated and the rest are dry-land cultivation. There are fish farming ponds with a total area of 550 hectares in the Tajan Plain, which are generally related to warm-water fish. Also, some of the ponds located in the area are used for aquaculture. The total water requirement of the Tajan Plain area (agriculture and aquaculture) is 492 million cubic meters, and in the upstream lands (the Tajan basin to the entrance to the plain), this requirement is estimated to be 106 million cubic meters. The total drinking, industrial and tourism drinking needs of the region (Sari, Miandoroud and Kiasar counties) are 7.68 million cubic meters per year. The estimated environmental demand of the Tajan River is also equivalent to 100 million cubic meters per year. Available water resources for various uses include the regulated water flow of the Shahid Rajaee Dam, the seasonal flow of the rivers in the middle basin, dam water storage, and groundwater resources. To compare uses with available water resources, three comparison levels including normal, dry, and very dry water years have been used. The volume of water that can be extracted from the Shahid Rajaee Dam in the first six months of the year for normal, dry, and very dry water years is 231, 194, and 122 million cubic meters, respectively. The volume of water that can be extracted from ponds and wells located in the area are estimated to be 12.8 and 176 million cubic meters per year, respectively.   Discussion and Conclusion A comparison of water needs and available resources indicates that the total water shortage in the Tajan Basin is 166, 231, and 324 million cubic meters in normal, dry, and very dry years, respectively. Similarly, in the Tajan Plain area, the shortages are estimated at 147, 212, and 305 million cubic meters for the same conditions. In other words, in a normal or normal water year, there is a water shortage of about 150 million cubic meters in the irrigation network and the Tajan Plain area. The reduction in available water resources, including decreased outflow from the Shahid Rajaee Dam, leads to resource constraints and consequently causes water shortages in the lands of the Tajan Plain. In the dry water year, the water shortage was mainly due to the decrease in discharge from the Shahid Rajaee reservoir dam and the rivers of the middle basin. Therefore, in addition to the necessity of managing water distribution and scheduling, as well as improving the Tajan irrigation network, which will partially reduce the amount of damage caused by water shortage, the construction of the planned dams on the Zaremroud and Chahardangeh rivers is very important in regulating the monthly discharge.

Abstract Introduction
Wheat (Triticum aestivum L.) has become very important as a valuable strategic product with high energy level. The importance of investigating environmental stresses and their role in predicting and evaluating the growth and crops yield is essential. A wide range of plant response to stress is extended to morphological, physiological and biochemical responses. Considering the rapid advancement in computer model development, plant growth models have emerged as a valuable tool to predict changes in production yield. These growth simulation models effectively incorporate the intricate influences of various factors, such as climate, soil characteristics, and management practices on crop yield. By doing so, they offer a cost-effective and time-efficient alternative to traditional field research methods.
 
Material and Methods
This research was conducted in the research farm of Varamin province, which has a silty loam soil texture. The latitude and longitude of the region are 35º 32ʹ N and 51º 64ʹ E, respectively. Its height above sea level is 21 meters. According to Demarten classification, Varamin has a temperate humid climate. The long-term mean temperature of Varamin is 11.18 ° C and the total long-term rainfall is 780 mm. In this study, in order to simulate irrigated wheat cv. Mehregan growth under drought stress, an experimental based on completely randomized blocks (CRBD) including: non-stress as control (NS), water stress at booting stage (WSB), water stress at flowering stage (WSF), water stress at milking stage (WSM) and water stress at doughing stage (WSD) with three replications during growth season 2019-2020 was carried out in Varamin, Iran. Crop growth simulation was done using SSM-wheat model. This model simulates growth and yield on a daily basis as a function of weather conditions, soil characteristics and crop management (cultivar, planting date, plant density, irrigation regime).
 
Results and Discussion
Based on the results, the simulation of the phenological stages of irrigated wheat cv. Mehregan under water stress condition using SSM-wheat model showed that there was no difference between observed and simulated values. Summary, the values of day to termination of seed growth (TSG) were observed under non- stress, stress in the booting stage, flowering, milking and doughing of the grains, 222, 219, 219, 221, 221 days, respectively andsimulation values with 224, 221, 220, 221, respectively. However, with their simulation values, there were slight differences with 224, 221, 220, 221, respectively. Acceptable values of RMSE (11.7 g.m^-2) and CV (3.5) indexes showed the high ability of the SSM model in simulating the grain yield of irrigated wheat cv. Mehregan under water stress conditions. Grain yield values were observed in non-stress conditions of 5783, water stress in booting, flowering, milking and doughing of the grain stages in 5423, 5160, 5006 and 5100 kg. h^-1, respectively. While the simulated values were 5630, 5220, 4920, 4680 and 4880 kg. h^-1, respectively. Based on the findings, observed and simulated values of leaf area index (LAI) were observed under water stress condition in the booting, flowering, milking and doughing of the grain stages (4.3 and 4.47), (4.33) and 4.46), (4.4 and 4.57) and (4.4 and 4.58) cm^-2, respectively. Evaluation of the 1000-grain weight of irrigated wheat cv. Mehregan under the water stress showed that the SSM model was highly accurate. RMSE (4.6 g.m^-2) and CV (1.8) values indicate the ability of the SSM model to simulate the 1000-grain weight of irrigated wheat cv. Mehregan. Also, the simulated values of the harvest index were 34.7 % in non-stress conditions, which decreased by 6 % compared to the observed value. Harvest index values were observed under water stress conditions in the in the booting, flowering, milking and doughing of the grain stages in 30.2, 29.3, 29.9 and 29.5 %, respectively. Compared to its observed values, it was reduced by 3, 3.5, 5, and 5.5 %, respectively.
 
Conclusion
Based on the findings, the slight difference between the observed and simulated values demonstrates the SSM model's capability to accurately capture water stress impacts on the phenological stages, grain yield, and yield components of irrigated wheat cv. Mehregan during critical growth stages, including booting, flowering, milking, and doughing. The results indicate that the SSM model is effective in simulating wheat growth under water stress conditions, showcasing its potential as a valuable tool for modeling irrigated wheat growth. The model's ability to account for water stress and its effects on various growth parameters makes it a reliable and efficient tool for predicting crop performance in water-limited environments.

Abstract Introduction: Surface irrigation systems are the oldest and common irrigation method. Surface irrigation is of low cost and energy requirements compared to sprinkler and drip irrigation systems. In general, a main large number of fields' data is needed to show the farm average condition. Infiltration parameters are one of the most important parameters in surface irrigation systems and it has led to increase the irrigation systems efficiency, especially since the characteristics of infiltration vary with time and place. The modified kostiakov-lewis equation is one of the most useful infiltration equations in surface irrigation. In the current study, the infiltration parameters of the modified kostiakov-lewis equation were determined with two sets of usual methods including direct methods such as two-point Elliot and Walker and Input-Output, computer models such as SIPAR_ID and IPARM. Finally, the results were compared with the results of field experiments. Materials and Methods: The current field was irrigated three times from 14 September to 31 October 2016 at the R 5-22 farm located in Salman Farsi Agro-Industry sugarcane fields with age of Raton 2. To collect the required data, the fields experiments were conducted on nine furrows of 250 m in length, 1.83m in space and 0.04% in slope, which all furrows were irrigated under three events and three inflow (1, 1.5 and 2 l/s), and fields’ data were obtained from experimental measurements during summer and autumn2016 at sugarcane fields of Salman Farsi Agro-Industry %. In the current study, the inflow rate and runoff were measured by W.S.C type 1 and 2 and all furrows divided into 10 stations. The advane time and infiltrated depth were measured at each stations. In this study 18 furrows were considered, nine furrows were used for testing and the other furrows had buffer roles.  The furrows were irrigated by closed-end method. In this study, three indicators of infiltrated volume in the root zone, advance time and runoff volume were used to evaluate the accuracy of estimation of infiltration parameters. Surface irrigation model: WinSRFR 4.1.3 was used to simulate irrigation phases and infiltration value in each method. In this study, zero inertia model was used for simulation. Results and Discussion: Results of this study showed that using the direct methods to estimate the infiltration parameters in WinSRFR 4.1.3 software improves the simulation process significantly. The results of the Two- Point and Input-Output method were showed a little difference with the results of the WinSRFR 4.1.3 software in simulation of the closed-end furrow irrigation process with sugarcane cultivated in furrows. The direct methods for infiltration parameters in furrow irrigation showed more accuracy than computer models in advance time , runoff and infiltrated water volumes. According to the results of this study, the Two-Point method in estimation of advance time with mean of RMSE, MAE and RE of 10.52, 14.91 and 10.1%, infiltrated water volume with mean of RMSE, MAE and RE of  9.6, 7.36 and  7.8 and runoff volume with mean of RMSE, MAE and RE of  8.8%, 8.7% and 1.2%, had a very acceptable performance.  Also, the RMSE and RE values of other direct method (input-output method) were 11.4% and 6.8% for infiltrated water volume, respectively, and 1.6 and 0.3% for runoff volume, respectively, shows that this method has high accuracy in estimating these two performance indicators although this method with an average of 25.11% and 27.2%  was not able to accurately simulate advance time. On the other hand, the results of computer models showed that the IPARM model with the average mean absolute error and relative error was 23.33, 15.5% of the advance time, 20.02 and 26.7% of the infiltrated volume and 11.81% and 1.8% estimated runoff volume, which was better than the SIPAR_ID model. Although computer models had acceptable performance in estimating infiltration parameters, direct methods performed better due to the use of more input data and data from all stages of irrigation. In general results of this study were showed that, if the direct methods for infiltration equations used Instead of the computers models in the designing, simulation and evaluation of the furrow irrigation systems, increased the accuracy of results to significantly and will improve and increase irrigation performance indicators.

Abstract Introduction
The world population has grown rapidly over the last 150 years and continues to do so, resulting in impacts on hydrologic resources at both a local and global scale (Yang et al., 2012). The competition for water between humans and ecosystems leads to complex interactions between hydrologic and social systems (liu et al., 2015). From the beginning of human history, it is located in floodplains. Floods can have large societal impacts, such as severe damage to urban areas, which are expected to grow around the world (Alfieriet al., 2018). In traditional hydrology, humans are either conceptualized as an external force to the system under study or taken into account as boundary conditions (Peel and Blöschl, 2011). Sivapalan et al. (2012) proposed a new model for investigating the interactions of the hydrological system and the social system. It explores the procedure coupled human-water system evolves and possible trajectories of its co-evolution, including the possibility of generating emergent, even unexpected, behaviors. Socio-hydrology must strive to be a quantitative science. There are several methods to control and mitigate flood risk, one of these methods is flood zoning (Jha et al., 2012). In last two decates, The Kalat city is flooded almost every year and many houses and historical sites in the city are damaged. Therefore, the main purpose of thisWe paper is to show investigated how changing human behavior with nature can affect the behavior of the natural system.
Method and Materials
Kalat city located in 59° 43' 23" to 59° 47' 41" northern latitude and 36° 59' 35" to 37° 00' 05" eastern longitude. The city is divided into 11 sub-basins. The city has experienced fast and inappropriate urbanization over the past few years. To collect our data, the annual reports of the Regional Water Organization and the Environment Organization of Khorasan Province were used.
SCS method was used to estimate the runoff peak discharge. Precipitation has been estimated for seven return periods: 2, 5, 10, 25, 50, 100, and 200 years. In this study, to analyze the sensitivity of runoff, we considered precipitation and curves number from 20% less to 20% more than the actual values in the study basin (at intervals of 5 %). We used the Cowan method to determine the roughness coefficient in this study. HEC-RAS model has been used for flood zoning. To determine the impact of various factors on the intensification of floods in Kalat city, we obtained questionnaires from relevant authorities. Likert scale was used to measure the results of the questionnaires. We prepared two questionnaires; first one is related to the inner city zone and includes the factors that intensify the occurrence of floods inside the city of Kalat, and it was classified into the following parts: 1) Local community 2) Managerial 3) Physical; and the second one includes the factors that intensify the flood in the upper part of Kalat city. We classified these factors into three parts: 1) Non-local community 2) Managerial 3) Environmental .
Results and Discussion
Results of sensitivity analyzes demonstrated that land-use and land cover change had a further effect on peak discharge. In sub-basin 1, by 20% increase in the curve number, the level of peak dumping increased by more than 111%, with a return period of 2 year; while a 20% increase in precipitation, in the same return period, rises the peak discharge only 3%. The peak discharge time in some sub-basins was brief due to the presence of impermeable surfaces, so that in sub-basins 4, 6, 7, and 8, the peak discharge time was less than 30 minutes. These results highlight the dangers of these floods and the need for proper flood planning and management in these sub-basins. The results of the Manning coefficient demonstrated that we can reduce flood damage by applying management measures in the future, as well as paying attention to the feedback between urbanization and the flood zone. Roughness control by applying management programs can reduce the area of flood zones to 0.1 square kilometers. In this case, buildings should be removed from the river, and there should be no structure in the path of the river. According to the questionnaires in the inner city part, the most fundamental factor in intensifying the flood damage was related to “activities of local people” with the average of 3.59. In the upper part of the city, the most influential factors were ascribed to “managerial factors” with the average of 3.79.
Conclusion
In a general conclusion, it can be concluded that the role of human factors in the occurrence and intensification of floods was much greater than rainfall. Therefore, in order to manage and control floods, it is necessary to prevent the change of land use and the reduction of permeability. And management programs should be aimed at increasing surface permeability. We suggest that more research be done on the role of economic and social factors in increasing flood risk in other climate zones.

Abstract Introduction: Due to the rapid rate of population growth, water resource topics wasmainly affected by the economic and social components, however, the importance of environmental issues in such projects has gained more attention. As pollution loads are increasing, it has become more essential to incorporate water quality in water resource management issues. Under this condition, optimal water allocation by considering multiple objectives of water quality and quantity issues can lead to sustainable and optimal benefit of stakeholders. This study was done in order to balance environmental and economic concerns in water resource allocation. Materials and Methods: Based on game theory concepts and fuzzy programming procedure, two new methodologies were developed for sustainable water resource allocation in river systems. The proposed methods which include a multi-objective bargaining and fuzzy programming approaches were utilized to analysis strategies of interaction between environmental protection and economical income. Two groups of players, consists of player 1 for environmental and player 2 for economic issues were considered in order to apply the developed models. As players will not be satisfied with the outcome of each other, they will begin the bargaining process. Throughout the bargaining rounds, players will reduce their expectations. After several negotiations, the interval between the reset goal values and outcomes will be decreased. The bargaining process will be finished if final solutions reach to the determined goals. In the study, the Total Dissolved Solids (TDS) were considered as water quality indicators of environmental objective function, since salinity is the important problem of the study area. Using crop production function in economic income objective function makes it possible to incorporate deficit irrigation in different crop growth stages. Since allocation problems include many decision variables, conventional (non-linear) crop production function will have high computational costs and linear form of it can reduce the complexity of the optimization model. Therefore,additive (linear) form of crop production function was taken into consideration instead of multiplicative form. Total pollution load discharged into the river (ton per year) and economical income of the system (thousand dollars per year) wasconsidered as environmental and economic values, respectively. During the fuzzy programming procedure, the purpose is to achieve a compromise solution. In this approach, the individual maximum and minimum values of objectives is used to define the membership function. This procedure will maximize the satisfaction degree of the constructed membership functions of the objectives. The presented methodology was illustrated in a part of Karoon-Dez river system between Gotvand dam, Dez dam and Ahvaz city, as a case study. The area of Karoon-Dez river basin is about 67000 square kilometers and it is located in the southwestern part of Iran. The selected area includes 8 agro-industrial and 3 traditional agricultural sub-sectors. Results and Discussion: Using a linear form of crop production function for calculating the total benefit of the system leads to significant reduction in run-time of the optimization model and make irrigation programming possible by regarding crop growth stages and the available water amount. The results of this study showed that Nash equilibrium, which provides a base for decision makers to choose a strategy, was reached at the fourth round of bargaining process. Moreover, balance between economic and environmental objectives is available by reducing economical expectation and environmental concerns from 553636 to 496216 thousand dollars per year and from 68264 to 87251 tons per year, respectively. In these cases, the annual allocated water to environmental and economical player will be 6123 MCM (5318 to agro-industrial sub-sectors and 805 to agricultural sub-sectors) and 6453 MCM (5730 to agro-industrial sub-sectors and 723 to agricultural sub-sectors) respectively. The results of the fuzzy programming approach demonstrated that at optimal condition, environmental and economic objective function was 85999 tons per year 500422 thousand dollars per year, respectively and allocated water to water users are 6354 MCM per year (agricultural and agro-industrial sub-sectors of the system will be (763 and 5591 MCM per year). Agro-Industrial sub-sector 3 will take the maximum allocated annual water (1789 MCM per year) and Agro-Industrial sub-sector 5 will receive the minimum annual allocated water (151 MCM per year). Comparison of two investigated approaches showed that their results are in agreement with each other. Conclusions: Results of applying the developed methodology to the Karoon-Dez river system demonstrated that it is effective and applicable to determine sustainable water allocation policies. Finding of this study reveals that the proposed framework can facilitate decision-making process and optimize allocated water to different water users under conflicting objectives. Therefore, the developed procedure can be used as a managerial tool for optimal water allocation strategies, which is in accordance with sustainable development approach. It is easy to apply the presented methodology to other river systems with high pollution loads of agricultural return flows.

Abstract Introduction: Determining the amount of watershed sedimentation and its spatial distribution by using field measurements in practice faces a serious challenge. In recent decades, hydrological models have been widely used by hydrologists and water resource managers as a tool for analysing water resource management systems. The SWAT model is one of the semi-physical and semi-distributed hydrological models that have been widely used in recent years. Despite the wide use of the SWAT, simulation of the sediment has been associated with a large error in comparison to flow. These errors may come from using empirical methods such as the sediment rating curve for estimating sediment based on measured data. Therefore, in this research, the capabilities of the genetic algorithm (GA) were used to optimize the relationship between discharge and sediment and further optimal equation used for calibration and validation of the model. Materials and Methods: The studied area is Fariman dam watershed with an area of 278.8 km2 which is located at latitude of 35 ˚ 33' to 35˚ 41' and longitude of 59 ˚ 34' to 59 ˚ 44' in Razavi Khorasan province. In this study, SWAT model was used to simulate runoff and sediment yield of Fariman dam watershed. In order to run the model, meteorological and hydrometric data including daily rainfall and maximum and minimum temperatures and sediment yield and discharge data, soil and land use maps of the watershed were achieved from relevant resources. The capabilities of the genetic algorithm were used to optimize the discharge -sediment relationship and were compared with sediment rating curve. For this purpose, optimization problem was defined for the genetic algorithm in MATLAB software as a search space of continuous values of the discharge –sediment coefficients. After that, sediment yield was extracted based on discharge data and calculated monthly sediment for SWAT calibration and validation. Sensitivity analysis, calibration and validation of the model were performed using the SUFI-2 algorithm using SWAT-CUP software. For this purpose using high sensitive parameters, the model was calibrated and validated for the period of 1991 to 2000. Results and Discussion: Optimal coefficients extracted by GA indicate a better performance of the genetic algorithm in estimating the sediment yield. The comparative results of the sediment estimation models, revealed better performance of the genetic algorithm with RMSE = 70.9, NSE =0.46 and R2= 0.72 than the sediment rating curve. According to senetivity analysis of SWAT model, twelve parameters for stream flow and seven parameters for sediment yield were found to be sensitive. The most sensitive parameters for stream flow were SCS runoff curve number (CN2), effective hydraulic conductivity in tributary channel (CH_K1) and base flow alpha factor for bank storage (ALPHA_BNK) and the most sensitive parameters for sediment yield were peak rate adjustment factor for sediment routing, USLE equation soil erodibility factor (USLE_K), sediment concentration in lateral flow and groundwater flow (LAT_SED) and exponent parameter for calculating sediment reentrained in channel sediment routing (SPEXP). The SWAT calibration and validation results showed that the Nash-Sutcliffe efficiency index for monthly sediment and discharge for calibration period was 0.75 and 0.73, respectively and in the validation period was 0.85 and 0.76, respectively. Calibration and validation of the SWAT model was done with genetic algorithm model as an optimal method for deriving sediment data from measured daily discharge. The Nash-Sutcliffe efficiency coefficient for monthly discharge was 0.75 and 0.85 in the calibration and validation periods. Nash-Sutcliffe efficiency coefficients for monthly sediment yield were 0.86 and 0.81 for the same periods. SWAT evaluation results indicate that the model simulation is acceptable for predicting sediment yield and river flow. The performance of SWAT model in predicting of sediment in low flow is poor, which can be due to the effect of the parameters and model simplifications in the simulation of the sediment load. Conclusions: In this research, simulation of runoff and sediment flow for Fariman dam watershed was performed using SWAT model. For this purpose, the capabilities of the genetic algorithm were used to optimize the relationship between discharge and sediment yields; then the results were used to calibrate and validate the SWAT model. The results indicate that genetics algorithm can be used for optimizing coefficient of sediment discharge equation and the result is better than sediment rating curve. Simulation of watershed hydrology using SWAT shows that the capability of the model in prediction of sediment yield and water flow is good. Using genetic algorithm to optimize the relationship between discharge and sediment has an important role in extracting daily sediment yield and simulation accuracy of the model. Also, the use of evolutionary algorithms can have a significant role in extracting the discharge -sediment relations, which usually is accompanied with a large error in experimental models such as a sediment rating curve.

Abstract Introduction Due to Iran's geographical location and climatic conditions, the quantity and quality of water resources are considered one of the limiting factors for agriculture in this country. Droughts in the last two decades, on the one hand, and lack of attention to the optimal use and proper exploitation of water, on the other hand, have exacerbated the water crisis in Iran. For this reason, the agricultural sector has witnessed serious developments and new perspectives on the rational exploitation of water resources, limited irrigation shortages, the use of saline water resources in agriculture, changing irrigation systems, and cultivating water-intensive plants over the same period. Quinoa has been introduced as a forage crop for ensuring food security in the world, which can tolerate drought stress conditions to some extent. However, the development of its cultivation under drought stress conditions in Khuzestan Province should be based on determining the limits of irrigation water quantities and determining its tolerance to salinity.   Material and Methods The present study was conducted to investigate the effect of different amounts of irrigation water and different levels of salinity on quantitative and qualitative parameters of quinoa. To carry out the work, quinoa was cultivated under drip and pulsed drip irrigation. The treatments studied included irrigation water quantity (I1: 60, I2: 80 and I3: 100% of field capacity), water quality (F (fresh): 0.5 and S (saline): 6 dS/m), and two irrigation managements: continuous drip (C) and pulsed drip (P). At the end of the growing season, sampling was performed to determine quantitative plant characteristics such as height, stem diameter, leaf area index, root length, root volume, fresh and dry root weight, and fresh and dry forage yield. Also, to investigate the effect of treatments on quinoa forage quality, qualitative parameters including leaf chlorophyll a and b content, leaf proline content, total digestible nutrients (TDN), crude protein (CP), Neutral detergent fiber (hemicellulose and lignin) (NDF), and Acid detergent fiber (hemicellulose-free cell wall) (ADF) percentage were measured. To investigate the distribution of salinity in the soil profile during and at the end of the growing season compared to its beginning, soil samples were taken from dug profiles in the center of all experimental plots at depths of 0-30 cm and 30-60 cm. These samples were transferred to the laboratory and saturated extraction was prepared from them. Then, the electrical conductivity of these samples was determined using an EC meter. All data collected from the experiment were entered into EXCEL 2019 software. After categorizing the data, SAS 9.1 software was used to analyze them. Data analysis of variance was performed at the 5% and 1% significance levels, and then means were compared using Duncan's multiple range test.   Result The results showed that the treatments of continuous drip irrigation with fresh water at 100% depth, and pulsed drip irrigation at 100% depth (first, second and, third pulses of fresh water) had the highest quantitative traits. Continuous drip irrigation with fresh water at 80% depth, and pulsed drip irrigation at 80% depth (first, second and, third pulses of fresh water) also had high quantitative traits. The highest values of plant height, stem diameter, leaf area index, fresh biomass, and dry biomass were 94 cm, 1.10 mm, 23.152 cm², 25.31420, and 14.8256 tons per hectare, respectively, which were obtained from the continuous drip irrigation treatment at 100% of the plant's water requirement using fresh water. In these treatments, the final soil salinity was close to the initial salinity at the time of the experiment, and the highest amounts of chlorophyll a and b and carotenoids were also observed. The TDN and ADF values were high in two treatments: continuous drip irrigation with fresh water and 100% depth, and pulsed drip irrigation and 100% depth (first, second and, third pulse of fresh water). However, these treatments had low soluble sugar, proline, and protein levels. Applying saline water alone or in combination with sweet pulses and water stress in treatments 2, 4, and 12- 30 increased the quality of the produced forage (due to high soluble sugar, proline, and protein). The highest water use efficiency was obtained from treatment 26, which included pulsed drip irrigation and a depth of 60% (first pulse of fresh water, second pulse of salin water, third pulse of fresh water).   Conclusion Therefore, considering that both water use efficiency and quality are important in forage production, it is recommended to use this treatment under conditions of saline water and pulsed drip irrigation.

Abstract Introduction: Iron is one of the essential micronutrients for plant growth. The total amount of iron in soil is often more than plant iron requirement, but the low solubility of iron compounds in many of soils leads to low uptake of this element by plant and eventually, results in iron deficiency symptoms in plant. Iron is the structural component of cytochromes, leghemoglobines and ferredoxins. This element participates in many vital activities of plants, such as photosynthesis, respiration and fixation of molecular nitrogen. Some of micaceous minerals including muscovite and phlogopite which contain significant amounts of iron are plentiful in soils of arid and semiarid regions of Iran. The purpose of this study was to evaluate the ability of two plant species (alfalfa and barley) to uptake structural iron from muscovite and phlogopite. Materials and Methods: The greenhouse experiment was conducted as factorial arrangement based on completely randomized design with three replicates. Treatments consisted of two plant species (alfalfa and barley), two types of micaceous minerals (phlogopite and muscovite) and two nutrient solutions (complete and iron-free).The experiment was done in 700 g pots containing a mixture of quartz sand (as the filling material), cocopeat and micaceous minerals (phlogopite and muscovite). Quartz sand and micaceous mineral were obtained from a mine near Hamadan City in Iran. For this purpose, X-ray elemental analysis fluorescence (XRF) was used to investigate the possibility of using quartz sand and micaceous mineral. Micaceous minerals were passed through a 140 mesh sieve and then, samples were saturated with Ca using a 0.5 M CaCl2 solution. To remove the excess Cl, saturated minerals were washed with distilled water several times and then samples were oven dried at 105 °C. Pots were filled with a mixture of 600 g quartz sand, micaceous mineral and cocopeat. The amount of mineral was added until there was 0.35% K2O in all pots. Two barley and alfalfa seeds were planted in each pot. During the growth period (150days), plants were irrigated and fed with distilled water and nutrient solutions, respectively. At the end of the growth period, shoots and roots of plants were harvested andiron contents of plants extracts were measured by atomic absorption. Results and Discussion: For two plant species, the results showed that iron concentration in the pots containing phlogopite and fed with iron-free nutrient solution was in a sufficient range for both barley and alfalfa. The amount of iron uptake by alfalfa in both substrates and nutrition solutions was more than barely. It seems that alfalfa is able to uptake more amount of iron due to the abundant root exudates. The highest amount of iron uptake by root is related to alfalfa cultivated in substrates containing phlogopite and fed with iron-free nutrient solution. The highest barley shoots weight is related to substrates containing phlogopite and muscovite fed with complete (with iron) nutrient solution, whereas in alfalfa, the highest shoot weight is related to phlogopite-containing substrates fed with iron-free nutrient solution. Plants cultivated in two substrates containing phlogopite and muscovite did not show deficiency symptoms until late growth period and appearance of plants fed with iron-free nutrient solution was completely similar to those fed with complete nutrient solution. The amount of iron uptake by roots is several times higher than that of shoots. High uptake of iron by plant roots are affected by phytosiderophores produced by plant roots. Phytosiderophores produce chelate Fe (III) in the rhizosphere. These chelates are absorbed into the apoplast of roots and Fe (III) is separated from them as a result of certain reactions, and takes the path to xylem. Conclusion: The results of this study indicate that iron structural phlogopite and muscovite minerals can provide iron requirement for plant during the growth season. Since phlogopiteis a tri-octahedral mineral, it has more Fe (II) and its structure is weaker than muscovite, and hence, is able to provide more iron for the plant during growth season. But muscovite is di-octahedral and its structure contains Al+3, so octahedral may not easily release its elements into the rhizosphere for the plants utilization. The factors influence the release of elements from micaceous minerals are structure and type of mineral. Alfalfa is able to release more iron from micaceous minerals thanks to its root systems and ability to produce more shoot. Since micaceous minerals have considerable amount of iron and are able to provide iron requirement for plant during growth season, it is recommended to investigate whether micaceous minerals are able to supply this element for longer growth periods.

Abstract Introduction: Heavy metal contamination not only adversely affects the chemical properties, availability of nutrients and biological activity of the soils, but also causes serious risk to the human health from entering the food chain. Cadmium as an unnecessary heavy metal is highly toxic to plants. Cadmium toxicity inhibits plant growth and even death. Metabolic processes such as photosynthesis and cellular respiration are disturbed due to cadmium toxicity. Among the heavy metals, zinc is an important nutrient in many biological processes such as photosynthesis, activity of antioxidant enzymes, proteins, hormones and other activities. Because of the similar chemical behavior of cadmium and zinc, interaction between the two metals is of interest to many researchers. Materials and Methods: In this study, to investigate the interaction effects of cadmium and zinc on shoot and root dry matter and chemical composition of corn (Zea mays cv. single cross 704), a factorial experiment as a randomized complete block design in triplicate with eight levels of cadmium (zero, 0.5, 2.5, 5, 10, 20, 40 and 80 mg Cd kg-1) and eight levels of zinc (zero, 5, 25, 50, 100, 200, 400 and 800 mg Zn kg-1) was conducted in a loamy sand soil under greenhouse conditions. After 60 days, the plants were harvested and dry weights of shoots and roots were determined. Moreover, after wet digestion, the concentrations of cadmium, zinc, iron, manganese and copper in these tissues were determined by flame atomic absorption spectrometry (Shimadzu-6300). Results and Discussion: Treatments with 800 mg Cd kg-1 showed symptoms of cadmium and or zinc toxicity at early stages of the growth. These plants died after 10 to 20 days of germination. The results showed that the cadmium and zinc interactions on shoot and root dry weights were significant. At 0.5, 2.5, 20 and 80 mg Cd kg-1 (except for Cd0.5-Zn25), application of 5 to 50 mg Zn kg-1 increased shoot dry weight. Higher levels of zinc supplementation exhibited adverse effects. At 5 and 10 mg Cd kg-1, supply of 5 to 100 mg Zn kg-1 was associated with an increase in shoot dry weight, but shoot growth was reduced at higher zinc levels. At 40 mg Cd kg-1, application levels of 5 to 200 mg Zn kg-1 increased shoot dry weight, whereas 400 mg Zn kg-1 showed adverse effects. Moreover, the cadmium and zinc interactions on chemical composition of corn were significant. Based on the results, at low levels of cadmium, zinc supplementation at each level increased the shoot and root cadmium concentrations, while at high levels of cadmium, low and high zinc supply caused a decrease and increase in the shoot as well as root cadmium concentrations, respectively. The concentration of a particular trend was observed on the shoot and root. Supplementation of zinc at each level of cadmium (except for 80 mg Cd kg-1), first increased and then decreased the iron concentration of shoots and roots. Application of zinc at each level of cadmium decreased manganese and copper concentrations in shoots and roots. Conclusions: According to the results, the ecological tolerance of corn to zinc was found to be 800 mg Zn kg-1. Also, the application level of zinc with positive effect on shoot dry weight increased with an increase in cadmium level. At all levels of cadmium, supplementation of zinc at medium levels prevented the accumulation of cadmium in shoots, while high and low levels of zinc intensified the cadmium accumulation. The highest accumulation of cadmium in roots was occurred at highest level of zinc. Zinc supplementation at each level of cadmium first increased and then decreased iron concentration in shoots and roots. However, zinc supply at each level of cadmium decreased copper and manganese concentrations in shoots and roots. As a conclusion, zinc at low levels diminished toxic effects and accumulation of cadmium, meanwhile high levels of zinc not only did not control cadmium but showed deleterious effects. The critical level of poisoning for cadmium in aerial parts of both plants in lower density in the soil (up to 90 mg kg-1 ) showed very little changes, but in higher density, it decreased in brassica napus and increased in zea mays. The critical level of poisoning on the aerial parts of both plants showed very little change with increasing the total density of cadmium in the soil.

Abstract Introduction: North of Khuzestan province is one of the major areas for autumn sugar beet planting. Conventional tillage (CT) is widely practiced by sugar beet growers in this region. CT in sugar beet consists of burning wheat residue, using deep plowing with a moldboard plow or ripper plowing followed by several passes of disking, leveling, and furrowing. These aggressive tillage practices have many negative consequences for soils. Losses of soil organic carbon decreases soil permeability and consequently increases soil erosion and surface runoff. Therefore, applying conservation agriculture principles in sugar beet planting, conservation of residues and elimination or reduction of tillage, can help to optimize water use management and improve soil health on a farm scale. The objectives of this study were (i) to determine the possibility of direct planting of autumn sugar beet in wheat residues, (ii) to estimate sugar beet yield and crop water productivity (WP) under CT, chisel (CH), minimum tillage (MT) and no-tillage (NT) systems, (iii) to evaluate the response of sugar beet cultivars (Sharif and Palma) to different soil tillage systems, and (iv) to determine the effect of soil tillage systems on some soil physical properties.
Materials and Methods: A field experiment was conducted for two years (2016—2017) at the Safiabad Dezful Agricultural Research Center (32° 14.44´-32°15.93´ and 48° 25.41´-48°47). The soil of the study site was deep, well-drained with a silty clay loam texture. The mean annual precipitation and evaporation are 317 and 2400 mm, respectively, with an elevation of 108 m above mean sea level. Irrigation water was supplied from the Dez irrigation network without any salinity restrictions. The experimental was conducted in a split-plot arrangement based on a randomized complete block design with three replicates. The main-plot treatment was tillage method and the subplot treatment was two sugar beet cultivars (Palma and Sharif). Tillage treatments included conventional tillage (CT) (moldboard ploughing + MT steps), chisel (CH) (chisel ploughing + MT steps), minimum tillage (MT) (two perpendicular disks, fertilizing centrifugal machine, disking, furrowing, planting with pneumatic row planter), and no-tillage (NT) (spraying, planting with NT pneumatic row planter). The length and width of each plot were 100 and 6 m, respectively, and row spacing was 75 cm.
Soil penetration resistance or cone index (CI) readings were recorded in 2 cm increments to a depth of 50 cm using SP1000 digital penetration tester to reflect the soil compaction. Soil bulk density was determined in 0-10 and 10-20 cm layers. In the first and second year, sugar beet samplings were done 216 and 220 days after planting, by harvesting a row of 75 cm with length of 10 m (7.5 m²). WP was calculated by dividing the root and sugar yield to irrigation water and effective rainfall (effective rainfall was calculated every year with SCS method). Composite data analysis and mean comparison were performed with MSTATC statistical software.
Results and Discussion: Results of CI showed no significant difference between four tillage methods at 0-10 cm depth. With increasing depth up to 30 cm, slight differences in soil compaction were observed for different tillage treatments, especially in the second year. Overall, compaction in the 0-50 cm profile in the CT and CH method were about 45% and 33%, respectively, lower than NT method, whereas in MT method it was about 37% higher than NT method. Results of root branch number analysis showed that the NT and CT treatments had the lowest branching (2.67 and 2.83, respectively) and the two CH and MT treatments had the highest branching (4.2 and 5.3, respectively). Therefore, NT had no negative effect on root growth of sugar beet. The results of bulk density measurements in the 0-10 cm layer were consistent with the results of the CI, but at depth of 10-20 cm, NT method with the highest bulk density (1.71 g cm^-3) had significant difference with the other three tillage methods. Tillage method had no significant effect on root and sugar yield and root and sugar WP. However, in CT treatment, root yield increased by 6-8.5% and sugar yield by 6-12%, while root and sugar WP in NT treatment was about 8% higher than in the other three tillage treatments. On the other hand, changing climate conditions, especially rainfall during two years of the experiment, resulted in significant interaction between year and cultivar for yield and WP at 1% probability level. In the first year, the yield of Sharif cultivar (86.7 t ha^-1) was higher than Palma (80.2 t ha^-1), but in the second year, despite the decreasing yield of both cultivars, higher resistance of Palma cultivar to Cercospora disease resulted in a significant increase in sugar yield and WP over last year.
Conclusion: The two-year results of this study showed that the direct planting of autumn sugar beet in wheat residues (NT) is possible. Sugar beet yield and WP were not significantly different in tillage methods, but NT reduced tillage traffic from 7 times to 2 times and reduced energy consumption. The response of the two sugar beet cultivars to different tillage methods was the same and among them the Palma cultivar had the highest yield because of its higher resistance to Cercospora disease.

Abstract Introduction: Magnetic susceptibility measurements can serve a variety of applications including the determination of changes in soil-forming processes, the study of parent material effects, understanding sedimentation processes, soil drainage conditions, and even the separation and identification of soil delineations. The technique is especially attractive since it is relatively rapid, non-destructive, and can be applied to both intact and disturbed samples of soils. Magnetic susceptibility is defined as the ratio of the total magnetization induced in a sample relative to the intensity of the magnetic field that produces the magnetization. Iron oxides are the most abundant of the metallic oxides in most soils; they are present in all climatic regions, in several mineral forms, and at variable concentrations. Typically, selective dissolution techniques are used to quantify the relative proportion of Fe oxides. Due to the large contribution of iron-bearing minerals to magnetic susceptibility, their presence in most soils, and the effects of the biophysical environment on them, pedologists have been paying growing attention to magnetic susceptibility as a means to understand soil and landscape processes. The effects of topography on χ were studied for example by many workers. They found that soil susceptibility changes with the position of a soil profile on a slope. Texture and drainage class assumed to be the main reasons. The soils of the Beshar Plain formed on the relatively same parent materials and are mainly affected by topography and land use. The objective of this study was to examine the role of topography and land use on pedogenic processes and their relation to soil χ, as well as, profile distribution of secondary Fe oxides, and the χ profiles. Materials and Methods: This study was conducted on the Beshar Plain, Kohgilouye Province, in southwest of Iran. Physiographically this plain comprises hill, piedmont plain, river traces, and plateau. Eleven representative pedons were dug along a transect crossing the main physiographical units. Five pedons demonstrated aquic soil moisture regime. The mean annual temperature and precipitation at the site was 14.7°C and 800 mm, respectively. Soil moisture and temperature regimes of the study area were xeric and thermic, respectively. The soils were classified according to soil taxonomy and WRB. The soil pH was measured in a saturation paste and electrical conductivity (EC) in a saturation extract. Cation exchange capacity (CEC) was determined using sodium acetate (NaOAc) at a pH of 8.2. Soil texture was determined using the pipette method. Calcium carbonate equivalent (CCE) was measured by acid neutralization. Organic carbon was determined by wet oxidation method. Pedogenic Fe (Feo) and pseudo-total Fe (Fen) were extracted with the CBD method and HNO3, respectively.The magnetic susceptibility of bulk samples was determined using a Bartington MS2 meter equipped with the MS2B Dual Frequency sensor, capable of taking measurements at both low (χlf at 0.46 kHz) and high (χhf at 4.6 kHz) frequencies. Results and Discussion: The soils were classified as taxonomic orders of Entisols, Mollisols, Inceptisols and Alfisols, according to the world reference base for soil resources (WRB) as reference soil groups of Kastanozems, Regosols, Gleysols, Luvisols, Fluvisols and cambisols. The dominant pedogenic processes in the soils were the accumulation of organic matter, the leaching of carbonates, and formation of calcic horizons, the mobilization of clay and development of argillic horizons. The results indicated that the soils are affected mainly by topography, drainage class and land use. Most pedons exhibited maximum of χ at the soil surface, suggesting preferential loss of diamagnetic components, as well as more pedogenic formation of antiferromagnetic minerals. Magnetic measurements showed that the χ values of aquic soils were much lower than those of non-aquic soils (43%). The highest value of χ was noted in pedons which are located on stable physiographic units and the lowest belong to those which are located on river lower terraces. Fed and fen was also positively correlated with χ in the soils studied. Aquic condition also decreased Fed and Fed/Fen, 44 and 65 percent, respectively with no clear effect on Fen. Low to medium amounts of χfd in the studied soils indicated that superparamagnetic gains are not too dominant in the soils. Higher values of χfd were typically observed in the A horizons than at depth, suggesting a greater proportion of ultrafine grains at soil surface. A positive correlation existed between χfd and χ in the soils.

Abstract Introduction: Nitrogen is the main component of fertilizer programs necessary for production of high quantity dryland barley. This element is the second limiting factor, after water in dryland areas. So for economic production of barley, the proper nitrogen fertilizer application is essential to increase seed quantity and quality in Iran dryland areas. Many researchers have been confirmed that dryland barley yield increased by nitrogen application management. Nitrogen fertilization in dryland areas can increase the use of soil moisture, and improve barley yields to some extent. Different studies have been confirmed interactions between water stress and nitrogen fertilizers on barley, especially under field conditions. From the nitrogen management factors, timing and amount of nitrogen application is known as the most important aspect. This project established in order to study nitrogen rates and nitrogen application time's effects on nitrogen requirement, nitrogen agronomy use efficiency (NUE) and crop characteristics of various dryland barley genotypes in cold and semi cold drylands of Iran. Materials and Methods: This study was carried out in split-split plot in a RCBD in Dryland Agricultural Research Institute (DARI), Maragheh; where nitrogen application times (fall, 1/2 in fall and 1/2 in spring and 2/3 in fall and 1/3 in spring) were assigned to the main plots, nitrogen rates to sub plot (0, 30, 60, 90 and 120 kg/ha), and 5 dryland barley genotypes to sub-sub plots (Sahand, Abidar, Dayton/Ranny, Alpha/ Gumhuriyet/ Sonja and B-C-74-2)in 4 replications during 2007-2010 years. The Rainfall were 177-498 mm.yr-1 (long term mean is 365 mm.yr-1) in cropping years in DARI station. Soil samples were collected from 0-25 cm for determining total N, P-Olsen, K-Ammonium acetate, TNV, OC, Soil texture, pH, EC and Fe, Mn, Zn and Cu-DTPA before sowing and collected from 0-2, 20-40 and 40-60 cm depths in sub-sub plots in shooting stage (GS32) for determining NO3− andNH4+. Ammonium measurement in the soil KCl extracts were down by spectrophotometry method and colorimetric reaction at 655 nm. Also, Absorption spectrophotometry method was used for determination of nitrate in soil extract based on its UV absorbance at 210 nm. In this method two measurements were carried out; one before (by Zn coated by Cu) and second after reduction of nitrate). Using the difference between these two measurements, concentration of nitrate in the extracts was determined. Results and Discussion: The results showed that nitrogen application rates significantly increased (p

Abstract Introduction
The lack of water resources and increase in water demand are among the effective factors in the imbalance of the water resources in each region, and it is necessary to manage the proper use of available water resources in all activities. Water in the agricultural sector is one of the main factors of production, which should be conveyed by irrigation systems to the field level and made available for the plant roots. The necessity of macro-planning in water management and consumption imposes a comprehensive study of the amount of water consumed in the agricultural sector. Hence, this study was conducted with the objective of directly measuring and field-assessing the applied water, water productivity, and water footprint associated with the primary crops cultivated in Markazi Province, all managed by local farmers.
Methodology
For this purpose, 141 farms were selected in the major production areas of the main agricultural and horticultural crops of Markazi province with the coordination of the Agricultural Jihad centers. Then, the volume of water applied was measured without interfering in the irrigation scheduling of the users. To do so, first, the flow rate of the water source (canal, well, aqueduct or spring) was measured with a suitable device (flume and meter) in each of the selected farms. Then, by carefully monitoring the irrigation schedule of the farm, including the time of each irrigation, the number of irrigation throughout the year, as well as measuring the area under crop cultivation, the amount of water used by the crop was measured for each of the selected farms during the season. Also, based on the measured data, the amounts of blue, green and gray water footprints were determined for each of the examined crops. For this purpose, the blue, green and gray water footprints of different crops were calculated using the framework provided by Hoekstra and Chapagain (2008), and Hoekstra et al., (2011).
Results and Discussion
The irrigation intervals in the studied fields varied between 3 and 15 days with an average of 8 days and the average irrigation depth varied between 26.2 and 99 mm with an average of 67.8 mm in different crops. The results showed that the average volume of applied water for the studied crops in Markazi province was 10782 cubic meters per hectare. Also, the minimum and maximum amount of applied water for the evaluated crops was as follows: barley 3783 and 7232, alfalfa 10382 and 19797, beans 8280 and 17840, watermelon 5333 and 7174, walnuts 4420 and 29600, almonds 3850 and 13932, peaches 6872 and 17727, cherries 7050 and 14645, pomegranates 7156 and 20790, and grapes 5937 and 18168 cubic meters per hectare. Furthermore, the average value of irrigation water efficiency index and water footprint was as follows: barley 0.46 and 1642, alfalfa 0.92 and 700, bean 2924 and 0.24, watermelon 9.37 and 117, walnut 0.1 and 6706, almonds 0.16 and 6857, peach 2.48 and 242, cherries 0.73 and 875, pomegranates 1.33 and 636, and grapes 11.2 and 322. Based on the obtained results, the average total water footprint index was equal to 2102 cubic meters per ton. On average, the almond with a water footprint of 6857 cubic meters per ton had the highest share in allocating the water footprint in the crop production of the province. Whereas, the lowest water footprint related to the watermelon with a water footprint of 117 cubic meters per ton. he average values of the irrigation application efficiency index, irrigation water productivity, and water footprint for the examined farms were 72.5%, 1.79 kg/m³, and 2,102 m³/ton, respectively. In summary, the results indicate that the combined volume of irrigation water and beneficial rainfall in the irrigated fields within Markazi Province surpasses the actual water demand of the crops. This underscores the substantial impact of irrigation management on water utilization in the region.
Conclusion
On average, the total volume of irrigation water and effective rainfall in irrigated fields and gardens in Markazi Province is more than the actual water requirement of the plant. In general, the results showed that irrigation management has a great impact on the amount of water use in the region. Based on the obtained results, considering that most of the farms and gardens receive water in an intermittent manner, in principle, no special attention is paid to the need for water and even effective rainfall, and the amount of water availability has the greatest impact on water consumption. Therefore, in order to reduce water consumption and improve water efficiency, it is suggested to manage the delivery of water to farmers during the season and according to their crop water needs. Also, the results of the water footprint can be used to improve water resource policies at the province level, land use studies, cropping pattern modification, and environmental sector policies.
 

Abstract Introduction: The field of ecohydraulics is rapidly growing as the society requires a better understanding of the interrelations amongst the dynamics of the physical processes pertaining to aquatic ecosystems and the modifications observed in their habitat as well as the biological responses of the organisms. Environmental flow science is a common tool for assessing the consequences of changing the flow regime of aquatic ecosystems and providing a minimum flow of aquatic species protection. Environmental Flows assessment is a global challenge involving a number of tangible and intangible segments of hydrology, hydraulics, biology, ecology, environment, socio-economics, and several other branches of engineering including water resources management. River impoundment (dams, weirs), water diversions and consequent modifications to flow regimes have highly destructive effects on aquatic species and ecosystems.     Materials and Methods: In this research, two most common hydrologic methods Tennant and FDC Shifting were compared with a habitat simulation method i.e. PHABSIM. Tennant method is the most popular hydrological method in rivers and is based on the historic flow data. Investigation of the relationship between hydrologic approaches and physical habitat simulation approach and presentation of new recommendations based on the ecological and hydrological data can be very useful for estimating environmental flow in planning phase of river projects. We used river habitat simulation program to model the depth and velocities around boulder clusters to evaluate the habitat for Capoeta habitat in Zarrin-Gol River. The Zarrin-Gol River is one of the rivers in Golestan province in northern Iran. The statistics required for hydrologic calculations were also collected from Zarrin-Gol hydrometry station during the 42-year statistical period (1353-1395). In this regard, after the field studies and the development of the habitat suitability model for the target species, the Habitat simulation of the flow was carried out and eventually the ecological flow regime was extracted. In order to identify the important habitat variables and assess their impact, the life pattern of fish species was divided into juvenile and adult life stages. Results and Discussion: Based on ecological assessment, the environmental water requirement of Gharahsoo river is 30% of mean annual flow for spring and summer and 10% of mean annual flow for autumn and winter seasons. It was found that application of Tennant and FDC Shifting methods led to dramatically low discharges as fixed minimum environmental flows, while habitat simulation method gave an acceptable estimation of ecological regime. However, habitat simulation technique assesses the allowable value of extraction from river flow dynamically, considering the ecological condition and average intermediate values. River conditions including flow velocity, water depth and river bed substrate are combined to form unique habitats facilitating the survival and growth of fish species populations.  Habitat forms are observed in a wide range of rivers depending on the diet and the river type such as Pool, Riffle and Run. The destruction of the Riffle substrate causes disruption and impacts the biological integrity of the current. According to the Q-WUA curve of the Riffle habitat in high waters and flood conditions, the area available for juveniles of the target species decreases because of the flood, morphology and habitat of the river, so large and continuous floods inhibit the opportunity to rebuild habitats from the river and endanger the lives of fish. One of the factors limiting the desirability of the habitat and thus reducing the available habitat in low river flows is the low flow velocity, as well as high stream flow flows. The maximum and minimum flow regime, required to maintain the Zarrin-Gol river ecosystem according to ecological needs, was 2.49 and 0.58 m3/s in April and November, respectively, with an average value of 1.25 m3/s (59 % of natural stream of the river). In the next step, habitat suitability distribution along the stream was investigated. This was performed for the full range of discharges. Habitat suitability distribution along the stream at different discharges indicated that the upstream part of the stream had the poorest habitat condition and moving towards the downstream parts, the habitat suitability condition was improved. Conclusion: Application of the Tennant method based on a hydrological system can be an inappropriate choice for determining the minimum flow to maintain the ecological environment of the river. According to the results, the PHABSIM model can simulate flow, habitat suitability of target species and the habitats dynamics accurately, which is highly required to protect the proper habitat of fish in river ecosystems.

Abstract Introduction: During the last decades, arid and semi-arid regions has faced a severe problem of depletion of groundwater resources due to the over-exploitation of the aquifer. Moreover, groundwater and surface water are not isolated components of the hydrologic system, but instead interact in a variety of aspects in which development of one commonly affects the other. Additionally, the interaction is often complicated by agricultural activities including surface water diversion, groundwater pumping and irrigation. This study presents an integrated SWAT-MODFLOW model that couples land surface hydrology and groundwater hydrology to determine spatial groundwater percolation patterns considering allowable groundwater pumping rates for the Neishaboor watershed, Iran. Within the integrated model, the pumped groundwater is applied as irrigation to the cultivated fields within the SWAT model, with deep percolation from the soil profile bottom applied to the MODFLOW model as recharge. The model is tested against observed stream flow and water table elevation, with model output then used to assess and quantify spatial-temporal patterns of groundwater recharge to the aquifer. Materials and Methods: The recently developed SWAT-MODFLOW modeling code simulates spatially-distributed hydrologic processes in the coupled land surface / aquifer system, with SWAT simulating land surface, soil zone, and stream flow routing processes and MODFLOW simulating groundwater flow and groundwater/surface water interaction processes. Modifications which is done to the modeling code includes: 1) Linking pumping from MODFLOW cells to SWAT HRUs for groundwater irrigation and 2) Imposing shallow water table percolation and lateral flow conditions for SWAT HRUs when the MODFLOW-simulated water table is within the soil profile of the HRU. The integrated SWAT-MODFLOW framework is tested in the Neishaboor watershed (9157 km2) for the 1998 to 2011 time period. Climate of the region is classified as semi-arid, with an average annual precipitation of 265 mm that varies considerably from one year to another. The mean annual temperatures changes from 13°C in the mountainous area to 13.8°C in the plain area and the annual potential evapotranspiration is about 2,335 mm. The main crops that are grown in the watershed is irrigated and rain fed wheat during fall and winter and corn silage during summer. Regarding previous studies, about 93.5% of the groundwater withdrawals in the Neishaboor watershed are consumed in agriculture, mostly for irrigation. Therefore, irrigation practices play a crucial role in the water resources balance in the study area. Within the integrated model, the pumped groundwater is applied as irrigation to the cultivated fields within the SWAT model, with deep percolation from the soil profile bottom applied to the MODFLOW model as recharge. The SWAT model was calibrated and tested in SWAT-CUP for the 2001-2009 and 2010-2011 periods, against stream flow and developed model was calibrated manually against groundwater level data. Results and Discussion: Annual average recharge, calculated from the daily recharge values pass from SWAT to MODFLOW, demonstrating higher recharge rates in the alluvial fans and upland plain. Observed and simulated stream discharge in four hydrometric stations demonstrate good similarity results with the observed hydrograph. The NS values for monthly discharge rates are considered acceptable, however, the field-estimated stream flow estimates contain a high degree of uncertainty. Simulated cell-wise groundwater hydraulic head at the end of the simulation is compared with observation values with the highest water table elevation occurring in the north east and low water table elevation occurring in the outlet. Comparing observed and simulated average groundwater levels at the 48 monitoring wells, the deviation from the 45-degree line is less than 2.5 m for over 73% of the circles. The manual calibrated model can capture the main temporal trend. Overall, the model well captures the long-term characteristics of the regional groundwater level. Conclusion: In this study, a new coupled model, referred to as SWAT-MODFLOW was used to model a dry and semi-arid region with a complicated irrigation system with groundwater pumping. A comprehensive model, will enable accurate simulations of stream flow and water table fluctuations in watersheds and aquifers respectably. In short, surface water infiltration is passed from SWAT to MODFLOW based on the contributing areas of the HRUs to the groundwater grid. Pumping agriculture water is then calculated and passed back to SWAT. The need for such a model is highlighted by the Neishaboor basin, where the agriculture is completely based on groundwater pumping. The case study in the Neishaboor basin demonstrated the applicability of the model for large, dry basins. The model will be used to determine best management practices for groundwater pumping in the region.

Abstract Introduction
 In arid and semi-arid regions, agricultural sustainability needs to improve the consumption of water and soil resources. Low rainfall, high evaporation, low water quality and less leaching of solutes in the soil due to limited water resources are the main problems in these areas. The quality of water and soil resources in the provinces of Fars, Khuzestan, Yazd, Golestan and Khorasan also shows that most of the wheat farming lands in these provinces are always facing salinity issues. According to the conducted studies, saline water can be successfully used in irrigation, but application of unconventional water by surface irrigation systems with low efficiency due to evaporation and high water salts leads to soil salinity. Micro-irrigation methods increase water use efficiency by reducing water consumption and increasing yield, so that drip irrigation efficiency of 91-80% and irrigation levels of 50-73% have been reported. In recent years, the use of drip irrigation system (such as tape on wheat fields) has been recommended to farmers as a water management solution. Micro-irrigation systems by reducing water consumption and increasing yields, improve water use efficiency. Drip tape irrigation system compared to other surface and sprinkler irrigation methods, due to short irrigation periods and reduction of evaporation losses and deep infiltration even for crops can be proposed as an alternative. Drip tape irrigation in wheat cultivation can increase water use efficiency up to 2 times. Also, in irrigation with salt water, while maintaining humidity in the environment, it reduces salinity stress and by consuming less water and reducing the amount of wetting, it introduces less solutes into the soil. This method has limitations in wheat fields due to costs and also the possibility of soil salinity problems, some of which can be overcome by increasing the distance between the laterals and reducing the consumption of drip irrigation (Tape) per unit area.
Materials and Methods
  In this study, during the 2020-2021 at the Salinity Research Center of Yazd Province (Iran), the effect of lateral distances on the surface and depth distribution of soil salinity was investigated. For this purpose, two irrigation water salinity treatments, including 3 and 8 dS / m and two flood (T1) and drip irrigation systems (Tape) with lateral distances of 60 (T2), 100 (T3) and 140 (T4) cm were considered. Irrigation management treatments included the use of the flooding method (as the dominant method in wheat fields) and the use of the Tape drip irrigation method (as the proposed method with very low water consumption). A distance of 60 cm was considered as the optimal distance with complete water overlap, a distance of 100 cm was considered as an economic distance with the possibility of deep moisture distribution and a distance of 140 cm was considered as a large lateral distance. To investigate the salinity distribution and the accumulation of salts in the soil, regular soil sampling of different treatments was the end of the season.
Results and Discussion
 In all irrigation treatments (saline and non-saline), despite the constant volume of water consumption per unit area of all treatments, in T3 and T4 treatments, irrigation depth increased compared to T2 treatment and reduced soil salinity in the wetting area (irrigated area). By increasing the horizontal distance of each point of the field from the lateral, the irrigation depth and leaching fraction decrease and consequently, the soil salinity of these points can also increase. Under non-saline irrigation conditions (salinity of 3 dS/m), soil salinity at intervals of zero (below the lateral), 15 and 30 cm, between 5.5 and 6.1 dS/m has been observed. Values below the threshold of tolerance to salinity of wheat plant and, in this regard, does not pose a risk to the plant. At a distance of 45, 60 and 70 cm from the water pipe, the salinity of the soil is higher than the threshold and if there is a plant in this area of the field, it will face serious damage.
Conclusion 
 The results showed that although the Tape method in saline conditions (8 dS/m) compared to non-saline conditions (3 dS/m) leads to higher accumulation of solutes in the soil and increases the possibility of plant damage, but according to the final results of this study, by increasing the distances of irrigation laterals and proportionally increasing the depth of irrigation and keeping the salts away from the planting bed, a more suitable environment for plant growth can be prepared and higher economic benefits of this measure can be obtained. Also, in terms of controlling soil salinity, the conditions have been such that treatment with lateral distance of 140 cm compared to treatments of 60 and 100 cm has led to lower amounts of soil salinity in the subsurface and has provided better conditions for the plant. Thus, by increasing the distances of laterals from 60 to 140 cm and, consequently, increasing the depth of irrigation, it was possible to transfer solutes to lower depths of the soil.

Abstract Introduction Nowadays, the application of variable-rate fertilization is primarily based on soil analysis maps. These maps play a crucial role in decision-making for fertilizer management and the optimization of plant nutrient use. However, the sampling distance is often determined without considering the spatial variability of soil properties, which can lead to reduced map accuracy and inappropriate fertilization recommendations. Previous studies have shown that the density and spacing of soil samples have a significant impact on the accuracy of geostatistical models and the quality of maps produced using methods such as kriging. Moreover, soil management practices, including varying fertilizer application patterns, crop rotation, and historical land use, can strongly influence the spatial patterns of soil nutrients. Therefore, investigating the effect of sampling distance on the spatial distribution of major soil nutrients, particularly available potassium, can help optimize soil sampling and provide more precise recommendations for variable-rate fertilization. The present study aimed to examine the effect of sampling distance on the spatial structure of available potassium in the agricultural soils of the Shahrekord Plain.   Material and Methods For this purpose, 120 soil samples were collected using a regular grid sampling design with a spacing of 1335 meters from the surface layer of agricultural soils in the Shahrekord plain, covering an area of 21400 ha, and the available potassium content was determined in the laboratory. Descriptive statistics of the data, including the minimum, maximum, mean, median, coefficient of variation, and skewness of the variable, were calculated, and the normality of the data distribution was assessed using histograms and the Kolmogorov–Smirnov test. The experimental variogram of available potassium was constructed, and various theoretical models were fitted to it. Subsequently, the variogram parameters and the spatial dependency class of the variable were determined. Model validation was performed by adjusting the initial parameters so that the final optimized model had a mean error (ME) close to zero and a minimum mean squared error (MSE). Ordinary kriging in ArcGIS 10.3 was then used to produce maps of available potassium.   Results and Discussion The available potassium in the soils ranged from 120 to 812 mg kg⁻¹, with a coefficient of variation of 38.2%. The data were not normally distributed; however, the log-transformed data followed a normal distribution. Geostatistical analysis indicated that the exponential model best fitted the data. The nugget effect was 0.108, and the range of this variable was estimated at 53300 meters, indicating that the selected sampling distance is much smaller than the spatial variability range; therefore, the sampling distance appears to be sufficient. However, the exponential variogram is nearly flat at short distances, showing little change in semivariance, which reflects the influence of strong soil management practices, such as varying fertilizer application patterns, crop rotation, and historical land use, on data dispersion. The spatial dependence of the studied variable was 50.2%, which falls into the moderate spatial dependence class. The mean error (ME) of the estimated available potassium was –0.0008, and the mean squared error (MSE) was 0.011, indicating the unbiasedness and high accuracy of the estimation. The maps produced using the kriging method exhibited acceptable accuracy. This was achieved despite the increased variability at short distances and the disruption of regular spatial patterns caused by intensive soil management practices.   Conclusion According to the findings, using an appropriate sampling distance is essential to accurately represent the spatial variability of major soil nutrients, particularly potassium. The findings of this study indicated that the current sampling distance is not sufficient to accurately represent the spatial variability of available potassium in the soils under investigation. Therefore, for future studies, it is recommended to investigate the effect of sampling distance at distances shorter than 1,335 meters to evaluate the model sensitivity and the accuracy of kriging maps at larger scales. This can help optimize soil sampling and provide more precise recommendations for variable-rate fertilizer application. Furthermore, it is recommended that future studies also consider the role of soil management practices in the spatial modeling of potassium, as these factors can strongly influence the spatial distribution of soil nutrients.   Acknowledgements The authors would like to thank the Soil Science Department of the University of Shahrekord for providing equipment and facilities.

Abstract Introduction: Soil erosion and sediment transportation decrease water resources, and cause many social and economic problems. On the other hand, sediment transportation by rivers causes problems such as water quality degradation, reservoirs sedimentation, redirect of rivers, or decrease in their transportability. Therefore, finding the proper methods in sediment yield study in watersheds is essential in planning and management of land and water resources.  Climatic characteristics, physiography, geology, and hydrology of basins are the most effective factors in producing and transporting sediments according to several sources, but the role and impact of some factors are more pronounced than the others in different areas. As a result, the objective of this study was to investigate and identify the most important climatic, physiographic, geological, and hydrological factors in several watersheds of the northeastern part of Iran, by applying Gamma Test (GT) and principal component analysis (PCA) techniques.
Materials and Methods: In this study, the data of discharge flow and suspended sediment concentration, and daily flow discharge recorded in 15 hydrometric stations in Mashhad and Neyshbour restricts and required maps were provided from the Regional Water Company of Khorasan Razavi, Iran. After drawing statistical bar graph period of suspended sediment, daily discharge, annual precipitation, and relatively adequate data, stations with the longest period and with the lowest deficit data were selected to determine the common statistical periods. Therefore, in this study, the time period of 1983-1984 to 2011-2012 was selected, and the run test was applied to control data quality and homogeneity. Then, the most effective factors of sediment yield were determined by principal component analysis (PCA) and Gamma Test (GT).
Results and Discussion: The results of the principal component analysis showed that 90 percent of the first five components justify the changes. Among the factors, area and gross gradient of the mainstream from the first component, the average annual flow rate of mainstream, meandering waterways of the mainstream from second component, and drainage density of third component were identified as the most important influencing factors on suspended sediment production. Ninety superior combinations of 1500 proposed combinations were obtained by Gamma Test to evaluate the effects of each parameter on suspended sediment yield. To determine the order of importance of the entered parameters, first, Gamma Test was performed on all 12 parameters. Gamma values of all cases for each proposed combination were compared. The results showed that the impact of these statistics was lowered by eliminating high gamma parameters and the removal of low values. The data analysis revealed that the low levels of gamma and high accuracy of ratio to find the desired outputs from entries. By lowering the gradient, the complexity of the model was lowered and more suitable model was provided. As a result, high levels of gradient represented the complexity of the final model. The results of the percentage values of each of the 12 variables were considered among the superior equations for estimating the suspended sediment composition. In this regard, the mean annual discharge, main channel length, area, average annual rainfall, and percentage of the outcrop of erosion sensitive rocks with a total of 63 percent of the proposed equations were the most important factors affecting the sediment yield in the study area. The average height parameter of area, the average and gross slope of the mainstream had the lowest presence among the optimized compounds.
Conclusion: Based on the results of the principal component analysis, the two factors of basin area and gross slope of the mainstream were selected as the most important factors affecting the amount of annual suspended sediment load, respectively. Based on the results of the Gamma Test, 12 main variables affecting suspended sediment load were identified and the effect of each of them on the production and transport of suspended sediment was determined. Based on the comparison of the results of the two methods of PCA and GT, it can be concluded that if the purpose of research or study is to prepare a model with the highest accuracy in estimating suspended sediment load, the 12-variable model of GT includes factors related to physiographical, geological, climatic and hydrological factors are suggested. However, if the preparation of a model with appropriate accuracy and a limited number of input variables is considered, a 5-variable model derived from the PCA method is proposed. At the same time, if the purpose is to prepare a model with the least input variables and their easy access and calculation and initial estimation of suspended sediments, a bivariate model (based on basin area and gross slope of the mainstream factors) resulting from PCA is proposed. According to the results of the present study, it can be concluded that the study of more parameters has provided grounds for evaluating their importance in sediment yield. Finally, due to the correlation of many parameters with each other, a limited number of parameters that have a more important role in suspended sediment estimation, were selected. Another finding of this study is the increase in the accuracy of the sediment model’s preparation due to achieving more important and effective parameters in sediment yield and identifying them in order to investigate the best sediment management measures in watersheds. It is suggested that similar research should be done in other watersheds with different conditions in terms of climatic conditions, topography, geology, and so on.

Abstract Introduction: Climate change has been one the most important subject in studies in the recent decades. Precipitation is an effective climatic parameter in the municipal and rural studies and in the industry, architecture, agriculture, climate and other fields. Trend analysis of average monthly and yearly rainfall investigated in many studies, but less researches probe regional rainfall analysis. In this study average yearly precipitation data measured at 31 synoptic stations of Iran in the period of 1961 to 2010 used to study regional variations of precipitation. In this order station divided to five regions by fuzzy clustering. Then, using the regional Kendall method, trend of precipitation investigated at five regions and all of Iran. Materials and Methods: Iran with an area of over 16480000 square kilometers is situated in the northern hemisphere and southwest of Asia. Almost all parts of Iran have four seasons. In general, a year can be divided into two warm and cold seasons. Iran with range annual precipitation of 62.1-344.8 mm is located between two meridians of eastern 44° and 64° and two orbits of northern 40° and 25°. In order to investigate trend of precipitation two Mann-Kendall and Regional Kendall tests used. Also to evaluate the regional trends the Fuzzy method applied to clustering the studied region. The classic form of Mann-Kendall test has been used in many studies. The null hypothesis (no trends) is accepted when , otherwise H0 is rejected and its opposite hypothesis, i.e. the existence of a trend is accepted (5, 13). To estimate regional trend, the mean S statistic of Regional Mann-Kendall introduced that was presented by Douglas et al (7). Fuzzy Clustering: Clustering the studied area was done using the Fuzzy clustering method. One of the first clustering methods that were based on the objective function and Euclidean distance was presented by Dunn in 1974 and then was generalized by Bezdak in 1981.The FCM clustering algorithm is modified type of K-Means clustering algorithm. This algorithm minimizes the variance of clusters (1). The assumption of this algorithm is that data are in a vector space and the objective of this algorithm is to minimize the sum of variance in the D v cluster. Results and Discussion: In this section the results of decreasing and increasing trend of annual precipitation of Iran can be observed in order to the data that recorded at provinces synoptic stations in the 1 and 5 percentage significance levels. Isfahan Synoptic station detected an increasing trend insignificant level of 5 percentages and the East Azerbaijan synoptic station followed a significant and severe decreasing trends. In order to investigate regional trend it is needed to use the clustering methods. After investigation the trend of mean annual precipitation at each station, the studied area was clustered using the Fuzzy clustering method and then the regional trend of Iran’s precipitation was evaluated. At first the number of different clusters investigated using the geographic properties and mean annual precipitation of the studied area and then with attention to the correlation of precipitation series in each cluster, five clusters selected to investigate the regional trend of precipitation. Overall the results showed that about 67 percentages of synoptic stations in center of provinces detected decreasing trend in the recent half century. Increasing the precipitation almost accrued in the center and northern part of Iran and other areas detected a decreasing precipitation trend in the studied data period that this subject is corresponded with Azerakhshi and et al (2). The observed trends over Iran and almost all stations and provinces were downward trend. This decreasing trend of precipitation also observed in Iran in the two past decades by Khalili et al (13). Conclusion: Result showed decreasing trend in the west, north of Iran at each station and regional scale. Results indicated also a significant downward trend at northwest, central and south-west of the country, non-significant downward trend in western of Iran and non-significant upward trends in northern regions and Caspian Sea margins in the regional analysis. The most decreasing trend of precipitation observed at the north west of Iran because of increasing temperature and climate changes in the recent years.

Abstract  
Introduction
Due to climate change, one of the limiting factors of crop production is environmental stress which, by disrupting the natural metabolism of the plant, limit plant growth and finally reduce crop production. Drought stress causes the greatest reduction in crop productivity compared to other environmental stresses. Therefore, the use of methods to reduce water consumption in agriculture is more important due to the lack of freshwater resources. Increasing water use efficiency and maintaining plant yield by reducing water consumption has a particular importance for crop production and should be paid special attention. Drought stress reduces photosynthesis, stomatal conductance, biomass, growth and consequently plant yield. The effects of drought stress on the yield of plants such as potatoes (Solanum tuberosum L.), wheat (Triticum aestivum L.), rice (Oryza sativa L.) etc., which play an important role in the nutrition and food of the world, has a great importance. Achieving the desired soil moisture range is one of the most important approaches to increase water use efficiency and not significantly reduce yield. For this goal, a factorial experiment was conducted in a completely randomized design with five replications in the research greenhouse of Ferdowsi University of Mashhad.
Materials and Methods
Factors studied in this experiment included three levels of irrigation 1- full irrigation (100% of field capacity), 2- medium drought stress (70% of field capacity), 3- partial root-zone drying (70% of field capacity), time of induction of water stress (two weeks after planting and 50% at flowering time) and two levels of phosphate (CaH₄[Po₄]₂ H₂O) fertilizer (based on soil analysis (25 mg.kg^-1) and adding 25% more than recommended (31 mg.kg^-1)) at the beginning of the period phosphate was mixed with soil inside the pot in greenhouse condition. Fontane potato cultivar was used in this study. In irrigation treatments, one part of the pots was stressed two weeks after planting and the second part of the pots were fully irrigated until the beginning of flowering and irrigation treatments were applied at 50% flowering stage. From the prepared samples, membrane stability index, osmotic potential, and relative water content were measured in the laboratory and at the end of experiment, plant height, tuber weight, biomass and plant water use efficiency were measured. Minitab 18 software was used to analyze the data.
Results and Discussion
The results showed that with increasing phosphate fertilizer from 25 mg.kg^-1 to 31 mg.kg^-1, plant biomass increased significantly and in all treatments biomass increased between 2 to 28% . Partial root-zone drying treatment showed a 17.4% increase in biomass. In the medium drought stress treatment, the total growth period and phosphorus level of 31 mg.kg^-1, the lowest water use efficiency was observed, and there was no significant difference in the medium drought stress treatment of the total growth period and the phosphorus level of 25 mg.kg^-1. Partial root-zone drying treatment of roots from flowering time and 31 mg.kg-1 P, with full irrigation treatment 25 mg.kg-1 P have the same water use efficiency, but the performance of this treatment  compared to full irrigation treatment was reduced by 28%. Water use efficiency in partial root-zone drying (intermittent irrigation) has increased compared to traditional irrigation, which indicates a more optimum use of water in the medium drought stress method. Full irrigation treatment had the highest tuber weight per plant and partial root-zone drying during the growing season treatment had the lowest tuber weight per plant (65%) compared to full irrigation. The partial root-zone drying treatment after flowering, ranked second after full irrigation treatment, for tuber weight per plant and more tuber weight per plant compared to other drought treatments. Using 31 mg.kg^-1 phosphate, tuber weight per plant in full irrigation treatment reached 332 g.plant^-1 which increased by 13% and was significantly different from all treatments. With increasing phosphate level from 25 mg.kg^-1 to 31 mg.kg^-1, in the partial root-zone drying treatment from flowering time, tuber weight per plant increased by 28% to 207 g.plant^-1. Tuber weight per plant in other drought treatments decreased with increasing phosphate level from 25 mg.kg^-1 to 31 mg.kg^-1, although this decrease was not statistically significant.
 
Conclusion
Compared to deficit irrigated methods, partial root-zone drying from the beginning of growth and full irrigation has the ability to use available nitrogen at the end of the growing season and has more greenery than other drought treatments. This effect probably explains the filling of the gland tubers at the end of the growing season and thus the keeping of yieldyield production. The best methods for saving water consumption and maintaining the yield, the partial root-zone drying methods is better than the medium drought stress method.