نشریه دانش آب و خاک
سال سی و دوم شماره 1 (بهار 1401)

Suitable planning for the use of limited water resources can increase the production of agricultural crops effectively. In this research, optimal cultivation areas were determined based on reservoir volume and available water scarcity conditions in Arasbaran plain. At first, the net benefit from cultivation in the period (2002-2011) obtained using the Stewart model and the region economic values. Optimal water allocation program was run using the linear programming for each time period of year for maximizing the net benefit objective function considering the restrictions. Optimization performed for five scenarios of available irrigation water (NIV) and for each of them, optimal annual cultivated areas for the proposed plants were obtained. By optimizing the annual cultivated areas, a constant optimal form was also obtained for the region. The results showed that the net benefit changes per unit volume of water, decreased with the increase of available water in both cases as a second degree curve and in all NIVs the benefit of the variable cultivated area was 7% higher. Also, the total net benefit of the annual optimal cultivated area for available water of 8 million cubic meters was 8% more than the fixed cultivated area, and for 10 to 16 million cubic meters, this value increases linearly from 11% to 18%, that shows the relative superiority of the variable optimal cultivated area without considering the management benefits of the fixed mode such as design, irrigation and mechanization.

Solar radiation is one of the most important climate parameters that has direct relationship with many hydrological and meteorological processes. Due to the lack of real time records of this parameter in meteorological stations, solar radiation estimation models based on meteorological parameters are usually applied in practical issues. The Angstrom-Prescott equation that works on the basis of the sunshine hours has been widely applied for calculating solar radiation values due to its simplicity and acceptability. So far, many studies have been conducted about calibrating coefficients of this equation based on the meteorological parameters. The purpose of this study was to evaluate the atmospheric air polutions effects on received solar radiation using the Angstrom-Prescott model. Calibration of the Angstrom-Prescott equation coefficients was performed using daily radiation data of Urmia and Tabriz stations during 3 years period (2014-2017) with taking into account the Air Pollution Index (API). Also,in order to compare the results of modified models with general equation of Angstrom-Prescott,different linear,exponential and logarithmic models were developed. In order to evaluate the models precision, RMSE, MABE, NSE and R2 indices were employed. The results of statistical analysis of the models indicated that the calibrated models of Urmia and Tabriz stations on the basis of the API and the logarithmic structure had the best perfermace to general equation of Angstrom-Prescott. The average values of the RMSE of the modified logarithmic model for Urmia and Tabriz were obtained 0.1263 and 0.1050 jcm-2day-1, respectively.

Water stored in the reservoir is one of the main sources of water supply in arid regions. Therefore, optimal operation of it is of utmost importance, especially in drought duration. In this study, optimal operation of Voshmgir dam using continues hedging policy optimized by linear programming (LP) and Partial swarm optimization Algorithm (PSO) that located in Golestan province north of Iran was investigated. The objective function is minimization of the Shortage index. In order to examine the effects of used hedging policy, 3 continuous drought years was considered. To evaluate the results of the models, evaluation criteria such as the percentage of water supply, reliability, vulnerability and stability indicators was used. The threshold volume changes per month was extracted and the base hedging rule curve for reservoir was presented. Evaluating the results of two models showed stability index in linear programming with 41.78 model was much higher than particle swarm algorithm with 6.416. Which indicates the higher performance of this model in the optimization of hedging policy in Voshmgir reservoir.

For the first time, in the current study, the discharge coefficient of labyrinth weirs was simulated using the Self-Adaptive Extreme Learning Machine (SAELM) artificial intelligence model in both cases including normal orientation labyrinth weirs (NLWs) and inverted orientation labyrinth weirs (ILWs). The Monte Carlo simulations were also implemented to evaluate the accuracy of the artificial intelligence model. In addition, the validation of the numerical model results was carried out by means of the k-fold cross validation approach. In this study, k was considered equal to 5. First, the most optimized neuron of the hidden layer was computed. The number of the hidden layer neurons was calculated 30. Also, by analyzing the results of different activation functions, it was concluded that the sigmoid activation function has higher accuracy than others. After that, the superior model was identified by conducting a sensitivity analysis. The superior model estimated the discharge coefficient values in terms of all input parameters. This model approximated discharge coefficient values of labyrinth weirs with reasonable accuracy. For example, the values of R2, the Scatter Index and the Nash–Sutcliffe efficiency coefficient for the superior model were calculated 0.966, 0.034 and 0.964, respectively. In addition, the ratio of the total head above the weir to the height of the weir crest (HT/P) and the ratio of length of apex geometry to width of a single cycle (A/w) were identified as the most effective parameters. Finally, a partial derivative sensitivity analysis (PDSA) was conducted for the input parameters.

Present research was carried out to evaluate the effect of different carbon sources on K release by Pseudomonas fluorescens and Aspergillus niger and modeling the effects of incubation time, pH and different amounts of carbon source on K release using central composite design. At the first step, 12 experiments were defined with a combination of different levels, and the effects of different carbon sources including glucose, sucrose and fructose at two levels of +1 (10 g.l-1) and -1 (5 g.l-1) on potassium dissolution of illite was studied. After selection of effective carbon source, different ranges of independent variables including incubation time, pH and carbon source were considered and experiment design has been made based on the coded values of them. Results showed that there is no difference between carbon sources, which were used at the first step of experiment, so each of them can be used as alternatives to each other in culture medium. According to the statistical analysis results of central composite design, pH has a positive impact on increasing the soluble potassium release (P>0.001). Maximum potassium release by bacteria and fungus, 109.75 and 170.3 mg.l-1 respectively, observed at central levels of incubation time and carbon source and pH = 10.36. Based on determination coefficient of, 91 and 87.8 percent of soluble potassium changes in the presence of bacteria and fungus can be explained by this central composite design model, respectively.

Prioritizing different types of irrigation systems is essential for proper management of soil and water resources in the south of Ahar (9000 hectares). For this purpose, the physical and chemical properties of 44 soil profiles (soil texture, depth, lime, gypsum, salinity and alkalinity) were used and the ability of the soil to be irrigated using the limitations system as well as the suitability of the study area for the drip, sprinkler and surface irrigation systems were determined by parametric method. The application of the limitation system results showed that soil and topography were the most important limiting factors and the irrigation capacity of the study area was in classes III (arable land) and IV (limited arable land) with approximate extension of 75% and 25% respectively. Based on the results of the parametric method for surface irrigation application, only 4% of the land is classified as S1 (highly suitable) and S2 (suitable), S3 (relatively suitable), N1 (almost non-suitable) and N2 (non-suitable) with extension of about 31%, 46%, 17% and 2% in the study area. In addition, the southern parts of the area were not suitable for surface irrigation due to the high slope, and the lands for sprinkler and drip irrigation classified in S2 and S3 classes and covers 70% and 25% of the study zones and so the rest of the lands are more susceptible to sprinkler irrigation than drip ones. Based on prepared maps, about 5000 hectares of lands

In order to study effect of mycorrhiza fungi application to reduced adverse effects of arsenic on wheat, a greenhouse experiment was conducted in Varamin, Tehran, Iran in a completely randomized design with three replication in 2018. The treatments included four levels of arsenic (0, 40, 80 and 120 mg.kg-1 of soil) and two levels mycorrhiza fungi application (with and with out mycorrhiza fungi application). The results showed that intraction effect of arsenic and mycorrhiza treatment was significant for all experimental traits. The increasing in arsenic levels caused a significant decreased in leaf area index, chlorophyll content, grain weight and total dry weight per plant. Whereas, increased proline content, superoxide dismutase and catalase enzyme activity. Also the results showed that mycorrhiza fungi application reduced adverse effects of arsenic and led to increas in yield components and decreased proline content, antioxidant activity in leaves. The highest leaf area index (6.88), total chlorophyll content (1.89 mg.g-1 FW), thousand grain weight (42.3 g) and total dry weight per plant (31.5 g) were achieved in without arsenic + mycorrhiza application. The highest malondialdehyde (13.77 µmol.g FW-1), prolin (4.06 mg.g-1 FW), superoxide dismutase, catalase and peroxidase enzyme activity (510.2, 182.2 and 14.18 unit activity,) were observed in 120 mg per kg of soil+ none application mycorrhiza. According results of the present study mycorrhiza fungi application reduces the harmful effects of arsenic stress and symbiosis with wheat plant results in higher yield components of wheat and concentration of phosphorous in the shoot of the plant.

In this study, the turbulent flow field in rectangular channels with side weir is simulated using the FLOW-3D software. To verify the modeling results, the experimental measurements obtained by Hager (1982) are used. Also, for simulating the flow turbulence the standard k-ε and RNG k-ε turbulence models are used. The numerical modeling results show that the RNG k-ε turbulence model has more accuracy. According to the modeling results, the RMSE and R2 values for the standard k-ε turbulence model are calculated 0.005 and 0.969, respectively. Meanwhile, these values for the RNG k-ε turbulence model are estimated 0.004 and 0.971, respectively. Also, analysis of the numerical results indicates the acceptable accuracy of the numerical model in predicting the experimental results. For example, the RMSE and correlation coefficient values for the mentioned model are calculated 0.004 and 0.971, respectively. Subsequently, the effects of the side weir inlet length on the flow pattern are investigated. For this purpose, three different numerical models with weirs with lengths of 1m, 0.7m and 0.5m are defined. According to the modeling results, by decreasing the inlet length the side Froude number value along the side weir decreases. In contrast, by decreasing the side weir inlet length the maximum value of the flow field pressure for the model with a inlet length of 0.5m is predicted. In other words, the maximum pressure values for the models with side weirs with lengths of 1m, 0.75m and 0.5m are calculated 271pa, 286pa and 317pa, respectively.

The presence of the in-flow hydraulic structures create gradually varied flow (GVF) profiles which the computation of the hydraulic parameters based on the dynamic equation of flow with high accuracy has significant aspect among researchers. In this study, while doing dimensionless process of flow dynamic equation using yn and yc, Gaussian Hyper-Geometric Function (GHF) has been implemented to solve the equation analytically for five main channel slopes namely Mild (M), Steep (S), Critical (C), Horizontal (H) and Adverse (A). also, a comparison has been done using laboratory data between the accuracy of numerical Rung-Kutta 4th order method and GHF analytical solver based on root mean square error (RMSE), determination coefficient (R2) and mean percent error € for M1, S2 and C3 profiles. While The values of RMSE and R2 indices for M1, S2 and C3 profiles for GHF solver obtained (0.0173,0.9986), (0.0167,0.9984) and (0.0204,0.9988) respectively, corresponds values for Rong-Kutta method were (0.0458,0.9864), (0.0259,0.991) and (0.0327,0.9869). The results showed that using GHF analytical solver to solve the differential equation of GVF is more accurate.

Channel design is one of the optimization issues aiming to minimize the cost of channel construction. In this definition, the amounts of sections variables, namely radius, slope side, bottom width and flow depth are calculated by minimizing cost of channels with regard to indicating the hydraulic flow constraint. In the current study, the optimal design problems are formulated in a nonlinear optimization framework with the objective function being a cost function per unit length of the channel has been expressed as the cost per unit length of the channel for lining, the depth-dependent unit volume earthwork cost and the cost of water lost. Using genetic algorithm, the parameters of four optimized channel sections including trapezoidal, rectangular, triangular and circular sections of channels were calculated. From the results obtained for restricting the flow equation in comparison with the total cost of construction of sections, circular section has less cost of construction. Using the proposed method, which has more precision and accuracy, several models with additional restriction of velocity, Froude number, and top width were considered for optimal design of the channel under special conditions. Restriction of velocity and Froude number caused increasing by %40 and %30 respectively, but restricted top width decrease about %48 of construction cost for trapezoidal, rectangular, and triangular sections. Restriction of Froude number, top width and velocity caused increasing, the cost construction of circular section.

Biochar as a soil amendment can control bioavailability of heavy metals in contaminated soils and can reduce the hazard of their transferring to the food chain. In order to investigate the effects of biochar derived from the apple and grape pruning wastes and wheat straw on bioavailability of Cd and growth of lettuce plants an experiment was conducted in a completely randomized design under greenhouse condition with the facrors of: 1) the concentration of Cd (0, 10 and 20 mg kg-1), 2) type of biochar (apple pruning, grape pruning and wheat straw) and 3) biochar level (0 (B0), 2 (B2) and 5 (B5) % w/w) in 3 replications. At the end of the lettuce growth period, some parameters including shoot dry weight, root dry weight, Cd concentrations in root and shoot, translocation factor (TF), bio concentration factor for shoot and root (BCF), and bioavailability of Cd in soil were measured. The results showed that the increase of the soil pollution level, raised the   intensity of the Cd bioavailability, Cd concentrations of shoots and roots, bio concentration factor of shoot and root (BCF). Furthermore, with increasing the level of biochar in soil, bioavailable Cd, Cd concentrations of roots and shoots were decreased in treatments (B5> B2> B0). Bioavailable Cd concentrations in soil in biochar treatments including apple pruning, grape pruning and wheat straw at the level of 5% w/w were decreased, by 46.81, 65.96 and 76.59 %, as compared to control respectively. Therefore biochar impact on decreasing Cd bioavailability depended on its raw material, biochar amount and metal concentrations.

In order to investigate the water uptake limit of maize at different growth stages and scheduling the irrigation time, research was conducted in Imam Khomeini International University as a factorial experiment in a randomized complete block design. In the control treatment, the water requirement of the plant was supplied. But stress treatments included applying water stress (up to the temporary wilting point), at growth stages of 6-leaf, 12-leaf, flowering and seeds doughing. In the period of water stress, stomatal resistance, canopy temperature and meteorological parameters were measured. Based on the response of crop parameters to water stress, the readily available water (RAW) and crop water stress index (CWSI) were determined. The amount of RAW and CWSI at the 6-leaf, 12-leaf, flowering and doughing stages, were calculated equal to 45, 66, 61 and 70 percent and 0.37, 0.54, 0.63, and 0.47, respectively. The results showed that crop sensitivity to water stress, was different at maize growth stages. The flowering stage of maize was the most sensitive stage to water stress. Therefore, based on crop response, the irrigation time was determined at the time of water stress. Also, by calculating the exact volume of water required and applying variable irrigation intervals during growth stages, the crop water requirement to be supplied and irrigation losses were prevented. Under these conditions, due to the different sensitivity of water absorption at growth stages, it was possible to increase the water productivity.