مجله آبیاری و زهکشی ایران
سال هفدهم شماره 1 (فروردین و اردیبهشت 1402)

Iran is located in the arid and semi-arid belt of the world, which is characterized by low rainfall, thunderstorms, flood flows, and high evapotranspiration. So, quantitative evaluation of evapotranspiration on a regional scale is necessary for water resources management, crop production, and environmental assessments in irrigated lands. In recent years, many crop models are developed for simulation of crop growth and yield in various fields and irrigation managements. These models can simulate crop growth and crop yield. AquaCrop model is a pervasive model and is developed by FAO that can be used in growth simulating and modeling of many crops. In this study, the effect of different methods for estimation of reference evapotranspiration (ETo) on actual evapotranspiration (ET) and biomass at five stations by AquaCrop model was studied and evaluated. For this purpose, the reference evapotranspiration rate was estimated by using two temperature methods and three radiation methods and the results were statistically evaluated by the reference method FAO-56. Based on the evaluation, temperature method, the Blaney-Criddle had for both parameters of ET and biomass in five stations with R2 value greater than 0.5 (strong), moderate to excellent NRMSE and NS close to one, the Turc and the Makkink, radiation methods, with R2 greater than 0.5, excellent NRMSE and NS equal to 0.99 for biomass in five stations were the best. Among the radiation methods for ET, the Priestley-Taylor method had medium and strong R2, good to medium NRMSE and NS equal to 0.96 in Qazvin and Mashhad stations and the Turc method with R2 greater than 0.5, excellent NRMSE and NS equal to 0.98 for Urmia had an optimal and better simulation compared to other estimation methods. Among the studied radiation methods, no suitable method was found to evaluate ET for Rasht and Yazd stations.

Cadmium is one of the most important toxic heavy elements for plants. Selenium is a necessary and useful element in increasing tolerance to environmental stresses in plants. In this research which was performed in a research greenhouse in Torbat-e Jam region, Iran during 2021, The effect of cadmium in 3 levels (0, 75 and 150 mgrperlit CdCl2, and selenium factor in 2 levels (0 and 5 mgrperlit Na2SeO4) and was done in three replications. The results showed that with the increase of cadmium stress levels from 0 to 75 and 150, fresh and dry weight, water productivity, essential oil percentage and plant height decreased. Also, foliar spraying of selenium increased above fresh and dry weight, water productivity, essential oil percentage and plant height respectively 67/33, 67/98, 68/11, 61/16 and 40/68 percent compared to the absence of selenium. The results of the interaction effects of cadmium and selenium showed that foliar spraying of selenium with concentrations of 5 milligrams per liter in cadmium stress levels increased fresh and dry weight, water productivity and plant height compared to not consuming of selenium. Also, the results showed that foliar spraying of selenium at cadmium stress levels caused a change in the concentration of iron, zinc, sodium, potassium and cadmium in the leaves of peppermint compared to the absence of foliar spraying of selenium. The results indicated that with the increase of cadmium stress levels from 0 to 75 and 150, selenium decreases the concentration of cadmium in peppermint leaves respectively 23/97, 14/84 and 14/23 percent. The results indicated that water productivity decreased with the increase of cadmium stress. Also, selenium foliar application reduced the effects of cadmium stress.

The concept of virtual water as the amount of water consumed to produce each kilogram of agricultural products is one of the ways to reduce the pressure on water resources. According to this concept, it is necessary to produce agricultural products in balance with the amount of water consumption and with the policy of reducing water consumption. Therefore, in the present study, different irrigation scenarios in the production of four strategic crops (wheat, barley, potato and sugar beet) in Chaharmahal-and-Bakhtiari province based on the concept of virtual water were investigated. For this purpose, first, using the water productivity outlook of this province, the amount of virtual water in the current and future conditions (2025 and 2030) was determined. Then, the calibrated AquaCrop was used to simulate the yield of plants under study based on different amounts of irrigation water. The results showed that the amount of irrigation water suitable for wheat, barley, potato, and sugar beet production was 3420, 1530, 4300 and 5020 cubic meters per hectare, respectively. These values decreased by 39, 70, 57 and 90%, respectively, compared to the current irrigation conditions in this province. The amount of virtual water consumed in the proposed amounts of irrigation water is 0.19, 0.03, 0.6 and 0.12 million cubic meters, respectively. The amounts of virtual water for the production of these crops were decreased by 28, 61, 33 and 12%, respectively. By selecting these values, about 7, 12, 5 and 10 percent of the pressure applied to the water resources of this province will be reduced, respectively. Therefore, it is suggested that the aforementioned amount for irrigation water be used for the cultivation of wheat, barley, potatoes and sugar beet in the farms of this province.

The aim of the present study is to investigate the effects of climate scenarios on the simulation of crop yields, available water, changes in cropping patterns and farmers' profit in Marodasht city. For this purpose, the Water-Yield Response approach and the positive mathematical programming model (PMP) were used. Also, daily data and LARS-WG model under RCP2.6, RCP4.5 and RCP8.5 scenarios in the future period of 2020-2080 have been used to simulate the climate of the region. Based on the results, the greatest decrease in yield is tomato, wheat and rice products and the greatest increase in yield is predicted in alfalfa and barley products The results of the research showed that climate change, assuming the constancy of water consumption, causes a decrease in the gross income of farmers, But assuming stability of water consumption and constancy of yield, the income in some scenarios is positive and even its reduction is less than the previous state.. As a result of yield adaptation, it will lead to change of cultivation pattern by farmers. The results of this study indicate that the cultivation pattern is changing towards crops that are less sensitive to lack of irrigation and at the same time have a significant yield, which guarantees the profitability of farmers. Optimizing management methods and using cultivars with less water requirement and adapted to climate changes in the agricultural sector of Marvdasht city are recommended as solutions to deal with the effects of climate change; Also, increasing the efficiency of water consumption by 10% in every 20 years, compared to the base year, greatly reduces the decrease in farmers' income and prevents the reduction of cultivated area.

In order to study irrigation frequency and plant density of Kochia (Kochia scoparia), Quinoa and forage sorghum, a field experiment was conducted during 2015 and 2016 at Salinity Station. The experiment was laid out in a randomized complete block design in form of split plot factorial experiment and replicated four times. At this research effects of irrigation frequency at four levels (irrigation after 5, 10, 15 and 20 days), and plant density at three levels (11.1, 16.7 and 33.3 plants per m2) on Koshia (Birjand and Sabzevar bulks), Quinoa (Santa Maria and Sajama Iranshahr) and verities of KFS3 and Speedfeed sorghums were investigated. Results showed that; Variety of quinoa Santa Maria had the most water content. Sabzevar bulk at irrigation every 5 days interval and 33.33 plants per m2 with dry yield of 7.64 ton ha-1 had the highest yield and yield components of dry yield of forage. Interraction effects results showed that; with increasing plant density and irrigation on time until plant density of 333000 plants per hectare koshias and quinoas dry matter increased but this increasing for forage sorghum accurse till plant density of 167000 plant ha-1. Sabzevar bulk at irrigation every 5 days interval and 33.33 plants per m2 with yield of 33.99 ton ha-1 had the highest yield. The suitable treatment of quinoa was Santa Maria at irrigation every 5 days interval and 16.7 plants per m2 with dry yield of 4.37 ton ha-1 had the highest dry yield and KFS3 at the same plant density and irrigation frequency with yield of 3.3 ton ha-1 had the less ranking. Intrection effects of treatments showed, Sabzevar bulk of koshia at irrigation every 5 days interval and 33 plants per m2 with yield of 34 ton ha-1 had the highest fresh forage yield.

Because of limited water resources in Iran, decrease the water seepages and increase the water are necessary. Water productivity and the management conditions of irrigation and drainage systems shows that more attention should be paid to this subject. This research was conducted in 2019 in tajan irrigation network in mazandaran province. The losses and efficiencies of water conveyance and distribution in the water conveyance network of tajan were estimated using field measurements. Initially, 16 intervals were selected to indicate the state of the network. Field measurements were made using the inflow outflow method for each interval. All measurements on selected ranges of the channels to minimize evaporation were carried out in the early morning using a flow velocity meter with three repetitions. Then the discharge of each part of the cross section was calculated and finally the discharge of the whole section was obtained. The results show that the canals conveyance efficiencies vary between 88.2% and 99.5% and on average about 95.8% was estimated. Also, the distribution efficiency of the network has changed between 68% and 96% and on average about 77.25% was estimated. To prevent water losses in irrigation water conveyance and distribution channels, things like the growth of weeds in the channels, the accumulation of sediment in the channels, the accumulation of garbage in the channels, the cracking of the channel lining, the crushing or displacement of concrete parts in the channels, the destruction caused by poor quality of materials used, the destruction caused by executive issues, It should be controlled and fixed.

Fars province is one of the prominent provinces in the country in the production of oranges and tangerines. Having sufficient information on the volume of irrigation water and water productivity in orange and tangerine orchards can lead to better management of water resources and increase water productivity. In this research, water productivity and irrigation water volume were measured in 60 orange and tangerine orchards in three regions of Fars province during the crop year 2019. Among the selected orchards, due to differences in irrigation management, the state of water resources and soil conditions, the volume of irrigation water varied from about 8800 to 24700 m3/ha/yr. The average total volume of irrigation water in orange and tangerine orchards was 15388 and 15093 m3/ha, respectively. The average volume of applied water, which is the sum of effective irrigation and rainfall, was 18289 and 17867 m3/ha, respectively. The average fruit yield for orange and tangerine orchards was estimated as 18.4 and 20.8 t/ha, respectively. The productivity of irrigation water in selected orchards was between 0.45 and 3.03 kg/m3 and on average for orange and tangerine it was 1.30 and 1.44 kg/m3 respectively. Comparing the volume of irrigation water with the gross water requirement showed that in the year of conducting the research, the volume of irrigation water was on average 4400 m3/ha or in other words 41% more than the required water. The average difference in the volume of irrigation water with the long-term gross water requirement was about 4000 m3/ha. Considering the area of orange and tangerine orchards in the three regions of Darab, Jahrom and Kazeroon, the amount of water saved will be 46, 8 and 14 Mm3/yr, respectively.

To investigate the effect of sulfuric acid on the reduction of drip clogging and the effect of acid on the efficiency of the drip irrigation system used and soil chemical characteristics, an experiment was conducted at three sites with different soil textures in the crop year 2016-2017 in Qom. These fields included Aliabad, Sharifabad, and Zalunabad. For this purpose, the coefficient of variation (CV) and the desired dripper flow equation (Netafim 8 liters per hour) were determined. Moreover, water distribution uniformity (EU), uniformity coefficient (CU), dripper flow rate changes (Qvar), and statistical uniformity coefficient (Uc) before and after acid washing were measured and the efficiency and performance of the drip irrigation system were evaluated. The average dripper openings of Aliabad, Sharifabad, and Zalunabad were 4.23, 35.7, and 4.72%, respectively, and the minimum-maximum opening ranges in these areas were determined to be 0.71-25%, and -2.47-112-41 and 1.89-10.65. The results also showed that the indices of water distribution uniformity, uniformity coefficient, drip flow rate changes, and statistical uniformity coefficient in three regions of Aliabad, Sharifabad, and Zalunabad before acid washing were 92.4, 97.6, 0.21, and 96.06%, 55.3, 84.6, 0.9 and 78.7% and 91.2, 97.2, 18.6 and 95.8%, respectively. These indices after acid washing were determined to be 96.4, 95.2, 0.12, and 94.4%, 0 and 94.4, 80, 88.5, 0.91, and 82%, and 96.6, 95.5, 13.2, and 94.4%, respectively. Accordingly, sulfuric acid has a significant effect on the reduction of dripper clogging. The evaluation of the chemical properties of the soil before and after acid washing also showed a change in these properties and a decrease in soil salinity due to the reaction of sulfuric acid with carbonates in the soil after acid washing.

Spillways are used to transfer and discharge the excess water collected behind the dams downstream. There are different types of spillways in terms of geometry and place of use, which are used based on the topography of the region, hydraulic and hydrological conditions, etc. Based on this, in the current research, the effect of the frontal slope of a simple and blocky stepped spillway with a semi-circular crest on the hydraulic parameters of the spillway has been investigated using the Flow-3D® model and the RNG turbulence model. Three values were considered for the slope of the front area of the spillways step and the range of critical depth was between 11.9 and 14.5 cm. Numerical simulation showed that increasing the angle of the front of the step relative to the horizon, or in other words, reducing the slope of the front of the step, has increased the relative energy dissipation, so that the amount of energy dissipation increases in the spillway with a 90 degree step compared to a step with a 60 degree angle are 13.88% and 28.89% higher than the 45 degree angle stairs. On the other hand, the use of blocks has increased the consumption of energy in the overflow with a 90-degree step compared to a 60-degree angle step by 7% and compared to a 45-degree angle step by 32.24%. Also, the value of the downstream relative depth increases with the increase of the flow rate and with the increase of the downstream energy loss, the descent number of the downstream area of the stepped spillway decreases, and this decrease is about 60% more at the angle of 90 degrees than the angles were 45 and 60 degrees.

Infiltration in the soil is one of the determining parameters in irrigation, which affects all factors related to irrigation evaluation. On the other hand, spatial and temporal variability of infiltration parameters are a major physical limitation in managing and achieving high application efficiency of surface irrigation. The objective of the present study is to evaluate scaling method in estimating the infiltration equation parameters in furrow irrigation based on Elliott-Walker, Shepard et al., Ebrahimian et al., infilt, Valiants and Milapali methods, and also to evaluation the accuracy of the middle point and end point for the scale process. For this purpose, a reference infiltration curve is considered and then using the time of to reach the middle and end of the furrow, the scale factor of that furrow is obtained. In this research, the measured data for six furrows with soil texture and different input data were considered. According to the results, if the furrow end point is used to calculate the scaling factor in the Scaling method, the accuracy of this method will be significantly increased .Based on the evaluation, Ebrahimian's method had the best results. In the infilt method, there is no noticeable difference between using the middle point and the end point. In many cases, using the middle point in order to obtain the parameters of the penetration equation overestimates the advance value. The simplicity of the one-point scaling method is one of the advantages of this method in comparison with other methods of obtaining penetration parameters

Evaporation and wind loss causes a decrease in the amount of water entering the soil and a change in the spraying pattern, which changes parameters such as uniformity coefficient (CU), water distribution uniformity (DU), potential efficiency of application in the lower quartile of land (PELQ), actual efficiency in Lower quartile (AELQ) and total efficiency (ET) are irrigated. The current research was conducted in a factorial way in the agricultural year of 2020-2021 in the agricultural lands of Chaghahroshi plain in Khoram Abad city. The studied factors include land type (F1: sugar beet field and F2: onion field), sprinkler height (L1: 75 cm and L2: 100 cm) and irrigation time (T1: morning, T2: evening and T3: night) with three repetitions. Evaporation and wind loss in the sugar beet field was about 0.95% more than the onion field, which caused the decrease of other parameters including uniformity coefficient (5.06%) and total efficiency (5%) in the sugar beet field compared to It became an onion farm. With the increase of sprinkler height, evaporation losses and wind blowing increased by 1.56%. The reduction of evaporation and wind loss in the sugar beet field at night compared to morning and evening was 2.1% and 5.6%, respectively. The increase of uniformity coefficient and uniformity of distribution in the sugar beet field at night was 5.8 and 6.5%, respectively, more than irrigation in the morning. The increase in the values of these parameters compared to evening time was 11.3 and 14.9 percent, respectively. Changing the irrigation time in the onion field had a greater effect on improving the irrigation efficiency indicators than the sugar beet field. The reason for that was the increase in losses in the morning (4%) and evening (6.5%) compared to night irrigation in the onion field.

Soil and water scarcity has become the main challenge encountering human, especially in arid and semi-arid regions of the world. In addition, due to economic limitations in developing countries, region prioritization for developing and modernization of irrigation and drainage networks should be considered. In this study cultivated lands of the Miankangi Plain in Hirmand County located in Sistan-o-Baluchestan Province has been prioritized, in order to irrigation system network development. At first, questionnaires were designed and more than 120 of them were completed by experts and researchers, then weighted based on statistical indicators. After that, based on the available reports, field research, preliminary studies and data analysis, the effective parameters were selected. Effective parameters for this scope have been divided to technical and socioeconomic groups. These parameters had different efficiency. Among technical factors in different climatic conditions, fertility and soil quality with 34 points (out of 100) and among socioeconomic factors population density with 25 points had the most weights (efficiencies) for classification. Eventually cultivated lands were classified and prioritized to 11 groups. Villages such as Alimorad, Poodineh and Rudini were located in the first priority and Dahmarde, Molla Abdollah with the lowest points in the last priority. It is suggested to use this method to better understand the effective factors in nearby villages for the development of irrigation and drainage network.

The simultaneity of sugarcane's dry season with summer heat and high evaporation makes it one of the most water-consuming plants, considering that sugarcane is cultivated in large areas in Khuzestan province Evaluation of water consumption water productivity in sugarcane cultivated lands is very important.the present study was conducted with the aim of evaluating the effect of subsurface drip irrigation on water productivity and quantitative and qualitative yield of sugarcane in the second Ratoon and comparing it with the conventional irrigation system (closed-end furrow irrigation). Experiment with a fixed working depth of 20-cm and two distances of droppers (L1=50, L2=60-cm) and two flow rates (Q1=2.3, Q2=3.6-lit/hr.). It was done with four repetitions and in the form of a block design and as a split plot. The results of variance analysis of quantitative traits showed that the highest stem height and sugarcane yield in the treatment (Q2.3, L50) were The order of 211-cm and 88-ton/ha was observed. The results of variance analysis of qualitative traits also showed that the highest yield of pure sugar with 11-ton/ha was related to the treatment (Q2.3 L50) and the lowest amount was 6.6-ton/ha. in conventional irrigation treatment (control). The highest water productivity per cane and sugar produced for the treatment (Q2.3, L50) was obtained, 4.64 and 0.58 kg/m3, respectively, which compared to the control treatment, caused There has been an increase of about 52% in water productivity. Finally, the treatment (Q2.3, L50) had the highest yield and water productivity.

In order to predict the behavior of soil-related phenomena, it is necessary to have knowledge about unsaturated flow and using models that provide optimal estimates of the retention curve and hydraulic conductivity of soils. Despite the widespread use of the classic van Genuchten-Mualem model (VGM), this model usually performs poorly in predicting hydraulic conductivity and modification of some of its parameters seems necessary. In this research, a number of 283 soils from different texture of the UNSODA bank were selected and divided into two sections of calibration and validation sections and their soil parameters were extracted and categorized. Then, by defining the modified unsaturated hydraulic conductivity (Ksc) instead of the saturated hydraulic conductivity (Ks) and determining the limits for l and n parameters, the hydraulic conductivity-moisture function of this model were solved using 24600 pairs of points li and nj for each soil of the three main soil texture classes. In the following, the optimal l value (l̂) of each texture class was selected based on the minimum value of the hydraulic conductivity estimation error using the root mean square error (RMSE) index and the n values that create the minimum errors were selected as the optimal pore size distribution coefficients of the hydraulic conductivity-moisture function (n̂opt). In order to create pedotransfer functions for estimating n̂opt, we ran stepwise regression in MATLAB software considering the condition of statistical significance (P-value=0.05) for independent variables and functions for each soil texture class. After creating pedotransfer functions, the results of the proposed method of this research (MVGM) were compared with the VGM model results using RMSE and Nash-Sutcliffe (NSE) indices. The results showed that in both sections of creating and validation functions, the MVGM performed better in estimating hydraulic conductivity and had a higher efficiency index for all classes of soil texture.

The growing population and rising incomes have increased the water demand for agricultural, industrial and urban use.  On the other hand, water supply has shifted from surface sources to groundwater sources. This has significantly reduced the storage of groundwater resources. The growth of urbanization and the existence of two cities of Tehran and Karaj in the Tehran-Karaj plain has increased the demand for water in the domestic sector and as a result has reduced the share of water consumption in the agricultural sector. For optimal water management with considering the water demand in different economic sectors, in this study, the effects of changes in water demand in the domestic sector on agricultural activities, its economic value have been estimated.  The Stone-Geary Utility method was used to estimate urban water demand and the positive mathematical programming approach was used to estimate the economic value and effects of urban water demand on the agricultural sector. The results showed that the water economic value in the agricultural sector is equal to 550 Toman per cubic meter. Now, if the share of the agricultural sector in groundwater decreases by 1, 5, 10 and 20%, the economic value of water in the agricultural sector will increase to 600, 703, 761 and 976 Toman per cubic meter. Due to the constraints created by water demand in the domestic sector and the reduction of water availability, in addition to pricing based on the economic value of water in the agricultural sector, policymakers are proposing incentive policies to invest in modern irrigation systems in order to increase more water productivity