مجله آبیاری و زهکشی ایران
سال دهم شماره 1 (فروردین و اردیبهشت 1395)

The use of unconventional water resources such as treated wastewater is an important strategy for solving the problem of water crisis. Drip irrigation is considered as the best method for irrigation when using wastewater. Emitter clogging is the most important problem in drip irrigation systems. The emitter clogging reduces the water distribution uniformity and increases the cost and operation time of the system. The purpose of this research was to investigate the effect of flushing frequencies (monthly flushing and flushing end of season) on the clogging reduction of Micro Flapper, Corona emitters and drip irrigation tape when using treated wastewater of Sanandaj city. For this purpose, a physical model of drip irrigation was designed and made in the laboratory. The results of this study indicated that, clogging rate of emitters increase with time, when using treated wastewater which, the highest and lowest emitter clogging related to Micro Flapper emitter (44.8 percent) and drip irrigation tape (35.1 percent), respectively. The flushing end of season caused clogging reduction of the above mentioned emitters to 2.6 and 25.8 percent, respectively. Also, the results showed that the monthly flushing is the best flushing frequency to reduce the clogging of the emitters and drip irrigation tape. The statistical results indicated that the effect of flushing frequency and the type of emitter on the emitters clogging was statistically significant at one percent level.

This paper shows an optimal water allocation and delivery model at two levels of irrigation networks, namely farm level and canal level, for maximizing of the net benefit. For this purpose, three sub models were developed to optimization of water allocation among different crops, water distribution during each crop growth stage, and water delivery scheduling between canal outlets. The model was performed on the K canal of Moghan irrigation network. With purpose of maximizing the net benefit, optimal water allocated among different crops, distribution of water during each crop growth stages, and water delivery factors at canal level were determined based on optimization procedures. Three water content scenarios were considered in the procedure: normal condition, 25 and 50 percent water deficit conditions. The results showed that the net return was reduced at 25 and 50 percent water deficit scenario, but the water productivity was increased 24% and 40% respectively for the other scenarios. The inflow to the distributary canal was 640 l/s, 590 l/s and 360 l/s in the scenarios, respectively. This indicates that the discharge of canal can be decreased in the deficit scenarios up to 8% and 44% less than normal scenario. Therefore it can reduce canal evaporation and seepage loses.

In order to delivery and distribution programs of water in irrigation network have been used the design and implementation of different structures. Lopac gate is one of the upstream control structures having some advantages such as, performing as overflow structure, easy automation, crossing sediments and floating bodies simultaneously. One of the effective tools to study control structures is mathematical model. Due to the unsteady nature of flow in irrigation canals, incorporation of mathematical model of control structure with hydrodynamic models, is necessary. In this research, the Various Hydraulic and Operation Conditions of Lopac Gate is introduced and mathematical model of Lopac gate is developed and linked with ICSS hydrodynamic model. The developed model is validated using physical model data. The maximum error obtained as 6%, which is acceptable for practical purposes. The model was tested on a canal of DEZ irrigation network in Iran under many different conditions. Results showed that, the model is performing well for tested applications and could be used in various studies of irrigation canals equipped with this structure.

This study was conducted to evaluate the water productivity of Amir kabir sugarcane agro-industry farms using landsat 8 satellite data. Actual evapotranspiration and yield of the final product were estimated using satellite data and then were compared with measures corresponding values collected from fields during 2012-2013 growing season. The total volume of sugarcane actual evapotranspiration during the growing season from 9328.5 hectares of cultivated farms was 160 million cubic meters and the yield of wet sugarcane was 520230 tons, which is equivalent to 56 tons per hectare. Average of water productivity for sugarcane according to the evapotranspiration and the irrigation water were 3.4 Kg/m3 and 1.6 Kg/m3 respectively. The water productivity data analysis in ARC-10 showed that there was a direct relationship between irrigation intervals of planted plots and water productivity. Therfore, it can be concluded that , by increasing irrigation intervals, and applying the same volume of irrigation water would cause, water productivity to increase. Also, the water productivity of CP48 103 variety was found to be higher than of CP69-1062 variety. The water productivity of sugarcane was inversely related to the age of the cultivated crops. As the age of the sugarcane crop increased from planting to R7, its water productivity decreased. It was concluded that the difference between the water productivity of various plot of Amirkabir sugarcane agroindustry farms could be attributed to the depth of applied irrigation,irrigation time and intervals, and also to the large difference between the ages of sugarcane plantations (plant to R7).

Using normal Kriging in the evaluation of groundwater quality can not specify the areas susceptible to pollution. In this study, to determine the extent of exceeded nitrate pollution (50 mg/L) as well as identifying the areas susceptible to pollution, nitrate data of 287 wells within an area of 320 square kilometers in Mashhad and the statistical range of 2002 to 2011 was analyzed by R software. The process of evaluation and analysis included re-arranging data sheets, detection of outliers, removing the trend, studying the isotropy, determination of the optimum variogram models for each year, and formulating the spatial and temporal Indicator Kriging. The results showed that Matern semivariogram was the best model for explaining the spatial structure data in each year. Also, in the statistical range respectively 7.1, 5.8, 7.2, 8.5, 8.6, 9.4, 10.4, 2.1, and 2.4 percent of the studied area has passed the pollution allowed limit. It seems that more polluted areas have been controlled since 200 by some strategies such as shutting down the polluted wells, preventing new well digging, transferring water from Doosti Dam, using appropriate agricultural wells for drinking section and implementation of wastewater collection network. In addition, respectively 10.4, 11.7, 12.4, 9.4, 14.3, . , 6, 11.6 and 11.5 percentage of total area was prone to pollution during these years. Therefore, these areas need more attention for monitoring and controlling the source of pollution.

In heterogeneous and layered soils, in order to a better management and description of chemicals movement on such media, perception of solute movement is very important. In this study, the effect of soil layers arrangement with different thicknesses on solute movement was investigated. For this purpose, two soils with different textures (i.e. loamy sand and clay loam) were used to prepare six two-layered columns (two 10cmcolumns, two 20cm-columns and two 30cm-columns), and the movement of sodium chloride in these columns was tested. First arrangement, namely the loamy sand layer was beneath the clay loam layer, was compared to second arrangement (the layers were swapped), and it was observed that the solute breakthrough and the appearance of peak concentration in the bottom of column were faster and the tail of breakthrough curve was shorter. By increasing the thickness of layers, the differences also increased, so that by swapping the two layers in 5 cm-layers, the difference between the times that breakthrough solute reaches to an almost constant concentration, the time of maximum concentration appearance and the duration of breakthrough curve tail time were 210, 250 and 40 minutes, respectively. Layers arrangement more than column length effected the solute movement, so that the peak concentration in second arrangement of 10cm-column was 40 min later than the first arrangement of 20cm-column and, the concentration in second arrangement of 20cm column was 100 min later than the first arrangement of 30cm-column. The solute movement was simulated by finite element method using the GeoStudio model. The simulation results have coefficient of determination (R2) more than 0.984 and root mean square error (RMSE) less than 0.530 g/L. This means that the simulation results were satisfactory.

Water and nitrogen are the most important parameters affecting the yield of different plants such as corn. The aim of this study was to investigate the response of field corn to different levels of water and nitrogen and simulating with Aquacrop model. Water treatments were included control (I100), water stress in vegetative growth, flowering and grain filling stages, each of them had two levels 80% and 60% of water requirement and application of nitrogen fertilizer in two levels of 220 (N100) and 110 (N50) Kg N/ha. Field results showed that various stages of crop growth was affected by water and nitrogen stresses.The results of analysis of variance showed that various water and nitrogen treatments had a significant effect on above ground biomass and grain yield at 1%. AquaCrop model was able to accurately simulate canopy cover, biomass and grain yield during the growth season. Simulation results showed that calibrated AquaCrop model can be used to a wide range of Iran.

The use of unconventional water, including salt water for irrigation is an unavoidable, due to the increasing demand for water, especially in arid and semi-arid. To determine effects of irrigation water salinity on corn yield and its yield components, 4 treatments of saline water with salinity of 2, 6, 9 and 12 ds/m in randomized complete block design (RCB) was conducted in Sabzevar region in the 2012-13 season. Results showed that increasing of water saline decreased corn yield and its yield components such as plant’s height, dry weight, leaf area, maize diameter, number of rows on ear, productivity, weight of 100 grain and number of grains, significantly. For every one unit increase in salinity, height, biomass and leaf area decreased 1.94, 6.16 and 1.85%, respectively. Salinity threshold (a) and line slope (b) was obtained 1.7 ds m-1 and 9.3%, respectively. Low salinity threshold and high line slope indicated that corn is very sensitivity to saline.

Irrigation with saline waters and solute transport to soil surface by capillary can accumulate solutes. Current study have been carried out to simulate the water flow and solute transport in soil by Hydrus model in order to determine the suitable depth of dripper in the grape garden that was located in Amirabad village in Birjand city in 2015.Samples were taken from the 0, 30, 60 and 90 cm of soil during the 3 irrigation interval and then the amount of soil sample moisture have been determined in the laboratory then the amount of moisture have been entered in Hydrus- 1D model. The amount of soil hydraulic parameters have been determined by inverse solution. Outputs of Hydrus- 1D have been entered in Hydrus- 3D model and the model have been executed. Results indicated that the amounts of Root Mean Square Weighted Error (RMSE), Mean Weighted Absolute Error (MAE) were 9 and 6 percent, respectively. According to the moisture and salinity profiles obtained from Hydrus-3D model, it was suggested to place dripper in depth of 32 cm. In order to check the accuracy of suggested depth Some Scenarios have been considered in Hydrus-2D model. In this scenarios, the dripper have been placed in the depths of 15, 20 and 25 cm. According to the obtained concentration profiles at the end of the simulation period for the mentioned depths, when the dripper have been placed in the depth of 25 cm, the amount of solute accumulation reaches to zero at the soil surface that confirms the results obtained by Hydrus- 3D so it is better to place dripper in the depth of 25-32 cm.

The presence of nitrate in water is one of the most important global concerns. Therefore use of cheap absorbents such as biochar and vermicompost is important as a solution environmental protection and management of crop residue. This study was conducted whit porpuse of compare of biochar and vermicompost sugarcane bagasse performance on nitrate removal from contaminated water and determines the optimum conditions for adsorption process. after providing of sugarcane bagasse biochar and vermicompost and determine of theirs characteristics, the effect of different parameter such as initial pH (2-11), dosage of adsorbent (1-10 g/L), solution temperature (10, 22 and 30 ° C), the presence of competing ions (phosphate, sulphate, carbonate and chloride) and contact time (0-180 min) was investigated on the efficiency of absorption. Then, different kinetic and isotherm models were fitted to the experimental data. The results of this study showed that the optimum pH of nitrate adsorption by sugarcane bagasse biochar and vermicompost was 4.64 and 3.78, respectively. Also optimum adsorbent dosage was obtained 2 gr/L. Among the competing anions, carbonate and chloride had the highest and the lowest impact on the reduction of nitrate removal and nitrate removal efficiency was increased as the temperature increases. According to kinetic experiment, equilibrium time for nitrate adsorption by biochar and was obtained 60 and 120 min, respectively. The higher removal of nitrate by biochar (73.7%) in compare to vermicompost (48%) was due to specific surface area, the amount of carbon and anionexchange capacity of sugarcane bagasse biochar is higher than vermicompost. The pseudo-second order adsorption kinetic model and Langmuir adsorption isotherm model showed the best fit to the experimental adsorption data.

Crop water requirement knowledge and precise estimation of plant evapotranspiration are essential for improving water use efficiency and efficient water management. Water balance approach utilizing lysimeters with correct measurement of inputs and outputs is an accurate method for crop water requirement estimation. This study aimed to determine crop coefficient (kc) and water requirements of three medicinal plants namely Silybum marianum (L.) Gaertn, Rosmarinus officinalis L. and Lavandula angustifolia Mill. using water balance approach in 2013–2014. Nine volumetric lysimeters were used to carry out the experiment in school of agriculture (Bajgah), Shiraz University. Actual daily evapotranspiration using water balance method was estimated using lysimeters. Reference evapotranspiration was calculated using climate data from the adjacent weather station applying FAO–Penman–Monteith model. Daily crop coefficient during the study period was estimated by dividing the actual evapotranspiration by reference evapotranspiration. According to the results the seasonal evapotranspiration of Silybum marianum estimated 372.6 mm and it’s crop coefficient was 0.3, 0.77, 1.04 and 0.85 during the initial, developing, mid and late season stages, respectively. Crop evapotranspiration of Lavender and Rosemary, obtained 1191.4 mm and 14534.6 mm, respectively. The maximum and minimum daily evapotranspiration of Rosemary obtained 8.17mm in August and 0.58mm in January. The corresponding minimum and maximum crop coefficient was 0.16 in January and 1.13 in August. The maximum and minimum daily evapotranspiration of Lavender obtained 7.82 mm in June and 0.62mm in January. Also the maximum and minimum crop coefficient of Lavender was 1.18 in June and 0.18 in January. Of three studied plants in limited time period and research conditions, Silybum marianum due to shorter growth period as a seasonally plant requires the lowest amount of water while Rosmarinus officinalis L. as a perennial plant requires the most amount of water. However, to increase the accuracy of findings it is highly recommended this experiment repeated for more seasons and in different areas.

Water is wasted during the storage, distribution and application in the field. In sprinkler irrigation systems Wind Drift and Evaporation Losses (WDEL) are known as the main part of losses due to the impact of climate variables on the droplets dispersed in the air. In arid and semi-arid and windy regions WDEL is high and lead to reduce the efficiency and performance of the sprinkler system. This study investigated the WDEL on classic sprinkler irrigation system in Dehgolan plain located in Kurdistan province. The experiments were done with three replications at the University Research Farm of Kurdistan in the Sarab village using the two sprinklers VYR-35 (3.96×2.38mm) and ZK30 (8×3.6mm) sprinklers with two riser heights (1 and 1.5 meters) at day and night irrigation times. Results showed that riser height, day and night irrigation and interaction between riser height and irrigation time had a significant effect on WDEL. So that, WDEL percent was 22.53 % and 6.94% for day and night irrigation, respectively. According to these results, nightly irrigation will help to improve irrigation efficiency. Also based on the results in the same conditions, riser height should be 1 meter.