Journal of Irrigation Sciences and Engineering
Year:2016 | Volume:39 | Issue:2|Papers Count:18

Air temperature is one of the most important indicators of climate change in global and regional scales, that its changes will affect also on the other climatic parameters and also on other sectors such as agriculture and water use in this section. With increasing air temperature is expected potential evapotranspiration increase. Therefore, in this study using time series were performed modeling and prediction monthly maximum and minimum temperatures of Mashhad plain. Then with the help of empirical formulas Hargreaves - Samani and by selecting crop coefficients were calculated potential evapotranspiration rates and crops water requirement of 5 major products with the largest area under irrigated including wheat, sugar beets, tomatoes, alfalfa, and apples for the base period (1987-2008) and next 10-years period (2009-2018). During the growing season, and were compared with each other. The results show that the maximum and minimum temperatures will increase respectively by 1.4 and 1oC. So that the maximum temperature more in warm seasons and minimum temperature more in cold seasons will increase. Prediction of potential evapotranspiration showed that the changes will be more affected by maximum temperature changes Also the comparison of water requirement of different crops indicated increase evapotranspiration in the future between the future and the base periods. So that among the five selected crops in Mashhad plain, sugar beet has the highest percentage of changes in water requirement equal to 2.8% (290 m3/ha).

Two major factors causing of scour around bridge piers are the down flow occurred in upstream part of the piers and separation of streamlines from piers called horseshoe vortex. Installation of a collar on a pier will reduce the power of the down flow and horseshoe vortex. In this study, the effects of placement of collar and netted collars on scour depth of cubic pier are investigated. The experimental flume was rectangular with the length of 7.3 meters, width of 0.56 m and a depth of 0.6 m. For this propose four collars included, one simple and three netted (with opening parts equal to 15 percent, 30 percent and 40 percent), are tested under clear water condition. The experiments were performed in laboratory flume on Hydraulics Laboratory of Shahid Chamran University. The collars were installed in three levels equal to 0.5B, 0.25B and on the bed. The results were compared with the pier without the collar, and showed that the netted collar reduce the maximum scour depth between 34 percent to 97 percent in comparison with the case of no collar used. Also in low Froude Numbers, the netted collars showed better protection in comparison with the simple one

One of the most effective techniques for removing the deposited sediments from reservoirs is pressure flushing which has only much local effects. It is often applied as a clearing process to remove sediment saround the entrance of intakes .In order to make rational design of bottom outlets and other sediment flushing structures, the understanding of the characteristics of a scour funnel in under pressure flushing is significant. The physical model was constructed in the Hydraulic Laboratory at the Water Sciences Engineerin Faculty of Shahid Chamran University of Ahvaz and by performing various experiments on the effect of bottom outlet shape on the volume and dimensions of flushing cone was experimentally investigated. For this purposes, the experiments on 4 bottom outlets with a circular, semicircular, rectangular and square cross-sectional area equal to 18 cm2, five water levels of 30, 45, 55, 65, 78 cm, resulting in five different discharges on the bottom outlet, was performed. The results of this survey revealed that the shape of the lower opening is an important parameter in hydraulic flushing, changing of which results in change of scouring diameter. Results also showed that for a specific water level in the reservoir and for a specific time the scouring dimension for square valves and semicircle valves are more than one of rectangular valves. The scouring dimensions of rectangular valves are more than one of circular valves. The difference is more perceptible in lower water heights (i. e. lower discharge). The length of scouring and the volume of flushing cone increases with incrsing head and is the least for circular valves.

The soil hydraulic conductivity (Ks) is very important parameters in soil physic and the designing of drainage systems. In this study the basic infiltration rate, infiltration rate and the saturated and unsaturated soil hydraulic conductivity were determined in a randomized complete block design with three treatments and three replications in a corn field in north of Khuzestan (Dezful) in 2013. The treatments were including No Tillage (NT), Minimum Tillage (MT) and conventional Tillage (CT) methods. In order to compare the effect of mesearing method of saturated hydraulic conductivity with two methods of double rings and disc permeameter on tillage methods the factorial test were used. The messuring of disc permeameter was performed in 15, 10, 5, 3, zero suctions. The results showed that the basic infiltration rate, infiltration rate and saturated and unsaturated (exept 10 and 15 suctions) hydraulic conductivity in CT method were significantly higher than the other methods of tillage (P<0.01). Comparing of the two measuring methods showed there were significantly difference between them. According to this the value of saturated hydraulic conductivity in disc permeameter method was higher than double rings method.

In order to investigate the performance of sugarcane bagasse in the removal of nitrate from effluent subsurface drainage water, a study was conducted at the physical models laboratory of Water Sciences Engineering Faculty of Shahid Chamran University of Ahvaz, in the summer of 2013 till the summer of 2014. A physical model with the dimensions of 40×120×150 cm, which simulated the drainage trench, was utilized in this experiment. Bagasse combined with by 3: 7 volume ratio, the combination installed as a filter besides the drainage pipe. In this study, the influent nitrate concentration was 160 mg.L-1. Influent nitrate flow was continues. At first, every two days, and then every four days the drainage pipe was sampled. Input and output drainage model solution sampled with plastic bottles. Then some parameters like Nitrate, NH4, PH and EC measured. The presence of bagasse as a carbon material in the soil caused the amount of nitrate to reduce from 160 milligrams per liter to 60 milligrams per liter; a reduction of nearly more than 60 percent. The amount of ammonium increased very little in this study. The use of sugar cane bagasse as a filter drainage, reduces the acidity of the drainage outlet. It had no effect on the electrical conductivity. Physical model results show that the clogging of the filter in this period was relatively low and carbon filter had good performance. At first, the water output velocity was high but it decreased by time. According to analytics, the difference between input and output parameters in level of five percent were significant for acidity and electrical conductivity.

FAO-56 Penman-Monteth (FPM) model is one of the most applied methods to estimate crop evapotranspiration; yet the accuracy of the model in greenhouses is still undetermined especially in non-standard conditions of water deficit and salinity. This study focused on the performance of the FPM model in estimating greenhouse and outdoor eggplant evapotranspiration (ETc), crop coefficient (Kc) and water stress coefficient (Ks) under different levels of water deficit and salinity. An area in the greenhouse and the outdoor field was assigned to grass cultivation as a reference crop. Daily reference (ET0) and crop evapotranspirations were measured by diurnal weighting of microlysimeters throughout the growing season (from May 19th to September 5th, 2012). The performance of the FPM model was evaluated by four statistical difference criterions along with regression indices. The ET0 values were properly estimated in the outdoor conditions but showed about 12 percent underestimation in the greenhouse; however, the trends of daily ET0changes were well predicted in both environments. Apparent differences in daily ETc variations were met during the growing season, for various levels and combinations of water stress. Best estimations of daily and mean 10-day ETc values were those of daily irrigated (I1) treatments in both environments. In mean 10-day ETc, better correlations were obtained between the measured and estimated values due to smoothened fluctuations in weather and data and soil moisture changes. Actual and calculated values of Ks along with the correctness of their estimations decreased with the intensity of water stresses in both environments. The variation patterns of daily Kc values was similar to those of the daily ETc. Mean 10-day values of Kc were properly estimated by the FPM model; yet outdoor estimations were accurate in all treatments.

Correct and essential design is one of the important factors in development and improvement of pressurized irrigation systems. This research was performed using Miriam-keller method in order to investigate drip irrigation system implemented in Shahid Rajaayi Agro-Industry, Dezful. To do this, five systems were selected as a drip irrigation system. These systems were different in terms of lateral pipe layout and nominal discharge of drippers. Drippers used in these systems were compensating emitters with 2.2, 4 and 8 liters/hour flow rates and had parallel and pig-tail configurations. To evaluate irrigation systems, Christiansen uniformity coefficient, emission uniformity, potential efficiency of low quarter and actual efficiency of low quarter parameters were used. Mean values of the above parameters in the evaluated systems were obtained 95.12%, 91.68%, 82.91% and 91.2%, respectively. Among systems evaluated, system D from plot 110, with pig-tail lateral layout and 8 liter/hour drippers was selected as the best system in terms of measured parameters. values of uniformity coefficient, emission uniformity, potential efficiency of low quarter and actual efficiency of low quarter for this system were 98, 95.8, 86.22 and 95.8 percent, respectively. Values of emission uniformity obtained for the evaluated five systems were in "Perfect" class. Low difference of values of Potential Efficiency of Low Quarter and Actual Efficiency of Low Quarter indicates good management of these systems and suitable design of them.

To derive optimal operation policies from multi-reservoir systems, applying the conflict multiple goals simultaneously is very important. In order to, this paper presents a multi-objective optimization-simulation model, which is consist of agriculture and minimum flow goals in a three dam water resources system. For this purpose, a discrete hedging rule with a non-dominated sorting genetic algorithm has been coupled to minimize the modified shortage index over a series of hydrological record of 48 years. The evaluation metrics are diversity metric and standard deviation, which obtained values of each are equal to 0.357 and 0.0111 respectively. The results show the efficient performance of this algorithm to obtain Pareto frontier. Also, multi-objective algorithms present a set of optimum solutions for users instead of a solution, thus it helps to make decision in supplying the conflict goals of agriculture and minimum flow in different and complicate operation conditions such as drought periods easily.

Since the agriculture field is the main water consumer, using techniques in order to increasing water use efficiency is necessary. Applying super absorbent polymer (SAP) could be a method to reduce consuming water in Iran. Another method to counter water crisis is using unconventional water in agriculture, which in this terms the study of physical and chemical changes of soil properties is important. This study with the aims of the effects of super absorbent polymer and salinity of irrigation water on available water, soil porosity and saturation hydraulic conductivity was done at the Water Engineering Faculty of Shahid Chamran University of Ahvaz. This research performed in two independent experiments with three replications according to a randomized complete block design with factorial layout in three levels of salinity irrigation water, two kinds of SAP, Iranian and French, each with three levels in winter and spring of 2014. The levels of using SAP included 0, 3 and 6 g SAP per kilogram soil (0, 0.3, 0.6 weight percentage) and treatment of salinity of irrigation included 2.6, 4, 6 dS/m. After two months irrigation under salinity water treatment, sampling to determine available water, soil porosity and saturation hydraulic conductivity was done. The results showed that increasing SAP increased available water and soil porosity and decreased saturation hydraulic conductivity significantly. Increasing of water salinity decreased available water and soil porosity at 5% significantly. The iranian polymer and the french polymer lead to raise water ability 1.45 and 1.96 times and increased porosity 33.61 and 40.75 percent more than the sample without polymer.

It is necessary to optimize the use of water resources in arid and semi-arid of world because of limited water resources, low performance efficiency, increasing population and demand for water.Suitable cropping patterns are very effective and efficient method for use of water. Due to limited water resources in Birjand plain, this research was conducted to optimization of crop pattern in the plain. For this purpose, crop pattern in Birjand plain (A) and 8 common crop patterns were studied. The method of multi-criteria decision analytic hierarchy process and LINGO programming model used to determine the best cropping pattern. Economic and social measures used to maximize net income, employment and labor and minimizing water consumption, cost and virtual water in both model. Results showed that profit and water is factor that is more important other than to determine crop pattern. Results show that saffron, cumin, barley, wheat, summer crops, vegetables, sugar beet, forage plant and cotton are the highest priority for cultivation. AHP results showed that 8, 2 and 4 models were determined the best cropping patterns so that in these models the forage plant (21.12%), wheat (36.74%) and wheat (46.76%) had the highest cultivation area, respectively. Model 8 due to had a low coefficient of determination (R2) in LINGO so this model is inappropriate. The cultivated wheat and vegetable in models 2 and 4 increased than cropping patterns prevalent in the region. Cucurbit plants, saffron, cotton and barley in Model 2 increased compared to the current model, while Model 4 decreased. Cumin decreased in model 2 but increased in model 4. Cultivation of forage plant and sugar beet in both models reduced compared to the current crop pattern.

Simulation of rainfall - runoff process is one of the most important tasks in water resources management and flood control studies. In this study, the rainfall – runoff process over Kakarza river located at Lorestan province, was simulated using the Bayesian neural network and the results were compared with the gene expression and support vector machine models. In this case, different combinations of monthly rainfall and runoff data in period of 1969-2013 were considered as the input data of the models. Four performance criteria namely, correlation coefficient, root mean square error, Nash-Sutcliff coefficient and bias were used to evaluate and compare the performance of the models. The results showed that the performance of the models were satisfactory. Results showed that, the Bayesian neural network model is more efficient than the other models in estimation of minimum, mean and peak of runoff.

The main challenge facing the agriculture sector is producing more food while using less water so it is needed to increase water use efficiency and optimal use of water resources, especially in arid areas. The main goal of this research is to study the effect of irrigation with municipal wastewater effluent and water use efficiency of maize in farms located in south- west of Shahr-e-kord. All of treatments were used in randomized complete block design with split plots and three applications with five factors including 100% well water (M1), 25% wastewater+75% well water (M2), 50% wastewater+50% well water (M3), 75% wastewater+25% well water and 100 % wastewater (M5) and four sub treatment factors according to the different amounts of water, wastewater and mixture of water and wastewater on the basis of water requirements (50% (L1), 65% (L2), 85% (L3) and 100% (L4)). In the different treatment types of water, M4 (25%well water and 75% wastewater) had dry matter yield. Regarding to total dry matter, the yield of biomass, grain and water use efficiency were more in M4 treatment and the less water use efficiency was determined in 100% wastewater treatment (M5). In different amounts of water treatments on the basis of total dry matter, the most total dry matter yield, biomass, grain and water use efficiency were determined in 100% crop water requirement treatment (L4). On the basis of biomass yield, 85% crop water requirement treatment (L3) had more water use efficiency. The results show that for total dry matter, biomass and grain yield 75% wastewater+25% well water was the best treatment in irrigation of considered area. On the other hand, wastewater contains nutrients and can be used without fertilizer consumption in this area, so it is useful in saving water and fertilizer.

Application of mulches not only affects the physical and chemical properties of soil, but improves infiltration maintenance. In this study, evaluated during four month, the effects of wheat straw, maize straw, sawdust, leaves and superab A200 on the soil physical properties including soil bulk density, capacity water in the soil and cumulative infiltration. The effects of mulch compared in both cases tillage and no tillage, under modle complete block randomized design experiment with split plot in time. Results showed Mulch reduces bulk density but over time, bulk density in all mulchs except of superab A200, were increasing. Use mulch experiments increased water-holding capacity of the soil. In case tillage treatments, wheat straw and in case no tillage treatments superab A200 increasing water-holding capacity. After time increase cumulative infiltration in the wheat straw, maize straw and superab A200 significantly, compared to sawdust and leave mulches.

Chutes are one type of the many hydraulic structures that cause in the formation of the waves and turbulence in the free surface of flow through super critical flow. In this study by the fluent software and by using volume of fluid model and PISO algorithm, the formation of the rolling waves in the physical model of azad damweir and numerical models have been considered. For this purpose, flow depth and weave heightare calculated along the chutes length for different discharges, widths and longitudinal slopes of the chute. The results indicate that roughness of the bed and walls impede the formation of the rolling wave, also the rolling waves are expected to be generated for sections of the chute when weave height tohydraulic depth ratio in that section is above 0.57.

Examining the properties and behavior of the flow in the rivers and its associated structures is one of complex phenomena that make the use of software inevitable. First, the results of laboratory test carried out by Duan et al. (2009) in Minnesota university, are used verification and comparison of numerical simulations of FLOW-3D (version 9.3). The vertical spur dike was first simulated to verify the model results and the inclined spur dike with 60° and 30° to the flow direction was then considered. The simulation performed with FLOW-3D, for 650 seconds using turbulence models (k-e, RNG, LES). By comparing different turbulence models with experimental results, the maximum scour depth at the tip of the spur dike was 8.82 cm. Then the maximum scour depth calculated by FLOW-3D in the turbulence models of (k-e, RNG, LES) was 9.1, 8.9, 9.1 cm. So the error in RNG turbulence model is about 9%, compare to the turbulence model k-e, and of LES shows more agreement. In the simulation, the maximum scour depth at the tip of the spur dike 60° and 30° was 8.75 and 6.5 cm respectively.

Experimental results of determining scour hole dimensions resulted from submerged circular jet in a plunge pool containing non-cohesive materials are presented in this paper. The effect of nozzle flow velocity, the height of nozzle installation and the bed particle diameters, are evaluated toward this end. Non-cohesive materials with average diameter of 4.06, 7.14, and 8.73 mm are used in this study. The elevation of jet installation toward the surface of plunge pool bed is changed with the values of 24, 35.5 and 44 cm. The nozzle flow velocity was differentiated between 2 and 10 meter per second. The comparison of observed results with previous studies show that the erosion parameter absolutely unable to normalized the effect of particle diameters, jet installation effect and nozzle flow velocity on the relative scour dimensions. The sensitive analysis on general introduced relations in this paper indicates that the variations of flow velocity and jet installation elevations has a double effect on estimating scour hole dimension in comparison to the material size and grading variations. The results also showed that armoring of the plunge bed has an important role in estimating relative parameters of scouring.