Original Article
Irrigation network management
rasu; Ghobadian; sara hshmati; seyed ehsan fatemi
Abstract
Extended Abstract Background and Objectives: Due to the high cost of designing, construction and operation of dam reservoirs and related facilities, Optimization in the construction of reservoirs and related facilities to increase productivity and reduce costs has been considered by designers. In ...
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Extended Abstract Background and Objectives: Due to the high cost of designing, construction and operation of dam reservoirs and related facilities, Optimization in the construction of reservoirs and related facilities to increase productivity and reduce costs has been considered by designers. In this regard, the development of computer software can be a great help to design engineers in such a way that boring manual calculations and calculation errors are reduced For this purpose, the main goal of the present study is to prepare and develop a computer model based on genetic algorithm in which the objective function that is the sum of the fixed and current costs of the transmission system during the useful life of the project, considering the velocity and pressure constrain was minimized. Simulation water hammer in the optimal system with and without control facilities is one of the secondary goals of this research. Materials and Methods: In this study, the optimal design of the pumping station and transmission line is performed based on optimizing using the binary genetic algorithm with the objective function of minimizing fixed and current costs of the transmission system and pumping station during the useful life of the project. The study area is the pump station and water transmission line of Biston dam that is located in the outside of Gamasiab river bed in Kermanshah province. In order to optimize the unit length price of 24 pipes of different materials from nominal diameter 110 to 2000 mm as well as the specifications of all domestic manufacturing pumps and some imported pumps were defined as a database in the model. The type of pump and suitable pipes of conveyance line are selected by minimizing the cost function by observing the pressure and velocity constraints. Result: Model validation results in design of conveyance line by three case: 1- Reservoir - pipe system with end valve, 2- Pipeline with side branches on the slope and 3- Transmission line between two points with irregular topography indicated that the model optimize the transmission line by observing the pressure and velocity constraints in such a way that even in the design of a part of transmission line that placed on downhill slop (case 3) by selecting the optimal smaller diameter prevent overpressure along the transmission line. Then results of the design of the Biston Dam transmission line showed that the diameter of the 1600 mm steel transmission pipe and the centrifugal pump model of 200-50-500 have the lowest cost during useful life of 20 years. The water hammer simulation results on optimal system showed that an Air chamber with a radius of 3 meters and a height of about 5.5 meters that in the initial conditions, it is half full of water and its air pressure is about 86, It keeps the pipeline safe from the point of view of water hammer and sudden shutdown of the pumping station. Conclusion: Reducing the constant and annual costs of conveyance line and pumping station of outside of river bed dams as much as possible can be effective in the economic explanation of the projects. In this research, in order to reduce the mentioned cost, optimal design of conveyance line and pumping station of outside of river bed Biston dams was considered. In this project it is necessary to transfer 3500 l/s water from Gamasyab river to Biston dam reservoirs during 6 months of the year (November to May) by the optimal transmission pipe line. For this purpose, a computer model was prepared and developed in which based on optimization by binary genetic algorithm method the transmission system is optimized. Model validation was performed using it for optimal design of several different cases and successful results were obtained. Then the optimization of the Biston dam transmission line was done. The result showed that use of 21 centrifugal pump model of 200-50-500 devices (84% efficiency and 78.5 m operating pressure) with steel pipe with a diameter of 1600 is optimal along the entire path. In this situation, the cost of purchase and piping the Biston water transfer project is 1,681,952$.
Original Article
Geotechnic
reza mohammadpour; Atefeh Taghi shahbazi; tooraj sabzvari; Mehdi Karami moghadam
Abstract
IntroductionDue to geotechnical and financial reasons, actual piers are built on foundation, while there is limited number of study available about effect of the foundation on the local scour. Overestimation of the scour depth results in designing a deep foundation level and thus leads to an uneconomical ...
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IntroductionDue to geotechnical and financial reasons, actual piers are built on foundation, while there is limited number of study available about effect of the foundation on the local scour. Overestimation of the scour depth results in designing a deep foundation level and thus leads to an uneconomical design of bridges. However, the underestimation of scour depth would result in shallow foundation and providing a chance to expose the foundation to the flow. It is definitely dangerous for bridge safety. Previously, extensive research has been carried out about local scour around uniform piers. However, only some studies are available in literature to predict the time variation of local scour at complex piers.In this study, time variation of local scour have been experimentally investigated around uniform and non-uniform rectangular piers under clear water conditions. The local scour is investigated with variation of foundation level (Z), pier dimension and foundation dimension. The results are compared at different foundation level.Materials and Methods A flume with rectangular cross section and the dimension of 12.0 m long, 0.4 m wide, and 0.6 m deep was chosen for all experiments. Three uniform and non-uniform rectangular piers were chosen for tests (Table 1). Uniform sediment with d50 = 0.70 mm maintain the clear water conditions, the flow velocity was set close to the critical velocity of sediment (U/Uc between 0.94 and 0.99).Results and Discussion The trend of local scour at non-uniform pier is time dependent. To investigate the effects of foundation level (Z) on temporal variation of local scour around pier, four levels of 0.0, 1.0, 2.0 .3.0 cm were chosen for Z. The experimental data and flow condition are given in Table 1. In this table, P and FP were selected for uniform and non-uniform piers, respectively. The scour depth develops to top of foundation quickly, and then the foundation postpones the scour development for a certain time (lag –time). It was observed that during of lag-time, the scour hole is slightly extended in parallel to and in front of the pier. In addition, development of local scour in parallel to pier (in the flow direction) is faster than those in front of abutment (upstream). The scour hole in the foundation nose is enlarged in the area, and it is somewhat deeper than other parts at the upstream side. The deepest depth at the upstream of non-uniform pier gradually develops around the sides of the foundation to create a shallow groove parallel to the foundation. Subsequently, the depth of the scour ahead of the foundation is more increased due to the formation of a vortex at upstream of the foundation. This vortex enlarges and deepens the scour at the corner of the foundation, and the sediments besides of the foundation are carried out to downstream of the abutment. Although, the foundation postpones development of scour depth firstly, but if the foundation exposes to the scour hole, the vortex in front of exposed foundation increases the scour depth. The lag-time (latency) directly depends on pier width (L), foundation width (Lf) and level of foundation under the sediment bed (Z). The rate of sediment transport decreases with increasing the scour hole dimension, and it will be stopped approximately close to the equilibrium scour depth. The reduction of scour depth due to lag –time is very useful to prevent the failure of bridge especially in the flood events that bridges are the main structures in transportation. Generally, the peak of flood may not be long-lasting to develop equilibrium scour depth and the flood may be stopped within lag-time. Therefore, the lag-time postpones the maximum scour depth and provides an opportunity to repair the bridge foundation after the flood events. Generally, For 0<Z/L1.2,the local scour increasing with increasing foundation level (Z) and for Z≥2.4L the local scour at compound pier is similar to uniform pier.Conclusions In this study, temporal variation of local scour at non-uniform piers is investigated experimentally under the clear water conditions. The non-uniform piers were included a rectangular pier founded on a larger rectangular pier. In all experiments, the scour depth is developed to top of foundation quickly, and then the foundation postpones the scour development for a certain time (lag–time). Duration of lag-time is depended on the dimension of pier, foundation size and the foundation level. A comparison between the uniform and non-uniform piers indicated that the trend of scour depth at non-uniform and uniform piers is similar to each other. This study highlights that a proper design of foundation level decreases the scour depth and increases the duration of scouring. Furthermore, the lag-time provides an opportunity to repair the bridge foundation after the flood events.
Original Article
Irrigation network management
Ebrahim ,Valizadegan; Somayeh Abbasi
Abstract
IntroductionFlumes are one of the simple tools for measuring flow rate in canals that the flow rate can be calculate only by measuring the flow depth at specific points of control section of them. Blanger (1849) and Bazin (1896) were the first to conduct experimental and theoretical studying on flumes. ...
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IntroductionFlumes are one of the simple tools for measuring flow rate in canals that the flow rate can be calculate only by measuring the flow depth at specific points of control section of them. Blanger (1849) and Bazin (1896) were the first to conduct experimental and theoretical studying on flumes. Since then, many research was done about hydraulic characteristics of different flumes by researchers such as Parshl (1900), Robinson (1968), Samani and Magalanez (1992, 1993), Proginelly and Bonacci (1997), Prabhat (1998), Samani and Magalanez (2000), Bdar and Gare (2014), Davis and Samani (2016) and Mohammadi and Vatankhah (2020). Many of mentioned researchers have done their research on rectangular channels. In this research, possibility of the creating control section by installing a prismatic pier on the central axis of floor in trapezoidal canal and flow measurement in free and submerged flow condition was investigated. MethodologyTo achieve discharge equations, many experiments were performed in free and submerged flow condition in a trapezoidal laboratory canal with length of 6 m, width of 46 cm, height of 70 cm and with adjustable side slope. Four prismatic piers with head angle of 90◦, width of 42, 40, 38 and 36 cm were tested. The height of each pier was considered equal to its width. The experiments were performed on 4 side slopes.Based on dimensional analysis, the following dimensionless equation was considered as basis of experiments for both free and submerged flow condition. (1) where Q is discharge, g is gravity acceleration, y1 is flow depth upstream of prismatic pier and Bc is calculated from the following equation.(2)where z is side slope of canal, B is width of canal and b is width of prismatic pier. On the base of 96 experiment in free flow condition (in a certain side slope, 6 experiment for a pier) and 288 experiment in submerged flow condition (in a certain side slope, 18 experiment for a pier with different submergence ratios) discharge equations for both free and submergence flow condition were obtained separately. Results and discussion On the base of performed experiments , variation of dimensionless parameters Q/(gBc5)0.5 versus y1/Bc corresponding to all 4 side slopes is presented in figure 1 and equations 3 and 4 in free and submerged flow condition respectively. (a) (b) Fig. 6- Variation of y1/Bc vs. Q/(gBc5)0.5 for different side slopes, a; free flow b; submerged flow(3) (4)According to equation 3 and 4, exponent of y1 in both equation 3 and 4 is larger than circular, trapezoidal and S-M flumes which are presented by Samani and Magallanes (1992, 1993 and 2000). This makes this flume ideal for water level variations than circular, trapezoidal and S-M flumes. To determine accuracy of the obtained relationships and graphs, statistical parameters, ME, RMSE and MARE, were used. Based on the relationship for all side slopes (equation 3 and 4) MARE is 8.3 and 10.2% for free and submerged flow conditions respectively. The results showed that, using of the flow measurement method in trapezoidal canals is Suitable for free flow conditions and can be used by accepting 12% error for submerged conditions. ConclusionsThe results showed that, - using of the flow measurement method in trapezoidal canals is ideal for free flow conditions (equation 3). - The flow measurement method in trapezoidal canals can be used by accepting 12% error for submerged flow conditions (equation 4).- Compared to circular, trapezoidal and S-M flumes, this flow measurement method has large sensitivity to variation of upstream water level - It is suggested that, the results of this research be used within the range of studied parameters.Keywords: Free flow conditions, Irrigation Canals, Prismatic Flumes, Submerged Flow conditionsflow conditions, Irrigation Canals, Prismatic Flumes, Submerged Flow conditions
Original Article
Irrigation network management
Iraj Rezapour; Mahmood Shafai Bajestan; Babak Aminnejad
Abstract
Introduction Transient flow in a pressurized pipe system is an intermediate state flow that arises between one constant flow and another. In other words, whenever the flow conditions change from a steady-state due to any deliberate or accidental disturbance, a transient flow is created in the pipeline ...
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Introduction Transient flow in a pressurized pipe system is an intermediate state flow that arises between one constant flow and another. In other words, whenever the flow conditions change from a steady-state due to any deliberate or accidental disturbance, a transient flow is created in the pipeline (Chaudhry, 2014). This phenomenon is one of the most severe cases of damage in pressurized pipelines.In many previous studies related to transient flow analysis, the pipe wall has been made of metal and concrete materials with elastic mechanical behavior. In recent years, the increasing use of plastic pipes (such as polyethylene and PVC) has led to the development of mechanical models of transient flow, taking into account the viscoelastic behavior of these materials.In recent years, polymer pipes such as polyethylene and PVC, due to their technical and economic advantages over other pipes such as steel, cast iron, concrete, and asbestos, have increased day by day. This makes the need to understand the structural behavior and hydraulic performance of polymer pipes even more urgent. The modeling method of polymer pipes for transient flows analysis has several fundamental differences from non-polymer pipes. These differences are mainly related to the interaction of fluid fluctuations with the characteristics of pipe wall structures. Polymers generally exhibit viscoelastic mechanical behavior that affects the intensity, formation, and damping of pressure fluctuations in transient currents. In these equations, it is usually assumed that the pipe wall is made of concrete and metal and has a linear elastic behavior. In comparison, polymer pipes have inelastic behavior.The present study aims to investigate the pressure response of viscoelastic pipeline under transient flow. For this purpose, first, the pressure signal's initial peak and the effects of line packing are investigated. The effect of the transient valve's closing time in different flows on the pressure signal is investigated in the following. Another important issue is the overpressure. In this research, laboratory values of overpressure are compared with the theoretically calculated values.MethodologyThe laboratory model of this research was designed and built in the hydraulic laboratory of the Faculty of Water Engineering, Shahid Chamran University of Ahvaz, to evaluate the response of the viscoelastic pipeline system under transient flow. The pipes are high-density polyethylene (HDPE) (SDR11, PE100, NP16) with a length of 158 meters, an inner diameter of 5.05 cm, and a thickness of 6.5 mm. According to the four stages of waterhammer, if the constant pressure of the pipeline is low, the pressure signal in the third stage, after returning from the tank and reaching the transient flow valve, enters pressures less than the vapor pressure of the fluid, and due to the column separation. This phenomenon reduces the pressure signal capability to detect other system malfunctions. To avoid this problem, a pressurized reservoir was used as the upstream boundary condition at the pipe system's upper boundary.Results and Discussion The initial peak pressure due to the effects of friction and fluid inertia and the delayed deformation of the pipe wall is completely weakened in the first period of the pressure wave and does not exist in subsequent periods. The transient flow signal analysis showed that the classical waterhammer equation could not predict the observed maximum transient pressure of fast transient in polyethylene pipe. The calculation of the wave speed in polyethylene pipes based on the modulus of static elasticity is significantly less than that of elasticity's dynamic modulus. As the valve's closing time increases, their maximum pressure peaks and pressure drop gradients decrease, and this peak gradually weakens and disappears. In addition, depending on the time difference between closing the valve, the pressure wave will have a time delay. The results showed that a significant energy drop with phase change in the pressure wave is observed in all measurement locations.ConclusionsAfter quickly closing the transient valve, a significant pressure peak is observed, followed by a sudden drop in the pressure signal. At a constant flow, the initial peak pressure decreases with increasing valve closing time. Suppose the calculations are based on the modulus of elasticity provided by the factory. Even if the elastic tube is assumed, the amount of overpressure is 16.6 to 37.65% less than the actual value.This is an important reason to consider polymer pipes' viscoelastic behavior by precision transient flow hydraulic models or to consider the dynamic modulus of elasticity, sometimes up to twice the static modulus of elasticity proposed by manufacturers, in the design phase.
Original Article
Irrigation network management
mohammad hadi fattahi; Ali Sinaee
Abstract
Introduction: Concerning the importance of water saving in Iran, as an arid and semi-arid country, dam construction plays a crucial role in water resources management. Spillways are one of the most important components of a dam. They are different in shape and function. Stepped spillway is one of the ...
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Introduction: Concerning the importance of water saving in Iran, as an arid and semi-arid country, dam construction plays a crucial role in water resources management. Spillways are one of the most important components of a dam. They are different in shape and function. Stepped spillway is one of the most designed and operated ones. Numerical simulation of the stepped spillway of Jare dam using FLOW 3D software and the geometric optimization of the steps' dimension using the multi-objective genetic algorithm is investigated in this research. The idea of using stepped spillways goes back to 3500 years ago (James et al., 2001). The oldest stepped spillway built in Iran has been recorded from 600 years ago. Studying the geometric features of stepped spillways in order to optimize the size and dimension of steps has also been the issue of interest for researchers (Chanson, 1996 and 20021; Pegram et al., 1999; Ferrari, 2010). Methodology:An experimental model of Stepped spillway of Jare Dam has been set up first in order to calibrate and verify the numerical model. Flow 3D software is applied for numeric simulation of the spillway and the multi objective genetic algorithm (NSGAII) is implemented to optimize the geometric dimensions. Calibration of the model has done after introducing the experimental models' geometry to FLOW 3D. Comparing the velocity data recorded by the numerical model and the experimental velocity data, the software has been verified.Turbulence modeling is the construction and use of a mathematical model to predict the effects of turbulence. Turbulence models are simplified constitutive equations that predict the statistical evolution of turbulent flows. K-epsilon (k-ε) turbulence model is a practical model to simulate the mean flow characteristics for turbulent flow conditions. It is a two-equation model which gives a general description of turbulence condition of the ambient flow by means of two transport equations (PDEs). The RNG model was developed using Re-Normalisation Group (RNG) methods to renormalize the Navier-Stokes equations, to monitor the effects of smaller scales of motion especially those of vertex movements. In k-ε model the eddy viscosity is determined from a single turbulence length scale, so the diffusion seen in the calculated turbulence is that which occurs only at the specified scale, although in real physical situations, all scales of motion will contribute to the turbulent diffusion especially those with more curvature streams. RNG turbulent model, as mathematical method that can be utilized to extract turbulence similar to the k- ε, results in a modified form of the epsilon equation. We have implemented both methods to simulate the turbulancd in the flow over the stepped spillway and to compare the effectiveness of both models when flow is dealing with a complicated solid as the Jare Dam spillway. Five different types have been considered for the geometry of the stepped spillway. Numbers of steps are designated 3 to 7 steps and are earmarked as the algorithm constrains. The variables are then defined and the fitness function of the algorithm is extracted. The multi objective genetic algorithm is then coded in MATLAB. In optimization procedure the geometric features including width, height and the number of steps in each five discussed type are calculated.Results and Discussion:Velocity results using two turbulent models, RNG and K-ε, have been calculated separately. The results of the RNG model depict better match in accordance to the physical model's velocity data with less than 10 percent error. In optimization procedure the stepped spillway with 4 steps, 0.072m width (1:5) and 0.0665m height (1:5), is considered as the most optimum choice regarding the economic and hydraulic concerns.Conclusion:Flow 3D software simulated the flow over the stepped spillway of Jare Dam quite acceptable. The simulating model depicted the most accuracy using the RNG turbulent model and the multi objective genetic algorithm used (NSGAII) suggested the 4 steps spillway as the most economic and functional choice for Jare stepped spillway.
Original Article
Irrigation network management
Atefeh Arab; Hosna Shafaei; kazem Esmaili
Abstract
Introduction
Study the soil erosion process, sediment transport capacity plays a vital role in the physical description of soil erosion processes. In recent years, researchers examining the sediment transport capacity under different laboratory conditions have shown that hydrodynamic parameters, especially ...
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Introduction
Study the soil erosion process, sediment transport capacity plays a vital role in the physical description of soil erosion processes. In recent years, researchers examining the sediment transport capacity under different laboratory conditions have shown that hydrodynamic parameters, especially shear stress and unit stream power have a significant effect on sediment transport capacity. The results of researchers' studies show that this assumption is not correct(Martin et al., 1991). Increasing the transverse slope of the plain flood changes the transition stress between the flow through the main channel and the floodplain. The presentation of a method for estimating the weight of sediments discharged from the channel was investigated (Karamisheva et al., 2005). Despite the studies, the effects of sediment size on sediment transport are still not well understood and considering that previous studies have been done in direct channel, the effect of longitudinal slope and transverse slope change by changing sediment particle size in composite channel is investigated and not well understood. It should be noted that various parameters affect the hydrodynamic conditions of river floodplains. Therefore, recognizing and investigating the factors affecting this case is of special importance in hydraulic science. One of the influential factors in the hydraulic and hydrodynamic conditions of floodplains is the lateral slope of floodplains. However, qualitative and quantitative study of the parameter requires the presentation of appropriate laboratory research methods. In this study, by aiming at the effect of lateral slope of floodplain on hydraulic and hydrodynamic conditions of flow, as well as the effect of granulation and hydraulic parameters on the amount of sediment output, an experimental design was presented to investigate this parameter. Shear stress varies in longitudinal and transverse slopes.
Methodology
The experiments were performed in a laboratory compound channel 12 meters long, 30 centimeters wide and 0.5 meters high. Flow field analysis and velocity vectors upstream of the overflow were performed using measured ADV 3D speedometer data. In this study, to show the overflow flow conditions on the deposition status behind the overflow wall, the horizontal velocity in the grid drawn in a section of the channel was used. During the experiments, tools embedded at the end of the channel were used to change the longitudinal slope of the channel. It should be noted that slopes of 0.002, 0.004 and 0.006 were used to change the slope.
Q = flow rate (liters per second); ho = water depth in the canal (meters), hs = sediment height (meters); hf = height of plain flood; b = plain flood width (meters), So = longitudinal slope of the canal (no dimension); Sc = transverse slope of the channel (without dimension), w = width of the main channel (meters); V = flow rate (meters per second); γ = weight mass of fluid (Newton per cubic meter); μ = water dynamic viscosity (Pascal-s); σ = fluid surface tension (Newtons per meter); ρ = fluid density (kg / m3); g = acceleration of the earth's gravity (meters per square second); B = total channel width (meters); Vs = sediment volume of the channel (cubic meters) and d50 = average particle diameter (mm). In the above parameters in relation to dimensional analysis and Puckingham theorem, some parameters can be omitted from the above parameters. For example, because the water thickness on the floodplain is large enough, surface tensile forces can be avoided. Also considering that the transverse slope and the length slope are dimensionless parameters. They can be taken out of calculations and introduced as a dimensionless number. To simplify dimensional analysis, it is better not to consider this parameter. With these interpretations it can be stated that:
Results and Discussion
As the shear stress increases at different longitudinal and transverse slopes, the sediment transport capacity increases. These findings indicate that the slope has a positive effect on shear stress. The results show that the transverse slope has a significant effect on the increase and change of shear stress with sediment transfer capacity and in the transverse slope of 0.5 and in different longitudinal slopes, increase in sediment transfer capacity is more and washed sediment increased (Fig.1). Sediment transport capacity measured with the unit stream power has changed in different slopes (Fig.2). With increasing depth of flow in main channel to depth of flow in floodplain, more sediment is removed from the flume and the least amount of sediment washed is when the longitudinal slope is equal to 0.002, transverse slope zero, and median particle diameter is 3mm, occurring in discharge of 1.6 l/s (Fig.3). As the Froude number increases, the amount of sediment output will increase more when the size of the sediment particle decreases.
conclusions
İn this study, the effect of grain size and hydraulic parameters on sediment transport in two hydraulic models with longitudinal slopes of 2,4 and 6 per thousand and transvers slopes of zero and 0.5 were investigated. The results showed that with increasing the longitudinal slope, at zero transverse slope, with decreasing particle size, the amount of output sediment would increase. Most leached sediment in zero transverse slope and longitudinal slope 0.006 has occurred. Further studies are needed considering the large particle size range and transverse slopes with greater range of variation.
Original Article
Irrigation network management
hossein Rabbaniha; AbdolMajid Liaghat; masoud Soltani
Abstract
Extended AbstractInvestigations and comparison of the ways to prevent saline water advancement in zones with the shallow water tableIntroduction One of the threating factors to freshwater resources is the advancement of saline water and intrusion into the groundwater aquifer. This problem occurs in coastal ...
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Extended AbstractInvestigations and comparison of the ways to prevent saline water advancement in zones with the shallow water tableIntroduction One of the threating factors to freshwater resources is the advancement of saline water and intrusion into the groundwater aquifer. This problem occurs in coastal zones and desert margins and reduces freshwater quality. Evaporation from the soil surface and the water table depth are factors affecting the salinity and salt distribution in the saturated and unsaturated zones. HYDRUS and the accompanying software package provide numerical models used to simulate the movement of water, solute and heat in a porous medium for saturated and unsaturated conditions. According to the existing reports on the ability of the HYDRUS model to simulate moisture and salinity, using it can help decide and consider how to prevent the salinity advancement.MethodologyIn this research, the advance of saline water with a concentration of 20 dS/m and a level of 25 cm towards freshwater with a concentration of 1 dS/m and a level of 10 cm in the domain of 360×70 cm is considered. Different scenarios were examined to prevent the progression of salinity using a validated model. The studied scenarios include inceptor pipe drainage, inceptor open drainage and subsurface barrier which were simulated using the HYDRUS-2D model. The parameter of the equations governing water flow and solute transport were estimated using observed moisture and salinity data and inverse solution tools in the HYDRUS-2D model. pipe and open drainage were considered at three distances of 270,180 and 90 cm from the freshwater reservoir and two depths of 15 and 5 cm from the impermeable layer. The effect of the subsurface dam on preventing the advance of saline water at three depths of 55, 65 and 70 were investigated.Results and Discussion Different scenarios of different drainage locations have been simulated to study salinity distribution and water table after 6 months. Regarding the location of the drainage site, three factors are important that have been studied: 1- The amount of water and salt outflow from the drainage 2- Controlling and preventing the advance of salinity 3- Its effect on the entry and exit of water from the freshwater aquifer. The location of surface and subsurface drainage showed different effects on salinity advancement. By changing the location of drainage from A to f the amount of drained water in pipe and open drainage decreased by 5.8 and 6.5 m3/m, respectively. Drainage location also affected actual evaporation from soil surface and salinity accumulation in the soil surface layer. In the cases of drainage where the lowest and highest evaporation from the soil surface occurs respectively, 15% difference was observed. In the case of open drainage at a distance of 90 cm from the freshwater reservoir and a depth of 5 cm from the impermeable layer, the amount of actual evaporation from the soil surface during the whole simulation period is greater than the actual evaporation in non-drained condition and also caused increased salinity between two reservoirs. The subsurface barrier has generally blocked the saline water flow only when it has reached the impermeable layer. The profile of the water table is broken due to very low hydraulic conductivity (about 0.1 m per day) when it reaches the subsurface barrier. The amount of failure and drop of the water table increased with increasing barrier depth.ConclusionsThe salinity distribution parameters in the area between two aquifers, discharged drain from drainage and its concentration and protection of freshwater aquifer are affected and can be considered according to the condition of each location. On the other hand, each of the scenarios has a positive and negative effect on these factors, so according to each sample and specific location, it must be decided how to prevent the progression of salinity (drainage or subsurface barrier) and their location.
review paper
Pressurized Irrigation Systems
afshin uossef gomrokchi; Abolghasem Haghayeghi
Abstract
One of the fastest solutions for optimal water and energy management in irrigation systems is to upgrade the existing position from the level of mechanization of the systems to its own automation. By applying process automation in irrigation systems that mainly involve installation of software and hardware ...
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One of the fastest solutions for optimal water and energy management in irrigation systems is to upgrade the existing position from the level of mechanization of the systems to its own automation. By applying process automation in irrigation systems that mainly involve installation of software and hardware equipment, instruments and software control, allowing optimal management of water and energy consumption and improve the efficiency of irrigation units is provided. With the entry of electronic science into the agricultural sector, in addition to the production of advanced equipment, there has been an increasing use of automated control systems in irrigation systems. This process is called control, automation or self-automation. According to scientific definitions, automation is the same as intelligent systems, including reducing manpower and the resulting error and precise control of the system work cycle. Severe dependence of mechanized systems on manpower to continuously monitor the performance of tools and equipment on the one hand, error due to the wrong action of the operator or delay in taking the necessary action on the other hand Taking measures will reduce productivity in mechanized irrigation systems. It is important to note that in the current approach to the development and operation of irrigation systems, especially pressurized irrigation systems, maximizing net profit over maximum crop production is preferred, so today the use of automation systems such as SCADA and telemetry Operation of irrigation systems is under increasing pressure. Supervisory control systems and data collection (SCADA) refers to large-scale control and measurement systems. SCADA is a control and monitoring system that collects information and then processes it. In other words, SCADA refers to a set of guidelines, standards and processes and is not a pre-complicated version for system control and monitoring. In fact, SCADA is a software package that sits on the executable hardware. In general, SCADA systems include the elements of instrumentation, control equipment, communication equipment, electrical equipment, software packages, central and local control room. Figure 4 shows the general structure of a SCADA system.It is important to note that a SCADA system is subject to several major problems in addition to the many benefits it can bring to a system. The main problem is that the cost of a telemetry and telecontrol system such as SCADA is high, especially when its equipment is standardized in the system. In many cases, however, the benefits of energy savings, labor, and better utilization justify this high cost. Another limitation of this type of system is the risk of unauthorized access to the control software (whether it is human access or software changes in the control device). Other major limitations of these systems are related telecommunication protocols. These are the language communication protocols used to receive and transmit information over the network. Also, these systems, or any other type of automation system, need specialized people to operate the system, and in general, the more complex the system, the more skilled users are needed. On the other hand, due to the fact that in this system, all changes must be applied dynamically in the network platform, the relevant hardware and software must be designed with high capabilities. Numerous examples of using SCADA in various sectors of industry, water and wastewater facilities and energy management have been implemented throughout the country, and today, despite high costs and some limitations, the use of telemetry-based operation methods and SCADA in the sector Various agricultural, livestock and fisheries have also found their way and their applications in this sector have always been expanding. One of the important applications of SCADA system in the field of agriculture has been the automation of irrigation systems. The first experience of using SCADA systems in the field of agricultural water management has been in the field of irrigation canal management. Over time, the use of this type of system in other sectors of water management and irrigation has developed more and more. SCADA systems used in the field of management of irrigation systems are similar in nature to other sectors such as water and sewage facilities and water transmission lines, but according to the structure of water management in the field and how different factors affect the equipment. Hardware and telecommunication protocols are different.
