Original Article
Pressurized Irrigation Systems
Mohammad Ali Shahrokhnia; Fariborz Abbasi; Abolfazl Naseri; Seyed Ebrahim Dehghanian; Amir Eslami; Nader Salamati; Esmaeil Moghbeli Damaneh; Eshagh Zare Mehrani
Abstract
Extended Abstract IntroductionMost regions of Iran are considered as arid and semi-arid regions. Water management in the agricultural sector is very important as the largest consumer of water resources in the country. In order to better plan and manage water resources in the agricultural sector, ...
Read More
Extended Abstract IntroductionMost regions of Iran are considered as arid and semi-arid regions. Water management in the agricultural sector is very important as the largest consumer of water resources in the country. In order to better plan and manage water resources in the agricultural sector, it is necessary to have sufficient information about the amount of water used in different products. Given the importance of its lemon product in the country, and conducting little research on this issue, determining the applied water for lemon orchards in the country can be useful for planning and macro decisions in the country. A review of literature shows that a lot of information has been collected in the world about the required water and the effect of different irrigation methods on citrus fruit yield. However, little research has been done on irrigating lemon trees under the management of gardeners. In Iran, little research has been done on the management of lemon irrigation. Therefore, in this study, the volume of applied water and water productivity of lemon trees in the country have been measured and evaluated.Methodology In this field study, irrigation water volume and lemon yield in over 210 selected orchards in Fars, Hormozgan, Kohgiluyeh, Boyer-Ahmad and South Kerman provinces were measured directly. Fruit yield was obtained in three consecutive years and their mean was used in the analysis. Analysis of variance was used to investigate the possible differences in yield, irrigation water volume and water productivity in lemon production. After determining the inflow of water to the garden by carefully monitoring the garden irrigation program and measuring the area under cultivation, the volume of irrigation water applied by lemon trees in each garden was measured. Multiplying the flow rate during the total irrigation period during the season, the amount of irrigation water volume was obtained. In each of the gardens, items such as soil texture of the gardens, electrical conductivity of soil and irrigation water, etc. were also measured. The amount of evapotranspiration of the lemon tree in each region was calculated using meteorological data of the station closest to the project implementation area in the last 10 years and the year of the research using the Penman-Montieth method. The results were compared with the calculated net required irrigation water and the values presented in the National Water Document (NETWAT).Results and DiscussionThe results showed that the differences in yield, applied water volume, and indicators related to water productivity were significant in the mentioned provinces. The weighted average yield of lemon was 21.7 tons per hectare. The weighted average volume of irrigation water and total applied water were 11938 and 12993 cubic meters per hectare, respectively. The weighted average irrigation water productivity was estimated to be 1.94 kg/m3. Weighted average water+long-term effective rainfall productivity was 1.59, kg/m3. Weighted average of water and current year effective rainfall productivity were 1.75 kg/m3, respectively. The proportion of irrigation water volume of lemon orchards with gross water requirement in selected provinces was similar. In general, the average difference between the depth of irrigation water and annual and long-term gross water requirement in the country was -17 and -1 percent, respectively. In the orchards under drip irrigation system compared to surface irrigation, fruit yield and water productivity increased 43 and 89 percent, while irrigation water volume decreased about 20 percent. Salinity of water and soil, age of trees, literacy level of gardeners, climate, soil texture were some of the factors that affected yield, water productivity and volume of irrigation water.ConclusionsAccurate determination of plant required water and volumetric water delivery can be very effective in reducing irrigation water and increasing water productivity. In addition to these two factors, adhering to irrigation scheduling in lemon orchards can produce the maximum yield per allotted amount of water. In creating or renovating of lemon orchards, cultivars should be planted that are resistant to cold and salinity and have the ability to export, while increasing the area under cultivation in proportion to water resources.
Original Article
Pressurized Irrigation Systems
mehdie mohammadkhanie; abbas sotoodehnia; Peyman Daneshkar Arasteh; Hadi Ramezani Etedali
Abstract
Introduction
Pressurized irrigation systems are efficient tools to improve agricultural water productivity. However, the implementation and operation of pressurized irrigation systems require energy supply, related tools, and equipment, followed by greenhouse gas emissions. In this regard, one of the ...
Read More
Introduction
Pressurized irrigation systems are efficient tools to improve agricultural water productivity. However, the implementation and operation of pressurized irrigation systems require energy supply, related tools, and equipment, followed by greenhouse gas emissions. In this regard, one of the factors in the degradation of the environment is the phenomenon of global warming due to carbon dioxide emissions. The country's agricultural authorities have considered and invested in developing and implementing pressurized irrigation systems as one of the main approaches for proper water use. Due to the phenomenon of global warming, the primary source of which is greenhouse gas emissions. Any activity in the production of equipment, energy, and mechanization of irrigation systems leads to the production of greenhouse gases, increasing the air temperature and crop water requirements. If the irrigation systems are evaluated from an environmental point of view, air pollutants emissions can be considered an influential factor. This issue has been neglected in the country concerning systems evaluation.
Materials and methods
In the present study, drip irrigation systems implemented in Qazvin province during 2010-2020 were randomly selected and evaluated for energy flow and greenhouse gas emissions. In this research, 17 drip irrigation systems, including pistachio, apple, peach, and nectarine crops, were randomly selected and studied in terms of energy flow and emissions of greenhouse gases. According to the energy equivalent coefficients and carbon dioxide emissions coefficient, the total input energy and carbon dioxide emissions for the drip irrigation systems were calculated. In this research, after collecting data on the drip irrigation systems, we used drilling machines, welding equipment, and manpower based on the equivalent energy extracted from the sources for each stage of equal energy in terms of Megajoules. The process of implementation and operation of the irrigation system was calculated. Then we used greenhouse gas emission coefficients for three crucial greenhouse gases: carbon dioxide, nitrogen oxide, and methane, and considered the global warming potential of each gas using the relation that "i" is The amount of carbon dioxide equivalent to the emitted from the installation and operation of the drip system.
Results and discussion
The results showed that the total annual energy consumption and carbon dioxide greenhouse gas emissions in the evaluated irrigation systems averaged 36,2022.68 MJ per hectare and 1974.07 Kg/ha, respectively. It was found that the highest contribution of energy consumption and carbon dioxide emissions, with 85% and 86%, respectively, are related to the operation stage of the pumping station system. Besides, the production and transporting of the system equipment accounted for 13% of energy consumption and 10.93% of carbon dioxide emission. According to the results of the energy calculations and carbon dioxide emissions and considering the operating period of 15 years for the drip irrigation systems, energy consumption and carbon dioxide emission are 534,035 GJ/ha and 29.611 tons/ha, respectively. These values were calculated based on considering the processes of equipment supply, system installation, and the operation of the pumping station.
Conclusion
The findings of this study showed that the amount of energy consumed and carbon dioxide emissions in different stages of drip irrigation systems were very different. The energy consumption in the pumping station to provide the required working pressure had the largest impact. Energy consumption could be reduced by applying water consumption management, selecting pumps with higher efficiency, and avoiding imposing additional load on the network. On the other hand, due to the efficiency of electricity production in power plants in Iran and its efficiency of transmission and distribution, if the mentioned efficiencies were improved, the equivalent of energy consumption due to electricity consumption in the pumping stage would be reduced. Due to the topographic conditions and geometric shape of farms and their distance from factories producing equipment, energy consumption and subsequent carbon dioxide emissions for different farms will not be a fixed number. The impact of all practical steps except pumping energy consumption will be reduced annually.
Original Article
Irrigation network management
Alireza Afzalian; seyed mohsen sajjadi; Mahmood shafai bajestan; javad Ahadiyan
Abstract
Extended AbstractThe side weirs are widely used in sewage networks to aerate streams, irrigation and drainage networks to control water levels for dewatering, rivers for coastal management, and flood management of dams. One of the newest types of weirs researchers have considered in recent years is the ...
Read More
Extended AbstractThe side weirs are widely used in sewage networks to aerate streams, irrigation and drainage networks to control water levels for dewatering, rivers for coastal management, and flood management of dams. One of the newest types of weirs researchers have considered in recent years is the piano key weir. Piano key weirs have a higher efficiency than other weirs due to their special geometry, especially the presence of upstream and downstream overhangs, as well as inlet and outlet keys. The use of piano key weirs as side weirs has received less attention from researchers, and because these weirs show better performance in discharge, more and more research is needed. The main objectives of the present study are first to investigate the effect of trapezoidal piano key weir height as one of the geometric parameters affecting the discharge coefficient and second to investigate the water surface profiles at the upstream and downstream ends and within the location of the weir in the main channel. In parallel with the main objectives, the study of the Dimarchi hypothesis in estimating the discharge coefficient and the study of discharge efficiency of the trapezoidal piano key is also followed. In this regard, four models of trapezoidal piano key overflow with a height of 10, 15, 20, and 25 cm (TPKSWp10, TPKSWp15, TPKSWp20, and TPKSWp25), a labyrinth trapezoidal weir model with a height of 20 cm (TNRSW) and also rectangular sharp crest weir as The control model (Lisw) was tested under the subcritical flow with the Froude numbers in the range of 0/10 to 0/74. De Marchi, in 1934, assuming that the specific energy was constant at the upstream and downstream ends, calculated an equation for estimating the discharge coefficient of the side weirs that were related to the hydraulic parameters of the flow at both the upstream and downstream ends of the weir. In this study, the main hypothesis for estimating the piano key weirs' discharge coefficient is the Di Marchi hypothesis. The results show that, firstly, due to the specific energy changes at the upstream and downstream ends of the trapezoidal piano key models (ΔE/E1), especially in the TPKSWp10 and TPKSWp15 models, and the occurrence of hydraulic jump that affects the essence of the flow, use the Dimarchi hypothesis And comparing the discharge coefficients of trapezoidal piano key side weirs should be done with caution. The discharge capacity of the side weirs is defined as the ratio of flow spill from them to the inflow to the main channel. The results of this study show that the discharge capacity of trapezoidal piano key weirs increases with increasing height due to the more uniform water surface profile, reducing the interference of the outlet blades of the inlet and side crest and reducing the vortex in the inlet openings and faster exiting than the outlet keys. In the TPKSWp25 model, the discharge capacity is 2/60 times higher than the Lisw, and for the TPKSWp20, TPKSWp15, and TNRSW models, it is 1/92, 1/59, and 1/38 times higher than the Lisw, respectively. Also, the water level decreases in the longitudinal section Z*=1 (on the crest weirs) and at the upstream end of the weir due to the increase in the longitudinal acceleration of the flow and being affected by the suction of the flow by the weir in this range in all experimental models. This water level reduction for TPKSWp15,20,25 models, and TNRSW models is almost the same and equal to 25%.IntroductionIn irrigation and drainage networks that are designed with a certain capacity, for various reasons, including improper operation by water collectors and in rivers and other natural channels, by imposing excessive capacity currently on them, excess current is created which can cause serious damage to them. And the economy of the project will be challenged and of course, it can lead to life-threatening risks. In the design of dams, according to the location of the dam and in order to use more of the volume of dams for flood control purposes or just more reservoir volume, sometimes the dam is located in such a way that the possibility of constructing a main weir perpendicular to the mainstream is technically and economically justified. Therefore, in such cases, the side weirs are introduced and designed as the main weirs of the dam. Also, in some dams that have been constructed with old hydrological information and meteorological statistics and information indicate that the weir will be potentially dangerous for future floods, the option of overflow correction or using side overflows as auxiliary overflows are suggested. Emin Emiroglu et al. (2010) performed about 2,900 experiments in the subcritical flow mode to analyze the water surface profile on the weir and the flow velocities along with the weir. Their results showed that the weir discharge coefficient in labyrinth weir mode is about 1.5 to 4 times higher than in rectangular weirs. Bagheri and Haidarpour (2012), by measuring the three-dimensional components of the flow velocity in the main channel near the rectangular side weir, concluded that the horizontal flow velocity component at the lower end of the stream decreases. Also, by examining the transverse and deep components of the flow, it was concluded that most of the flow is discharged from the lower end of the weir. Using physical models, Michelazzo (2015) proposed a new approach to solving the Dimarchi equation for zero-height side weirs in an open canal. To solve this model, the flow conditions were considered subcritical and the substrate constant. Solving them without using numerical methods makes it possible to estimate the weir outflow according to upstream and downstream hydraulic conditions. Aydin (2015), by placing the sill on the bed of the canal in three positions of the upstream end, the downstream end and in the middle of the weir, concluded that the presence of an obstacle at the lower end of the weir increases the lateral rectangular weir coefficient. Maranzoni et al. (Maranzoni, 2017) performed numerical and laboratory analyses on a side weir in a rectangular convergent channel. Their experiments, which were performed under subcritical and sustained flow conditions, show that the number of downstream landings and the dimensionless height of the weir has the greatest effect on the flow rate through the lateral weir in a converging channel. The approach of studies in recent years has tended to increase the efficiency and innovation in the use of new geometries of lateral weirs as well as new strategies and methods for estimating the discharge coefficient of these weirs. These findings include Ghaderi et al.'s (2020) studies to use numerical models to estimate the flow rate of trapezoidal zigzag weirs, Karimi et al. (2018) on the use of piano key weirs with a rectangular plan As side weirs, Saghari et al.'s (2019) studies and Seyed Javad et al. (2019) studies on the use of trapezoidal piano key weirs and Dibaco & Scorzini (2019) studies to estimate The lateral weir flow coefficient using neural network methods was pointed out. MethodologyConsidering several geometric parameters that affect the discharge coefficient of trapezoidal piano key side weirs, this study was designed to achieve the two main objectives of investigating the effect of trapezoidal piano key side weir height on its discharge coefficient and investigating the longitudinal profiles of flow depth in the main channel. In parallel with the main objectives, this study follows the study of the Dimarchi hypothesis in estimating the discharge coefficient of the piano key weir as well as its discharge capacity of it. In this regard, four trapezoidal piano key weir models differ only in height and therefore the inclination of the inlet and outlet keys, one trapezoidal labyrinth weir model, and a rectangular linear model as a control model will be tested in different Froude numbers.In line with the purpose of the present study, six models were designed and built. These models included a sharp rectangular linear model (control model), a trapezoidal labyrinth model, and four trapezoidal piano key weir models with heights of 10, 15, 20, and 25 (Figure 1). Figure 1 shows all the models in three perspective views, plan and cross-section.Results and Discussion Adjusting the water level in irrigation and drainage networks in order not to disrupt the operation of reservoirs b creating a water level profile at the upstream end of the reservoir and also the pressure on the body of piano s, especially the side crown and inlet and outlet gutters according to the thickness and materials used. They are important topics for design engineers in irrigation and drainage networks and spillway design. In the present study, two types of diagrams have been used to investigate the effect of the height of trapezoidal piano weirs on the water surface profile due to the complexity of the flow pattern and the simultaneous effect of geometric and hydraulic parameters of the weir and better analysis of these parameters on the water surface profile.Figure 3-a shows the Head-discharge curve of experimental models and 3-b shows the average flow rate of experimental models compared to the control model. As shown in this figure, for all dimensionless Y1/P ratios, the discharge through the TNRSW is higher than the control model (Lisw). Also, the flow rate through TPKSWP20 is higher than the TNRSW model. It is worth noting that in all dimensionless dimensions Y1/P, the flow through the piano key weir with a height of 10cm is less than all models. This rate is even 30% lower compared to the control model. The high velocity of the flow in the main channel and the impossibility of discharging the current even from the downstream cycle, which plays the greatest role in discharging the side weir, in the TPKSWp10 model reduces the effective length of the overflow crest in discharging the flow and is the main reason for this difference. Also, as shown in this figure, the flow rate of the TPKSWp25 model is higher than other models. A comparison of average flow rate overflows in Y1/P ratios and the Froude range of the present study shows that the average flow rates of TPKSWp25, TPKSWp20, TNRSW, and TPKSWp15 models are 2/60, 1/92, 1/59 and 1/38 times higher than the control model, respectively.
Original Article
Irrigation network management
Ali reza Hassanoghli; Zohreh Heidaryzad; Mahmoud Mashal; Maryam Varavipoor
Abstract
Extended AbstractIntroductionIn today's agriculture, the use of different chemical and organic fertilizers is inevitable via to adding the amount of production. However, in some cases, application of fertilizers could result to introduce of some pollutants such as nitrates into the environment and water ...
Read More
Extended AbstractIntroductionIn today's agriculture, the use of different chemical and organic fertilizers is inevitable via to adding the amount of production. However, in some cases, application of fertilizers could result to introduce of some pollutants such as nitrates into the environment and water and soil resources. In such a condition, the application of urea coated fertilizers or slow released may cause less pollution. In this research, the amount of nitrate transport in soil profile was investigated due to the application of some common chemical and organic fertilizers in comparison with slow release urea (sulfur coated) fertilizer (SCU).MethodologyFor this purpose, 15 cylindrical columns of soil and water, with a height of 150 cm and a diameter of 10 cm were designed, constructed and used. The columns were filled up to a height of 120 cm with a sandy loam soil. Drainages were installed at different depths of the columns. The amount of applied fertilizers was calculated and applied based on the amount of nitrogen required for the tomato plant. In this research, a statistical factorial with completely randomized design was used to study the factors including: type of fertilizer (no fertilizer as control treatment, urea, ammonium nitrate, coated urea and poultry manure); sampling depth of drainage water (30, 60 , 90 and 120 cm from the soil surface); irrigation rotation (5 times) and sampling intervals in each irrigation (5 times based on specific volumes of drainage water discharge of a complete purvolum of soil) with three replications.Results and DiscussionThe results of the analysis of variance indicated that the effects of the type of applied fertilizer, irrigation rotation and sampling time on the amount of nitrate measured in the effluent samples (nitrate leaching) were statistically significant at the 1% level. But nitrate concentration in the samples prepared from the different depths did not show significant changes. Investigating the mean values of nitrates in drainage water showed that nitrate transfer to soil depth was the highest in ammonium nitrate application (with a mean of 51.67 mg/l) and was the lowest in control treatment (with a mean of 38.39 mg/l). Also, urea fertilizers (with a mean of 48.16 mg/l), poultry (with a mean of 40.70 mg/l) and coated urea (with a mean of 39.88 mg/l) were placed in between them, respectively, and the differences were statistically significant at one percent level.ConclusionsIn general, application of coated urea (SCU) fertilizer could have a clear effect on reducing nitrate leaching to soil depth, especially in the condition of this research and in comparison with other types of common fertilizers.
Original Article
River engineering
Marzieh Badzanchin; mohammad bahrami yarahmadi; Mahmood Shafai Bajestan
Abstract
Extended AbstractIntroductionManning's equation is the most popular equation to determine the flow resistance in the steady and uniform flows. The amount of flow resistance in alluvial rivers depends on the type of bed form and its geometrical characteristics. In ripple and dune bed forms, which are ...
Read More
Extended AbstractIntroductionManning's equation is the most popular equation to determine the flow resistance in the steady and uniform flows. The amount of flow resistance in alluvial rivers depends on the type of bed form and its geometrical characteristics. In ripple and dune bed forms, which are formed at Froude numbers less than one (lower flow regime), the flow separation from their crest is the main factor of flow resistance (Shafai Bajestan, 2008; Julien, 2010). The effect of bed form on flow resistance have been studied by few researchers such as: Talebbeydokhti et al. (2006), Omid et al. (2010), Nasiri Dehsorkhi et al. (2011), Chegini and Pender (2012), Kabiri et al. (2014), Samadi-Boroujeni et al. (2014), Kwoll et al. (2016), and Heydari (2020). However, no research has been observed regarding the effect of the dune bed form height on Manning's roughness coefficient. Therefore, the main goal of the present study is to investigate the effect of dunes with different height of 1, 2, 3, and 4 cm on Manning's roughness coefficient in a straight flume under different discharges and bed slopes.MethodologyThe experiments were performed in a straight flume of 12 m in length and 0.30 m wide (Figure 1). In this study, different flow discharge of 10, 15, 20, 25, and 30 l/s and different bed slopes of 0.00001, 0.0001, 0.0005, 0.001, and 0.0015 were tested. Each dune was made in an asymmetric triangular shape with cement-sand mortar. The dune's height was equal to 1, 2, 3, and 4 cm, and the its length was selected as 25 cm. After each dune was built, the sediment with average size (d50) of 0.45 mm was glued to its surface. The total number of experiments in the present study was 100. Dune bed form dimensions were in lower flow regime. All the experiments were carried out at lower flow regime with, the Froude number values ranged from 0.44 to 0.7.Results and discussionFigure 4 shows the variation of the Manning's roughness coefficient against relative submergence (y/Δ) for dunes with a height of 1 cm. This figure shows that, with increasing relative submergence and bed slope, Manning's roughness coefficient decreased.Figure 5 shows the changes in the Manning's roughness coefficient against Froude number for dunes with different heights (slope of 0.0001). It can be seen that as the Froude number increased, the Manning's roughness coefficient decreased. Figure 7 illustrates the effect of Δ/λ on the Manning's roughness coefficient. This figure shows that the Manning's roughness coefficient increased with increasing Δ/λ. Calculations showed that the Manning's roughness coefficient in dunes with Δ/λ = 0.08, 0.12, and 0.16 was, on average, 17, 30, and 55% more than dune with Δ/λ = 0.04, respectively.Figure 8 shows the effect of the dune bed form height on the Manning's roughness coefficient. By increasing bed form height, Manning's roughness coefficient increased. Calculations showed that the Manning's roughness coefficient in dunes with height of 2, 3, and 4 cm was, on average, 16, 31, and 55% more than dune with a height of 1 cm, respectively.Conclusions The results of this study shows that with increasing the Froude number and the relative submergence (y/Δ), the flow resistance or Manning's roughness coefficient decreases. Moreover, the increase in the Δ/λ and the bed form height leads to an increase in Manning's roughness coefficient. Calculations showed that the Manning's roughness coefficient in dunes with height of 2, 3, and 4 cm was, on average, 16, 31, and 55% more than dune with a height of 1 cm, respectively. In addition, the form Manning's roughness coefficient (nb'') for dunes with heights of 1, 2, 3, and 4 cm is, on average, 30.7, 40.2, 46. 5, and 53.4% of the total Manning's roughness coefficient (nb), respectively.
Original Article
Hydraulic
zahra nikbakht; Alireza Emadi; Mohammad Mirnaseri
Abstract
IntroductionIn recent years, pollution of surface water resources, especially rivers, has posed an environmental challenge. Pollution from municipal or industrial wastewater and waste disposal into rivers are important problems for human societies to protect the environment. Knowing the level of river ...
Read More
IntroductionIn recent years, pollution of surface water resources, especially rivers, has posed an environmental challenge. Pollution from municipal or industrial wastewater and waste disposal into rivers are important problems for human societies to protect the environment. Knowing the level of river water pollution as one of the sources of human water needs is essential and therefore modeling the quality of river water is very important. Hydraulic structures in rivers are one of the ways to control pollution in open-channel flows. Check dams are one of the types of these structures that due to the porosity of their environment can play a controlling role in the transport of contamination by increasing hyporheic exchanges as well as transient storage of contamination in their porous media. Transient storage model (TSM) is one of the methods of pollution transport analysis, especially in rivers with high hyporheic exchanges. The efficiency of the (TSM) is in the correct estimation of the four parameters of the model (Dx, As, A and α). Previous studies have not investigated the effect of hyporheic exchanges due to gabion check dams on the four parameters of thel (TSM). In this study, the effect of gabion check dams on pollution transport and the four parameters of the (TSM) with OTIS numerical model were investigated. MethodologyExperiments of tracer material (NaCl) were performed in a flume with a length of 12 m, a width of 0.5 m and a height of 0.7 m in four flow discharges (2.5, 5 and 7.5 lit/s). An ultrasonic flow meter was used to measure the flow discharge in all experiments. Materials with medium diameter (D50) of 11.85 mm and porosity (n) of 0.28 were used to create a sedimentary bed with a length of 12 m and a thickness of 12 cm at the bottom of the flume. In this study, two types of gabion check dams with medium diameter (dg) of 11 mm (fine-grained) and 19 mm (coarse-grained) were used. In each experiment (except for the control experiment), 1 to 3 check dams were used at intervals of 2.5, 5 and 7.5 meters from the beginning of the flume, respectively. In this study, check dams with lengths of 0.75 and 0.35 m, widths of 0.5 and heights of 0.4 m were used. The length of the flume was divided into four equal reaches (L1, L2, L3 and L4). Two sensors were placed to measure the electrical conductivity (EC) of water at the end of each reach to measure the amount of contamination. Micro-propeller and ultrasonic depth-gauge were used to measure the velocity (V) and depth (h) of water flow in each reach. The laboratory results in L4 reach were simulated by the OTIS-P numerical model and the four parameters of the (TSM) were estimated. Results and DiscussionThe results showed that gabion check dams increased the transient storage of solute in the porous media of such dams, thus reducing the peak contamination concentration (Cmax) in the main flow area. On the other hand, check dams in the flow path will act as a sedimentary bed-form, which increases the hyporheic exchanges between the main flow area and the porous media of such dams. Increasing hyporheic exchanges into the porous media of the dams will also reduce the (Cmax) in the main flow area. Increasing hyporheic exchanges into the porous media of the dams also reduces the contamination concentration (Cmax) in the main flow area. Reducing the (Cmax) in the main flow area will also increase the longitudinal dispersion coefficient (Dx).Comparison between the storage zone exchange coefficients (α) estimated by the OTIS-P numerical model showed that these coefficients decreased with decreasing the length of check dams (a). Reducing the length of check dams (a) will reduce the space of the porous media in the flow path. Therefore, the solute will leave these storage zones with a shorter residence time, so the storage zone exchange coefficient (α) decreases with decreasing the length of check dams (a). Gabion check dams made of fine-grained materials reduce the exchange discharge between the check dams and the main flow area. The use of fine-grained materials reduces the rate of contamination transfer to the downstream reaches, so the (Cmax) in the downstream reaches will decrease, so the(Dx) will increase in the fourth interval (L4). Conclusions- Increasing the number of gabion dams (N) from one dam to three dams caused an approximately 1.43 to 1.71 times the value the (Dx). - Increasing the length of gabion dams (a) from 35 cm to 75 cm caused approximately 1.43 to 2.49 times the value of the(Dx). - Increasing the length of gabion dams (a) from 35 cm to 75 cm caused an approximately 1.10 to 4.43 times the value of the (α). - The use of fine-grained materials in gabion dams increased the (α).
Original Article
Pressurized Irrigation Systems
syeed Hassan mousavifazl; Amir Eslami; hadi afshar; Ardalan Zolfagharan; Mohammad Karimi; ali keykha; mansor moayeri; Fariborz Abbasi; Javad baghani; ab naseri
Abstract
Introduction Melon, with the scientific name Cucumis melon L, is an annual plant belonging to the Cucurbitaceae family (Mas, 1986). Melon is one of the most important products, which is rich in absorbable vitamins and minerals needed by the human body. According to the statistics of the World Food ...
Read More
Introduction Melon, with the scientific name Cucumis melon L, is an annual plant belonging to the Cucurbitaceae family (Mas, 1986). Melon is one of the most important products, which is rich in absorbable vitamins and minerals needed by the human body. According to the statistics of the World Food Organization (FAO), Iran with the production of 1731 thousand tons of melons in 2018, was the third producer after China (with the production of 12727 thousand tons) and Turkey (with the production of 1754 thousand tons), and the countries of India, Kazakhstan and America are ranked 4th to 6th in the world with 1231, 894 and 872 thousand tons respectively. Improving water productivity in crop production is necessary due to limited water resources in Iran. According to the surveys conducted on the volume of irrigation water (water applied) or the water given by farmers to melon cultivation, there are no accurate and reliable statistics in the country, and no relatively accurate measurement or estimation has been done in the country. On the other, melon cultivation is important in Iran, so it is necessary to study the volume of applied water in production of this product. In iran, development of pressurized irrigation systems has been one of the main programs in developing agricultural sector in the past few decades. Assessing the effects of these systems can be important in increasing of water ues management, national policies and planning. In this article, based on the field data of the research, it is tried to explain the amount of water used and water productivity of melons in the country and the effect of irrigation management (traditional and modern) on the amount of water given to melons.MethodologyIn order to determine the volume of water used, yield and water productivity of melon crop with the management of farmers in Khorasan Razavi, Fars, Khuzestan, Semnan and Sistan and Baluchestan provinces in calendar year of 2020, 138 melon farms were selected. In these farms, the volume of applied water by farmers was measured. Water irrigation applied (water used) were compared with the net irrigation requirements estimated by the FAO Penman-Monteith method using meteorological data from the last 10 years, as well as the values of the national water document. In this study, the method of analysis of variance is used to investigate the possible differences in yield, applied water and water productivity in melon production. Data adequacy was assessed by using the method provided by Sarmad et al. (2001). Then, the effect of drip irrigation method on applied water, application efficiency and physical water productivity was investigated in the study areas. Results and DiscussionThe results showed that the differences in yield, applied water and water productivity indices in melon production were significant in selected provinces (P ≤ 0.01). The average weighted of yield, applied water and water productivity in Iran were 24962 kg / ha, 7117 m3/ha and 3.4 kg / m3, respectively. The total water for irrigating melon in Iran was estimated at 570.8 million cubic meters. The average yield of melon in furrow and tape irrigation was 20,954 and 24,500 (kg/ha), respectively. In other words, the average yield in tape irrigation method was 14.5% more than furrow irrigation method.The average volume of water in furrow and tape irrigation methods was 7940 and 6073 (m3/ha), respectively. The average volume of irrigation water in the tape irrigation method showed a decrease of 23.5% compared to the volume of irrigation water in the furrow method. The average water productivity in furrow and tape irrigation methods was 3 and 4.3 kg/m3 per hectare, respectively. The average water productivity in tape irrigation method showed an increase of 30% compared to the average of furrow irrigation. ConclusionsThe results of this research showed that tape irrigation method can improve yield, water consumption management and water productivity for melon. Also, the results of this study provide useful information on applied irrigation water management indicators in melon production to managers and water decision makers within Iran. The results of this research show that the use of drip irrigation systems (tape irrigation system) for melon cultivation in the country (and other row crops) can increase water productivity and reduce water consumption in the agricultural sector. However, the operation management of these systems in the country has a relatively long distance from the desired level
