Original Article
Hydraulic
Fatemeh mahmoudi Monfared; Massumeh Rostamabadi; Hojjat Allah Yonesi
Abstract
Extended AbstractIntroduction Compound channels are hydraulic sections consisting of the main channel and flood plains. In natural rivers, the formation of a compound cross-section is common because, during floods, a part of the river discharge is carried by the flood plains. In nature, flood plains ...
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Extended AbstractIntroduction Compound channels are hydraulic sections consisting of the main channel and flood plains. In natural rivers, the formation of a compound cross-section is common because, during floods, a part of the river discharge is carried by the flood plains. In nature, flood plains are usually covered with vegetation that affects the flow transfer capacity in the flood plain and the main channel. Knowing the hydraulic flow conditions and the interaction of the main channel and the floodplain is necessary to protect human lives and facilities. Many experimental and numerical studies have been carried out in compound channels with vegetation (Myers et al., 2001., Hosseini, 2004., Kang and Choi, 2006., Huai et al., 2009, Proust et al., 2013., Hamidifar et al., 2013., Yonesi et al., 2014., Theoharris and Panagiotis, 2016., Hamidifar et al., 2016., Kumar et al., 2016., Shankar and Kumar, 2018., Samadi Rahim et al., 2020., Dovlati and Rezaei, 2021., Shokri and Mehdipour, 2021., Zang et al., 2022., and Samadi Rahim et al., 2023). According to the review of previous studies, most of them have been done in straight compound channels, but the numerical study of asymmetric compound channels with divergent floodplains covered by vegetation has rarely been of interest. Despite the high accuracy of laboratory studies in investigating hydraulic phenomena, high costs, limited laboratory space, and scale effects have also inclined researchers to use numerical methods. Numerical methods can be very efficient for investigating the effects of different parameters on a phenomenon by spending less time and money, provided that the numerical model results have been validated. The current research aim is to study the flow mechanism numerically in a diverging compound channel with vegetation and to investigate the relative depth change in the flow mechanism.MethodologyFor the purpose of this research, the 3D flow field in a compound channel with a divergent floodplain in two cases, with and without vegetation, at three relative depths (the ratio of the flow depth in the floodplain to the flow depth in the main channel) has been simulated. Flow3D was used and validated. Then, velocity contours, velocity profiles, flow depth, and discharge in the flood plain and the main channel for the two mentioned states were compared and analyzed.Results and Discussion The results showed that in both cases, by the increase in relative depth, the maximum velocity in the main channel decreased. In floodplains without vegetation, at the beginning of the divergence, the depth-averaged velocity is about 80% of the main channel one. And as it progresses towards the end of the divergence, this ratio has gradually increased. The vegetation and its resistance to the flow caused a decrease in this ratio of 30 to 60 percent. By increasing depth, vegetation creates more resistance to the flow, and the resistance vegetation effect dominated by the effect of relative depth. The amount of depth-averaged velocity reduction in floodplain due to vegetation compared to the condition without vegetation for the relative depths of 0.15, 0.25, and 0.35 was 85, 82 and 84%, respectively. Accordingly, the depth-averaged velocity increase in the main channel was 12, 25, and 30%. The investigation of the changes in the flow depth from the beginning to the end of the channel showed that for Dr=0.15, floodplain without vegetation have led to an increase of 3.7% in the flow depth in the main channel from the beginning to the end of the divergence area. The vegetation has prevented the rapid increase in flow depth, and an increase of about 0.7% occurred gradually up to a distance of about two times the length of the divergence area, and then there is a 1.5% increase in depth. At Dr=0.35, about 4.5% increase in flow depth has occurred in the main channel, but despite vegetation, the flow depth has gradually increased by 1.7%. Investigating the effect of vegetation and relative depth on the amount of flow passing through the main channel and floodplain showed that the flow in the main channel is always higher than the flow in the floodplain, and the highest amount of flow passes through the main channel in the case of vegetation. With the increase in relative depth, the amount of flow passing through the floodplain has increased while the amount of flow passing through the main channel has decreased. About 80% of the discharge has passed through the main channel and 20% through the floodplain. With the increase in relative depth, the flow through the floodplain has reached 38%. The vegetation has increased the flow through the main channel between 4 and 9 percent.ConclusionsIn this research, the flow field is simulated in an asymmetric compound channel with a diverging floodplain. The simulation is carried out at different relative depths for two states, with and without vegetation, using Flow3D. The high-velocity core of the flow occurred in the center line of the main channel and below the free surface. The quantitative value of the depth-averaged velocity difference in the main channel and the flood plain in the relative depths of 0.15, 0.25, and 0.35 in the case of no vegetation is 36, 22, and 20%, respectively, and with vegetation is 91, 89, and 90%. That is, with the increase in relative depth, the difference in depth-averaged velocity in the floodplain and the main channel has decreased, but in the case of vegetation, relative depth changing has not led to depth-averaged velocity difference, and the difference is due to the presence of vegetation. By increasing the cross-section’s width and decreasing the flow velocity, increasing the depth can be justified to keep the specific energy constant. This phenomenon continued to occur with increasing relative depth. The vegetation and preventing the flow from entering the floodplain has led to a gradual increase in flow depth at divergence region. The discharge in floodplain is always lower than in the main channel.
Original Article
Hydraulic
ali ranjbin; Mahdi Esmaeili varaki; Maryam Navabian; Shahram Niazi
Abstract
Extended Abstract
Introduction
Water quality changes with the penetration of water from the surface of the earth to the subsurface layers, which are accompanied by the passage of subsurface of earth crust with different chemical composition. The most important issues is the increase in the concentration ...
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Extended Abstract
Introduction
Water quality changes with the penetration of water from the surface of the earth to the subsurface layers, which are accompanied by the passage of subsurface of earth crust with different chemical composition. The most important issues is the increase in the concentration of iron and manganese. Therefore, almost underground water sources have significant amounts of iron and manganese. At high concentrations, those may cause the growth of iron and manganese bacteria, increase pathogenic microorganisms, create bitter taste and unpleasant smell in water, create red and brown spots on appliances and blockage water distribution systems. One of the main steps in the water purification process is the removal of iron and manganese ions. Among these methods, the use of oxidation is more widely used due to less operational costs. Use of an aerator is the main part of this method. Stepped weirs are one of the economical devices for the aeration of water that has acceptable performance. In this research, application of a pyramid-shaped stepped weir with and without sill on increase the dissolved oxygen concentration under various flow discharge was investigated experimentally.
Experimental Setup and procedure
Experiments have been carried out on a stepped-pyramidal weir model in the Hydraulic Modeling Laboratory at of University of Guilan. The physical model of the stepped-pyramid weir is made of PVC panels with a constant slope of 1:2 and the number of steps is 6, with dimensions of 4 cm high and 8 cm long. The weir was installed on Iron’s tank with dimensions of 1.5 m length and 1.5 m in width and 1 m height. A centrifugal pump device with maximum flow rate of 8 l/s was used to provide desired flow discharge. In order to measure the flow rate, an ultrasonic flow meter was used with an accuracy of ±0.01 l/s.
In each geometry of the weir and desired flow rate, first the concentration of dissolved oxygen in the water supply tank was reduced to 2 mg/l using Na2SO3 solution, then variation of dissolved oxygen concentration was measured by 2 oxygen meters (DO meter) model AL20Oxi manufactured by Aqualytic company, which was installed on both sides of the tank, until the dissolved oxygen concentration reached on its initial level.
In this research, totally 30 tests were carried out to consider effect of the stepped-pyramidal weir on increasing the dissolved oxygen concentration.
Results and discussion
The performance of stepped-pyramidal weirs with different geometries at h/yc equal to 7.4 (flow discharge of 2 l/s) for the first step indicates that for stepped-pyramidal weir without sill, the falling jet from the steps have gradually decreased in thickness and it falls discontinuously in steps 5 and 6. By installing the sill at the end of each step, although turbulence and mixing of air and water occurred by formation of hydraulic jump but due to the reduction in the thickness of the falling jet, the intensity of mixing is low and, the performance of stepped-pyramidal weirs with end sill reduced. For the mentioned flow rate, the time to reach DO to from 2 to 7 mg/l for different stepped-pyramidal weir geometries is 857 seconds on average which injected 2.3 mg.l/s dissolved oxygen into the water content of recipient tank.
By increasing the flow rate to h/yc equal to 5.6 (flow discharge of 3 l/s) for the first step, the thickness of the falling jet and corresponding flow velocity increases and the overall performance of the stepped-pyramidal weir to increasing dissolved oxygen improved. For mentioned flow discharge, the time of increase of DO to reach its initial level is 735 seconds on average, which dissolved oxygen injected by rate of 2.5 mg.l/s into the water content of the recipient tank.
by further increase of flow discharge to 6 l/s (h/yc equal to 6) turbulence and mixing of air and water intensified by formation of hydraulic jump. Also, in the mentioned flow and relative critical depth, more turbulence was observed at the end of each steps along with the sill or labyrinth sill. The results show that, with the exception of the SG3 geometry (stepped-pyramidal weir with sill and labyrinth with the space of 4h), the other structures had similar performance. The results showed that the time duration of DO concentration from 2 to 7 mg/l is 395 seconds on average, the lowest value of which was related to SG2 geometry (stepped-pyramidal weir with sill) which could inject dissolved oxygen on an average of 2.3 mg.l/s into water content of the recipient tank.
At the maximum h/yc equal to 3.2 (flow rate of 7 l/s) for the first step, the mixing of air bubbles and turbulence of flow on each step causes the labyrinth sill with small length could better performance due to more separation of falling jet of over passing. The time duration to reach the DO concentration from 2 to 7 mg/l is 294 seconds on average. The SG5 geometry (stepped-pyramidal weir with labyrinth having internal space of h) had the best performance. In general, dissolved oxygen is injected into water content of the recipient tank at an average of 2.7 mg.l/s.
Conclusion
The results showed that at the low thickness of overpassing flow with h/yc> 10, simple stepped-pyramidal weir had better performance than other geometries and could inject 2.9 mg.l/s of dissolved oxygen into the water. The comparison of the results indicates that as the flow rate increases, due to the increase of turbulence and mixing of air bubbles into overpassing flow at each step, the performance of the steps with a simple and labyrinth sill improves, so that their performance to inject dissolved oxygen is from 2 to 3.3 mg.l/s. In general, among the different geometries of the stepped-pyramidal weir, the SG2 geometry had the best performance.
Experiments have been carried out on a stepped-pyramidal weir model in the Hydraulic Modeling Laboratory at of University of Guilan. The physical model of the stepped-pyramid weir is made of PVC panels with a constant slope of 1:2 and the number of steps is 6, with dimensions of 4 cm high and 8 cm long. The weir was installed on Iron’s tank with dimensions of 1.5 m length and 1.5 m in width and 1 m height. A centrifugal pump device with maximum flow rate of 8 l/s was used to provide desired flow discharge. In order to measure the flow rate, an ultrasonic flow meter was used with an accuracy of ±0.01 l/s.In each geometry of the weir and desired flow rate, first the concentration of dissolved oxygen in the water supply tank was reduced to 2 mg/l using Na2SO3 solution, then variation of dissolved oxygen concentration was measured by 2 oxygen meters (DOmeter) model AL20Oxi manufactured by Aqualytic company, which was installed on both sides of the tank, until the dissolved oxygen concentration reached on its initial level.In this research, totally 30 tests were carried out to consider effect of the stepped-pyramidal weir on increasing the dissolved oxygen concentration. Results and discussionThe performance of stepped-pyramidal weirs with different geometries at h/yc equal to 7.4 (flow discharge of 2 l/s) for the first step indicates that for stepped-pyramidal weir without sill, the falling jet from the steps have gradually decreased in thickness and it falls discontinuously in steps 5 and 6. By installing the sill at the end of each step, although turbulence and mixing of air and water occurred by formation of hydraulic jump but ue to the reduction in the thickness of the falling jet, the intensity of mixing is low and, the performance of stepped-pyramidal weirs with end sill reduced. For the mentioned flow rate, the time to reach DO to from 2 to 7 mg/l for different stepped-pyramidal weir geometries is 857 seconds on average which injected 2.3 mg.l/s dissolved oxygen into the water content of recipient tank.By increasing the flow rate to h/yc equal to 5.6 (flow discharge of 3 l/s) for the first step, the thickness of the falling jet and corresponding flow velocity increases and the overall performance of the stepped-pyramidal weir to increasing dissolved oxygen improved. For mentioned flow discharge, the time of increase of DO to reach its initial level is 735 seconds on average, which dissolved oxygen injected by rate of 2.5 mg.l/s into the water content of the recipient tank.by further increase of flow discharge to 6 l/s (h/yc equal to 6) turbulence and mixing of air and water intensified by formation of hydraulic jump. Also, in the mentioned flow and relative critical depth, more turbulence was observed at the end of each steps along with the sill or labyrinth sill. The results show that, with the exception of the SG3 geometry (stepped-pyramidal weir with sill and labyrinth with the space of 4h), the other structures had similar performance. The results showed that the time duration of DO concentration from 2 to 7 mg/l is 395 seconds on average, the lowest value of which was related to SG2 geometry (stepped-pyramidal weir with sill) which could inject dissolved oxygen on an average of 2.3 mg.l/s into water content of the recipient tank.At the maximum h/yc equal to 3.2 (flow rate of 7 l/s) for the first step, the mixing of air bubbles and turbulence of flow on each step causes the labyrinth sill with small length could better performance due to more separation of falling jet of over passing. The time duration to reach the DO concentration from 2 to 7 mg/l is 294 seconds on average. The SG5 geometry (stepped-pyramidal weir with labyrinth having internal space of h) had the best performance. In general, dissolved oxygen is injected into water content of the recipient tank at an average of 2.7 mg.l/s.
Original Article
Irrigation network management
Milad Rezaei; Hojat Ahmadi; Malihe Bayram
Abstract
Extended Abstract
Introduction
In arid and semi-arid regions like Iran, which have recently faced a severe water crisis, evaporation negatively impacts the quality of surface and groundwater resources. Increased evaporation rates lead to a higher concentration of salts and minerals in water bodies, ...
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Extended Abstract
Introduction
In arid and semi-arid regions like Iran, which have recently faced a severe water crisis, evaporation negatively impacts the quality of surface and groundwater resources. Increased evaporation rates lead to a higher concentration of salts and minerals in water bodies, which degrades not only water quality but also soil quality, leading to soil erosion and diminished crop yields. Controlling evaporation is therefore critical in managing such crises and preventing further severe consequences.
The volume of water lost due to evaporation from water reservoirs, which have relatively large surface areas, compared to the volume of stored water, exceeds the amount used in crop production. Advanced countries use a variety of methods and cover the reservoirs to reduce evaporation from both water surfaces and soils. These include physical methods (applying used tires, floating bolls, making light-permeable concrete slabs), chemical methods (applying fatty alcohols, hexadecanol, octadecanol, etc.), as well as growing certain plant species like duckweed.
Water management strategies such as water demand management, reusing wastewater, applying water surface covers, and improving the efficiency of water resource use, particularly in agriculture are essential Prioritizing water projects is also part of effective water management. However, methods that reduce evaporation while also generating energy are considered superior. One of the best covers for this purpose is solar panels for electricity generation.
Given Iran's low average precipitation (250 mm) compared to the global average (850 mm) and its high solar energy potential, utilizing this valuable resource can be highly beneficial in controlling evaporation from water surfaces. Consequently, this approach is cost-effective and economically viable compared to many other methods and is crucial for water conservation (Nematollahi et al, 2015; Álvarez et al, 2006; Soltani et al, 2018; Sepaskhah, 2018; Rezazadeh et al, 2020; Farzin & Alizadeh, 2015).
Materials and Method
In this research, climatic data for the city of Miandoab were obtained from the West Azerbaijan Province Meteorological Organization; data were analyzed. Key factors such as temperature, precipitation, humidity, solar radiation, and wind speed were studied to assess how the implementation of solar panels on irrigation canals might reduce their impact.
The analysis was carried out using Meteonorm software, a unique blend of trustworthy data sources and advanced calculation tools, providing access to normal years and registered time series. This software is used worldwide to create climatic data for a plethora of locations. It allows for the analysis of annual and monthly variations in temperature, precipitation, and solar radiation on a global scale, combined with databases and interpolation algorithms for different scenarios covering the period of 2010 to 2200.
Weather forecasts were generated with algorithms using the HadCM3 model, which is based on a simple autoregressive model, to produce realistic future monthly data (Remund et al, 2010). In the fourth IPCC report, the main emission scenarios, B1, A1B, and A2 ranged from the most optimistic to the most
pessimistic; these were replaced in the fifth report with RCP scenarios 2.6, 4.5, 6.0, and 8.5 (Mansouri et al., 2018). Furthermore, the study utilized PVSYST software for comprehensive simulations of solar photovoltaic systems, grid-connected, off-grid, and solar pump systems, analyzing shading effects and enabling the input of meteorological data from various sources, including personal data input manually. Finally, the analysis and reporting of these data were made possible (Khammar et al., 2020).
The optimization of photovoltaic systems depended on orientation according to the solar path (solar angle at local noon) as well as axial deviation to achieve maximum solar irradiance. Inputting geographical coordinates enhances the accuracy of the simulation results, adapting the projections to real-world settings. These data are based on NASA satellite measurements available for various geographical locations worldwide.
Results and Discussion
The study highlights the significant solar energy potential at the Miandoab wastewater treatment plant, with an estimated annual production of 131,000 kilowatt-hours. This capacity is sufficient to power around 271 water pump motors for six hours per day, demonstrating the viability of integrating solar energy into water management systems. Solar energy peaks in June, but higher summer temperatures reduce efficiency, illustrating the importance of temperature considerations when designing and placing solar modules. Additionally, floating solar panels serve the dual purpose of energy generation and reducing water loss through evaporation, preventing approximately 467.7 cubic meters of water loss annually, a critical factor in regions where water scarcity is a concern.
However, the study has some limitations. First, the analysis does not account for energy storage solutions such as batteries, which would be necessary for consistent power supply during off-peak solar hours. Second, while the panels reduce evaporation, their long-term impact on water quality and plant maintenance requires further investigation. Additionally, variations in solar radiation throughout the year may affect power consistency, especially during winter months. The economic analysis also assumes fixed energy prices and solar tariffs, which could fluctuate over time.Practically, the integration of floating solar panels can lead to self-sufficiency in energy production at the treatment plant, reducing dependency on external power sources and providing a return on investment within approximately 6.2 years. Furthermore, surplus electricity could be directed to nearby irrigation systems or local households, increasing the overall utility of the installation. Environmentally, the reduction in evaporation and carbon dioxide emissions supports sustainable development goals.
Conclution
The study concludes that floating solar panels offer a cost-effective, environmentally beneficial solution to water evaporation and energy production. It is recommended that future work include detailed cost-benefit analyses of energy storage systems to improve reliability, along with monitoring the impact of solar panels on water quality. Expanding the project to similar facilities in water-scarce regions could further enhance sustainability efforts and maximize the benefits of this technology.
Original Article
Irrigation network management
Amir Eslami; Mohammad Mehdi Nakhjavanimoghaddam; Mohammadmehdi Gasemi; Akbar Jokar
Abstract
Extended AbstractIntroduction Recognizing and removing production obstacles such as climate changes and drought and water shortage challenges, on one hand, and performance instability and Inappropriate product quality, on the other hand, has doubled the importance of paying attention to applied research ...
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Extended AbstractIntroduction Recognizing and removing production obstacles such as climate changes and drought and water shortage challenges, on one hand, and performance instability and Inappropriate product quality, on the other hand, has doubled the importance of paying attention to applied research and transfer of technical knowledge to the field of production. Therefore, the present research was conducted with the aim of investigating the impact of farmers' management in different climates of cotton-producing areas of Fars province on the irrigation water productivity index.MethodologyThis research was carried out in the field in order to determine the cotton irrigation water in the fields under the management of farmers during one cropping season (2018-2019) in Larestan, Darab and Fasa areas in Fars province. A total of 20 experimental farms were selected. Registration of irrigation program and measurement of water source flow using WSC flume device and volumetric meter were also done. After determining the flow rate of the water source, according to the number of hours of irrigation, the applied irrigation water in each irrigation turn was determined in each of the selected fields. The simplest method that can be used in farmers' fields to estimate the physical productivity of irrigation water of a plant is to measure the yield and amount of irrigation water during the cropping season. In order to estimate the pure water requirement of cotton in the study areas, first, the reference evapotranspiration was calculated using the ETo-calculator software (Raes, 2012) according to the FAO Penman-Monteith method. The meteorological information used included daily average maximum and minimum air temperature, maximum and minimum relative humidity, wind speed at a height of 10 meters (m/s) and the number of sunny hours per day in a statistical period of 10 years. In order to determine plant coefficient values in different stages of cotton growth, first, according to field observations, the four stages of cotton growth were determined. Then the plant coefficients related to each growth stage were selected based on the proposal of FAO publication 56 (Allen et al., 1998). Considering the efficiency of 60 and 90% for surface and drip irrigation systems, respectively (Abassi et al., 2015), the gross water requirement of farms was obtained.Results and Discussion The average yield of cotton in Larestan, Darab and Fasa cities is 4300, 5775 and 3080 kg per hectare, respectively. As it is known, the lowest crop yield was obtained in Fasa district, which could be due to high soil salinity. According to the research of Nakhjavani Moghadam et al. (Nakhjavani Moghadam et al., 2019), the average yield of cotton in the country is reported to be 3383.5 kg per hectare, which has increased by 27 and 70 percent in Larestan and Darab, respectively, and the cotton average yield in Fasa is 9 The percentage has decreased. The average amount of irrigation water in selected farms and 18 farms that were irrigated by surface irrigation method was 9944 and 9899 cubic meters per hectare, respectively. The average water productivity in the selected farms of the province was 0.5 kg/m3, which is 16.3% higher than the national average reported by Nakhjavani Moghadam et al. Also, the average water productivity in the surface irrigation method was 0.49 kg/m3. The average water requirement of cotton in the selected farms of Fars province was calculated as 849, 888 and 989 mm, respectively, based on 10-year meteorological data, meteorological data of the project implementation year and the national water document. Surface and drip irrigation methods in Darab city did not have significant statistical differences in any of the indicators.ConclusionsTaking into account the latest statistics on the area under cotton cultivation in Fars province (19,269 hectares), the volume of water consumed in all the cotton fields of the province is estimated at 191 million cubic meters per year. The results showed that the average indicators of yield, irrigation water and productivity of cotton irrigation water in 18 selected farms of the province that were irrigated by surface method were 4450 kg/ha, 9899 m3/ha and 0.5 kg/m3, respectively. Based on the results of this research, it is recommended that the optimal planting and harvesting dates are observed by the operators on June 20 and November 1, respectively. On the other hand, by accepting the amount of regulated deficit irrigation (20-25%) during the growth period, the optimal irrigation water amount regardless of the leaching coefficient for the cotton plant in these areas with the surface irrigation method should be considered between 9000 and 10000 cubic meters per hectare. It is also emphasized that before planting, farmers should take the soil sample and test it and perform optimal fertilization management according to the recommendations of experts.
Original Article
Geotechnic
Nader Abbassi; Maral Sarkari; Afshin Khorsand; Reza Bahramlou
Abstract
Extended AbstractIntroduction Swelling and shrinking soils are problematic soils that destroy structures built on them if their behavior is not recognized and the necessary measures are not taken. The potential of swelling or shrinkage soils depends on ...
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Extended AbstractIntroduction Swelling and shrinking soils are problematic soils that destroy structures built on them if their behavior is not recognized and the necessary measures are not taken. The potential of swelling or shrinkage soils depends on various factors, such as the type of clay minerals and the chemical properties of the water. When developing the theoretical concept of swelling soil, factors such as mineralogy, soil structure, and pore water affecting physical factors (such as density, moisture value, and plastic properties) should be considered. Determining the swelling percentage and swelling pressure of clay soils is an important tool to explain and predict the behavior of clay soils. One of the most important properties of clay soils is their sensitivity to volume changes due to swelling and contraction, which lead to soil movement. According to the studies conducted on various aspects of swelling, shrinkage and also the effect of the amount and type of salinity on soil properties such as structure, grain stability and shear strength, it seems that much research on the effect of the amount and type of salinity on the swelling and shrinkage behavior of soil has not yet been conducted; therefore, this research attempts to investigate as much as possible the effects of different amounts of sodium carbonate on the swelling and shrinkage behavior of clay soils. Several objectives were pursued in compiling and conducting this research, including investigating the effects of different amounts of sodium carbonate on swelling percentage, swelling pressure, volumetric and linear shrinkage, and determining the effects of chemical characteristics such as EC on the indices of shrinkage and swelling.MethodologyIn order to investigate the effects of the amount of sodium carbonate on the swelling and shrinkage properties of soils, synthetic samples with different amounts of sodium carbonate were used in this study. For this purpose, a sample of clay soil from Kamalabad region of Karaj was first prepared. In order to identify and determine the physical and mechanical properties of the soil used, identification and classification tests were carried out including granularity, Atterberg limits, compaction properties, specific gravity, swelling and shrinkage indices and also chemical properties were studied on the samples based on ASTM standards.The shrinkage limit was used to determine the shrinkage capacity and specifications of the samples. There are two methods, volumetric and linear, to determine the shrinkage limit. The laboratory method for determining the shrinkage limit is provided as a standard by the ASTM Institute under the number D-427. To determine the percentage of swelling and the swelling pressure of soils with different proportions of sodium carbonate, the swelling test was carried out according to the standard (ASTM D4546). First, the soil sample prepared by the dynamic method was tamped into special rings, and then each of the rings containing the sample was placed in a normal consolidation device.Results and Discussion The results show that the sodium carbonate salt had no significant effect on the optimum moisture values and the maximum dry density of the soil samples tested. With the increase in the amount of EC, caused by the change in the amount of sodium carbonate in the original soil, the linear shrinkage and volume shrinkage limit also increased with an almost regular trend, and for the sample with EC=12.58 ds/m, the linear shrinkage and volume shrinkage limit decreased.The results show that when the sodium carbonate content is increased from zero to 1%, the swelling percentage increases with a sharp slope, and when the sodium carbonate salt content is increased to 2%, the swelling percentage decreases from 32.75 to 9.87. If you increase the percentage of sodium carbonate salt from 2 to 5%, the percentage of swelling increases from 9.87 to 11.53 with a slight slope. As you increase the EC from 1.47 to 2.8 (dS/m) the inflation percentage increases from 11.13 to 32.75 and as you increase the EC from 2.8 to 12.58 (dS/m) the inflation percentage decreases from 32.75 to 9.87 and as you increase the EC from 12.58 to 51.8 (dS/m) the inflation percentage increases from 9.87 to 11.53.The graphs of changes in swelling pressure with changes in EC and percentage of sodium carbonate also showed that with an increase in EC from 1.47 to 2.8 (dS/m), the level of swelling pressure increased from 10.12 to 79 kilopascals, with an increase in EC from 8 2.58 to 12.58 (dS/m), the swelling pressure decreased from 79 to 17.30 with a steep increase, and with the increase in EC from 12.58 to 51.8 (dS/m), the swelling pressure decreased from 17.30 to 23 with a very slight increase. By increasing the percentage of sodium carbonate from zero to 1 %, the source pressure increased, and by increasing the percentage of salt from 1 to 2 %, the source pressure decreased, and by increasing the percentage of sodium carbonate from 2 to 5 %, the source pressure decreased with a slight gradient.ConclusionsBased on the surveys and experiments carried out as part of this study, the following conclusions can be drawn and established:From the results of the density test of synthetic samples, it was concluded that the effect of sodium carbonate depends on the amount of salt; thus, up to about 1% with the increase of salt content, there is no particular relationship between salt content and optimum moisture and maximum dry density, but at values between 1 and 5%, optimum moisture decreases and maximum dry density increases.From the results of the swelling test of synthetic samples, it was concluded that the effect of sodium carbonate depends on the amount of salt; thus, up to about 1%, the swelling pressure increases with increasing salt content, but at values between 1 and 5%, the swelling pressure decreases.From the results of the volume contraction test of synthetic samples, it was concluded that the effect of sodium carbonate salt depends on the amount of salt; thus, up to about 1%, the amount of volumetric shrinkage decreases with the increase of the salt percentage, but at values between 1 and 10%, the amount of the volumetric shrinkage limit increases.From the results of the linear shrinkage test of synthetic samples, it was concluded that the effect of sodium carbonate salt depends on the amount of salt; so that up to about 1%, the linear shrinkage limit increases with the increase of salt content, but at values between 1 and 5%, the number of linear shrinkage decreases.
technical paper
Irrigation network management
Nader Heydari
Abstract
Participatory irrigation management (PIM) and at utmost level irrigation management transfer (IMT) are processes that have been carried out in the water sector of most countries all around the world for more than two decades. In Iran, such activities have also been carried out in different aspects including ...
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Participatory irrigation management (PIM) and at utmost level irrigation management transfer (IMT) are processes that have been carried out in the water sector of most countries all around the world for more than two decades. In Iran, such activities have also been carried out in different aspects including mainstreaming of its literature; entering it into the programs, laws, and macro-level policies, the establishment of a few number of Water Users Associations (WUA), and implementing PIM on a limited scale and in some pilot projects in recent years. According to surveys, the process of this issue in the country has been slow, scattered and has faced different problems and challenges. The review of scientific sources and the investigation and analysis carried out for the problem finding regarding the subject in this study indicate that the implementation of the PIM and IMT programs have various issues and challenges in Iran, which important ones are:1) issues of being in charge of the matter, 2) lack of necessary coordination, parallel work and interference of different agencies in each other's affairs 3) absence or lack of necessary determination and will regarding the issue despite its importance and different emphasis in the laws and macro-level documents, 4) the long time passed and the necessity of various changes in the structure of water management due to the growing crisis of water shortage in the country, 5) centralization and not having or not giving the necessary place to WUA from the aspects of the structure, the description of duties and authorities and their ultimate independence, 6) weaknesses in the empowerment of WUA and necessary facilitations for their formation and sustainability, 7) lack of necessary infrastructures and inconvenience of work from various aspects such as non-volumetric delivery of water, closure and or non-implementation of some related laws and regulations, indecision of the relevant organization in doing their work, and competition of water distribution companies to create WUA and relevant conflict of interest issues, 8) lack of necessary research and field studies regarding the issue, 9) the emergence of new challenges in the objectives of the subject and the introduction of some new terms in the discourse of the definition of WUA, specifically in Iran, such as the introduction of the term “land use” into the topic, i.e., calling it as water and land exploitation associations instead of just WUA, and 10) special issues and challenges in the creation and stability of well or underground water users associations (W-WUA). A lot of time (more than three decades) has passed since the introduction of PIM to the scientific and executive literature on water management. There is a long pause in its complete and effective implementation in Iran. During this period some new debates in the country's water management such as creating local water markets, water accounting, water reallocation, etc., have emerged. Moreover, the growing shortage of water resources and the issues of climate change over this period bring the continuation of PIM in the country into a new field and environment. All these necessitate newer studies for revisions in PIM and IMT implementation methods and approaches by taking into account the socio-cultural issues of the regions and on a case-by-case basis.
