Irrigation and Drainage Structures Engineering Research

Original Article Hydraulic

Investigation of Specific Energy Stability in Converging Side Weirs with Guiding Structures

Amirreza Shahriari; Mehdi Daryaee; SeyedMahmood Kashefipour; Mohammadreza Zayeri

Volume 26, Spring , April 2025, Pages 18-1

https://doi.org/10.22092/idser.2025.368890.1610

Abstract

Introduction Side weirs are widely used hydraulic structures in irrigation, drainage, and flood control systems. These structures allow excess water to be diverted from the main channel, helping to manage flow capacity effectively. In converging channels, the presence of guiding structures, such as ... Read More Introduction Side weirs are widely used hydraulic structures in irrigation, drainage, and flood control systems. These structures allow excess water to be diverted from the main channel, helping to manage flow capacity effectively. In converging channels, the presence of guiding structures, such as flow deflectors, can influence the hydraulic performance of side weirs. Recent studies have highlighted the potential of guiding structures to enhance discharge capacity. However, uncertainties persist regarding the impact of convergence and added structures on specific energy variations in the main channel. The classical assumption of spatially varied flow with lateral outflow suggests that specific energy remains constant along the weir. This study aims to evaluate the validity of this assumption in converging channels with guiding structures by investigating specific energy variations using numerical simulations. Methodology A three-dimensional numerical model was developed using FLOW-3D to simulate flow over a converging side weir. The experimental setup by Maranzoni et al., (2017) was used as a reference for model validation. The numerical domain consisted of a converging channel with a side weir, and guiding structures were placed on the weir crest at three different longitudinal positions (upstream, middle, and downstream) with installation angles of 60°, 90°, and 120° relative to the horizontal. The Reynolds-averaged Navier-Stokes (RANS) equations were solved using the RNG k-ε turbulence model. Boundary conditions included a specified flow rate at the inlet, a pressure outlet at the downstream boundary, and wall conditions for the channel boundaries. Grid independence was ensured by testing different mesh resolutions, with the final model consisting of approximately 1.5 million cells. The numerical model was validated against experimental data, with a maximum simulation error of less than 4%. Results and Discussion The numerical results showed that guiding structures influenced specific energy variations along the weir. The middle position of the weir exhibited the least change in specific energy (0.8%) , making it the optimal location for installing guiding structures. In contrast, upstream and downstream placements resulted in greater energy variations, with mean differences of 1.17% and 1.37%, respectively. The effect of installation angle on specific energy variations was negligible. Across different angles, the mean variation ranged from 1.03% to 1.22%, indicating that the angle of installation had little impact on energy conservation. The influence of the inflow Froude number was also examined. For Froude numbers below 0.3, specific energy variations remained under 0.5%. As the Froude number increased to 0.45, energy variations reached 1.6%, which is still within an acceptable range. These findings suggest that specific energy variations are more sensitive to the location of guiding structures than their installation angle. The results confirm that the classical assumption of constant specific energy in spatially varied flow with lateral outflow holds even in converging channels with guiding structures. Although minor deviations were observed, they were within acceptable limits for practical applications. Conclusions In this study, by comparing the simulation results with experimental data, it was found that the model used for simulating flow over side weirs possesses high accuracy and reliably predicts the actual performance of these structures. One of the key aspects of this research is the accurate simulation of side weirs in converging channels. Despite numerous studies in this area, especially in recent years, certain aspects of the design and hydraulic behavior of these types of weirs still require more detailed investigation and numerical modeling. The findings of this study demonstrated that the classical concept of specific energy stability in gradually varied flow with decreasing discharge remains valid even under converging conditions and in the presence of guiding structures. The average difference in specific energy between the upstream and downstream of the weir in all simulations was 1.24%. Additionally, the influence of the Froude number on the increase in specific energy variations was clearly observed. However, within the range of Froude numbers less than 0.5, which is typically dominant in irrigation and drainage channels, specific energy variations did not exceed 3%. Finally, for future research, it is recommended to investigate the effects of factors such as the crest height of the side weir, the presence of orifices within the weir structure, and the influence of supercritical flow regimes on specific energy variations along side weirs, in order to develop a more comprehensive understanding of their hydraulic behavior. Acknowledgement We are grateful to the Research Council of Shahid Chamran University of Ahvaz for financial support (GN: SCU.WH1402.31370).

Original Article Irrigation network management

Exploring Key Drivers Affecting the Development of Farmers' Resilience Capacity in the Face of Water Scarcity

mojtaba noori; Rouhallah Rezaei; mohammad kazem rahimi

Volume 26, Spring , April 2025, Pages 42-19

https://doi.org/10.22092/idser.2025.368874.1609

Abstract

Introduction Water scarcity can result from drought, a decline in water resources, or a combination of both factors. Under these conditions, the term "crisis" aptly describes the situation. The global water crisis is among the most significant threats facing humanity; ... Read More Introduction Water scarcity can result from drought, a decline in water resources, or a combination of both factors. Under these conditions, the term "crisis" aptly describes the situation. The global water crisis is among the most significant threats facing humanity; it is estimated that approximately 3.5 billion people will experience water shortages by 2025, with global water demand projected to rise by 30% by 2050. To mitigate farmers' vulnerability and mitigate the impacts of water scarcity, the concept of resilience has gained attention. Resilience reflects the capacity of an individual or system to adapt effectively during critical situations and identify rational strategies to overcome crises. Today, resilience serves not only as a tool for crisis management but also as a preventive and predictive measure aimed at maintaining orderly continuity under various conditions. Notably, the agricultural sector faces earlier and more severe consequences of water scarcity than other sectors due to the direct threats it poses to farmers' livelihoods and national food security. Given this critical importance, the objective of this study is to identify and analyze key drivers that influence the development of farmers' resilience against water scarcity crises. Materials and Methods Given that "capacity development" pertains to future-oriented activities, this study utilized the critical uncertainty approach and the cross-effects matrix, common methods in futures research, to identify relevant drivers. Initially, a comprehensive review of existing literature was conducted to identify significant issues related to resilience against water scarcity. After summarizing, consolidating, and eliminating redundant or overlapping concepts, these factors were compiled into questionnaires and presented during semi-structured interviews with experts, specialists, and key informants. Participants rated each factor based on "importance" and "uncertainty" for the horizon of 1413 using a five-point Likert scale (very low, low, medium, high, very high). Subsequently, experts weighted and ranked these factors according to their perceived importance and uncertainty. Interaction analysis was then performed to examine interrelationships among key factors, assessing their mutual influence. This method, implemented through specialized futures research software MICMAC, is particularly suitable for analyzing variable interdependencies and compiling expert insights. MICMAC employs a matrix-based approach to elucidate the relationships among influential factors in qualitative research. Results Using the critical uncertainty approach, factors identified as both highly important and uncertain were deemed key drivers. Average weights assigned to each factor were plotted onto an importance-uncertainty matrix, allowing the selection of critical factors. Identified factors included: (1) reforming policies that incentivize the production of water-intensive crops; (2) acceptance of the severity of the crisis within the agricultural community; (3) systemic governance of agricultural water resources; (4) promoting optimal water-use practices among farmers; (5) controlling excessive agricultural water extraction; (6) reforming regional cropping patterns; and (7) promoting sustainable livelihoods independent of water-intensive practices. Results demonstrated that policy reforms targeting water-intensive crop production, enhancing water-use culture among farmers, and adjusting regional cropping patterns significantly impact farmers' resilience to water scarcity. Additionally, key-dependent factors highly influenced by others were the agricultural community's acknowledgement of crisis severity, systemic governance of agricultural water resources, and regulation of excessive water withdrawals. Conclusions This study identified three primary drivers crucial to developing farmers' resilience in Zanjan province: recognizing the severity of the water crisis, adopting systemic governance approaches to water resources, and regulating excessive agricultural water withdrawals. These drivers are interconnected, implying that changes in one factor will inevitably influence the others. Effective management of these drivers is thus essential for advancing resilience among farmers facing water scarcity. Given the critical status of water resources in Zanjan, where five out of seven plains are classified as prohibited or critical zones, provincial administrators and planners, along with the broader agricultural community, must acknowledge the depth of this crisis. By adopting systemic approaches and managing water consumption responsibly, significant strides can be made towards building resilience to the ongoing water scarcity crisis.

Evaluation of the Volume of Applied Water and Agricultural Water Productivity in Walnut Production Regions in the Country

Volume 23, Issue 89 , June 2023, , Pages 1-20

https://doi.org/10.22092/idser.2023.361315.1534

Abstract

IntroductionWalnut is one of the most valuable garden products of the country, which will be very profitable for gardeners if the water and food needs are met on time. During the growth period, the walnut tree goes through different stages, during these stages, the lack of sufficient and timely irrigation ... Read More IntroductionWalnut is one of the most valuable garden products of the country, which will be very profitable for gardeners if the water and food needs are met on time. During the growth period, the walnut tree goes through different stages, during these stages, the lack of sufficient and timely irrigation will affect not only the crop of the same year, but also the quantitative and qualitative production of the next years. The results of various researches have shown that the walnut tree is sensitive to the lack of water and the lack of soil moisture leads to a decrease in yield and the quality of the product in terms of color and size. Researches in the country are mainly focused on determining the water requirements of walnut trees, the effects of low irrigation and the quality of irrigation water on the quantitative and qualitative performance of walnuts, and not many researches have been done on determining the amount of water used by walnut trees in the country. The review of the articles shows that walnut is one of the water-bearing products among garden products, and due to the severe limitation of water resources in the centers of production of this product in the world, many researches focused on determining the amount of water used for walnut trees and low management. It has been irrigated. On the other hand, the researches carried out in the country have mainly been carried out either in limited areas or in the form of research projects on the scale of experimental plots. Therefore, there is almost no comprehensive report on measuring and estimating the volume of water used for this water-bearing product in the country. Based on this, in the current research, the amount of water consumed by walnut gardeners in the country has been measured.MethodologyConsidering that the main purpose of the research was to measure the volume of water used for walnut production in different regions of the country, the water given by gardeners for walnut production during two cropping seasons was measured without interfering in irrigation management and at the level of users' gardens. Is. In this research, due to the fact that the yield of walnut is affected by the age and climatic factors such as frosts, the measurements were made during two consecutive crop years 1396-1397 and 1397-1398. Based on this, the provinces of Hamedan, Kerman, Lorestan, East Azerbaijan, Kermanshah, Chaharmahal and Bakhtiari, Kohgiluyeh and Boyerahmad, Zanjan, Fars, Markazi and Qazvin, where the area under cultivation and the amount of walnut production in them are about 70 and 75% of the whole country, respectively. include, were selected as pilot areas for the implementation of the current research. After that, in each province, city or cities, the top producers of the mentioned product were determined in terms of the level of cultivation and production, and finally, the desired gardens were selected in the cities. In this regard, we tried to select the gardens in such a way that they cover most of the conditions such as climate, garden area, planting intervals, soil texture, water and soil salinity, irrigation methods and different managements, etc. The volume of water supplied was measured with the WSC flume or ultrasonic flow meter without interfering with the irrigation program.Results and DiscussionThe results of the research showed that the volume of applied water of walnut orchards in the studied areas varied from 3050 to 14800 m3/ha and its weighted average in the country was about 7000 m3/ha. Also, the amount of water used in the selected gardens in two methods of surface and drip irrigation was obtained as 7675 and 5709 m3/ha, respectively. The two-year average yield of walnuts in the production areas varied from 520 to 3280 kg/ha and its weight average was 1235 kg/ha. Based on this, the productivity index of irrigation water varies from 0.04 to 0.71 kg/m3 and its average weight in the country is about 0.20 kg/m3. The general results of the research indicate that in the investigated provinces, the amount of water used in walnut orchards is less than the gross water requirement of this product and there is a kind of forced under-irrigation in walnut orchards.

The Feasibility of Using New Technologies in the Modification and Reconstruction of Water Transmission Channels During Operation (Case Study: The Main Channel of Moghan Irrigation Network- Iran)

Volume 24, Issue 91 , November 2023, , Pages 22-49

https://doi.org/10.22092/idser.2023.362797.1548

Abstract

Extended Abstract Introuction This study aims to examine building modern irrigation networks to provide the possibility of productivity of water and soil resources by creating facilities, in which the optimal technical principles and criteria of hydraulic and economic design ... Read More Extended Abstract Introuction This study aims to examine building modern irrigation networks to provide the possibility of productivity of water and soil resources by creating facilities, in which the optimal technical principles and criteria of hydraulic and economic design are observed. In this regard, the main water transfer channel plays a vital and exceptional role in supplying the required water for agricultural lands covered by the network and for the prosperity of the regional and national agricultural economy. Covering the water transmission channels in operation is always one of the numerous problems and problems of operation and maintenance of large irrigation networks in the world. In Iran, due to the major issues and problems of exploitation in the lands covered by modern networks, such as land drainage due to water leakage from the bodies of earthen canals, concrete covering of canals has always been considered to prevent water wastage, and it is on the agenda. The deputy of water resources affairs of the Ministry of Energy and regional water companies was established. The main canal of the South Moghan irrigation network in Iran with a transfer capacity of 80 cubic meters per second, the main channel of Upper Garabagh with a capacity of 110 cubic meters per second and the main water transfer channel of Upper Shirvan with a capacity of 85 cubic meters per second in the Republic of Azerbaijan are among them. Material and Methods The withdrawal of water needed by the Moghan irrigation and drainage network from the Aras River is directed through the Mil and Moghan diversion dam before entering the main channel to a sediment catchment basin to trap suspended sediments in it. This calm sediment collection pond with a maximum water intake of 95 cubic meters per second has four rectangular units and each unit consists of three galleries, 15 cubic meters of which are returned to the river after washing, and the rest enters the main channel. In the current state, due to the reduction of vegetation in the middle basin of the Aras River at a distance of 260 km from the Aras Reservoir Dam upstream of the Mil and Moghan Diversion Dam and the subsequent increase in the concentration of suspended load in the Aras River, the trapping efficiency of the suspended load in the sedimentation basin has decreased to its minimum value. For this reason, sediments exceeding the permissible limit of 18 to 25 g/L enter the water transfer channel. Even though more than 45 years of the useful life of the network have passed, covering operations of the main channel with materials, such as impermeable soil (compaction of bed soil, cover with a thin compacted layer of clay, cover with bentonite) or concrete cover to prevent washing water and reduce water loss from the earthen body of the main channel has happened very little and locally. Results and Discussion Considering the necessity of realizing the research objectives, the feasibility of using the proposed method to carry out the executive operations of improvement, reconstruction, and concrete covering of the soil section of the canal, without interrupting the water flow in the main water transmission channel of South Moghan from its kilometer 1 to 11, was conducted (Hasanpour and Tabatabai, 2010). The method of constructing a temporary diverting channel along the main channel by constructing earthen dikes in the cross-section of the main channel to cut off the water flow within the scope of operational operations of the enclosed sections between the dikes and directing the required water flow by creating a diverting section in the side wall of the channel upstream of the earthen dike into the temporary diversion channel and re-directing the water flow through the end earthen dyke downstream into the main channel for the implementation of repair and reconstruction operations and concrete coating in several operating intervals of the earth section of the channel without interrupting the water flow by spending exorbitant costs of the construction operation of the temporary diversion channel and the concrete cover of the main channel were done. Therefore, due to the imposition of excessive and unconventional financial burden in the method of using a temporary diversion channel on the implementation of the main channel modification and reconstruction plan, to reduce the excessive conventional costs, the new method of "wall structure of mobile separating blades" as a solution suitable and cost-effective for its use and application in the repair and reconstruction of the canal was suggested. The regional water company also promised to assist in the application and use of the new technology proposed to operate the project in the main Moghan canal, based on the urgent need and necessity of the issue. In this method, the minimum cost is 2.7 times lower than the cost of constructing a diversion channel per unit length (1 km). Also, in carrying out dredging operations, cleaning and smoothing the section of the main canal of southern Moghan, similar to the long-boom excavator, which was invented by Professor Telman Hajief to carry out dredging operations in special conditions and channels with large sections, using modern technology, was used. (Hashmi-Shadheni et al., 2016) Conclusions Since the well-known methods and proposals are accompanied by defects even after completion, therefore a new effective method was developed under the title of "mobile separating blade wall method", which is the mechanism of operationalizing the technical and technological parameters of its construction widely. It was investigated and researched. First, the operation of the mobile separating blade wall structure in laboratory conditions was investigated experimentally. The division of the main channel sections in the method of the mobile separating blade wall structure, drying the enclosed operation field, carrying out soil operations, concreting, and its technological technology was presented, and determined, that in this method, carrying out the operation of covering the sections of the water transmission channel using concrete panels Arme will be ready, easier and very affordable. Also, the calculation of the technical and economic comparison indicators of the construction, along with the transfer of the required costs downstream with different methods showed that the mobile dividing wall method is very suitable and economical in terms of technical, technological, and economic aspects in the major repairs and reconstruction of the main channels. The proposed method is a new technique that for its application in production, there will be an urgent need to conduct practical research in nature. Therefore, it is suggested that the presented method be conducted and evaluated for other networks so that all the country's networks can be improved and modified more cost-effectively.

Study Indicators of Environmental Flow and PHABSIM EcoHydraulic Model to Estimation of Ecological Optimal Release Flow Range from Latyan Dam Reservoir

Volume 23, Issue 89 , June 2023, , Pages 21-46

https://doi.org/10.22092/idser.2023.361807.1537

Abstract

Extended AbstractIntroduction The study of fish habitats is important for us to understand better the impacts of reservoir construction on river ecosystems. Hydropeaking hydropower plants are the main source of renewable energy, meeting sub-daily peaks in electricity demand. Dam reservoir ... Read More Extended AbstractIntroduction The study of fish habitats is important for us to understand better the impacts of reservoir construction on river ecosystems. Hydropeaking hydropower plants are the main source of renewable energy, meeting sub-daily peaks in electricity demand. Dam reservoir that regulates river water to supply different sectors demands such as drinking water, agriculture, and hydropower generation and this ignores the need for water in the river as the first beneficiary. The development of a rational watershed planning and management plan (develop a suitable ecological flow scenarios) is significant for the survival, reproduction, and development of fish. Recently, several classical approaches were used to estimate ecological flow, including hydrologic, hydraulic, and a habitat suitability modeling approach. The hydrological approach determines ecological flow based on historical hydrological data, of which one representative method is the Tennant method. The hydraulic approach determines the ecological flow according to the wetted perimeter of the cross section of the river. Hydrological and hydraulic approaches are favored because of their simplicity and ease of calculation, but both of them lack the biological mechanisms and biological requirements. Fortunately, the habitat suitability modeling approach combines the knowledge of hydraulics and biology to establish the relationship between habitat and hydraulic factors. It has certain advantages in the evaluation of ecological flow and has attracted more and more researchers’ attention. The most classical habitat suitability modeling approach is the instream flow incremental methodology (IFIM) and its physical habitat simulation component (PHABSIM), which includes the suitability of habitat target species to a series of hydraulic factors such as flow velocity and water depth to build a habitat suitability index model. The habitat suitability modeling approach provides the best range of hydraulic factors such as flow for habitat target species, which has certain reference significance for guiding reservoir operation. Therefore, environmental flow determination is one of the effective methods that can create a suitable potential to reduce the negative effects of river regulation and habitat protection.Methodology In this study, three methods based on hydrology, Tennant method, Ecodeficit, and the method of variability of hydrological indicators were used to evaluate environmental flow, and the PHABSIM ecohydraulic model was used to obtain habitat suitability and ecological flow regime in the downstream of of Latyan Dam. Also, the effect of the ecological flow regime on the habitat conditions and flow fluctuations caused by the operation of the hydroelectric power plant was evaluated. Based on the hydrological data and field investigation results, the Tennant method describes the status of the river flow regime by the percentage of the mean annual flow. The Tennant method determines the relationships between the river flow regime and aquatic organisms, river landscapes and entrainment. The alterations of the river flow downstream of the dam in the conditions of the hydropeaking regime of hydroelectric plant operation and after its change to the run-of-river and interventional operation were characterized. Ecodeficit and surplus are two comprehensive measures to illustrate the overall impact of dam on stream flow character. The non-dimensional metrics of ecodeficit and ecosurplus are relying on the flow duration curve (FDC). The ecosurplus and ecodeficit can be computed using either a period of recorded FDC or a median annual FDC. The Physical Habitat Simulation Model (PHABSIM) is proposed to simulate the relationship between streamflow and physical habitat for various life stages of target fish species, and thus to determine the optimal ecological flow of the representative river reach.The classical PHABSIM includes two components, namely hydraulic simulation and habitat modeling. On the basis of that, one-dimension hydraulic simulation model is proposed to determine characteristics of the stream in terms of depth and velocity as a function of discharge. As for habitat modelling, the river sectors and aquatic species most vulnerable to the variation of streamflow should be identified initially. Then, the Habitat Suitability Index (HSI) is introduced to reflect the preferences of target fish species with regards to the flow velocity, depth, and channel properties. Basically, HSI was determined according to the number of fish population appearing at the target point. The maximum value of HSI is set at 1.0, and the rest of the HSI values are determined in terms of relative ratio to the maximum value. Then, the Weighted Usable Areas (WUA) is employed to reflect the amount of physical habitat that available can be calculated for fish species at different flow condition, which as an aggregate of the product of a composite HSI. In terms of ecological constraint, maintaining at least 75% of largest WUA is set as an example in optimization modelling, to describe the detailed process to incorporate the ecological demand into reservoirs operation under one certain recovery level.Results and Discussion Based on the results, the environmental flow in the range of 2.5-18.55 m3/s was calculated as the amount of release flow needed to stabilize the fish species and habitat of Jajrood River. Also, the low flow months (July to November) compared to the high flow months (March to June), need to consider a higher proportion of the average monthly flow than the mean annual flow as the minimum required environmental flow. The reservoir operation makes flow series flat and the duration of a single pulse increases compared with flow series before construction. It is obvious that the hydrological parameters of natural flow have a lager alteration due to the construction and operation of reservoir, which may change the downstream riverine structure and threaten freshwater biodiversity. It was demonstrated that the operation of the hydroelectric power plant in the hydropeaking system is the cause of a large flow alteration in respect of the frequency and duration of low- and high-flow pulses and the rate and frequency of change in the flow. The change in the manner of operation of the hydroelectric power plant affected the reduction in the degree of transformation of most features of the flow. The magnitude of monthly flow and extreme flow decreases (73% and 82%, respectively), leading to lower river depth and decreased nutrient exchanges between rivers and floodplains. The number of low pulses each year increases obviously (90%), leading to increased biotic interaction, such as competition and predation. Trend of maximum and mean flow ratio and maximum and minimum flow ratio has attenuated in reservoir after dam construction. The hydrological variation may cause losses of habitats, disconnectedness from upstream riverine habitats and adjacent backwaters, and loss of recreational access. These changes will weaken the aquatic ecosystem of the Jajrood River itself and reduce its ecological status. In this case, promoting the regulation capacity of hydropower stations in the Jajrood River may be one way to avoid this damage. Conclusions Preoptimized measures, such as ecological instream structures and joint eco-operation schemes of mainstreams and tributaries, may be used to cope with the impacts of climate change on the process of migrating, spawning, hatching and other critical periods in the fish life cycle. A more reasonable and reliable ecological flow range can be obtained based on the habitat model in this paper, which provides the best scenario for water resources planning and management in the Jajrood River Basin. The results show that the range of basic ecological flow demand range is 1.65–5.93 m3/s, the range of suitable ecological flow demand is 2.5–18.55 m3/s. In the demand process across the year, the demand is the largest from March to June, while the demand is the smallest from July to November. This study provides a useful framework for releasing the desired flow from the dam reservoir by considering the analysis of the natural hydrological and ecological conditions of aquatic habitats, in order to restore and manage the river ecosystem.

Evaluation of environmental performance of mole drain on rice cultivation in paddy fields

Volume 24, Issue 92 , March 2024, , Pages 131-106

https://doi.org/10.22092/idser.2024.365355.1575

Abstract

Extended Abstract Introduction It is possible to effectively control water in paddy fields, prevent flooding problems, and create optimal conditions for the growth of agricultural products with simultaneous and correct management of irrigation and drainage. Due to the high initial cost of the construction ... Read More Extended Abstract Introduction It is possible to effectively control water in paddy fields, prevent flooding problems, and create optimal conditions for the growth of agricultural products with simultaneous and correct management of irrigation and drainage. Due to the high initial cost of the construction of subsurface drainage, Mole drainage is a suitable and more economical alternative in clay soils. Constructing the mole drain at a critical depth and passing the water through the cracks, improves the soil conditions and removes excess water from the soil surface. Mulqueen (1985), reported that gravel mole drain is a suitable alternative to traditional mole drain. Considering the limited studies in the field of mole drainage, the purpose of this study is to evaluate the performance of low-cost mole drainage for draining excess water from paddy fields and its environmental effects. Therefore, the effect of traditional mole and gravel mole drain on drainage water quality and control of the water table of paddy fields in the mid and end of rice season was investigated. Materials and Methods The experiment was conducted in the agricultural year of 2022-2023 in the research farm of the Faculty of Agricultural Sciences, University of Guilan (IRAN). The split-plot experiment was implemented in a randomized complete block design in three replications under the main drainage treatment on two levels: (1) Traditional mole drain (without gravel) and (2) Gravel mole drain and the sub-treatment of irrigation method in two levels: (1) Flood irrigation and (2) Alternative irrigation. In the stages of tillering and harvesting, mid and end season drainage were done respectively. During the drainage period, the water table was measured with a piezometer. By sampling the drainage water, its quality parameters including acidity, electrical conductivity, nitrate, nitrite, phosphate, sulfate, chloride, total suspended and dissolved solids, sodium, calcium, magnesium, and ammonium were measured. The results of the investigated treatments were statistically analyzed using SAS software. Results and Discussion With the start of mid season drainage, after one day, the water table reached the middle of the soil profile and more than half of the root development depth was in anaerobic conditions. Five days after the drainage in the traditional mole drain, the depth of root development was in aerobic conditions. The highest value in average acidity and sodium adsorption ratio was 6.99 and 4.65 meq/l respectively in mid season in gravel mole drain and flood irrigation. The highest concentration of ammonium and nitrate in mid season drainage was 0.20 and 0.21 mg/l, respectively, and the highest average electrical conductivity and total dissolved solids at the end season were 3845 µS/cm and 2475 mg/l, respectively, in traditional mole drain and flood irrigation. In mid and end season drainage, the amount of total suspended solids in the mole drain with gravel was 60% and 88% higher than the traditional mole drain, respectively. The highest concentration of nitrite was obtained in the gravel mole drain and flood irrigation with a value of 6.75 mg/l during mid season drainage. The average concentration of phosphate and sulfate in gravel mole drain compared to the traditional mole in mid and end season decreased by 25 and 30%, respectively, and sulfate by 3 and 5.5%. Also, the average concentration of chloride in the gravel mole drain was lower than the traditional one. Conclusion The comparison of results indicated that the average amounts of electrical conductivity, total dissolved solids, sodium adsorption ratio, sodium, ammonium, phosphate, sulfate, and chloride of drainage water in mid and end season were lower in gravel mole drain than that in traditional one. The results of statistical analysis showed that the treatment of drainage, irrigation, and time at the level of one and five percent were effective on most of the parameters, while the values of electrical conductivity, total dissolved solids, and nitrite of the drainage water showed that their difference was not significant. The traditional mole drain was more successful in controlling the water table. A comparison of the quality parameters of drainage water with the standard of the Iranian Environmental Protection Organization for the discharge of drainage water into surface waters showed that most of the parameters, except for ammonium and total suspended solids, were within the permissible limits.

A Review of Water Consumption Management Indicators of different Crops in Iran

Volume 25, Issue 94 , June 2024, , Pages 1-16

https://doi.org/10.22092/idser.2024.364605.1569

Abstract

Extended AbstractIntroduction In terms of water consumption in different sectors, in Iran as in other countries, a significant part of surface and groundwater resources is used in agricultural sector. For the amount of water consumed in Iran's agricultural sector, different numbers have been reported ... Read More Extended AbstractIntroduction In terms of water consumption in different sectors, in Iran as in other countries, a significant part of surface and groundwater resources is used in agricultural sector. For the amount of water consumed in Iran's agricultural sector, different numbers have been reported in various sources. In the past three decades, water consumption in agricultural sector in various sources and methods has been reported between 44 and 86 billion cubic meters (Movaheddanesh, 1994; Ghodratnema, 1998; Mohammad-Vali-Samani, 2005; Nasseri et al., 2017; 2018). The physical water productivity is also one of the important indicators of irrigation management, which is determined by using the amount of product produced per unit of applied irrigation water. Abbasi et al. (2017) estimated and analyzed water productivity values in Iran for different years. They estimated the values of water productivity varying from 0.94 to 1.29 kg/m3 and average being 1.07 kg/m3. Abbasi et al. (2019) also showed that water productivity index in Iran had an upward trend with a slope of 0.045 kg per year. It varied from 1.0 kg/m3 in 2008 to about 1.45 kg/m3 in 2017. Past researches regarding the estimation of water consumption in agricultural sector have been reported with estimation methods such as water balance method, which was not accurate and was associated with errors. On the other hand, the figures presented for the amount of water consumed in agricultural sector are very different and there are doubts about their accuracy. Despite the importance of the issue, accurate information on the amount of irrigation water for agricultural crops in different regions of Iran is not available and this issue has always been one of the main concerns of the water industry managers and planners. Therefore, carrying out a research work that leads to more accurate numbers about the amount of applied irrigation water for different crops, can be of great help to the decision-making of officials related to water and agriculture. The main goal of this article is a comprehensive evaluation of water management indicators in agricultural sector (including the water productivity and applied irrigation water for different crops). MethodologyField measurements including applied irrigation water and crop yield were carried out for at least one cropping season in the production hubs of each crop. Twelve crops included 12 wheat, rice, barley, fodder corn, alfalfa, sugar beet, sugar cane, beans, sunflower, cotton, rapeseed, and soybean, 17 garden crops included saffron, apple, olive, orange, tangerine, peach, nectarine, plum, lemon, fig, grape, date, pomegranate, walnut, almond, pistachio, and cherry and 6 vegetable and summer crops were tomato, watermelon, potato, cucumber, melon, and onion. These crops covered more than 85% of the cultivated area and irrigated lands in different provinces. For each crop, applied irrigation water was measured in a crop season and the yield for one year or the average of two years, but for garden plants, due to climate changes and frost damages, the average yield of 1-3 years was determined and used in the analysis. Physical water productivity of irrigation water from the ratio of crop yield to applied irrigation water and water productivity from the ratio of crop yield to water (total volume of irrigation water and effective precipitation) and gross income per unit of applied irrigation water was calculated from the product of crop yield in the sales price divided by the applied irrigation water. In this research, the cluster analysis model was used to determine the homogeneous crops. Results and DiscussionThe results showed that applied irrigation water for different crops varied from 3984 for rapeseed to 32500 cubic meters per hectare for sugarcane. So that the weighted average applied irrigation water of 35 studied crops was determined to be 8032 cubic meters per hectare. This index was 9162, 7669 and 7247 cubic meters per hectare for garden, agricultural, vegetable and summer crops, respectively. Also, the total applied water used for the 35 studied crops was estimated at 61.7 billion cubic meters and the total irrigation water for other crops that were not evaluated in this research was estimated at 9.4 billion cubic meters. The total water used in irrigated crops was estimated at 71 billion cubic meters, which was about 70% of the total renewable water in Iran. The weighted average of irrigation water productivity and water productivity of the studied crops was determined as 1.9 and 1.5 kg/m3, respectively. Saffron and pistachio provided the highest gross income per unit of irrigation water and sugarcane, soybean, barley, fodder corn, wheat and alfalfa had the lowest values. ConclusionsThe results of this research provided valuable information for managers and decision makers in different provinces of Iran.

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