Iranian Water Research Journal

Abstract Introduction:
Hydraulic jump is an important phenomenon in free-surface flows that occurs when a supercritical flow transitions to subcritical conditions. This process involves a sudden change in flow velocity, which results in significant energy dissipation through variations in flow intensity, turbulence, and wave formation. The hydraulic jump plays a crucial role in the design and operation of hydraulic structures and channels, as it influences velocity distribution, water depth, and energy levels along the flow, ultimately affecting system stability and performance. The primary objective of this research is to introduce an innovative method for determining conjugate depths and hydraulic jump length. This method employs a rectangular water jet with rapid free characteristics to excite the flow and alter jump properties. By simulating real flow conditions through the application of this jet, the study aims to improve the accuracy of hydraulic jump modeling and provide insights for practical hydraulic design.
Methods:
This experimental study was performed in a rectangular glass-walled channel with dimensions of 10 m length, 0.3 m width, and 0.5 m height. To investigate the effects of jet angle, flow rate, and bed roughness on hydraulic jump characteristics, a total of 63 tests were conducted under varying conditions. Three different fall heights and three jet discharges (2, 2.5, and 3 L/s) were applied in combination with three Froude numbers (6.5, 8.3, and 9.5). Bed roughness was introduced at two different heights (0.03 m and 0.04 m) and at two distances (d and 2d) to simulate variable surface conditions. The independent variables included jet flow rate, angle, and bed roughness, which were specifically chosen to evaluate their influence on jump features.
Two complementary measurement methods were used to capture jump parameters. First, a direct method employed a fabric tape measure fixed along the channel wall to continuously record depth and length of the jump. This provided accurate data on the variation of water depth during the hydraulic jump. Second, an indirect method used high-resolution photography to capture detailed images of flow patterns, which were later processed with Grafar software to extract jump dimensions and analyze flow behavior. These combined approaches enhanced the precision of parameter measurement and ensured reliable evaluation of the effects of experimental variables.
Results:
The experiments revealed that the effect of jet angle on the hydraulic jump varied with flow conditions. At a specific threshold, termed the “ineffective angle,” changes in jet angle had no effect on jump position. Increasing the angle beyond this point caused upstream movement of the jump, until a maximum displacement angle was reached beyond which no further change occurred. Variations in jet angle and discharge significantly influenced jump length, secondary depth, energy dissipation, and shear stress on the channel bed. For example, at a Froude number of 6.5, a jet angle of 129°, and discharge of 3 L/s over triangular bed roughness, secondary depth increased by 21% compared with the smooth bed case. Similarly, at an angle of 63° with 3 L/s and Froude number 6.5, the secondary depth ratio rose by 20.96%. Conversely, under maximum Froude number and jet angle greater than the ineffective angle (145°), jump length decreased by 30.16%. Energy dissipation was also reduced under certain conditions; at a 60° angle with maximum Froude number and 3 L/s discharge, dissipation decreased by 22.4%. The largest reduction, 25.76%, occurred at 145° with maximum discharge and minimum Froude number on a rough bed. Furthermore, bed shear stress increased under maximum angle conditions, while at angles smaller than the ineffective angle, negative D values indicated higher secondary depths compared to a classic jump. The lowest D value (−21) was observed at 63°, 3 L/s discharge, and minimum Froude number in the smooth bed case. Positive D values at higher angles showed reduced secondary depths compared to classic jumps, with the maximum value (20.9) occurring at 129° and maximum discharge with minimum Froude number on triangular roughness.
Conclusion:
This study demonstrated that the use of a rectangular water jet significantly affects hydraulic jump behavior. When applied at angles greater than the ineffective angle, the jet reduced jump length, energy dissipation, and conjugate depths. Under maximum discharge and high Froude numbers, bed shear stress increased, altering flow velocity distribution and turbulence. These results highlight the importance of controlling jet parameters for effective energy management in hydraulic structures. The findings can be directly applied in the design and optimization of channels, spillways, and flood control systems to improve energy dissipation efficiency and enhance structural safety under intense flow conditions.

Abstract Introduction:
Floods are among the natural disasters that pose a serious threat to lives and property. Flood frequency analysis is essential for estimating design discharges for hydraulic structures and managing flood risk. Two primary methods for estimating design floods include statistical and hydrological approaches. Statistical methods typically use probability distribution functions such as Gumbel, log-normal, and Pearson Type III to analyze peak discharges. In areas with insufficient recorded data, rainfall data and regional analyses are utilized. Low-probability events and sparse historical data significantly impact analysis results. These data may lead to deviations in discharge estimations and alter return period assessments. Various statistical methods have been introduced for identifying and removing outliers; however, incorporating historical data can enhance modeling accuracy. Studies have shown that including historical data in statistical analyses improves the precision of design flood estimates. This study aims to examine outlier data at the Takht Khan hydrometric station, located in the Godarkhosh River Basin, Ilam, and analyze the impact of removing or retaining these data on the accuracy of discharge estimates for different return periods.
Methods:
This study investigates flood estimation in the Godarkhosh River watershed in Ilam Province, Iran, using statistical and hydrological analysis methods. The watershed, covering approximately 810 km², consists of mountainous terrain with seasonal river discharge variations. Key meteorological and hydrometric data were collected, including 34 years of rainfall and discharge records. Outlier detection is crucial in hydrological studies as extreme values can significantly impact statistical analyses and flood prediction accuracy. This study employed three methods for identifying outliers: graphical methods (box plots and scatter plots), statistical methods (Z-score analysis), and model-based methods (cluster analysis).The box plot method visualizes data dispersion and identifies extreme values, while scatter plots reveal potential anomalies in variable relationships. The Z-score method standardizes data by measuring deviations from the mean, with values exceeding ±3 considered outliers. Cluster analysis groups similar data points and detects anomalies based on deviations from main clusters. For flood frequency analysis across different return periods, the Log-Pearson Type III distribution was selected for discharge modeling based on the goodness-of-fit tests, including the Anderson–Darling and Chi-square tests. Given the natural skewness of flood data, this distribution provides more reliable estimates of peak discharge for various return periods. The method involves logarithmic transformation of the data, calculation of the mean, standard deviation, and skewness coefficient, followed by fitting the Pearson Type III distribution. Accurate flood estimation is essential for the design of hydraulic structures and effective flood risk management. Identifying and appropriately handling outlier data improves data quality and enhances the reliability of hydrological modeling. The findings of this study highlight the importance of simultaneously using multiple outlier detection techniques to improve statistical analyses and increase the accuracy of flood prediction in watersheds prone to extreme hydrological events.
Results:
Descriptive analysis of the hydrological data for the Godarkhush River indicated that for two key variables of annual maximum discharge and annual maximum precipitation, the skewness and kurtosis values were 3.87 and 17.53 for discharge, and 2.11 and 5.01 for precipitation, respectively. These values reflect a distribution with notable positive skewness and high kurtosis, commonly indicative of the presence of outliers in the dataset. Outliers can significantly affect statistical analyses and hydrological modeling; thus, their identification is crucial. To detect outliers, multiple methods were employed, including Box Plot, Z-Score method, and Cluster Analysis. The results consistently identified the discharge data for the year 2015, with a value of 2,160 m³/s, as an outlier across all methods. Subsequently, to determine the most suitable probability distribution for modeling annual maximum discharges, four common distributions (Log-Pearson Type III, Log-Normal, Weibull, and Gumbel Max) were evaluated using the EasyFit statistical software. According to the Anderson–Darling test, which is particularly sensitive to deviations in the tails of the distribution, the Log-Pearson Type III distribution yielded the lowest statistic (0.341), indicating the best fit. Similarly, based on the Chi-Squared test, this distribution also showed the best agreement with the observed data. Therefore, Log-Pearson Type III was selected as the most appropriate distribution for modeling annual peak discharge data in this study. To estimate design discharge values using the Log-Pearson Type III distribution, key distribution parameters (mean, standard deviation, and skewness) were calculated for the Takht-e-Khan hydrometric station under both conditions of with and without the identified outlier. The results showed that the inclusion of the outlier increased the mean annual discharge from 231.87 to 288.59 m³/s, highlighting the significant impact of extreme flood events on computed values. The skewness also increased by 1.77 units when the outlier was included. Moreover, kurtosis rose from 4.29 to 17.53 under the same condition, suggesting that including rare extreme events can considerably alter design flow estimations. Following this, design discharge values were calculated using the Log-Pearson Type III distribution for various return periods (5 to 1000 years), both with and without the outlier. The results revealed that for short return periods, the differences in design discharge between the two scenarios were minimal. However, for medium-term return periods (25 to 100 years), the disparity increased with the return period. For instance, at a 50-year return period, the design discharge was estimated at 1,481.5 m³/s with the outlier and 894.15 m³/s without it that indicated a 39.64% reduction when the outlier was excluded. Similarly, in long-term return periods (200 to 1000 years), the differences became even more pronounced. For the 1000-year return period, the design discharge was calculated at 7,152.4 m³/s with the outlier, and 2,532.9 m³/s without it, reflecting a 64.58% decrease that demonstrated the substantial influence of outlier events on long-term hydrological estimates.
Conclusion:
The findings of the study emphasize that managing outlier data and making the correct decision about including or excluding it from datasets, especially in flood analysis and design discharge estimation, can significantly affect the accuracy of predictions and hydrological designs. Based on the results, the flood discharge data for the year 2015 (2160 m³/s) was identified as an outlier. Due to its significant deviation from other data, this outlier can cause major changes in the design discharge estimates. Excluding this data from the dataset leads to a considerable reduction in the design discharge for long return periods, which could result in underestimating the risk of severe floods. Moreover, including the discharge data in 2015, as an exceptional data point, in the calculations improves the accuracy of predictions and the design of hydrological structures. These results highlight the importance of proper management of outlier data and the correct decision-making process regarding its inclusion or exclusion in order to avoid significant errors in predictions and designs.

Abstract Introduction:
Natural lakes and wetlands are vital ecosystems that play a crucial role in maintaining biodiversity and regulating the water cycle. The rising demand for water in agriculture and irrigation has significantly impacted these ecosystems. To address this global challenge, water-saving irrigation technologies have been proposed as one of the key solutions. In the present study, with the assumption that reducing water consumption in farms around wetlands can help restore wetlands, existing technologies were employed to reduce irrigation water consumption on some farms around Tashk and Bakhtegan wetlands in Fars province.
Methods:
To achieve this objective, 17 farms and orchards were selected in the counties of Arsenjan, Estahban, and Abadeh Tashak. The selected orchards included pomegranate, pistachio, and apple, while the chosen farms comprised cotton, forage corn, and grain corn. Appropriate technologies were identified and implemented for each farm and orchard, based on field visits. The technologies applied regarding modifications to the irrigation system, determination of irrigation scheduling, and the enhancement of tree watering basins. Each farm or orchard was divided into two plots: one was managed under the farmer's conventional practices (control), and the other with water-saving technologies (treatment). Over a period of one year, the farms were managed with these technologies were compared with those under traditional management. Factors such as crop yield, volume of irrigation water used, and water productivity were measured and analyzed using paired t-tests. Additionally, the carbon footprint of the selected farms was assessed. An economic analysis was conducted, considering all costs and revenues generated on the farms and orchards. Land preparation for planting cotton and corn in experimental treatments was done using a compound tiller. Cotton was planted with Bakhtegan variety seeds at a rate of 25 kg/ha and corn with 704 variety seeds at a rate of 25 kg/ha with pneumatic row tiller. Cotton weeds were controlled chemically (trifluralin herbicide, 2.5 liters/ha) and mechanically with a hoe cultivator in the sixth and eighth weeks after planting. In the case of corn, weeding was done with Tufordi herbicide at a rate of 1.5 liters/ha at the 5-7 leaf stage of corn and using a hoe cultivator 25 days after corn emergence. Cotton was harvested by workers, grain corn by a combine and forage corn with a chopper. A rotary plow (at least with two discs and rollers) was used for the control treatment, Non-delinted cotton seeds (hairy seeds) were sown at a rate of 250 kg/ha with a centrifugal seeder. By modifying the land preparation operations with a compound tiller and sowing with a pneumatic row-cutter, 25 kg/ha less seed was used in addition to reducing the traffic of tractors and agricultural machinery.
Results:
The results indicated that the yield levels in the treated farms increased between 7% and 55%. The the lowest and highest increases observed in forage corn and cotton fields, respectively. Irrigation water decreased by 20% to 31% in apple orchards and grain corn fields, respectively. Consequently, the water productivity improved by 43% to 113% in forage corn and cotton farms. Statistically, the differences in yield, irrigation water, and water productivity between the control and treated farms were significant at the 1% level. The effectiveness of the employed technologies led to a reduction in carbon footprint by 12% to 26%, particularly in pistachio orchards and cotton fields. Economic analyses revealed that under current conditions and without considering the true value of water, the implementation of water-saving technologies increased economic profit by 14% to 70%, specifically for forage corn and pomegranate orchards. However, when accounting for the true value of water, although the percentage of economic profit increased, the actual profit decreased compared to the scenario that did not consider the true value of water. This resulted in negative economic profit for pomegranate orchards under conventional farmer management (control). Thus, while pomegranate orchards may provide significant profits for local farmers, they are not economically viable in terms of water usage. This highlights the importance of considering water economics in agricultural practices.
Concussion:
Although technologies such as drip irrigation and deficit irrigation improve crop water productivity, a balance must be struck between expanding these systems, increasing the area under cultivation by farmers, and ensuring water availability for natural ecosystems. Limited access to advanced water-saving technologies limits efforts to protect wetlands and lakes. More research is also needed on how to divert excess irrigation water to help adjacent wetlands. Few studies have been conducted to assess the long-term water-saving effects of modern irrigation systems on aquatic ecosystems. Future research on water governance frameworks that address both irrigation efficiency and ecosystem sustainability is critical. Policies that encourage farmers to adopt water-saving technologies while preserving natural wetlands are essential. Water-saving irrigation technologies are a promising approach to balancing agricultural productivity and the conservation of natural lakes and wetlands. However, addressing existing challenges through integrated frameworks, long-term monitoring, and policy reforms can help achieve sustainable water resource management while protecting critical ecosystems.

Abstract Introduction:
Coasts, as sensitive ecosystems and diverse habitats, require protection. Human activities and climate change can exacerbate erosion and degradation of these ecosystems. Understanding water flow patterns and sediment transport is crucial for developing effective solutions for coastal management and reducing of hazards from storms and sea-level rise. Coasts, as the interface between land and sea, are influenced by water flows, sedimentation processes, and erosion. Fluid dynamics theories, such as the Navier-Stokes equations, describe the behavior of flows and their impact on sediment distribution. Sediment transport models, such as equilibrium sediment models, also aid in analyzing sedimentation and erosion mechanisms. Environmental and climatic impacts, especially through climate change models, add new dimensions to this topic.
Methods:

Coastal communities rely on gray infrastructure such as breakwaters and seawalls to reduce flood risk. These structures absorb and deflect wave energy, but they can impact the morphology of downstream currents. Breakwaters are located on sandy beaches and trap sediment on their landward side, but they can increase erosion on downstream beaches. Offshore breakwaters are located in deeper water and reduce sand flow, but they can intensify wave action in unprotected areas. Seawalls are used to protect coastlines; however, they can increase erosion and expose inland areas to flood risk. Wave control structures cannot sustainably manage flood risk, and require high maintenance costs. These structures fragment and destroy natural habitats and have limited ecological function. Moreover, they cannot adapt to climate change and rising sea levels. Using vegetation to increase coastal resilience and reduce the impact of floods is a promising approach. However, little information exists regarding the longevity of vegetation for flood risk management, so further research is needed. Coastal vegetation is recognized as an effective defense against natural and human disturbances. These plants support diverse ecosystems and provide habitats for various species. Mangrove trees, with their complex root systems, create shelters for mammals, birds, and reptiles. Salt marshes are also productive ecosystems that support unique plant and animal species. Seagrasses provide important habitats for marine life and contribute to the life cycle of aquatic organisms. Coastal vegetation plays a significant role in mitigating the effects of climate change and accounts for 14% of the carbon dioxide absorbed by oceans. Seagrass beds comprise 10 to 18 percent of the total ocean carbon storage. These ecosystems help stabilize the coastline and prevent erosion by retaining sediments. White mangroves in Iran enhance soil stability and prevent coastal erosion. Overall, coastal vegetation is effective on reducing flood risks and provides environmental and climatic benefits.
Results:
This research evaluated the role of vegetated coastal habitats in flood risk management, focusing on their mechanisms, benefits, and challenges. Coastal areas, home to more than one-third of the world's population, face growing flood risks due to climate change, including sea-level rise and increased storm intensity. While traditional solutions such as breakwaters and seawalls are effective at a local level in reducing coastal flood risk, they pose significant long-term environmental problems, including down-drift erosion and increased vulnerability to flooding. In contrast, vegetated areas such as mangroves, salt marshes, and seagrass beds offer opportunities as sustainable alternatives for flood risk reduction, functioning through wave attenuation, sediment stabilization, and storm surge reduction. Furthermore, these solutions provide multiple benefits, such as promoting biodiversity, improving water quality and facilitating carbon sequestration. However, implementing vegetation on a larger scale faces various challenges, including: ecological and environmental limitations related to the response, behavior, and dynamics of coastal ecosystems; socio-economic and policy limitations; and a lack of empirical evidence regarding their effectiveness and sustainability within the timeframes required for coastal management. Moreover, evaluating and measuring the long-term effectiveness of these solutions in flood and inundation risk management remains challenging due to insufficient empirical data and the complexities of coastal systems.
Conclusion:
This review examined studies on coastal protection, focusing on flow patterns, sediment transport, and coastal flood control through vegetation such as mangroves, seagrasses, and salt marshes. The interaction of vegetation with waves’ dynamics, challenges, uncertainties, and data scarcity for vegetation-based coastal flood protection were also discussed. The results of this review could contribute to the developing sustainable and effective solutions for coastal management and protection.

Abstract Introduction:
In recent decades, population growth, urbanization, and climate change have increased pressure on water resources, making drought a major crisis in cities like Tehran. Tehran’s semi-arid climate and geography lead to frequent droughts that reduce the quality of life and threaten sustainable development. Hydrological and meteorological indices, especially the Standardized Precipitation Index (SPI), based on recorded precipitation remain the standard for estimating drought over various timescales, enabling short and long term forecasts. Although short statistical periods limit analyses, they are standard in remote sensing and do not compromise accuracy. Reliable drought assessment requires high quality ground data; scarcity or errors can skew drought timing, severity, and impact estimates. This study validates Google Earth Engine satellite data against ground SPI measurements (r = 0.29) and applies pixel-level analysis to retain spatial detail. Building on composite indicator findings from urban contexts, the current study has addressed research gaps in Tehran by deriving drought indices via remote sensing. These cost effective, repeatable, and scalable methods could overcome meteorological data limitations and link meteorological drought to vegetation health indicators.
Methods:
This study evaluates drought indicators in Tehran by integrating remote sensing and meteorological data from January 2000 to December 2022, covering a 23-year period to approach the recommended 30-year climatological baseline. The meteorological data includes precipitation from local stations and NASA''s GPM product, as well as soil moisture data from the Global Land Data Assimilation System (GLDAS) and local monitoring networks. The Standardized Precipitation Index (SPI) was calculated using rainfall data at six temporal scales (1, 3, 6, 9, 12, and 24 months) to quantify meteorological drought and serve as a reference for evaluating remote sensing indicators. Satellite-derived variables were accessed via Google Earth Engine, including the Normalized Difference Vegetation Index (NDVI) and land surface temperature (LST), both of which were corrected for atmospheric and geometric distortions. Monthly NDVI composites were created to align with meteorological data, facilitating the analysis of vegetation dynamics and temperature variations in Tehran. The datasets were co-registered to a common 1 km grid for pixel-level analysis, allowing for a direct comparison between SPI and remote sensing indices. This comprehensive framework enhances our understanding of urban drought monitoring by evaluating the strengths and weaknesses of both meteorological and remote sensing methods. The findings offer beneficial perspectives on urban planning and environmental management, assisting stakeholders in making informed decisions about drought response and resource management in Tehran.
Results:






نسخه پیش نویس





The analysis of composite drought indices across various timescales (monthly, seasonal, and annual) ed significant sensitivities and patterns in response to climate variability. Monthly fluctuations in these indices highlighted their responsiveness to short-term changes, with the Vegetation Health Index (VHI) ranging from 47% in 2022 to 65% in 2020. Such variations may indicated vegetation stress stemming from rising temperatures, alterations in irrigation, or changes in water management practices. Similarly, the Standardized Drought Condition Index (SDCI) exhibited sharp shifts between 20% and 70%, reflecting rapid transitions between wet and dry periods, a trend also observed in other composite indicators. At the seasonal level, distinct cycles were apparent. The Optimized Vegetation Drought Index (OVDI), which aligns with plant growth patterns, peaked in spring and summer while declining in autumn and winter. The SDCI also displayed seasonal patterns but with greater year-to-year variability, suggesting that meteorological factors can diverge from vegetation responses. This divergence underscores the influence of sudden weather changes, such as unexpected droughts or heavy rainfall, on how vegetation adapttions. Understanding these dynamics is crucial for developing effective agricultural strategies and managing water resources in the context of climate change. On an annual scale, long-term trends came into focus. From 2000 to 2012, the SDCI showed a slight downward trend, indicating a prolonged drought, before gradually improving. In contrast, the OVDI has been steadily increasing since 2012, suggesting vegetation recovery and improved hydrological conditions. Comparing these indices highlights the complex nature of drought, revealing instances where vegetation-focused metrics diverge from those based on meteorological data.
Conclusion:
The temporal trend of droughts periodic patterns, with the years 2000–2002 classified mainly as the moderate drought category, while 2003–2006 showed a relative improvement and a trend towards mild or no drought conditions. The return to moderate to severe droughts in 2007–2010, followed by a gradual improvement from 2011 to 2020 (with exceptions such as 2013 and 2015, which experienced moderate droughts), emphasizes the need for continuous monitoring. On a monthly and seasonal scale, the months of February, July, and November, and the summer season, showed the highest drought intensity, while April and October, and the winter season, were more favorable. Mann-Kendall trend analysis revealed that SDCI showed significant decreasing trends at seasonal (P=0.049) and annual (P=0.018) scales, indicating drought intensification. Conversely, vegetation indices (VCI, VHI, NDVI) exhibited significant increasing trends, suggesting vegetation recovery despite meteorological drought conditions.Correlation analysis also highlighted the pivotal role of composite indices. These indices not only had strong correlations with independent factors (such as precipitation and vegetation), but also provided the ability to accurately reflect changes at different time scales. Precipitation indices such as SPI and PCI, with their perfect correlation, are ideal tools for assessing droughts caused by rainfall deficiency, while the role of temperature (exacerbation) and vegetation (modification) emphasizes the importance of a multidimensional approach.

Abstract Introduction:
Estahban, a county in Fars Province, Iran, known for its extensive orchards primarily devoted to rain-fed fig cultivation. In recent years, decrease in rainfall has resulted in inadequate water availability for these orchards, prompting many farmers to resort to intensive irrigation practices. Previous research has indicated that the impact of water stress on fig trees is a significant topic that requires further research. Given the importance of determining the water needs of fig trees and the economic viability of fig production in the Estahban region, this study aimed to investigate the effects of varying irrigation water volumes on these trees. The analysis focused on the quantity, quality, and economic aspects of the produced yield. Ultimately, suitable strategies were proposed to protect the trees from the risk of drying out and to ensure economically viable production.
Methods:
This study was executed using a randomized complete block design in four replications and five treatments, applied to Sabz variety of fig trees. The experiments were conducted at the Estahban Fig Research Station, over a two-year period. The irrigation treatments were set at 0%, 25%, 50%, 75%, and 100% of the estimated water requirements, calculated using the Penman-Monteith method. Measurements were taken for both quantitative and qualitative characteristics of the figs, and water productivity was assessed, alongside an economic evaluation of the different irrigation levels. This economic analysis was conducted under two scenarios: one that considered the actual value of water and one that did not. Statistical data analysis was carried out using SAS 9.13 software, with mean comparisons among the various treatments performed via Duncan's test. Considering that the amount of rainfall in the first and second years differed significantly (448 and 73 millimeters), the volume of water applied in these two years also showed a notable disparity. In fact, the first year was characterized as a wet year, while the second year was classified as a dry year. Consequently, it is evident that the irrigation water levels in the two experimental years had a significant difference.
Results:
The findings indicated that increasing the irrigation rate, while remaining within the plant's water requirement range, led to enhancements in the vegetative, physiological, and both quantitative and qualitative characteristics of the figs. The optimal condition was observed in the non-stress treatment (100% water requirement), which necessitated 5.8 cubic meters of water per tree. A comparison of the average quantitative and qualitative traits of fig fruit revealed that an increase in irrigation levels led to a significant rise in the diameter of fresh fruit, the percentage of early fruits, the number of pollinated inflorescences, yield, and the weight of individual fig fruits. Consequently, treatment 5 (100% water requirement) was identified as the most effective treatment. Furthermore, the various irrigation levels did not have a significant impact on the traits of mid-season fruit percentage, the number of unripe and unpollinated fruits. The crop yields for the no-irrigation and full irrigation treatments were recorded at 3119 and 7671 grams per tree, respectively. In the first year, the water productivity for the second treatment was 1.32 kilograms per cubic meter, significantly higher than that of the other treatments. However, in the second year and over the two-year average, the control treatment without irrigation exhibited the highest water productivity values at 4.01 and 2.52 kilograms per cubic meter, respectively. This indicates that with increased irrigation water, the water productivity decreased. Furthermore, the economic evaluation results under standard conditions, which did not account for the actual value of water, revealed that the more irrigated treatments yielded greater net benefits compared to the other treatments, with no significant difference in the benefit-cost ratio (ranging from 2.49 to 2.31). Nevertheless, economic analyses that accounted for the actual value of water revealed that the more irrigated treatments lacked economic priority, with a significant difference in the benefit-cost ratio among the treatments ranging from 2.46 to 1.20. The most economically advantageous treatment was identified as the rain-fed treatment.
Conclusion:
This research indicated that the actual value of water is a crucial factor in the economic evaluation of irrigation practices in rain-fed fig orchards, significantly influencing the outcomes achieved. Given that farmers typically do not incur the true cost of water, irrigation appears to be economically advantageous for them; however, it is not deemed cost-effective when considering the limited water resources at the national macro level.

Abstract Introduction:
Riverbank and canal erosion significantly disrupt the morphological and ecological equilibrium of river systems, posing serious threats to aquatic habitats, agricultural lands, infrastructure, and human settlements in riparian zones. This degradation not only contributes to the loss and reduction of adjacent land areas but also diminishes water quality by increasing sediment load and turbidity. Among various hydraulic countermeasures, breakwaters have proven to be one of the most effective and practical solutions for controlling and mitigating erosion along riverbanks and canal shores. These structures are primarily employed to deflect and redirect the flow of water away from vulnerable banks towards the center of the channel, thereby reducing the shear stress acting on the banks and preventing further erosion. The widespread use of breakwaters in river engineering is largely attributed to their cost-effectiveness, ease of installation, and adaptability to various environmental conditions. Breakwaters are classified according to several criteria. Based on construction material, they may be composed of wood, concrete, stone, or composite materials. In terms of permeability, breakwaters are categorized as permeable (which allow partial flow through the structure, promoting energy dissipation and sediment deposition) and impermeable (which fully obstruct the flow and divert it more sharply). With respect to submergence, they can be either submerged or non-submerged, influencing how they interact with surface flows. Functionally, breakwaters are designed to serve distinct roles: energy-absorbing (to reduce flow momentum), energy-dissipating (to break turbulence and eddies), or water-diverting (to change the direction of the main current). While impermeable breakwaters create strong deflection zones, permeable ones reduce the velocity of flow gradually, thus offering a more natural transition and enhanced sediment stabilization. Understanding these classifications and their hydraulic impacts is crucial for selecting appropriate breakwater configurations in river restoration and erosion control projects.
Methods:
To analyze the hydraulic behavior of flow and turbulence structures around spur dikes, a comprehensive series of controlled laboratory experiments was conducted. The accuracy and reliability of the results were ensured by an optimized experimental design, precise and calibrated measurement instruments, and well-defined geometric configurations of the experimental setup. All experiments were performed in a glass flume, located at the Hydraulic Laboratory of Isfahan University of Technology, which was a specialized experimental channel with a length of 15 meters, a width of 0.9 meters, and a height of 0.6 meters. The flume was equipped with a high-precision feeding pump, a digital flowmeter to accurately measure discharge, and an energy dissipator installed at the inlet to stabilize flow. Water was supplied continuously from two interconnected reservoirs to ensure steady flow conditions throughout the experiments. Water depth measurements were conducted using a rail depth gauge with an accuracy of ±1 mm. A tailgate located at the downstream end of the flume allowed precise control of flow depth and submergence conditions. Flow visualization techniques were employed using a dye injection system with potassium permanganate, enabling clear identification of recirculation zones and stagnation points within the flow field. The flow entered the flume through a calming tank and a stilling basin, ensuring fully developed flow profiles over an approach length of 10 meters before reaching the spur dikes. Two types of spur dikes were examined: impermeable structures made of stone and permeable structures constructed from gabions. The impermeable dikes had widths of 20, 30, and 50 cm, whereas the permeable dikes maintained a constant width of 30 cm with a porosity of approximately 41%. The first spur dike was positioned 7.5 meters from the inlet. Various submergence levels, including non-submerged, semi-submerged, and fully submerged conditions, were tested, defined by the submergence ratio Sr = h/H. In total, 39 tests were conducted under a wide range of flow rates and structural configurations. The detailed results and analyses are provided in the following sections.
Results:
This section presents the analysis of results obtained from 39 experimental tests, focusing on the characterization of recirculation zones downstream of permeable and impermeable spur dikes. The influence of hydraulic and structural parameters such as discharge rate, spur dikes width, submergence ratio, and porosity on the length of the recirculation zone was systematically evaluated. For impermeable spur dikes, tests were conducted with widths of 20, 30, and 50 cm under three flow discharges of 29, 49, and 65 L/s. Results showed that for narrower spur dikes, increasing submergence led to a shorter recirculation zone. At a width of 30 cm and a discharge of 29 L/s, increasing submergence ratio from 0.37 to 0.47 reduced the recirculation zone length from 105 cm to 90 cm. In contrast, wider spur dikes (50 cm) exhibited longer recirculation zones at higher discharges, reaching up to 205 cm at 65 L/s, likely due to greater flow deflection and enhanced vortex stability. In tests with permeable spur dikes (41% porosity, 30 cm width), the recirculation zones were consistently longer, reaching 208 cm at 65 L/s. This was attributed to smoother internal flow through the structure, leading to momentum diffusion and broader recirculation. To study the effect of spur dike spacing, a second dike was positioned at varying distances relative to the first. When placed precisely at the end of the first recirculation zone (160 cm), the second zone extended to 118 cm. However, placing the second spur dike at upstream (120 cm) or downstream (199 cm) reduced the length to 100 cm and 80 cm, respectively. These findings highlighted the importance of optimal spur dike spacing for maximizing flow control efficiency. In summary, spur dike width, porosity, and placement significantly affected flow structures. Wider and permeable spur dikes were more effective in forming extended recirculation zones, while optimal spacing between multiple spur dikes enhanced their combined performance.
Conclusion:
Based on the findings of this study, the hydraulic behavior of the stagnant zone formed downstream of scour protections was thoroughly investigated through a series of physical experiments under varying conditions, including flow discharge, spur dike width, porosity, and submergence levels. The results demonstrated that the spur dike width and flow discharge had a significant impact on the length of the stagnant zone. Increasing the spur dike width and discharge led to a noticeable extension of the stagnant zone, as these factors enhance the energy redistribution and recirculation of flow. In contrast, higher submergence ratios, especially in cases of deep submergence, reduced the stagnant zone length due to the diminished influence of the spur dike structure on the flow. Moreover, permeable spur dikes were more effective in forming a larger stagnant zone than impermeable ones, aligning with previous studies. Additionally, the positioning of a second spur dike had a notable effect, with its placement at the end of the stagnant zone providing the best performance in terms of reducing lateral erosion. Overall, the optimal design of spur dike configurations requires a careful balance of hydraulic and geometric factors to enhance hydraulic stability and mitigate erosion in waterway structures.

Abstract Introduction:
Water scarcity and drought are among the most common agricultural problems in Iran. Therefore, finding solutions to enhance the resistance of agricultural crops such as button mushrooms resistant to drought stress is of particular importance. Increasing soil water retention and irrigation management are vital to preventing water scarcity and physiological stress in agricultural crops. Therefor the amount of water available to plants and its measurement has been of interest to farmers and researchers. One of the solutions considered in recent years for optimal management of soil water status is the addition of organic amendments to the soil, including biochar. Biochar can change the physical properties, improving access to water, air, and nutrients for the plant, and as a result, affect the growth and yield of agricultural crops. Therefore, irrigation of casing soil under button mushroom cultivation should also be managed according to these changes to prevent inefficient irrigation.
Methods:
This study was conducted in a completely randomized factorial design with three factors: type of casing soil at four levels, amount of biochar at four levels, and size of biochar particles at two levels. The experiments had three replications. The control treatment consisted of casing soil used in the factory with a combination of North peat, South peat, and spent mushroom compost (SMC) in equal weight ratios. The experiments involved a total number of 29 treatments across 87 experimental plots at the Negin Fasl compost and mushroom production factory, located in Shahrekord city, Iran, in 2023. In this regard, the initial casing soil compositions including North peat, peat vermicompost, cow manure vermicompost, and mushroom compost vermicompost were prepared. To prepare different treatments, biochar derived from pruning waste of plum and pomegranate trees, with particle sizes of 0–1 mm and 1–2 mm, was added at 5%, 10%, and 15% by weight to the aforementioned casing soil compositions with a 20-day incubation period. Then, 15 days after the compost loading operation in the button of mushroom cultivation hall, when 70% of the compost bed was covered with mushroom mycelium, the casing stage began. For each square meter of the cultivation bed, 32 kg of casing soil was added as described in the experimental treatments in the form of caking. After the casing stage, sampling the casing soil was carried out from each experimental plot using a metal cylinder with a diameter and height of 4.5 and 5 cm, respectively. Finally, the soil moisture characteristic curve obtained by measuring moisture at suctions of 0, 10, 20, 50, 60, 80, and 100 hectopascals. The indices of air volume percentage after irrigation (AIR), available water (EAW), water buffering capacity (WBC), water holding capacity (WHC), and their integral energy were calculated. Then, the obtained data were analyzed using SPSS software.
Results:

The results showed that the application of biochar led to a decrease in AIR in the studied soils which could be due to the high frequency of fine pores that were affected after irrigation. The highest volumetric percentage of air after irrigation was observed in the S₀ treatment (0.17) and the lowest in the S₄l₂z₁ treatment (0.02), which had no significant difference with the S₃l₃z₂ treatment (0.02). The application of biochar in different soils except for the S₁ treatment did not cause any changes in the EAW value compared to the commercial casing soil and the EAW value of all treatments was at the optimal level. The application of biochar to the casing soil resulted in an increase in the WBC value of water and this increase led to enhance in water retention in the casing soil. However, WHC value in the S₁l_o, S₂l_o, S₃l_o and S₄l_o treatments decreased by 34, 29, 5 and 19 percent compared with the S₀ treatment, respectively. The results showed that the variation of EI_AIR among different casing soils and also commercial casing soil was small; also in all four studied soil types EI_AIR increased after irrigation with increasing biochar application. Soil water availability for plants was almost constant in the moisture range of 10 to 50 hPa. The application of biochar to casing soil increased this energy requirement but this increase was not significant. Also, the amount of energy required for water absorption in the moisture range between 50 and 100 hPa was almost the same among different casing soils and also commercial casing soil. There was no significant difference between the energy requirements of these soils, but the application of biochar -except for soil S₁- led to an increase in EI_WBC, although this increase was not significant.
Conclusion:
Overall, the results showed that adding biochar to casing soil did not cause any problems in terms of soil aeration and kept the amount of accessible soil water at an optimal level. However despite the increase in the amount of water buffering capacity (WBC) and water holding capacity (WHC) in the soil, the amount of integral energy (EI) increased due to the increase in the specific surface area of the soil, making water extraction more difficult. Therefore, it seems that using biochar as a percentage replacement for casing soil does not cause a significant change in soil water availability compared to commercial and conventional casing soil.