Original Article
Hydraulic
Reza Farzanpour; Salah Kouchakzadeh; Shabnam Moghispour
Abstract
Extended AbstractIntroductionHistorically, the determination of Manning's roughness coefficient, n, has relied on two approaches: (1) field measurements, and (2) laboratory experiments in flumes where quasi-uniform flow is artificially established. While field data are most realistic, they suffer from ...
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Extended AbstractIntroductionHistorically, the determination of Manning's roughness coefficient, n, has relied on two approaches: (1) field measurements, and (2) laboratory experiments in flumes where quasi-uniform flow is artificially established. While field data are most realistic, they suffer from uncontrolled variables and high costs. Laboratory studies offer controlled conditions but face a fundamental challenge: establishing truly uniform flow in a flume requires a long channel length, precise slope adjustment, and a downstream control that balances friction losses—a condition that is rarely achieved in practiceStudies by Tracy and Lester (1961) and Kazemipour and Apelt (1979, 1982, 1999) demonstrated that even in relatively long flumes, achieving true uniform flow is difficult and time-consuming. Moreover, in natural rivers, uniform flow is the exception rather than the rule; gradually varied flow dominates due to changes in cross-section, slope, and roughness along the channel.This study proposes a paradigm shift: instead of forcing uniform flow in the laboratory—which introduces uncertainty and limits repeatability— the GVF was used as the basis for estimating Manning's coefficient. The M2 profile provides a well-defined water-surface profile that can be accurately measured and compared with theoretical GVF solutions. By optimizing n to minimize the discrepancy between observed and computed profiles, we obtain a robust estimate of the roughness coefficient that is both physically meaningful and practically reproducible.The primary objectives of this research were: To develop and validate a GVF-based methodology for estimating Manning's n in a laboratory flume; To investigate the effects of three different bed roughness types on n; to quantify the influence of longitudinal slope and discharge on n; to compare the experimental results with theoretical resistance laws and assess the flow regime (hydraulically smooth, transitional, or rough); to perform a sensitivity analysis regarding the choice of reference depth for roughness-height estimation.MethodologyExperimental SetupExperiments were conducted in a rectangular flume located at the Central Water Research Laboratory of the University of Tehran. The flume has a length of 12 m, a width of 0.8 m, and a depth of 0.6 m. The flume is mounted on an adjustable platform capable of setting longitudinal slopes. Water-surface profiles were measured using data-acquisition system designed for the current research. Three bed materials, 9 longitudinal slopes, and 9 discharges were tested. Experimental Procedure and Data AnalysisFor each bed roughness the desired slope was set, and the flow was established. The downstream gate was fully opened to create a free overfall, generating an M2 gradually varied profile. After steady-state conditions were reached, the water surface elevations along the flume were recorded.Manning's n was determined by solving the standard GVF equation for a prismatic channel. For each experimental profile, the value of n was optimized to find the best match between the observed and the computed profiles. The equivalent roughness height, ks, was then calculated.Results and DiscussionThe optimized Manning's n values for all 81 runs are summarized in Tables 1–3 of the main Contrary to some previous studies (e.g., Merry, 2017; Yilmaz et al., 2023), which reported a decreasing trend of n with increasing discharge, the results did not show a systematic or monotonic relationship. For most roughness–slope combinations, n remained approximately consistent across the discharge range. Small fluctuations (typically ±0.002) were observed but did not follow a consistent pattern. This suggests that within the tested range of relative submergence, the effect of discharge on bulk resistance is secondary to the geometric roughness characteristics. Similarly, slope variations produced only minor changes in n.Computed shear Reynolds numbers ( ) revealed that both bed materials of C2 and C3 operated in the fully rough turbulent regime ( ), confirming that viscous effects were negligible. In contrast, the galvanized bed (C1) fell within the transitional regime.Because the piezometers were connected to the flume floor (i.e., below the installed mesh covers), measured depths included the physical thickness of the roughness elements. To assess whether this introduced systematic bias, the reference depth was artificially reduced by 0.5 cm, 1.0 cm, and 1.5 cm, and the entire optimization was repeated. The resulting changes in ks were consistently less than 1%, and the flow regime classification remained unchanged. This demonstrates that the methodology is robust and insensitive to minor uncertainties in vertical datum selection.ConclusionsThis study validates a novel experimental approach for estimating Manning's n using gradually varied flow (M2 profiles), which offers a practical, repeatable, and lower‑uncertainty alternative to conventional uniform‑flow methods in laboratory flumes. By leveraging gradually varied flow—which prevails in natural channels—this approach bridges the gap between laboratory studies and field applications, offering a physically relevant framework for river engineering and flood modeling.Keywords: Equivalent roughness, Longitudinal slope, Manning's roughness coefficient, Open Channels, Shear Reynolds number Conflict of Interest The authors declare that they have no conflict of interest. All authors have read and approved the final manuscript. Funding The corresponding author conducted this study as an extension of the research project entitled “Experimental Investigation of the Effects of Hydraulic Crossing Structure Geometry on the Trapping of Large Woody Debris and the Aggravation of Flood Hazards,” carried out at the Soil Conservation and Watershed Management Research Institute. The present research was undertaken to develop practical measures for reducing flood risks associated with woody debris accumulation at bridges. No financial support was received from any public, commercial, or non-profit organization for conducting, writing, or publishing this study. Data Availability Statements All relevant data and results supporting the findings of this study are presented within the article. The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request. Author Contribution All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by all authors. The first draft of the manuscript was written by R.F. and all authors commented on previous versions of the manuscript (R.F., S.K., and S.M.). The final revisions have been applied by S.K. and Moreover, all authors have read and approved the final manuscript.All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts. AcknowledgementThe vice dean for research affair of the University of Tehran is Acknowledged for providing the research facility of the Central Lab for Water Research
Review paper
Irrigation network management
Nasrin Khodamoradi vatan; Hojat Ahmadi
Abstract
Extended AbstractIntroductionRiver intakes constitute critical hydraulic infrastructure for sustainable water resource management. A primary challenge in the design and operation of these structures is sediment management, as excessive sedimentation significantly impairs storage capacity and operational ...
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Extended AbstractIntroductionRiver intakes constitute critical hydraulic infrastructure for sustainable water resource management. A primary challenge in the design and operation of these structures is sediment management, as excessive sedimentation significantly impairs storage capacity and operational efficiency. The intake angle is a pivotal geometric parameter governing flow patterns and sediment transport mechanisms, exerting a substantial influence on the sedimentation process within the river–intake system. The present study provides a systematic literature review covering an 81-year period (1944–2025). We synthesized findings from 132 peer-reviewed articles sourced from reputable domestic and international scientific databases. Following a comprehensive thematic classification, the literature was analyzed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework. Conceptual synthesis of the reviewed evidence underscores that the intake angle is a fundamental design variable for effective sediment control. These findings offer practical insights for hydraulic engineers and practitioners, facilitating the optimization of intake configurations and enhancing overall water resource management strategies.Materials and MethodsThis study employs a systematic and documentary review to analyze the hydraulic and sediment-control performance of lateral intakes in open channels. Drawing upon 132 national and international publications retrieved from reputable databases between 1944 and 2025, the research synthesizes findings from both laboratory and numerical investigations. The analysis, structured under the PRISMA framework and complemented by a conceptual review approach, identifies the key hydraulic, geometric, and sedimentary parameters affecting intake efficiency. Results indicate that optimized intake angle and position, along with geometric modifications such as sloped walls, submerged vanes, and deflector structures, substantially reduce vortex formation and sediment entry. Numerical modeling using tools such as FLUENT, FLOW‑3D, and SSIIM demonstrates high agreement with experimental data, validating its use for design optimization. Moreover, hybrid and multi‑component designs integrating vanes, sills, and guide walls achieve sediment reduction rates exceeding 70%. The study concludes that sustainable and efficient water‑diversion systems require an integrated design approach balancing hydraulic performance, sediment dynamics, and site‑specific topographic conditions, supported by advanced numerical modeling and experimental validation. ResultsThe review of eleven studies published between 1944 and 2025 revealed consistent patterns in the hydraulic behavior and sediment‑control performance of lateral intakes. Analysis of laboratory and numerical investigations indicated that variations in intake angle, channel curvature, discharge ratio, and intake geometry have the most significant impact on vortex formation, flow separation, and sediment entry. Experimental results showed that reducing the intake angle generally decreases sediment intrusion, while positioning the intake along the outer bend improves flow distribution and minimizes scour depth. Numerical simulations using CFD models such as FLUENT provided strong agreement with experimental findings, confirming the critical role of geometric configuration and shear stress in controlling flow behavior. After multiple comparative evaluations, seven major parameters were identified as the dominant factors governing intake efficiency: intake angle, bend conditions, bed shear stress, relative curvature‑to‑depth ratio, geometry and dimensions of the intake, discharge ratio, and Froude number. These parameters form a unified analytical framework for optimizing intake design to achieve minimal sediment intrusion and stable hydraulic operation.ConclusionsA comprehensive review of studies conducted between 1944 and 2025 revealed that the hydraulic performance of lateral intakes in open channels is strongly governed by geometric configuration and flow conditions. The intake angle, discharge ratio, and intake position along the channel bend are among the most influential parameters controlling flow patterns, vortex formation, and sediment entry. Findings from previous research indicate that intake angles of 45°–60° effectively minimize flow separation, while positioning the intake on the outer bend (at angles of 115°–135°) enhances flow uniformity and reduces local scour. Both numerical and physical investigations confirm that the geometry of the intake and sidewalls—particularly curved or rounded-corner designs—and regulation of hydrodynamic parameters such as the Froude number play a decisive role in sediment control. The strong agreement between laboratory observations and advanced computational models further supports the reliability of numerical approaches for optimized design.Overall, achieving stable hydraulic performance in lateral intakes requires an integrated approach that simultaneously considers optimal intake geometry and position, improved hydraulic conditions, and the use of auxiliary structures. Despite significant progress in laboratory and numerical studies, research gaps remain—particularly in field-scale investigations, sediment characterization, and interaction analyses of combined structures under complex flow conditions. Future developments in three-dimensional numerical modeling and large-scale field experiments could substantially enhance understanding of these interactions and lead to more sustainable strategies for sediment management and intake efficiency. Conflict of InterestThe authors declare that they have no conflict of interest regarding the preparation and publication of the materials and findings presented in this study. FundingThe authors received no financial support for the research, authorship, or publication of this article. Data Availability Statements The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request. Authors’ ContributionsAll authors contributed equally to the conceptualization of the study, preparation of the original draft, and subsequent revisionsAcknowledgementThe authors wish to express their sincere gratitude to the Editor and the two anonymous reviewers for their insightful comments and constructive feedback, which significantly improved the quality of this manuscript. We also thank the Regional Water Company of Qazvin for providing the necessary data for this research.
Original Article
Irrigation network management
Zeynab Rahimi Atani; Mohammad Bijankhan; Hadi Ramezani Etedali; Hamed Mazandaranizadeh; Sara Fakuri; Sakineh Kohi; Mina Gholizadeh
Abstract
Extended AbstractIntroductionGroundwater resources play a vital role in sustaining agricultural activities in arid and semi-arid regions. In Iran, over 75% of irrigation water is supplied from aquifers (Yazdanpanah et al., 2019), making groundwater the primary source of agricultural production. However, ...
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Extended AbstractIntroductionGroundwater resources play a vital role in sustaining agricultural activities in arid and semi-arid regions. In Iran, over 75% of irrigation water is supplied from aquifers (Yazdanpanah et al., 2019), making groundwater the primary source of agricultural production. However, continuous groundwater level decline due to overexploitation, reduced natural recharge, and climate change has made accurate monitoring of groundwater abstraction an essential requirement forsustainable water resource management. Direct measurement of well discharge faces numerous challenges, including high equipment costs, operational difficulties, spatial distribution of wells, and the presence of unauthorized wells. While smart water meters have been introduced as a solution for abstraction control, their widespread implementation is constrained by high installation and maintenance costs. In contrast, most agricultural wells are already equipped with electricity meters that continuously record power consumption data, presenting a cost-effective alternative for indirect discharge estimation (Wang et al., 2020; Alam et al., 2023). This study investigates the feasibility of estimating agricultural well discharge using electricity meter data and physical well characteristics through an Artificial Neural Network (ANN). The novelty of this research lies in developing a cost-effective approach that eliminates the need for expensive flow measurement equipment, relying solely on accessible electricity consumption data.MethodologyStudy Area and Data CollectionThe research was conducted in Qazvin Province, central Iran, characterized by diverse climatic conditions and intensive agricultural activities. Field data were collected from 70 agricultural wells, including geographical coordinates, well depth, pipe diameter, electricity consumption parameters, and measured discharge values. Due to incomplete power records, 35 wells with reliable data were selected for modeling. Discharge measurements obtained using an ultrasonic flowmeter served as reference data.Artificial Neural Network ModelingA multilayer perceptron (MLP) neural network was implemented in the MATLAB environment using the Levenberg–Marquardt training algorithm. Eight scenarios were defined to evaluate the sensitivity of model performance to various combinations of input parameters, including power consumption, well depth, pipe diameter, geographical coordinates, and aeration condition. The dataset was randomly divided into training (70%), validation (15%), and testing (15%) subsets. Model performance was evaluated using the coefficient of determination (R²), Mean Squared Error (MSE), and Mean Absolute Percentage Error (MAPE). Different numbers of neurons (5 to 10) were tested to identify the optimal network architecture. Results and DiscussionModel Performance and Scenario SelectionThe ANN successfully estimated agricultural well discharge using electricity meter data and well characteristics. Among the evaluated scenarios, Scenario 7 comprising power consumption, well depth, pipe diameter, and geographical coordinates—demonstrated the most stable and reliable performance across training, validation, and testing stages. Although Scenario 8, which included aeration condition, produced slightly lower error during training, it required operational parameters difficult to obtain in practice. Consequently, Scenario 7 was selected as the optimal model. The optimal ANN architecture consisted of one hidden layer with 10 neurons, achieving the highest coefficient of determination (R²=0/9204) and lowest prediction error (MAPE=13/96%). The model achieved average errors of approximately 15%, 13%, and 14% during training, validation, and testing phases, respectively.Analysis of Input VariablesPower consumption was identified as the most influential variable, consistent with the hydraulic power equation (P = ρ·g·Q·H/η), which establishes a direct physical relationship between power and discharge. Well depth affects pumping head (H), while pipe diameter influences friction losses. Geographical coordinates were incorporated into the model to account for spatial heterogeneity in hydrogeological conditions across the study area, as variations in aquifer thickness, sediment texture, hydraulic conductivity, and water table depth are not uniformly distributed throughout the Qazvin Plain.Comparison with Previous StudiesThe results align with findings by Alam et al. (2023), who achieved R²≈0/92 in alluvial aquifers, and Wang et al. (2020), who reported errors below 20% for energy-to-water conversion. The model performance (R²=0/9204) is comparable to Salimi et al. (2023), who obtained R²=0/825 using Random Forest, and Salamat et al. (2023), who achieved 0/945 accuracy using SVM-PSO. Although the dataset (35 wells) is limited compared to previous studies (e.g., 236–359 samples), the model demonstrates competitive performance, confirming the feasibility of the proposed approach.Limitations and Sources of ErrorThe main limitations include: (1) limited sample size (35 wells), increasing the risk of overfitting, mitigated by early stopping and simple network architecture; (2) lack of comparison with other machine learning algorithms (e.g., Random Forest, SVM, XGBoost); (3) absence of hydrogeological variables such as water table level, dynamic head, and pump specifications; (4) limited temporal sampling (August–November 2023), not capturing seasonal variations; and (5) regional specificity, requiring local calibration for application in other areas. Key sources of error include pump efficiency variations, groundwater level fluctuations, voltage instability, aeration, and differences in maintenance conditions.ConclusionsThis study demonstrates that combining electricity meter data with artificial neural networks provides a practical, cost-effective approach for estimating agricultural well discharge. The proposed method eliminates the need for expensive smart water meters while maintaining acceptable accuracy (R²=0/9204, MAPE=13/96%). Power consumption, well depth, pipe diameter, and geographical location were identified as key predictors. The approach can support groundwater monitoring programs, improve water resource management, and assist policymakers in implementing sustainable abstraction strategies. Future research should expand the dataset, incorporate temporal variations, compare multiple algorithms (Random Forest, SVM, XGBoost), and include hydrogeological variables (water table, dynamic head, pump characteristics) to enhance model accuracy and generalizability.Conflict of InterestThe authors declare that they have no conflict of interest regarding the preparation and publication of the materials and findings presented in this study.FundingThe authors received no financial support for the research, authorship, or publication of this article.Data Availability StatementThe datasets generated and analyzed during this study are not publicly available due to applicable restrictions, but are available from the corresponding author upon reasonable request.Author ContributionsConceptualization: Z. Rahimi Atani, M. Bijankhan, H. Ramazani; Methodology: Z. Rahimi Atani, H. Mazandaranizadeh; Software: Z. Rahimi Atani, H. Mazandaranizadeh; Validation: M. Bijankhan, H. Ramazani; Formal analysis: Z. Rahimi Atani, M. Bijankhan; Investigation: Z. Rahimi Atani, M. Gholizadeh, S. Koohi, Fakouri; Resources: Z. Rahimi Atani; Data curation: M. Bijankhan, H. Ramazani, M. Gholizadeh, S. Koohi, Fakouri; Writing—original draft: Z. Rahimi Atani; Writing—review and editing: M. Bijankhan; Visualization: Z. Rahimi Atani; Supervision: M. Bijankhan, H. Ramazani; Project administration: M. Bijankhan. All authors have read and agreed to the published version of the manuscript.AcknowledgementThe authors would like to express their sincere gratitude to the Qazvin Regional Water Company for providing access to well data and facilitating field measurements. This research was supported by the Imam Khomeini International University (IKIU), Qazvin, Iran. The authors also acknowledge the cooperation of local farmers and agricultural well owners who participated in this study. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Original Article
River engineering
Seyed Zanyar Nikkhah; Javad Ahadiyan; Seyed Mahmood Kashefipour; Seyed Mohsen Sajjadi
Abstract
Extended AbstractIntroductionLateral intakes are widely used for diverting water from rivers to irrigation, municipal, and industrial systems. However, the complex flow pattern that develops near the intake entrance may reduce diversion efficiency and alter the hydraulic characteristics of the approaching ...
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Extended AbstractIntroductionLateral intakes are widely used for diverting water from rivers to irrigation, municipal, and industrial systems. However, the complex flow pattern that develops near the intake entrance may reduce diversion efficiency and alter the hydraulic characteristics of the approaching flow. Among the structural measures proposed to improve intake performance, splitter walls installed parallel to the main flow have attracted attention because they can modify the flow pattern with limited changes to the channel geometry. Although previous studies have investigated various approaches to improve the hydraulic performance of lateral intakes, the effect of the splitter wall-to-intake distance has received limited attention. Therefore, this study experimentally evaluates the effect of two splitter wall-to-intake distances (L = 0 and 1 m) on upstream and downstream flow depths, flow velocity at three locations along the wall, and diverted discharge under different approach discharges and downstream gate-opening conditions. MethodologyExperiments were conducted in the Hydraulics Laboratory of Shahid Chamran University of Ahvaz using a physical model of a main channel with a lateral intake oriented at 79° relative to the main-channel flow direction. Four approach discharges (40, 50, 60, and 70 L/s) and three downstream gate-opening conditions (closed, one gate opened, and two gates opened) were examined. A splitter wall installed parallel to the main flow was tested at two splitter wall-to-intake distances (L = 0 and 1 m), together with a reference case without the wall. Flow depths upstream and downstream of the splitter wall were measured, while flow velocity was recorded at three locations along the wall (upstream end, midpoint, and downstream end) using an electromagnetic current meter (ACM3-RS). The diverted discharge into the lateral intake was determined using a rectangular sharp-crested weir installed at the intake outlet. Percentage changes in flow depth and diverted discharge were calculated relative to the corresponding reference case without the splitter wall. Results and DiscussionInstalling the splitter wall altered the hydraulic characteristics of the approaching flow compared with the corresponding reference case without the wall. In almost all experimental conditions, the upstream flow depth decreased, mainly because of local flow acceleration near the upstream end of the splitter wall. The greatest reduction in upstream flow depth, 5.69% relative to the corresponding reference case, occurred at an approach discharge of 40 L/s, with one gate opened and the splitter wall installed at L = 1 m. In contrast, the downstream flow depth generally increased after the splitter wall, reflecting a redistribution of the flow profile along the main channel. This increase was more pronounced for L = 0 m. The maximum downstream flow-depth increase, 40.3% relative to the corresponding reference case, occurred at an approach discharge of 70 L/s, with one gate opened and the splitter wall installed at L = 0 m. Flow velocity measurements at the upstream end, midpoint, and downstream end of the splitter wall showed a clear longitudinal variation along the wall. The highest velocity was recorded at the upstream end, whereas the lowest velocity occurred at the midpoint. At an approach discharge of 40 L/s, the reduction in velocity between the measurement locations ranged from 3.1% to 26.5%, depending on the splitter wall-to-intake distance and gate-opening condition. The velocity increased again toward the downstream end of the wall, consistent with the observed increase in flow depth downstream of the wall.The splitter wall also improved the diversion performance of the lateral intake. Compared with the corresponding reference case without the wall, the diverted discharge increased for both splitter wall-to-intake distances under the tested gate-opening conditions. The L = 0 m configuration generally produced higher diverted discharges than the L = 1 m configuration. The maximum increase in diverted discharge, 14.97% relative to the corresponding reference case, was observed at an approach discharge of 70 L/s, with the splitter wall installed at L = 0 m and two downstream gates opened under free-flow conditions. Overall, the results show that the splitter wall-to-intake distance affects the hydraulic characteristics of the main-channel flow and the amount of water diverted into the lateral intake. ConclusionsThe experimental results showed that installing a splitter wall modified the flow-depth and velocity distributions along the main channel and increased the diverted discharge compared with the corresponding reference cases without the wall. The L = 0 m configuration generally provided greater diversion improvement than L = 1 m. The maximum increase in diverted discharge was 14.97%, observed at an approach discharge of 70 L/s with two downstream gates opened under free-flow conditions. These findings suggest that positioning a splitter wall close to the lateral intake may provide a simple hydraulic measure for improving diversion performance. However, further investigation of construction requirements, field applicability, and scale effects is needed before its practical implementation can be assessed. Conflict of InterestsThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. FundingThe authors received no financial support for the research, authorship, and publication of this article. Data AvailabilityThe datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. Author ContributionsS.Z.N : Software, Validation, Formal Analysis, Investigation, Data Curation, Writing-original draft, Visualization. J.A: Conceptualization, software, Validation, Investigation, Resources, Writing-review and editing, Visualization, Supervision, Project administration, Funding acquisition. S.M.K: Methodology, Validation, Investigation, Visualization. S.M.S: Validation, Investigation, Visualization.AcknowledgmentThe authors express their gratitude to all individuals who assisted in the advancement of this research, particularly the professors and staff of the Department of Hydraulic Structures, Faculty of Water and Environmental Sciences, Shahid Chamran University of Ahvaz.
Original Article
Hydraulic
Seyed Mohammad Zare; Sohrab Nazari
Abstract
Extended Abstract
Introduction
Local scour downstream of hydraulic structures is an important concern in the design and long-term safety of spillways and energy dissipation systems. High-velocity flow issuing from ski-jump buckets interacts with the downstream water ...
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Extended Abstract
Introduction
Local scour downstream of hydraulic structures is an important concern in the design and long-term safety of spillways and energy dissipation systems. High-velocity flow issuing from ski-jump buckets interacts with the downstream water and movable bed, resulting in the formation of scour holes. The characteristics of these scour holes depend on hydraulic conditions, sediment properties, tailwater depth, and bucket geometry. Among these factors, bucket geometry can influence the measured scour response downstream. Although numerous studies have investigated scour downstream of ski-jump buckets, comparative experimental studies focusing on different bucket geometries remain limited. Therefore, the present study investigated the influence of circular and triangular ski-jump bucket geometries on downstream scour characteristics. The main hypothesis of this study was that changing the bucket geometry under similar hydraulic and sediment conditions could significantly modify the downstream scour response. Accordingly, the objective was to experimentally compare the effects of circular and triangular ski-jump buckets on the maximum scour depth (ds) and the distance from the bucket to the location of maximum scour (Ls). In addition, power-law regression models were developed to predict these scour characteristics.
Materials and Methods
A series of physical model experiments was conducted using circular and triangular ski-jump buckets under controlled laboratory conditions. The experimental program included different hydraulic and geometric conditions and consisted of 108 experimental runs. A movable sediment bed was used to evaluate the downstream scour response. The maximum scour depth (ds) and the distance to the location of maximum scour (Ls) were considered as the principal dependent variables. The effects of discharge, tailwater conditions, and characteristic geometric parameters of the buckets were investigated. Dimensional analysis was used to identify the governing dimensionless parameters. Based on the experimental data, separate multivariable power-law regression models were developed for each bucket geometry and scour parameter. The performance of the proposed models was evaluated using the coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE), root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE). One-to-one plots and residual analyses were also used to assess the agreement between measured and predicted values and to identify possible systematic errors. Furthermore, statistical tests were performed to evaluate the significance of differences between the scour characteristics produced by the two bucket geometries at a 5% significance level. Each experimental condition was conducted once, and independent repeated tests were not performed for all conditions. Consequently, between-run variability could not be directly quantified. However, the sediment bed was prepared and leveled before each experiment, and the hydraulic and geometric conditions were controlled according to the experimental design.
Results and Discussion
The results showed that discharge was one of the principal parameters affecting downstream scour development. Increasing discharge generally increased both the maximum scour depth and the distance to the location of maximum scour for both circular and triangular buckets. Comparison of the two geometries revealed clear differences in their measured scour responses. Within the investigated range of experimental conditions, the triangular ski-jump bucket produced a lower average maximum scour depth than the circular bucket. The average reduction in maximum scour depth was approximately 11%. The distance to the location of maximum scour also differed between the two configurations. The triangular bucket increased this distance by approximately 40% compared with the circular bucket. Therefore, under the investigated laboratory conditions, the maximum scour occurred farther downstream when the triangular configuration was used. Statistical comparisons confirmed that the differences between the circular and triangular buckets were significant at the 5% significance level for both maximum scour depth and the location of maximum scour. These results indicate that bucket geometry has a significant effect on the measured scour response. The proposed power-law regression models provided satisfactory predictions within the range of the experimental data. The statistical performance indices showed good overall agreement between measured and predicted values. In addition, the one-to-one plots demonstrated that the predicted values were reasonably distributed around the line of equality. Residual analyses also supported the overall adequacy of the proposed models. The residuals were generally distributed around zero, with no pronounced systematic pattern. However, the normality assumption was not equally supported for all models. Therefore, model performance was assessed using a combination of statistical indices and graphical analyses. The results provide direct experimental evidence that bucket geometry affects downstream scour characteristics. However, hydraulic variables such as velocity distribution, residual jet energy, pressure distribution, and bed shear stress were not directly measured. Therefore, the detailed hydrodynamic mechanisms responsible for the observed differences cannot be confirmed directly and require further investigation.
Conclusions
This study experimentally investigated the influence of circular and triangular ski-jump bucket geometries on downstream local scour characteristics. The results demonstrated that discharge and bucket geometry significantly affected the maximum scour depth and the location of maximum scour. Increasing discharge generally increased both scour depth and the downstream distance to the location of maximum scour. Within the investigated experimental range, the triangular bucket reduced the average maximum scour depth by approximately 11% compared with the circular bucket. In contrast, the distance to the location of maximum scour increased by approximately 40% for the triangular configuration. Statistical analyses confirmed that the differences between the two geometries were significant for both investigated scour parameters. Furthermore, the proposed multivariable power-law regression models showed satisfactory predictive capability within the range of the experimental data. The combined use of statistical performance indices, one-to-one plots, and residual analyses supported the overall applicability of the developed models. Overall, the findings confirm that ski-jump bucket geometry is an important factor influencing downstream scour characteristics. Under the laboratory conditions investigated, the triangular bucket showed more favorable performance in terms of reducing maximum scour depth while shifting the location of maximum scour farther downstream. The absence of repeated tests and the lack of direct measurements of jet hydrodynamic characteristics are limitations of the present study. Future investigations should include repeated experiments under representative conditions and direct measurements of flow characteristics to provide a better understanding of the mechanisms governing downstream scour.
Conflict of Interest
The authors declare that they have no conflict of interest regarding the preparation and publication of the materials and findings presented in this study.
Funding
The authors received no financial support for the research, authorship, or publication of this article.
Data Availability Statements
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.
Author Contribution
Seyed Mohammad Zare: Data Collection, Working in Laboratory and Sohrab Nazari: Writing, Methodology, Investigation and Data Curation, Analysis, Guidance and Supervision, Text Editing, Completion and Data Collection.
Acknowledgement
The authors wish to express their sincere gratitude to the Editor, two anonymous reviewers and the copy editor for their insightful comments and constructive feedback, which significantly improved the quality of this manuscript.
Original Article
Irrigation network management
Hossein Khalili Shayan; Mohammad Hamzehdoost Hassan Kiadeh; Abolfazl Barghi Khezerloo
Abstract
Extended AbstractIntroductionTraditional approaches to regulating irrigation canals rely heavily on manual discharge measurements and operator judgment, both of which are labor-intensive and error-prone. The advent of Supervisory Control and Data Acquisition (SCADA) systems, Remote Terminal Units (RTUs), ...
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Extended AbstractIntroductionTraditional approaches to regulating irrigation canals rely heavily on manual discharge measurements and operator judgment, both of which are labor-intensive and error-prone. The advent of Supervisory Control and Data Acquisition (SCADA) systems, Remote Terminal Units (RTUs), level sensors, and wireless data transmission has opened new horizons for achieving precision water delivery. However, the successful deployment of such technology’s hinges upon the accuracy and reliability of the underlying hydraulic measurement instruments and the control algorithms that interpret their readings. This study investigated the use of radial gates, which exist at most inlet and delivery points in the country's irrigation networks, as measurement structures.MethodologyUsing the as-built map of the inlet gates of the West Dez canal and using energy and momentum equations, the rating of the estimated gate discharge was derived for different combinations of the upstream water level and the percentage of opening. A total of 2,337 field measurement series were taken at various combinations of opening, upstream water level, and discharge.Results and discutionThe results of this study indicate the applicability of radial gates in estimating the amount of discharge delivered downstream with appropriate accuracy, based on field measurements at the inlet gates of the main canal of the West Dez. It was found that the rating proposed in the present study, without local calibration, has the ability to predict the inlet flow to the main canal of the West Dez irrigation network with an average absolute relative error of less than 4 percent.Continuous monitoring of the flow rate entering the irrigation network requires continuous monitoring of changes in the upstream water level and the opening percentage of each gate. During this study, by installing an online VIGILEVEL level gauge and sending water level information in real time every half hour to the Water Query software system, as well as sending the opening percentage of the left and right gates entering the network after each opening change by the operator to the system, it became possible to continuously monitor changes in the volume of flow entering the West Dez irrigation network. Accordingly, during the 97 days of this study, the volume of flow entering the West Dez irrigation network, equal to 508 million cubic meters, was monitored with an error of less than 4 percent.Considering the average error of about 10-15 percent in measuring the entry flow into the country's modern irrigation networks, the application of the proposed method, with an average absolute relative error of less than 5 percent, could lead to the management of a water volume of at least 600 million cubic meters annually. Meanwhile, the proposed method in this study will reduce the cost of equipping entry points to the country's modern irrigation networks by at least approximately 1.6 million Dollars (equivalent to 3,750 billion Rials) compared with electronic flow measurement devices.ConclusionThis research explores the application of control gates in irrigation networks, emphasizing their role in regulating water flow and optimizing irrigation efficiency. This research demonstrates that the integration of accurate water level sensing, hydraulically validated discharge rating equations, and modern telemetry and control infrastructure constitutes an effective and practical strategy for enhancing water management in irrigation networks. The field-validated system achieved high measurement precision, enabling volumetric water delivery that closely matches agricultural demand while significantly mitigating conveyance losses. The results further confirm that the performance of automated discharge measurement is critically sensitive to the gate opening. The proposed methodology is generalizable and could be adapted to other control structures, canal geometries, and climatic contexts with appropriate recalibration. Conflict of InterestThe authors declare that they have no conflict of interest. All authors have read and approved the final manuscript. FundingThe authors received no financial support for the research, authorship, and publication of this article. Data Availability StatementsAll information and results are presented in the text of the article. The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request. Author ContributionAll authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by all authors. The first draft of the manuscript was written by H.K.S, and all authors commented on previous versions of the manuscript (H.K.S, M.H.H.K, and A.B.K). The final revisions have been applied by H.K.S. Moreover, all authors have read and approved the final manuscript. All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts. AcknowledgementThe authors appreciate the support of the Iran Water Resources Management Company and the Northern Khuzestan Irrigation Networks Operation Company in providing conditions for periodic visits to the Dez irrigation network.
