Original Article
Irrigation network management
Afshin َAshrafzadeh; Jaber Salehpour Laghani
Abstract
Introduction The management of treated wastewater is a critical issue in addressing water scarcity and ensuring environmental sustainability, particularly in regions like Guilan Province, Iran, where agricultural, urban, and industrial activities strain water resources. ...
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Introduction The management of treated wastewater is a critical issue in addressing water scarcity and ensuring environmental sustainability, particularly in regions like Guilan Province, Iran, where agricultural, urban, and industrial activities strain water resources. This study aims to investigate regional preferences for pricing methods of treated wastewater, cost-based, market-based, subsidized, and environmental, in various parts of Guilan, characterized by differing environmental priorities. The research addresses the problem of aligning pricing strategies with local needs to enhance sustainable wastewater reuse. Existing literature highlights the importance of wastewater reuse for agriculture and environmental protection (Areosa et al., 2024; Hajjar et al., 2025) and the role of pricing in resource management (Beecher & Gould, 2018; Fagundes & Marques, 2023). However, studies focusing on regional variations in pricing preferences, especially in Iran, remain limited (Deh-Haghi et al., 2020; Zafari Koloukhi et al., 2021). This study employs a mixed-methods approach, combining quantitative (Kruskal-Wallis test, Random Forest) and qualitative (thematic analysis, conceptual network) techniques to analyse data from 55 stakeholders across four regions with varying environmental priorities. The main results reveal distinct regional preferences, with subsidized and environmental methods favoured in high-priority areas and cost-based and market-based methods in lower-priority regions, underscoring the need for tailored pricing policies. MethodologyThe research was conducted in Guilan Province, a key agricultural region in northern of Iran, known for its humid climate and sensitive ecosystems like the Anzali International Lagoon. The province was divided into four categories based on environmental priority: very high (e.g., Rasht, Anzali), high (e.g., Someh Sara), medium (e.g., Lahijan), and low (e.g., Khomam). Data were collected from 55 stakeholders, including farmers, experts in water and environmental issues, and representatives of local institutions, using a structured questionnaire. The questionnaire comprised demographic details, 20 Likert-scale questions assessing the four pricing methods, choice scenarios, and open-ended questions for qualitative insights. Quantitative analysis included descriptive statistics, Cronbach’s alpha for reliability, Kruskal-Wallis tests for inter-regional differences, and Random Forest modeling to identify influential factors. Qualitative analysis involved thematic analysis, keyword frequency counts, and conceptual network mapping using Python (version 3.8) and libraries like Pandas, Scikit-learn, and NetworkX. The research questions focused on identifying preferred pricing methods, their influencing factors, and qualitative explanations of these preferences. The mixed-methods approach was chosen to capture both statistical trends and nuanced stakeholder perspectives, ensuring relevance to both theoretical frameworks (e.g., sustainable resource pricing) and practical policy design. Results and DiscussionThe findings indicate significant regional variation in pricing preferences. In very high-priority areas (e.g., Rasht), the subsidized method (mean score 4.73, 57.14% preference) and environmental method (mean 4.42, 28.57%) were most favored, reflecting the urgent need for government support and environmental protection amid severe pollution (e.g., Anzali Lagoon). In high-priority areas (e.g., Someh Sara), the subsidized method (mean 4.06) led, with cost-based (mean 3.76) and market-based (mean 3.57) methods also notable, suggesting a balance between affordability and economic considerations. Medium-priority areas (e.g., Lahijan) preferred the market-based method (mean 3.93, 64.29%), driven by high agricultural demand for wastewater, while low-priority areas (e.g., Khomam) favored the cost-based method (mean 3.93, 37.50%), emphasizing financial transparency. Kruskal-Wallis tests confirmed significant differences for subsidized (p=0.001) and environmental (p=0.001) methods across regions, but not for cost-based (p=0.206) or market-based (p=0.323) methods. Random Forest analysis identified the environmental method as the most influential (importance 0.284), followed by market-based (0.261), subsidized (0.228), and cost-based (0.226). Qualitative analysis revealed dominant themes: subsidized and environmental concerns in high-priority areas, market-based in medium-priority, and cost-based in low-priority areas. A conceptual network showed strong links between subsidized and environmental methods (weight 18), reflecting stakeholder priorities. These results align with studies emphasizing economic and environmental factors in wastewater pricing (Deh-Haghi et al., 2020; Obaideen et al., 2022) but offer novel insights into regional specificity. ConclusionsThe study concludes that pricing preferences for treated wastewater in Guilan Province are closely tied to regional environmental priorities. Subsidized and environmental methods dominate in areas with severe pollution, while market-based and cost-based methods suit regions with stable water resources or lower pollution. Limitations include a modest sample size (55 stakeholders) and cross-sectional data, which may not capture long-term trends. The findings suggest that pricing policies must be region-specific to balance economic viability and environmental sustainability. Theoretical implications include reinforcing the role of context in resource pricing models, while practical implications involve guiding policymakers to prioritize subsidies in high-priority areas and market mechanisms in agricultural hubs. Future research should explore cost-benefit analyses and longitudinal impacts of pricing strategies. AcknowledgementHereby, we would like to express our sincere gratitude to the stakeholders in Guilan Province for their participation in completing the questionnaires. We also appreciate the provincial organizations for providing access to the data used in this study. Our heartfelt thanks go to the Editor-in-Chief and esteemed reviewers whose valuable comments greatly contributed to enhancing the quality of this article.
Original Article
Hydraulic
Ebrahim Valizadegan; Farzad Jalili
Abstract
Introduction
Despite the development and construction of advanced equipment for measuring discharge in canals, sharp crested weirs are always used in irrigation and water supply networks due to their simplicity in operation and low cost. Extensive research has been done to obtain the discharge calculation ...
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Introduction
Despite the development and construction of advanced equipment for measuring discharge in canals, sharp crested weirs are always used in irrigation and water supply networks due to their simplicity in operation and low cost. Extensive research has been done to obtain the discharge calculation relationship in all types of sharp crested weirs. To increase the efficiency and accuracy of weirs, researchers have performed various researches by applying various changes in the geometry of sharp crested weirs, such as Borghei et al. 2003, Igathinathane et al. 2007, Nicosia et al. 2019, Vatankhah and Khamisabadi 2019, Diwedar et al. 2022, Zeinivand et al. 2024 and other researches. Flow calculation relationships using triangular sharp crested weirs have been developed for the special conditions of installing these weirs, one of these conditions is the location of the vertex of the weir at a certain height from the bottom of the canal (P<0). In this research, a 90 degree triangular sharp crested weir was installed in the canal so that the vertex of the weir be the same level with the bottom of the canal in the central axis (P=0). To find the flow calculation relationship, several experiments were carried out in free and submerged conditions in 2 canals with different floor width.
Methodology
The modified head-discharge equation for triangular sharp crested weir proposed by Kindsvater and Carter (1957) (Eq. 1) was the basis for conducting experiments and arriving at the discharge calculation relationships in free flow conditions.
(1)
(2)
In the above equations, Q = flow rate, He = effective height of water on vertex of the weir, g = acceleration of gravity, q = angle of the weir vertex, Cd = discharge coefficient, which is affected by the geometry of the weir, H = water height on the vertex of weir and Kh = a quantity that depends on the characteristics of the fluid and the angle of the vertex of weir, and its value is presented in a graph for water at a temperature of 5 to 30 degrees Celsius. In submerged flow conditions, following functional equations were based for conducting experiments and arriving at the discharge calculation equations.
(3)
(4)
Where H1 and H2 = flow depth in the upstream and downstream of the weir respectively, Qs = submerged flow rate, Qf = free flow rate per H1.
10 experiments in free flow and 77 experiments in submerged flow conditions conducted in a flume with a length of 3, width of 0.2 and height of 0.2 meters with an adjustable floor slope in the hydraulic laboratory. To verify the obtained results, all the experiments were repeated again in another flume with a floor width of 25 cm.
Results and Discussion
Based on equation 1 and experiments in the canal with floor width of 20 cm, the variation of the measured flow (Q) with the theoretical flow (Qtheo.) is shown in Figure 1-a. In order to check the accuracy of the obtained graph and equation, all the experiments were repeated by installing another 90o triangular sharp crested weir in another flume (with a floor width of 25 cm). Based on the these experiments (validation tests), the value of Cd coefficients were obtained as 0.6602 (Fig.1-b), same as fig. 1-a, (Fig.1-b).
(a) (b)
Fig. 1- variation of the measured flow (Q) with the theoretical flow (Qtheo.), a, in canal with floor width of 20 cm b, in canal with floor width of 25cm
Also based on Eq. 3 and 4, the following equations are obtained to discharge calculation under the submerged flow conditions.
(5)
(6)
Conclusions
In this research, a 90 degree triangular sharp crested weir was installed in the flume so that the vertex of the weir be the same level with the bottom of the channel in the central axis. After conducting several tests in the canal with a floor width of 20 cm, the relationships for calculating the discharge under free and submerged flow conditions were obtained based on dimensional analysis and the general relationship for calculating the discharge in triangular sharp crested weirs. In order to check the accuracy of the obtained relationships and verify them, experiments were carried out in another laboratory channel with a floor width of 25 cm (both in free flow and submerged flow conditions). The accuracy of the obtained relationships was evaluated using statistical functions of mean absolute value of relative error (MARE) and root mean square error (RMSE) for both channels. Results indicate the high accuracy of discharge calculation relationships both in free flow and submerged flow conditions. Based on the obtained results,both in free flow and submerged flow conditions, the flow permeability of triangular sharp crested weirs with P=0 is higher than weirs with P>0.
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