نشریه تحقیقات مهندسی سازه های آبیاری و زهکشی
سال بیست و چهارم شماره 90 (بهار 1402)

Despite the importance of determining indicators of water consumption management in the agricultural sector for use in national macro-planning, so far, indicators of water consumption management in the production of agricultural and horticultural crops have received less attention. This matter is of double importance regarding the programs to improve the efficiency of water consumption. In this regard, the determination of the volume of applied water, as one of the important and influential indicators in agricultural planning, should be considered. Therefore, conducting a research that can lead to more accurate information about the amount of water used for various agricultural and horticultural crops in the country is necessary and necessary, and its results can be of great help to the decision-making of officials related to water and agriculture.

Qazvin province is one of the poles of olive production in the country, and the most important olive growing areas of the province are located in Tarem region, between Gilan and Zanjan provinces. The cultivated area of olive orchards in the province in 2017 was 9,300 hectares, and the area of fertile olive orchards was about 6,500 hectares. Also, the average yield of olives in the province is estimated at 2977 kg/hectare. This research was conducted with the aim of directly measuring the water consumption of olives in the olive production pole of Qazvin province (Taram region). Olive is the main product of gardeners in most villages of this region and is the only source of income for many villagers. So that more than 90% of gardeners' economy depends on the production of olives, and olives are their main product in 45 villages out of 105 villages in the region. In this regard, due to the severe limitation of water resources in the region and the development of new olive orchards, it is necessary to pay attention to the amount of water consumed by the orchards and plan based on the monitoring of the current state of water resources exploitation. In this research, measuring the amount of olive water consumed by considering various factors such as; Irrigation method, size of garden plots, soil texture, quality of water and soil resources, planting intervals and the level of education of the users were done. For this purpose, selected gardens for measuring water consumption were chosen in such a way as to cover the diversity of these factors. The volume of water given was measured with WSC flume (depending on the flow rate from type 3 to 5) or ultrasonic flow meter without interfering in the farmers' irrigation program. In the current research, in order to monitor the flow rate of the pumping station in pressurized irrigation systems, an ultrasonic flow meter device model PERCISION FLOW190PD was used and after the hydraulic test and calibration, the flow rate of the pumping station was measured in the selected gardens. After determining the amount of water entering the garden by carefully monitoring the garden irrigation schedule (watering time, irrigation cycle, number of irrigation times during the growth period), the amount of water consumed by the olive crop was measured for each of the selected gardens. Also, effective rainfall was estimated by SCS method.

The results showed that the range of irrigation water depth changes was between 5 and 30 mm with an average of 18 mm and a standard deviation of 17.7 mm. The minimum and maximum number of irrigations were 18 and 90 with an average of 39 and a standard deviation of 19.91. The average volume of applied water in the studied olive orchards in Tarem region was 6006 m3/ha with a standard deviation of 1517 m3/ha in all types of irrigation methods. The average yield of olives in the studied orchards in 2018 was equal to 5.46 tons/ha with a standard deviation of 4.8 tons/ha, which was higher than the average yield of the province (3 tons/ha). According to the amount of water consumed and the yield, the average irrigation water efficiency in the studied orchards is 1.13 kg/m3 and the irrigation water efficiency and effective rainfall is equal to 0.78 kg/m3. In this regard, the highest index of agricultural water productivity index was recorded in dense olive groves of the region with the amount of 3.58 kg/m3. The most important reasons for the high agricultural water productivity index can be mentioned such as appropriate plant nutrition, proper fertilization of the land and soil texture modification, observance of horticulture principles, low-problem irrigation system, regular and correct irrigation cycle, and trained workers.

Piano key weirs are a kind of non-linear weirs, initially introduced by Hydrocoop (Blanc and Lempérière, 2001). Piano key weirs (PKWs) include inlet and outlet keys as well as an inclined surface. They are also a part of the crest, extending beyond the weir base and, thus, creating bulges upstream and downstream (Eslinger and Crookston, 2020). Due to their high compatibility with the site and their economic and hydraulic performance, PKWs have been used in more than 34 structures in North America, Europe, Asia, and Australia on gravity dams (e.g., Malarce Dam, France), embankment dams (e.g. Lake Peachtree Dam, GA, USA), and river structures (e.g. Dakmi 2 and Van Phong Barrage, Vietnam).
There is a wide range of studies addressing the discharge coefficient of PKWs, but the energy dissipation of rectangular, and trapezoidal PKWs has not been compared so far. Hence, it seems necessary to evaluate the energy dissipation of these three plans.

Tests were conducted in the hydraulic lab of Tarbiat Modares University, Tehran to assess the energy dissipation and flow properties downstream of rectangular and trapezoidal PKWs. Tests were performed using a 10×0.75×10 m flume (Fig. 1). The water was provided by an underground sump. PK weir was installed and sealed at 4 m away from the flume inlet, so the minimum flow turbulence was achieved. The discharge flow was adjusted by changing the speed of the pumps using a control panel. The upstream and downstream flow depths were measured at 4P (Crookston, 2010) and 10P (Eslinger and Crookston, 2010) away from the weir upstream and downstream, respectively, using digital point gage with an accuracy of ±0.1 mm. The weir specifications are listed in Table 1. Experiments were conducted for various discharges and approach flow depths.

The flow field upstream of PKWs was almost uniform and no turbulence was observed on the water surface. The flow deviated near the PKW with streamlines along inlet and outlet keys and over the weir walls. Flow deviation led to an increased unit discharge in the outlet keys. Meanwhile, the local velocity was increased, leading to a positive acceleration. The observations showed that this was accompanied by water level decline and increased downstream turbulence. The upper front of the PKW and the upstream overhang length contributed to energy dissipation.
The flow jet passing over the crest was accompanied by the interaction of three colliding jets. The interaction was the result of the collision between the flow nappies from lateral crests and the flow in the outlet keys (Fig. 4). The resulting interactions led to significant turbulence, and expansion of flow at the downstream. As the head increased, the outlet key discharge (in the space between two side walls of the PKW outlet key) were increased, and energy dissipation was limited.
Fig. 5 shows variations of the energy dissipation for rectangular and trapezoidal PKWs. The relative energy dissipation by the trapezoidal PKW was more than that of rectangular PKW, by average of abbot 3%. Fig. 6 shows the residual energy of the PKW versus discharge for rectangular and trapezoidal PKWs. It is clear that as the discharge increased, E1/E2 increased. Furthermore, the ascending rate of E1/E2 was higher for lower discharges. This is due to the local submersion upstream of the weir at high discharge.

Energy dissipation of trapezoidal PKWs are higher than rectangular PKWs.
The average discharge coefficient for trapezoidal PKWs is higher than rectangular PKW.
The flow characteristics is different for rectangular and trapezoidal PKWs. For Ht/P≤0.15, no aeration is occurred. For 0.15<Ht/P<0.45, a week hydraulic jump is formed at the end of the weir outlet keys. New equation was obtained for estimation of energy dissipation.

Irrigation modernization is the process of updating and improving an existing irrigation plan in order to achieve advanced technical, economic, or social goals. This research was carried out with the aim of developing a basic road map for the modernization of irrigation networks and emphasizing the related issues and challenges in the agricultural water sector of Iran. By combining the results of the main and key influencing factors in the basic roadmap for the modernization of irrigation networks related to the expected goals; issues, problems, and obstacles; strategies/solutions (actions); the type of modernization and its location in the network; priority indicators in the selection of networks; effectiveness monitoring indicators and methods; and how the discussion of modernization enters to the laws, macro-level documents, and development plans; were identified and compiled. Based on the results, the group of economic-social and institutional-political-legal issues and problems is more important than the issues of other groups, i.e. technical and environmental. Among the key issues of this group, the issues of empowering users, the exploitation system, the level of acceptance and participation of users, and weaknesses in proper and systematic coordination and communication between the institutions in charge of the issue, could be mentioned.Other important challenges from the aspects of implementing the road map and adopting policies and solutions for the modernization of irrigation networks in the Iran country include: a comprehensive approach to modernization and its implementation from the water supply source, the water conveyance network, the farm , and the irrigation system ("practically irrigation irrigation") and the challenge of delivering volumetric and accurate water for use instead of delivering it based on the water rights; issues and challenges related to the training of specialized human resources (experts and extension staff); and capacity building in operators to create modern farmers.
Other important and challenging points from the aspect of implementing the road map and adopting modernization policies and solutions in the country are: In the process of implementing the modernization roadmap, the entire system, that is, from the water supply source, the conveyance network (both main and secondary canals), to the farm and the irrigation system, should be seen together and integrated, as far as the consensus of opinion is that the title of this integrated process should be called "irrigation modernization" (not irrigation network modernization).
 The challenge of paying attention to the rehabilitation and its integration and simultaneous implementation with the main activities of modernization.
 Modernization is one of the requirements of changing the supply-based water distribution system to a water demand-based distribution system. But at the same time, it should be noted that due to the lack of water in the networks due to drought, climate change, the expansion of the cultivated area, etc., and as a result of the increase in water demand, the water requirement of the command areas of the network should be provided by a conjunctive method and modernization should not cause social tensions in the network in this regard.
 The challenge of creating the platform and hardware and software infrastructures necessary for social and cooperative management of operation and maintenance of networks and in the framework of compiling and establishing a "participatory water exploitation system".
 The challenge of volume delivery of water and the accurate determination of applied and required water in the farm, considering that water delivery is based solely on traditional and historical concepts and methods, and the existence of previous traditional and outdated water rights is another challenge in the field of implementing modernization.
 Issues and challenges related to the weaknesses in the training of experts in the field of modernization and required technologies and the lack of related research projects in universities and research institutes.
 Challenges related to weaknesses in specialized training for extension staff and farmers and overall weaknesses in capacity building and the problem of creating modern farmers.

The effective use of water for irrigation requires that flow discharge and flow volume be measured carefully. Venturi flumes are widely-used structures for monitoring flow discharges in canal networks (Venturi tubes used in pipelines). Venturi was the first that observed the effect of a local contraction in a conduit on flow velocity distribution. The Venturi flumes have a local constriction. These devices may be built in different shapes and generally are very accurate when operated under free outflow conditions. Longitudinal section of the Venturi flumes has a constant bottom slope, or the bottom has a local sill or hump. The Venturi flume with an arc-shaped inlet is referred to as Khafagi flume. Montana flume is also a flume without diverging downstream wall. The polygonal-shaped flumes are simpler in construction than curve-shaped flumes and are less expensive due to plan shaped elements. The Parshall flume is characterized by a specific shape with variousdegrees of convergence and divergence. Since development of the Parshall flume in 1926, many studies have been made to simplify, reduce construction costs, increase performance and accuracy of the flumes. A review of the literature of the subject shows that the study of hydraulics in flow measurement flumes is mainly based on laboratory research, and although numerical modeling is of interest, due to the complexity of the geometry of the section and the Contraction of the triangular shape, their accuracy is not reported to be acceptable. On the other hand, researchers have tried to develop and use soft computing models to estimate flow characteristics in such sections due to the hydraulic complexity of these types of flumes, which according to published reports, their accuracy has been suitable in all types of sections. Therefore, in this research, the development of data group classification model, support vector machine (SVM) model and random forest algorithm were developed to estimate the Discharge in flumes with triangular contraction.

By investigating the hydraulics of flow in flumes, researchers have found that the Discharge depends on the width of the contraction at the location of the structure, the horizontal and vertical slopes of the triangular walls, and the relative depth of the flow. Therefore, in the present study, for the development of GMDH, SVM and RF models, five dimensionless input parameters were considered. GMDH algorithm has been widely used in solving various hydraulic engineering problems. One of the most important applications of this method is the estimation of erosion around the bridge base, downstream of the cup-shaped launcher, and the discharge coefficient of flow measurement structures such as overflows. The SVM model is divided into two main groups a) Support Vector Classification model and b) Support Vector Regression model or SVR for short. The support vector machine classification model is used to solve data classification problems that are placed in different classes, and the support vector machine regression model is used to solve forecasting problems.

First, the collected data are divided into two categories, training and testing. It should be noted that the number of collected data is 592, and in this research, 80% of the data was assigned to training and the remaining 20% to testing. The training data is used for calibration and the test data is used for validation. Due to the fact that the collected data do not have a time series nature, they were randomly assigned to each of the training and testing groups. First, the results of the random forest model are presented. The reason for the priority of presenting the results of the random forest model compared to other modes used in this research is the identification of the most important effective parameters in the development process of the random forest model in the modeling and estimation of Discharge.

First, the collected data are divided into two categories, training and testing. It should be noted that the number of collected data is 592, and in this research, 80% of the data was assigned to training and the remaining 20% to testing. The training data is used for calibration and the test data is used for validation. Due to the fact that the collected data do not have a time series nature, they were randomly assigned to each of the training and testing groups. First, the results of the random forest model are presented. The reason for the priority of presenting the results of the random forest model compared to other modes used in this research is the identification of the most important effective parameters in the development process of the random forest model in the modeling and estimation of Discharge.

Iran is characterized by a dry and semi-arid climate. The limited irrigated arable land in and the need for increasing food production due to the upward trend in population growth, coupled with water scarcity and Iran's heavy reliance on irrigation, have led to a heightened importance of water productivity in agricultural sector. In this regard, for the purpose of identifying and understanding the agricultural potential of farmlands, the analysis and estimation of physical water productivity can be utilized. The main objective of conducting this research is to evaluate various interpolation methods and to select the most appropriate method for estimating the physical water productivity of the sugar beet. Additionally, the study aims to investigate the spatial distribution pattern of sugar beet production in its major cultivation centers across Iran.

To accomplish this research, 108 field measured data obtained from selected sugar beet farms across Iran for the agricultural year 2016-2017 were used. Data on crop yield, irrigation water, and a ten-year average effective precipitation were collected, and the water productivity index of sugar beet was calculated for the selected farms.To achieve this goal, initially, the data was analyzed using the capabilities of the SPSS software. Descriptive statistical analysis was conducted, and similar regions were classified into independent and homogeneous groups (by drawing a dendrogram). Additionally, the spatial analysis of the data was carried out using the GS+ software. Furthermore, various interpolation methods were employed to create a classification map using the Geographic Information System (GIS) software. These methods encompass algebraic methods, including weighted inverse distance, radial basis function, global polynomial, and local polynomial methods, as well as geostatistical methods like ordinary kriging, simple kriging, and universal kriging. To assess the different interpolation methods, validation methods were employed, and accuracy index values such as Mean Bias Error (MBE), Mean Absolute Relative Error (MARE), Mean Squared Error (MSE), Mean Absolute Deviation (MAD), and Root Mean Square Error (RMSE) were utilized.

The results of the present study revealed that the water productivity index for sugar beet ranged from 2.60 to 13.11 kg/m³, with an average of 6.30 kg/m³. Despite the high standard deviation, the findings indicate a significant potential and high capacity for improving water productivity and crop performance in the sugar beet production hubs in Iran. Among the examined interpolation methods, the Radial Basis Function method with a completely regular spline model (CRS) exhibited acceptable accuracy (MBE=0.009) for generating the water productivity zoning map. The analysis of the generated map suggested that the western regions of the country, especially Kermanshah province, have higher water productivity index values compared to other parts of the country, making them more suitable for sugar beet cultivation. Furthermore, cluster analysis results for influential factors such as variety type, soil salinity, and irrigation water salinity indicated that within the study area, about 5% of the potential sugar beet cultivation areas could be divided into 23 distinct clusters. The minimum and maximum water productivity index were observed in cluster 11 (2.64 kg/m³) and cluster 3 (11.025 kg/m³), respectively.
Based on the low level of correlation coefficient according to the results of the Pearson correlation test, the physical productivity of water utilization can be influenced by various factors other than precipitation and climate parameters. These factors include salinity of water, soil salinity, total irrigation water, average effective precipitation (over a ten-year period), and crop yield. It can be concluded that, in addition to precipitation and climatic parameters, other constant factors including management factors have an impact on improving the physical efficiency of water utilization.

Given the high water consumption in agricultural sector and the need for increased production in cultivated lands, evaluating the water produvtivity of high-water-demand crops such as sugar beet in Iran is essential. Understanding its current state and obtaining comprehensive information from fields, as well as monitoring cultivated fields, are necessary for decision-making and macro-level planning to enhance and improve water productivity of sugar beet cultivation in Iran. However, due to the extensive cultivation area, costs, limited resources, and time constraints, this task is challenging and often unfeasible. To address this, the potential of interpolation tools can be utilized. These tools have the capability to extrapolate point-based information to spatial information (area-wide). Results have shown that the highest and lowest error values were associated with the kriging interpolation method and the radial basis function (completely regularized spline) method, respectively, for creating zoning maps. In conclusion, it can be stated that through interpolation, if there is a strong correlation between the data, a better understanding of the spatial distribution of water productivity can be achieved in the study area.

The consolidation and the subsequent settlement can lead to the land subsidence, building destruction, pipeline ruptures in water supply networks, and damage to the asphalt pavement. In soil consolidation analyses and many other geotechnical problems, the uncertainty of geotechnical variables and their spatial variations is of significant importance. As a result, the uncertainty-based approaches are currently employed to consider these problems rather than deterministic analyses. In this regard, some researches have demonstrated the considerable influence of the random variables of hydraulic conductivity and volume compressibility on the soil consolidation phenomenon. However, the studies have rarely addressed the correlation between these random variables and its effect on the probabilistic consolidation analysis. The current research aims at investigating the impact of correlation between two random variables of hydraulic conductivity and volume compressibility using copula functions via the development of a computer program in MATLAB. The performance of different copula functions in the bivariate probabilistic analysis of consolidation and the temporal variations of pore water pressure distributions are studied in a case study in Guilan province of Iran.

In this research, a computer program was developed in MATLAB to estimate the marginal distributions of two random variables of hydraulic conductivity and soil volume compressibility. Then the bivariate probability distributions of two random variables were obtained using two copula groups of Archimedean (Clayton, Gumbel and Frank) and elliptic (Gaussian and t-student). The bivariate distributions of random variables were applied to estimate the temporal pore water pressure distributions during consolidation in soil depths of 2 and 4 meters. The best joint probability distribution and the corresponding copula function was determined on MvCAT software based on the correlation of random variables and using certain criteria such as AIC, BIC, RMSE, and NSE. As a feature of developed computer program in this research,1000 pair values of hydraulic conductivity and volumetric compressibility were generated by copula functions (from the primary 24 field data) in order to create more accurate results. Then, after numerically solving the governing differential equation of consolidation using the implicit central finite difference method, the probability distributions of pore water pressure over time including the probability density functions (PDFs) and cumulative distribution functions (CDFs) were calculated using different copulas and compared with each other.

The results showed that the inverse Gaussian distribution properly fits to the marginal distributions of each single random variable, according to BIC criterion. In this research, Kendall’s correlartion coefficient showed a positive correlation between the random variables of hydraulic conductivity and soil volume compressibility. After 15 days from the beginning of consolidation with an initial loading of 400 kPa, the pore water pressures in the depth of 2 meters were estimated equal to 398.75, 398.9 and 398.95 kPa for Clayton, Gumbel and Clayton copulas, respectively. Whereas the pore pressure in the same depth were obtained equal to 399 and 399.05 kPa for Gaussian and t-student copulas, respectively. In the depth of 4 meters, Clayton, Gumbel and Clayton copulas, estimated the pore pressures equal to 399.54, 399.55, 399.54 kPa, respectively. It shows that Archimedean copulas create almost similar results in deeper regions within a soil layer. For elliptical copulas in the depth of 4 meters, the pore water pressures were calculated equal to 399.8 and 399.75 kPa for Gaussian and t-student copulas, respectively.

Considering the correlation of random variables, it is concluded that Archimedean copulas are more accurate in extreme values than elliptic copulas but elliptic copulas according to AIC, BIC and other evaluation criteria provide better balance between the number of parameters, the accuracy and the complexity of model. Generally, for both Archimedean and elliptic copulas, the temporal variations of pore water distributions show an increase in uncertainty with time via changing from sharp and narrow curves to flat and wide curves. Moreover, the consolidation rate (pore pressure dissipation rate) is slower for elliptic copulas than Archimedean copulas. Gaussian copula was found to be the best copula among all investigated copulas. The error of neglecting the correlation of random variables is bigger when a shallow foundation is to be designed by an engineer. Meanwhile, the consolidation rate is overestimated when the correlation of random variables is ignored.