Irrigation and Drainage Structures Engineering Research

Original Article Irrigation network management

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

Fariborz Abbasi; M. Akbari; Abolfazl Nasseri; Nader Abbassi; J. Baghani; M. Joleini; Mohammad Ali Shahrokhnia; Mohammad Mehdi Nakhjavanimoghaddam; Saloome Sepehri Sadeghian; M. Moayeri; A.R. Hassanoghli; Abolghasem Haghayeghi; Ali Ghadami Firouzabadi; syeed Hassan mousavifazl; M.R. Yazdani

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

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

Abstract

Extended AbstractIn terms of water consumption in different sectors, in Iran as in other countries, a significant part of surface and groundwater resources is used in agricultural sector. For the amount of water consumed in Iran's agricultural sector, different numbers have been reported in various sources. ... Read More Extended AbstractIn terms of water consumption in different sectors, in Iran as in other countries, a significant part of surface and groundwater resources is used in agricultural sector. For the amount of water consumed in Iran's agricultural sector, different numbers have been reported in various sources. In the past three decades, water consumption in agricultural sector in various sources and methods has been reported between 44 and 86 billion cubic meters (Movaheddanesh, 1994; Ghodratnema, 1998; Mohammad-Vali-Samani, 2005; Nasseri et al., 2017; 2018). The physical water productivity is also one of the important indicators of irrigation management, which is determined by using the amount of product produced per unit of applied irrigation water. Abbasi et al. (2017) estimated and analyzed water productivity values in Iran for different years. They estimated the values of water productivity varying from 0.94 to 1.29 kg/m3 and average being 1.07 kg/m3. Abbasi et al. (2019) also showed that water productivity index in Iran had an upward trend with a slope of 0.045 kg per year. It varied from 1.0 kg/m3 in 2008 to about 1.45 kg/m3 in 2017. Past researches regarding the estimation of water consumption in agricultural sector have been reported with estimation methods such as water balance method, which is not accurate and is associated with errors. On the other hand, the figures presented for the amount of water consumed in agricultural sector are very different and there are doubts about their accuracy. Despite the importance of the issue, accurate information on the amount of irrigation water for agricultural crops in different regions of Iran is not available and this issue has always been one of the main concerns of the water industry managers and planners. Therefore, carrying out a research work that lead to more accurate numbers about the amount of applied irrigation water for different crops, can be of great help to the decision-making of officials related to water and agriculture. Therefore, the main goal of this article is a comprehensive evaluation of water management indicators in agricultural sector (including the water productivity and applied irrigation water for different crops).MethodologyField measurements including applied irrigation water and crop yield were carried out for at least one cropping season in the production hubs of each crop. The studied crops include 12 agricultural crops (wheat, rice, barley, fodder corn, alfalfa, sugar beet, sugar cane, beans, sunflower, cotton, rapeseed, soybean), 17 garden crops (saffron, apple, olive, orange, tangerine, peach, nectarine, plum, lemon, fig, grape, date, pomegranate, walnut, almond, pistachio, cherry) and 6 vegetable and summer crops (tomato, watermelon, potato, cucumber, melon, onion). These crops covered more than 85% of the cultivated area and irrigated lands in different provinces. For each crop, applied irrigation water was measured in a crop season and the yield for one year or the average of two years, but for garden plants, due to climate changes and frost that affect the yield, the average yield of 1-3 years was determined and used in the analysis. Physical water productivity of irrigation water from the ratio of crop yield to applied irrigation water and water productivity from the ratio of crop yield to water (total volume of irrigation water and effective precipitation) and gross income per unit of applied irrigation water was calculated from the product of crop yield in the sales price divided by the applied irrigation water. In this research, the cluster analysis model was used to determine the homogeneous crops.Results and DiscussionThe results showed that applied irrigation water for different crops varies from 3984 for rapeseed to 32500 cubic meters per hectare for sugarcane. So that the weighted average applied irrigation water of 35 studied crops was determined to be 8032 cubic meters per hectare.This index was 9162, 7669 and 7247 cubic meters per hectare, respectively, for garden, agricultural, vegetable and summer crops. Also, the total applied water used for the 35 studied crops was estimated at 61.7 billion cubic meters and the total irrigation water for other crops that were not evaluated in this research was estimated at 9.4 billion cubic meters. The total water used in irrigated crops is estimated at 71.1 billion cubic meters, which is about 70% of the total renewable water in Iran. The weighted average of irrigation water productivity and water productivity of the studied crops was determined as 1.9 and 1.5 kg/m3, respectively. Saffron and pistachio provided the highest gross income per unit of irrigation water and sugarcane, soybean, barley, fodder corn, wheat and alfalfa had the lowest values.ConclusionsThe results of this research provide valuable information for managers and decision makers in different provinces of Iran.

Original Article Irrigation network management

The effect of cropping pattern modification on the physical and economic productivity of crop irrigation water in Fars province (Case study: Qaderabad-Madarsolaman plain)

Amir Eslami; Abdolrasool Shirvanian; Reza Zareian

Volume 25, Issue 94 , August 2024, Pages 17-37

https://doi.org/10.22092/idser.2024.366325.1583

Abstract

The sharp drop in the water level of the underground aquifers in the plains shows the lack of a suitable approach to create synergy between all the stakeholders in the water sector in the management of water resources. On the other hand, the undeniable limitation of water resources has led to the adoption ... Read More The sharp drop in the water level of the underground aquifers in the plains shows the lack of a suitable approach to create synergy between all the stakeholders in the water sector in the management of water resources. On the other hand, the undeniable limitation of water resources has led to the adoption of integrated water resources management as a requirement. In this regard, in an agricultural plain, there should be a matching of underground water resources with programmable water in order to reduce the severity of the created crisis and help to balance the plain over time. Therefore, avoiding horizontal development in the agricultural sector and increasing water productivity should be on the agenda of decision makers, especially in the planning of cropping patterns. This research has been carried out with the aim of improving the cultivation pattern in improving the physical and economic productivity of water in the Qaderabad-Madarsolaman plain of Fars province. The required data of the products include crop calendar, price at the time of harvest, production cost, yield, monthly programmable amount of plain water and monthly irrigation water amount of each crop related to crop year 2021-2022, which is in the form of documents from Jihad- Agriculture Organization. and the regional water company of Fars province was collected. Data analysis was done by mathematical programming method using GAMS software. The results showed that after implementing the model and determining the optimal cultivation pattern, the number of agricultural products in the plain increased by 50%. So that the number of products reached 18 products from 12 products. Also, the area under cultivation of crops in the optimal cultivation pattern decreased by 27% and reached 3861 ha from 5303 ha. Meanwhile, the amount of irrigation water of the optimal pattern caused a 26% reduction in the consumption of underground water resources. In addition, the amount of crop production in the current and optimal model was 8,469,3000 and 6,947,060 kg, respectively, and the decrease in the cultivated area has caused an 18% decrease in this index in the optimized model. However, the economic efficiency of the entire plain in the current and optimal model was calculated as 1975.37 and 2035.60 billion rials, respectively, which indicates a three percent increase in the optimal model. With regard to the direct effects of the modification of the cultivation pattern of the Qaderabad-Madarsolaman plain, including the increase in the number of agricultural products of the plain and the introduction of six crops with the highest economic water productivity into the optimal cultivation pattern, as well as the reduction of the area under cultivation of crops in the optimal cultivation pattern, and the increase of the economic efficiency of the entire plain in this pattern, it is expected that the index of physical productivity and economic productivity of the whole plain will also change. So, the physical water productivity index of the whole plain in the current and optimal model was obtained as 2.56 and 2.84 kg/m3, respectively. In the same way, the water economic productivity index of the whole plain was calculated as 59,607 and 83,086 rials per cubic meter, respectively. Therefore, the modification of the cultivation pattern in the Qaderabad-Madarsolaman plain resulted in the annual saving of 8.64 million cubic meters of water, an 11% increase in physical productivity, and a 39.4% increase in the economic productivity of water. Based on this, focusing on the water productivity index in the form of improving physical and economic productivity can be followed as a suitable approach to create synergy between all stakeholders and beneficiaries of the water sector in the management of water resources in the agricultural sector. In this approach, by focusing on increasing water productivity, in a defined time period, while minimizing the amount of production reduction, and by increasing the livelihood level of the users, it is possible to reduce the agricultural water consumption in the plains to the amount of programmable water.

Original Article Pressurized Irrigation Systems

Investigating of the Volume of Irrigation Water, yield and water productivity in cotton fields In Razavi Khorasan province

mohammad Joleini; Abolghasem Haghayeghi; Mohammad Mehdi Nakhjavanimoghaddam

Volume 25, Issue 94 , August 2024, Pages 38-51

https://doi.org/10.22092/idser.2024.366301.1584

Abstract

This project was carried out in the field in order to determine the useful water of tomatoes in the fields under the management of farmers during one cropping season (2018). Six cities of Bardaskan, Nyshabor, Sabzevar, Khaf, Roshtkhar and Sarakhs were selected in Razavi Khorasan province, which have ... Read More This project was carried out in the field in order to determine the useful water of tomatoes in the fields under the management of farmers during one cropping season (2018). Six cities of Bardaskan, Nyshabor, Sabzevar, Khaf, Roshtkhar and Sarakhs were selected in Razavi Khorasan province, which have the largest area under cotton cultivation. At first, based on the data required by the project, a questionnaire containing necessary information for investigation and logical conclusion was prepared. The required data of the selected farms in each city were either measured or through face-to-face interviews with the farmer or were calculated and completed according to the data of the previous two stages. The measurements were carried out in type of water source, irrigation network and method and water source discharge, total level The field and area under cultivation of cotton crop, variety, planting arrangement, planting date, soil texture, electrical conductivity of irrigation water and soil saturation extract, date of first irrigation, irrigation cycle and different irrigation methods, etc. The Measured Applied water were compared with the net irrigation water requirement estimated by the Penman-Monteith method using the last 10 years meteorological data (2009 to 2018) and also with the national water document values. Crop yield was recorded at the end of the growing season and water productivity was calculated as the ratio of yield to total water (irrigation applied water and effective rainfall). The results showed that the amount of applied water, the amount of cotton yield and the water productivity in Bardaskan region were 7369 m3/ha, 4583 kg/ha and 0.638 kg/m3, respectively. The amount of applied water, the amount of cotton yield and the water productivity in Nysahabor region were determined as 9773 m3/ha, 3554 kg/ha and 0.528 kg/m3, respectively. The amount of applied water, the amount of cotton yield and the water productivity in Sabzevar region were 9173 m3/ha, 3033 kg/ha and 0.225 kg/m3, respectively. In khaf region the amount of applied water, the amount of cotton yield and the water productivity were 14791 m3/ha, 2821 kg/ha and 0.194 kg/m3, respectively. The amount of applied water, the amount of cotton yield and the water productivity in Roshtkhar region were 11281 m3/ha, 3466 kg/ha and 0.327 kg/m3, respectively and The amount of applied water, the amount of Cotton yield and the water productivity in Sarakhs region were determined as 9004 m3/ha, 2113 kg/ha and 0.265 kg/m3, respectively. The average amount of applied water, the amount of cotton yield and the water productivity in above six regions were determined as 9830 m3/ha, 3078 kg/ha and 0.357 kg/m3, respectively. Also, the average volume of irrigation water, yield and productivity of water in the surface irrigation method were 10175 m3/ha, 2892 kg/ha and 0.318 kg/m3respectively, and in the drip irrigation method are 7242 m3/ha 4470 kg/ha and 0.649 kg/m3 was obtained.In Razavi Khorasan province, underground water sources are facing a reservoir deficit. Therefore, efforts towards better use of extracted water and reducing exploitation of underground water resources are inevitable. In this project, the water given by the farmers for cotton production during one cropping season and without expert intervention in the irrigation management of the farmer was measured in the six plains of Bardaskan, Nyshabor, Sabzevar, Khaf, Roshtkhar and Sarakhs cities, which had the largest area under cotton cultivation in Razavi Khorasan province. The method of irrigation of the fields was surface and drip irrigation (type). The results showed that the average applied water, yield and water productivity in all investigated cotton fields were 9830 cubic meters per hectare, 3078 kg per hectare and 0.357 kg per cubic meter of water, respectively. The difference between the volume of applied water, performance and water efficiency in two methods of surface and drip irrigation was significant. Under the drip irrigation system, the amount of applied water is 30% less (7242 cubic meters per hectare versus 10175), the yield is 55% higher (4470 kg/hectare versus 2892) and the water productivity is about 104% higher (0.649 kg/cubic meter in vs. 0/318) was from the surface irrigation method.

River engineering

Experimental investigation of effect of labyrinth and apron on local scour downstream of stepped weirs

soroush gharibi; Mahdi Esmaeili varaki; Sahameddin Mahmoudi Kurdistani; Amir malekpour

Volume 22, Issue 85 , April 2022, , Pages 1-26

https://doi.org/10.22092/idser.2021.355768.1483

Abstract

IntorductionControl of river bed erosion and consequently river banks is one of the important goals in river training projects. Instream grade-control structures [i.e. cross-vane, J-Hook vane, W-weir, log vane, block ramps, sills, etc.] are commonly used to stabilize the riverbed keeping the river slope ... Read More IntorductionControl of river bed erosion and consequently river banks is one of the important goals in river training projects. Instream grade-control structures [i.e. cross-vane, J-Hook vane, W-weir, log vane, block ramps, sills, etc.] are commonly used to stabilize the riverbed keeping the river slope in an equilibrium condition. When the steep river is wide, the mentioned instream structures are not the appropriate solutions. Stepped weirs are a type of spillways that creating a nappe flow over the steps, along with a high energy dissipation, lead to a reduction of downstream scour depth. Stepped weirs also can be employed as grade-control structures in the case of wide rivers. Scour depth and energy dissipation downstream of stepped weirs depend on the flow pattern over steps which depends on the weirs slope (i.e. ratio of the height to the length of the step), number of steps, constructing material and downstream hydraulic conditions (Chanson, 2002). Due to the role of scour formed at the downstream of these structures on their safety and stability, in the present study, effect of the installation of apron on variation of scour characteristics at the downstream of stepped weirs with and without labyrinths was investigated experimentally.Experimental Setup and procedureExperiments were performed for different flow conditions and weirs slopes of 1: 1 and 1: 2. The experimental measurements were conducted in the physical hydraulics modelling laboratory of the University of Guilan, Iran, in a flume with a rectangular cross-section that was 1.5 m width,1 m depth and 12.5 m length. A centrifugal pump supplied the required flow rate up to 90 L/s. The flow discharge was measured by ultrasonic flowmeter installed on the suction pipe with an accuracy of ± 0.1 l/s. In order to supply sediment particles for the sedimentary bed, sand with a uniform diameter of 2.68 mm was prepared and placed at the recess box with length of 2 m, width of 1.5 m and height of 0.30 m at downstream of weirs.The stepped weirs with slope of 1:1 and 1:2 consisted of five steps made of sheet metal panels. Aprons length are 0.135 (1/3P) and 0.27 (2/3P) meters. The labyrinths geometries was based on the results of research by Kazempor et al., (2019) that had the most suitable performance on reducing scour depth, was chosen. Primarily experiments indicating that the equilibrium bed condition was reached at 6 hours. For each experiment, after installing the weir, labyrinths and aprons and adjusting the sedimentary bed, the flow gradually entered into the laboratory flume and the flow depth gradually was raised. After adjusting the flow discharge, by regulating the downstream butterfly gate, the desired downstream depth was obtained. for all experiments, the temporal development of the scour depth for 6 hours at different time steps was taken by a digital camera and then digitizing using Grapher9 software. Final scour depth at the end of tests was measured using the Laser scanner Leica.Results and discussionThe results showed that by increasing the discharge to maximum value, installation of the apron LA1 at downstream of the stepped-labyrinth weirs SL1K1LA1 with an average 30% reduction of the temporal maximum scour depth had the best performance. The results indicate that by increasing the apron length to LA2, the SL1LA2 weir with an average of 54% reduction of the maximum temporal scour depth had the highest performance.By reduction of stepped weir to 1:2 and installing apron length of LA1 the maximum flow discharge, by the installation of apron length of LA1 stepped-labyrinth weirs SL2K4LA1 with an average reduction of 21% had the best performance on reduction of temporal scour depth. Also by increasing apron length to LA2 length, the stepped-labyrinth weirs of SL2K4LA2 had the most desirable performance with an average reduction of 34% on temporal scour depth.ConclusionComparison of the results of the equilibrium scour depth of the yc/h range from 0.34 to 0.54 for stepped weir with slope of 1:1 showed that by installation of apron length of LA1, the equilibrium scour depth at the downstream of SL1LA2, SL1K1LA2 and SL1K2LA2 weirs reduced 38%, 34% and 45%, respectively, compared to SL1 weir. By increasing the apron length to LA2, the equilibrium scour depth at the downstream of SL1LA2, SL1K1LA2 and SL1K2LA2 decreased by 65, 65 and 63%, respectively in comparison with SL1. At a stepped weir with slope of 1:2, that by installation of apron length of LA1 the equilibrium scour depth of SL2LA1, SL2K3LA1 and SL2K4LA1 weirs was reduced 8, 1 and 10%, respectively, compared to SL2 weir. By increasing the apron length to LA2, the equilibrium scour depth downstream of SL2LA2, SL2K3LA2 and SL2K4LA2 weirs decreased 44, 50 and 48% on compared to SL2 weir, respectively.

Irrigation network management

Evaluation of expert views and opinions on the modernization of irrigation networks in Iran

Nader Heydari; Saloome Sepehri Sadeghian; Jalal Aboalhasani

Volume 23, Issue 88 , February 2023, , Pages 1-26

https://doi.org/10.22092/idser.2023.360237.1527

Abstract

FAO defines irrigation modernization as a combination strategy of institutional, managerial and technological changes with the aim of changing from a purely supply-oriented operational mode to a service-oriented one. While the International Commission on Irrigation and Drainage (ICID) defines irrigation ... Read More FAO defines irrigation modernization as a combination strategy of institutional, managerial and technological changes with the aim of changing from a purely supply-oriented operational mode to a service-oriented one. While the International Commission on Irrigation and Drainage (ICID) defines irrigation modernization as the process of improving the existing project to meet new project criteria. This definition includes changes in existing facilities, operational procedures, management, and institutional aspects (Arif et al., 2019; Burt, 2013). Population growth and greater demand for water to produce agricultural products on the one hand and the occurrence of droughts and climate change on the other hand have led to a sharp decrease in water resources and the lack of water needed in the agricultural sector, as the largest water consuming sector in Iran. Due to the lack of water resources stored behind dams and water supply reservoirs, in practice only 2.9 million hectares of the 3.2 million hectares of main irrigation networks in Iran are being exploited. Due to the water crisis and the need to optimize water use in irrigation networks, modernization of these networks in the country is more important than ever. Therefore, the purpose of this paper is to examine the issues and challenges of modernization of irrigation networks in Iran from the perspective of experts and executives related to the subject. This research is in line with the first stage of a comprehensive study on the subject and the development of a road map for the modernization of irrigation networks in the conditions of water resource shortage. For this purpose, after a comprehensive review of scientific sources, a specialized questionnaire was compiled with the cooperation and opinion of the relevant executive bodies in charge of the subject. In the questionnaire, the following points were raised: the importance and priority of modernization, the level of attention given to the issue and the speed with which action was taken, the potential inhibiting factors, the factors that drive and facilitate the process, the impact of modernization on the various components of water management in the network and its agricultural production, effective parameters and necessary criteria in the selection and prioritization of networks for modernization, internal and external obstacles to the implementation of the modernization process, the effect of modernization on actual water saving, and other opinions and suggestions. Based on the results, the majority of the respondents emphasized the necessity of modernization of irrigation networks in Iran. The results of counting and evaluating various key and effective components and factors regarding the process of modernization of irrigation networks with different degrees of importance (more than 50 components with very high to high degree of importance) indicate that the implementation of this process is complex and it requires many factors, variables, and infrastructure to be available. It is on this basis that most scientific literature recommend that this process should be gradual and with sufficient study. Overall, many background-infrastructural factors play a role in the process of modernization of irrigation networks in Iran. However, components or factors such as policies and laws, institutional and political reforms, volumetric delivery of water, socio-economic criteria, empowerment of utilization systems, definition and main goal from modernization, issues of delivery and distribution of water, O&M costs, effects of modernization on real water saving, and improving the production and livelihood of farmers, have a great role in this regard. The impact of modernization on various performance indicators of the network, especially the actual water saving, the purpose and specific definition of modernization, the way of participation of stakeholders in the work process, and the issues of O&M after modernization process, are among the important issues that need further studies. In this article, the results of the analysis and evaluation of the opinions obtained from the stakeholders regarding the modernization of irrigation networks in Iran are presented. Also, the discussions and analyzes necessary for the first step in "compilation of the road map for the modernization of irrigation networks in Iran" have been carried out.

Irrigation network management

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

Nader Abbassi; REZA BAHRAMLOO; moin rezvani; Ali Ghadami Firouzabadi; afshin uossef gomrokchi; ramin nikanfar; abolfazl nasseri; Fariborz Abbasi; Rahim Alimohammadi Nafchi; mohammad abasi; Mustafa Goodarzi; Mohammad Ali Shahrokhnia; hamid riahi; Samar Behrouzinia; samira vahedi

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

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

Abstract

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

Irrigation network management

Experimental investigation of the effect of the height of the trapezoidal piano key side weir on the discharge coefficient and water level profiles.

Alireza Afzalian; seyed mohsen sajjadi; Mahmood shafai bajestan; javad Ahadiyan

Volume 23, Issue 87 , October 2022, , Pages 47-76

https://doi.org/10.22092/idser.2022.359228.1518

Abstract

The side weirs are widely used in sewage networks to aerate streams, irrigation and drainage networks to control water levels for dewatering, rivers for coastal management, and flood management of dams. One of the newest types of weirs researchers have considered in recent years is the piano key weir. ... Read More The side weirs are widely used in sewage networks to aerate streams, irrigation and drainage networks to control water levels for dewatering, rivers for coastal management, and flood management of dams. One of the newest types of weirs researchers have considered in recent years is the piano key weir. Piano key weirs have a higher efficiency than other weirs due to their special geometry, especially the presence of upstream and downstream overhangs, as well as inlet and outlet keys. The use of piano key weirs as side weirs has received less attention from researchers, and because these weirs show better performance in discharge, more and more research is needed. The main objectives of the present study are first to investigate the effect of trapezoidal piano key weir height as one of the geometric parameters affecting the discharge coefficient and second to investigate the water surface profiles at the upstream and downstream ends and within the location of the weir in the main channel. In parallel with the main objectives, the study of the Dimarchi hypothesis in estimating the discharge coefficient and the study of discharge efficiency of the trapezoidal piano key is also followed. In this regard, four models of trapezoidal piano key overflow with a height of 10, 15, 20, and 25 cm (TPKSWp10, TPKSWp15, TPKSWp20, and TPKSWp25), a labyrinth trapezoidal weir model with a height of 20 cm (TNRSW) and also rectangular sharp crest weir as The control model (Lisw) was tested under the subcritical flow with the Froude numbers in the range of 0.10 to 0.74. De Marchi, in 1934, assuming that the specific energy was constant at the upstream and downstream ends, calculated an equation for estimating the discharge coefficient of the side weirs that were related to the hydraulic parameters of the flow at both the upstream and downstream ends of the weir. In this study, the main hypothesis for estimating the piano key weirs' discharge coefficient is the Di Marchi hypothesis. The results show that, firstly, due to the specific energy changes at the upstream and downstream ends of the trapezoidal piano key models (ΔE/E1), especially in the TPKSWp10 and TPKSWp15 models, and the occurrence of hydraulic jump that affects the essence of the flow, use the Dimarchi hypothesis And comparing the discharge coefficients of trapezoidal piano key side weirs should be done with caution. The discharge capacity of the side weirs is defined as the ratio of flow spill from them to the inflow to the main channel. The results of this study show that the discharge capacity of trapezoidal piano key weirs increases with increasing height due to the more uniform water surface profile, reducing the interference of the outlet blades of the inlet and side crest and reducing the vortex in the inlet openings and faster exiting than the outlet keys. In the TPKSWp25 model, the discharge capacity is 2.60 times higher than the Lisw, and for the TPKSWp20, TPKSWp15, and TNRSW models, it is 1.92, 1.59, and 1.38 times higher than the Lisw, respectively. In the present study, two types of diagrams have been used to investigate the effect of the height of trapezoidal piano weirs on the water surface profile due to the complexity of the flow pattern and the simultaneous effect of geometric and hydraulic parameters of the weir and better analysis of these parameters on the water surface profile Also, the water level decreases in the longitudinal section Z*=1 (on the crest weirs) and at the upstream end of the weir due to the increase in the longitudinal acceleration of the flow and being affected by the suction of the flow by the weir in this range in all experimental models. This water level reduction for TPKSWp15,20,25 models and TNRSW models is almost the same and equal to 25%.

Hydraulic

Experimental Study of Hydraulic Properties of Flow over Vertical Shaft Spillway with Bow-Tied Shape Inlet

Samira Talebi; Ghorban Mahtabi; Masoud Karbasi; Masoud Akbari

Volume 22, Issue 85 , April 2022, , Pages 41-58

https://doi.org/10.22092/idser.2022.357719.1501

Abstract

Extended AbstractExperimental Study of Hydraulic Properties of Flow over Vertical Shaft Spillway with Bow-Tied Shape InletIntroduction A spillway is a structure used to provide the controlled release of water from a dam or levee downstream, typically into the riverbed of the dammed river itself. One ... Read More Extended AbstractExperimental Study of Hydraulic Properties of Flow over Vertical Shaft Spillway with Bow-Tied Shape InletIntroduction A spillway is a structure used to provide the controlled release of water from a dam or levee downstream, typically into the riverbed of the dammed river itself. One of the types of spillway used in dams is vertical shaft spillway or the same as morning glory spillway. One of the methods to increase the flow rate and reduce the occurrence of vortex currents in the spillway is to modify the shape of the inlet of the spillways. In recent years, spillways with daisy, piano key and zigzag inlets have been proposed known as spiral spillways. A review of the results of previous research shows that the common goal in the study of vertical shaft spillways is to pass the flood flows with the highest possible discharge and the lowest water level and reducing the eff destructive effects of vortex currents. In previous researches, issues such as the effect of the inlet type of vertical shaft spillway and geometric parameters of the structure on the discharge coefficient and the study of vortex occurrence conditions and hydraulic flow of vertical shaft spillway. In this research a new shape of vertical shaft inlet in form of Bow-tied spillway was introduced and discharge coefficient of these spillways was investigated using a series of experiments.MethodologyThe experiments of this research were performed in a metal cube tank with 1.5 m length, 1 m height and 1 m width with transparent Plexiglas side walls in the hydraulic laboratory of Department of Water Engineering at Zanjan University. Bow-tied spillways were examined with different angles of the bow-tie (60-150 degree) in both cases of with middle arc and without middle arc and the results were compared with a morning glory spillway. In this research, by preparing eight bow-tie spillways and a morning glory spillway with a total length of 60 cm and considering the hydraulic conditions (H/D), 72 experiments were run to investigate the effect of the geometric shape of the spillway on the discharge coefficient.Results and Discussion Results showed that in Bow-tied models without middle arc, increase of the bow-tie angle leads to reduce the flow interference and increase of flow discharge over the spillway. So that B-150 model (with 150 bow-tie angle) had higher discharge coefficient than the other models of bow-tied. This model had better hydraulic performance than morning glory spillway (10 percent). Also, economic advantage of this model was higher than morning glory spillway (31 percent). Results of the tip position of the bow-tie spillway show in tip angle of 120 degree, the tip position of the bow-tie has a significant effect on the discharge coefficient of the spillway, but with increasing the bow tip angle from 120 to 150, the tip position of the bow-tie spillway did not have much effect on the discharge coefficient. In Bow-tied models with middle arc, change of bow-tie angle had no significant effect on discharge coefficient and hydraulic performance of these models was lower than morning glory spillway (5.3-9.7). This could be due to the interference of fall currents and the low internal area of these models.ConclusionsComparison of the hydraulic performance of bow-tie models with morning glory spillway shows that the B-150 model has the highest hydraulic performance (10%) compared to other models. On the other hand, this spillway has a better economic advantage (31%) than the morning glory spillway. In the construction of reservoir dams, especially earthen dams, the major part of the executive cost is related to the implementation of concrete structures of emergency spillway. In this situation, by choosing Bow-tied spillway with optimal geometry, a suitable economic savings can be achieved along with improving the hydraulic conditions of the flow.Keywords: Bow-tied spillway , Discharge coefficient, Morning glory spillway, Vertical shaft

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