Irrigation network management
Atena Hazeri; RASOOL Ghobadian; Mohammad Mehdi Heidari
Abstract
Background and Objectives: Proper design of technical and hydraulic parameters plays an essential role in the success of a pressurized irrigation or urban water distribution project and its economy. Therefore, engineers should be able to select the best solution in different stages in terms of design, ...
Read More
Background and Objectives: Proper design of technical and hydraulic parameters plays an essential role in the success of a pressurized irrigation or urban water distribution project and its economy. Therefore, engineers should be able to select the best solution in different stages in terms of design, construction, maintenance and operation according to the existing limitations and make the necessary decisions.The ultimate objective of such decisions is to minimize costs or maximize benefits by considering limitations.The objectives defined for each system may be different but it is certain that in today's engineering world, one-sided objectives are never defined.Today, meta-exploration optimization methods for the optimal design of irrigation and water supply networks have been considered.It is not possible to compare one-objective and two-objective methods in appearance. But in the two-objective method, one of the objectives is defined in such a way that it eventually goes to zero this comparison is possible.Materials and Methods: Hence in the present study, the optimal design of a pressurized network with one-objective binary genetic algorithm and two- objective NSGAII has been done.Genetic algorithm is a method that evaluates different designs through trial and error with analogy criteria and maintains the best designs and eventually achieves the proper design. Multi-objective optimization is a sub-branch of the MCDM multi-criteria decision-making set that takes place among an unlimited set of possible solutions. In such cases unlike single-objective optimization problems, due to the existence of several conflicting goals, a set of answers is obtained instead of just one answer. In order to compare the two methods in terms of accuracy of results and speed of calculations the second objective function in NSGA-II was defined as the sum of the pressure deficiencies in the network. Observance of minimum pressure constraints in the network causes the value of this objective function to reach zero and the results of the two methods are comparable. In order to analyze the network and obtain the pipe flow and pressure in the system nodes, the matrix shape of the gradient method was used. Computer code was developed for single-objective (GA) and multi-objective (NSGAII) optimization methods in VB programming environment. Also, the simulation code according to the matrix shape of the gradient method was prepared in this programming environment. Finally, All the codes were linked to each other.Result: In order to validate the NSGA-II developed cod, its ability to solve several constrained and none- constrained multi-objective mathematical problems was proposed. The results showed that there is a very good agreement between the results of the present model and the results presented by previous researchers. In order to validate the genetic algorithm model, the model was used to solve the linear and nonlinear constrained optimizations problems that have analytical solutions. it has been shown that the results obtained from the model are exactly equal to the results of analytical solutions. After verifying the prepared codes from a programming point of view, a proposed two-loop network consisting of 7 pipes and 8 nodes whit one earth reservoir was designed with both GA and NSGA-II algorithms. The result showed, estimated cost of implementing the studied network by tow method was the same and with a difference of less than 1%, while the cost of calculations in NSGA-II method was estimated to be about 2% of the genetic algorithm method. That is, the time to reach the optimal answer in NSGA-II method is 50 times faster than GA method. Conclusion: Given that the cost of calculations in the NSGA-II method is much lower than the GA method, the use of this method to optimal design of water presuurized network is recommended, Provided that in this method the second objective function is defined in such a way that if all the constraints are observed, its value will be close to zero. For this purpose, the objective function of the sum of pressure deficiencies Was deemed appropriate.
River engineering
soroush gharibi; Mahdi Esmaeili varaki; Sahameddin Mahmoudi Kurdistani; Amir malekpour
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
Nader Heydari; Saloome Sepehri Sadeghian; Jalal Aboalhasani
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
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
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
Alireza Afzalian; seyed mohsen sajjadi; Mahmood shafai bajestan; javad Ahadiyan
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%.
)
