Original Article
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 ...
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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.
Original Article
Irrigation network management
Mohammad Karimi; Fariborz Abbasi; Mohammad Joleini
Abstract
Extended AbstractIntroductionWater management in the agricultural sector is very important as the largest consumer of water resources in the country. Estimation or determination of water use management indicators, including the amount of water consumed, irrigation efficiency and water productivity of ...
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Extended AbstractIntroductionWater management in the agricultural sector is very important as the largest consumer of water resources in the country. Estimation or determination of water use management indicators, including the amount of water consumed, irrigation efficiency and water productivity of various agricultural and horticultural crops in the country, is one of the most important key indicators in macro-planning related to supply of water, allocation and consumption in different sectors including agriculture. The volume of water used by agricultural crops as one of the indicators for evaluating the optimal use of water resources and plays a very important role in the management and macro-planning in the field of water management and engineering. Grapes is one of the most important horticultural crops in terms of cultivation area, economic and high nutritional values. Iran with an annual production of 2.8 million tons, is among the top countries in the production of grape product in the world. However, there are not accurate information on the volume of irrigation applied water and water productivity of this product inIran. Therefore, this study was conducted with the aim of measurement of applied water at field scale and evaluation of water productivity of grape in vineyards farms at different hubs of this crop production in Khorasan Razavi province. MethodologyIn Khorasan Razavi province, 2 cities with the highest area under vineyard cultivation were selected for evaluation, Kashmar and Khalilabad. To conduct this research, 6 vineyards in Kashmar region and 6 other vineyards in Khalilabad region have been selected. The volume of irrigation water was measured in these 12 vineyards during the irrigation season. The measurements were carried out in different irrigation and planting methods, various soils, different salinity of irrigation water and soil and different grape varieties during the growing season of 2018-2019 without interfering with the farmer's irrigation management. The measured values were compared with the gross irrigation water requirement estimated by the Penman-Monteith method using the last 10 years meteorological data and also with the national water document values. Crop yield was recorded at the end of the growing season and water productivity was calucated as the ratio of yield to total water (irrigation applied water and effective rainfall). Analysis of variance was used to investigate the possible difference between applied water and water efficiency among the hubs.Results and DiscussionThe results showed that the amount of applied water, the amount of grape yield and the water productivity in Kashmir region were 12049 m3/ha, 19 ton/ha and 1.76 kg/m3, respectively. The amount of applied water, the amount of grape yield and the water productivity in Khalilabad region were determined as 10827 m3/ha, 27.3 ton/ha and 2.59 kg/m3, respectively. The average amount of applied water and the amount of grape yield in the above two regions were determined as 11146 m3/ha and 23.2 ton/ha, respectively. The average water productivity was calculated as 2.17 kg/m3. The efficiency of water application in selected vineyards in the two regions of Kashmir and Khalilabad was 62.65% and 66.66%, respectively. The average efficiency of water application in the selected vineyards was 64.60%.ConclusionsAccording to the latest research conducted (Abbasi et al., 2020), the average amount of irrigation water and water productivity in the country's vineyards are 6669 m3/ha and 2.63 kg/m3, respectively. The average amount of irrigation water and the water productivity in the vineyards of this research area were 11146 m3/ha and 2.17 kg/m3, respectively. By comparing these results with national results, it was concluded that the amount of irrigation water in grape production in Razavi Khorasan Province is about 40.2% higher than the national average and the water productivity is about 17.5% lower than the national average. Considering that the surface irrigation method is often used to irrigate grape orchards in Razavi Khorasan province, improving the performance of the surface irrigation method by using methods to reduce evaporation such as mulching and using low pressure irrigation methods such as irrigation with hydroflume in order to reduce water consumption should be considered in the short term. For the drip irrigation method, the potential value of water applied efficiency is considered to be 90% Abbasi et al. (Abbasi et al., 2016). In the drip irrigation method, the gross requirement of grape irrigation is calculated (using the Penman-Monteith method and based on the statistics and meteorological data of the last ten years), extracted based on the national water document and the book "Estimation of Water requirement by Garden Plants" respectively. It will be reduced to 7762.9, 8177.8 and 8300.0 m3/ha. Therefore, by changing the irrigation method from surface to drip irrigation, the gross irrigation requirement decreases by 26.3%. Therefore, in the long term, it is recommended to change the surface irrigation method to drip irrigation.
Original Article
Hydraulic
Ehsan Ebrahimi; Mahmoud Shafai Bajestan; Babak Aminnejad
Abstract
Extended AbstractIntroduction In recent years, due to the increase in population, demands, and water consumption, the limitation of freshwater resources on the one hand, and the lack of comprehensive and targeted management programs in the water resources sector, on the other hand, there are many problems ...
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Extended AbstractIntroduction In recent years, due to the increase in population, demands, and water consumption, the limitation of freshwater resources on the one hand, and the lack of comprehensive and targeted management programs in the water resources sector, on the other hand, there are many problems facing water resources management. It has created countries. One of the sources of water wastage in water supply systems is the presence of illegal connections.This research investigates the effect of illegal connections on the transient pressure signal in viscoelastic pipelines. This research can be the basis for detection methods of illegal connections based on transient flow analysis in the future. Most past research has been done numerically to detect illegal connections based on transient flow. More work has been done on the elastic pipe system than the laboratory research.MethodologyIn this research, building a laboratory model of a suitable viscoelastic polyethylene pipe system has been tried to investigate the effect of illegal connections on the pressure signal at Shahid Chamran University of Ahvaz, Ahvaz. The experimental program consisted of hydraulic transient tests with simulated illegal connections. The pipeline is made of HDPE with PE100 and NP16 bar. The pipeline's total length is about 158 meters, with built-in sloping rings upwards. The pipes are fixed to a metal structure to restrain them from axial movement. The analysis includes removing noise from experimental signals, calculating overpressure in the time domain, and generating the system's frequency response using a Fast Fourier transform (FFT). There are different methods to remove the noises in the laboratory pressures. However, to avoid removing the valuable information of the pressure signal, by comparing different noise removal methods, including moving average, a frequency filter, etc., the best method for the transient was using the Butterworth low-pass frequency filter. In this method, by transferring the pressure signal from the time domain to the frequency domain, the high frequencies of the wave, which are mainly caused by environmental conditions, are removed, and the low frequencies of the signal are preserved.Results and Discussion Comparing the behavior of an intact pipe system and a pipe with a leak showed that compared to these systems, the pipe with an illegal connection has a more complex behavior and cannot be solved with a multi-step approach. In fault-finding methods based on transient with this behavior that causes a phase change in the signal, it is inevitable to optimize all the decision variables together or look for another mathematical approach to solve such problems. Knowing the behavior of a viscoelastic pipe with an illegal viscoelastic connection can be a way to decide to provide new solutions in the frequency domain.ConclusionsComparing the effect of the illegal connection with different lengths shows that with the increase in the length of the branch, its reflection is more intense and its impact on lowering the pressure signal is more evident. In general, the illegal connection's presence causes the signal's phase change, which increases over time. The comparison of the effect of transient intensity on the pressure response of the pipe system with the presence of the illegal connection shows that with the increase in the transient intensity, only the signal difference increases, which is caused by the more substantial reflection of the illegal connection. Also, approaching the transient valve, the amount of phase difference becomes more intense with time and the contrast of signals increases. The comparison of pressure fluctuations in the time domain shows that the activation of the bifurcation exerts more attenuation on the transient flow wave. However, there is no noticeable phase change in the pressure signal.
Original Article
River engineering
Rezvan Valizadeh; Ali Arman; RASOOL Ghobadian
Abstract
Extended AbstractIntroductionDue to the importance of the topic in the fluid transfer industry, the way of pipelines across the width and bed of the rivers has been considered especially in recent decades. In practice, the passage of pipelines through meandering rivers and river bends is unavoidable. ...
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Extended AbstractIntroductionDue to the importance of the topic in the fluid transfer industry, the way of pipelines across the width and bed of the rivers has been considered especially in recent decades. In practice, the passage of pipelines through meandering rivers and river bends is unavoidable. In this research, local scouring of buried and semi-buried pipe in 90-degree mild bend under different scenarios was investigated. The results of this research can help the functioning of rivers and their interaction with structures in the river such as buried and semi-buried pipelines, predicting the amount of water washing around them and using its results in the design and placement of these pipelines.MethodologyThe laboratory model on which the scenarios of this research are based includes an arc-shaped channel located in the hydraulic laboratory and physical models of the water science and engineering department of Razi University. In this arc-shaped flume, the length of the upstream span is 5.4 meters, the length of the downstream span is 4.5 meters, the inner radius is 1.6 meters, the outer radius is 2.1 meters, the height is 0.6 meters, and the floor width is 0.5 meters. In order to check the correct functioning of the physical model and to trust its results, an experiment was conducted without the presence of the pipe buried in the bend. In this experiment, the flow descent number equal to 0.32 and sediments with a uniform grain and a diameter of 0.85 mm and a thickness of 15 cm were placed in the flume bed. After conducting the test for 6 hours and not observing the movement of the bed load, the pump was finally turned off and after the complete drainage of the flume, the bed profile was measured.Results and Discussion The effect of the placement angle of the repeller pipe relative to the mild arc (θ) on the scouring patternThe results showed that by placing the pipe in the repulsive state, the amount of scour after the pipe and under the pipe has increased compared to the attracting state. According to the placement angles, it was observed that in repulsive mode, with the increase of the placement angle of the pipe in the bend, the amount of scouring after and under the pipe has increased. The effect of the placement angle of the attracting pipe relative to the mild arc (θ) on the scouring pattern In the absorbant state, it was observed that by approaching the beginning of the arc and reducing the placement angle of the pipe due to the non-alignment of the flow direction with the pipe direction, the amount of scour after the pipe decreased, but the process of scouring under the pipe was observed as in the repulsive state. The effect of pipe placement depth on scouring patternBy increasing the depth of pipe placement, it was observed that the effect of the pipe on local erosion has decreased; Even in some simulation scenarios, the placement of the pipe in the depths with the ratio of the placement height to width of the channel of 0.06 buried pipe has no effect on the local erosion. It can be concluded that at depths equal to or greater than The ratio of placement depth to channel width is 0.06, the effect of local scouring caused by the buried and semi-buried pipe is minimal, and as a result, it causes the least damages.ConclusionsThe results showed that by placing the pipe in the repulsive state, the amount of scour after the pipe and under the pipe has increased compared to the attracting state. According to the placement angles, it was observed that in repulsive mode, with the increase of the placement angle of the pipe in the arch, the amount of scouring after and under the pipe has increased. However, in the absorbiant state, it was observed that by approaching the beginning of the arc and reducing the placement angle of the pipe due to the non-alignment of the flow direction with the direction of the pipe, the amount of scouring after the pipe decreased, but the process of scouring under the pipe was observed as in the repulsive state.
Original Article
Pressurized Irrigation Systems
Seyed Reza Zaheri Kashani; Seyed Majid Mirlatifi; Hosein Dehghanisanij
Abstract
Extended AbstractIntroductionRosa Damascene Mill. is cultivated in the most parts of Iran. This flowers are worldwide well known for their fine fragrance and are harvested to produce rose oil used in perfumery or to make rose water. Due to the lack of water resources in the world, especially in arid ...
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Extended AbstractIntroductionRosa Damascene Mill. is cultivated in the most parts of Iran. This flowers are worldwide well known for their fine fragrance and are harvested to produce rose oil used in perfumery or to make rose water. Due to the lack of water resources in the world, especially in arid and semi-arid areas such as Iran, accurate estimates of the crop water requirements are necessary and essential for planning and managing irrigation events in the field. One method among the many available ones for estimating the crop evapotranspiration is the use of the reference evapotranspiration (grass) and crop coefficients. Crop coefficients can be variable due to the differences in plant variety, climatic conditions and the type of water, soil and plant managements. Therefore, for a more accurate estimate of crop evapotranspiration, local crop coefficients should be derived and used. The purpose of this research is to determine the crop coefficients of the Rosa Damascene Mill. under a two-row drip irrigation system using the soil water balance method in the Ghamsar region.MethodologyThis research was conducted during 2022 in a 53-hectare Rosa Damascene Mill. farm in the Ghamsar city. The soil moisture content prior and after each irrigation event was measured by gravimetric method. The actual evapotranspiration of the Rosa Damascene Mill. was calculated during the growing season as the residual term of the soil water balance equation. The crop coefficient was obtained by dividing the actual evapotranspiration of the Rosa Damascene Mill. by the reference evapotranspiration. ET0 Calculator and Crop Wat software were used to calculate reference evapotranspiration by the FAO- Penman- Monteith equation using the daily meteorological data recorded at the nearest weather station. In order to evaluate the usefulness of the irrigation water consumed, the water productivity indicators were determined. Using 8 volumetric flow meters that were installed at the beginning of 8 irrigation trickle lateral pipes in different parts of the field, the volume of water entering 4 control-rows of Rosa Damascene Mill. during the growing season was measured. Also, harvested flowers of the Rosa Damascene Mill. (YC) in each one of these control-rows were weighed separately and irrigation water productivity and water use productivity were determined for each one of the control-rows.Result and Discussion The Crop Wat and ET0 Calculator software estimated the seasonal reference evapotranspiration during the growing season to be 1147 and 1155 mm, respectively. The depth of water consumed by the Rosa Damascene Mill. in the wetted area by the water coming out of the emitters during the 188-day growing season of Rosa Damascene Mill. was 997 mm. The cumulative depth of water infiltrated into the wetted area was equal to 1017 mm. It should be noted that the depth of water consumption in the wetted area is not equal to the actual evapotranspiration of the Rosa Damascene Mill., because the actual evapotranspiration of the crop was calculated per unit of field area (sum of wetted and non- wetted areas), while the depth of water consumption in the wetted area was calculated. The minimum and maximum crop coefficients during the growing season were 0.6 and 1.2, respectively. The weight of the wet Rosa Damascene Mill. flower harvested from the entire farm, which is about 40 hectares cultivated out of the 53 hectares total, was equal to 130 tons. Therefore, the average yield of wet Rosa Damascene Mill. flower in the 40 hectares cultivated area was 3.25 tons per hectare. The highest amount of irrigation water productivity obtained from a control-row was 0.81 kg/m3. The average yield of Rosa Damascene Mill. flower in the evaluated control-rows was 48.25 kg per row, where the average irrigation water productivity was 0.78 kg/m3.ConclusionsThe reported crop coefficient values in the Karaj region are higher than the crop coefficient values obtained in the Ghamsar region during most of the growing season. This difference can be attributed to the differences in the climate and the type of irrigation system used, the type of crop variety, and the way the crop was managed. With the increase of irrigation volume in the studied rows, it was observed that the yield and irrigation water productivity increased. By generalizing the conditions of the control-row A to the whole farm, it was determined that if the whole farm was irrigated with a volume of 156,000 m3 during the growing season, the yield of the whole farm would had reached about 130 tons. By generalizing the conditions of control-row D to the whole farm, it was determined that if the whole farm was irrigated during the growing season with a volume of 148,725 m3, the yield of the whole farm would had been about 110 tons. Therefore, by saving 7275 m3 of irrigation water, the yield of the entire farm would decrease by about 20 tons.
Original Article
River engineering
amir moradinejad; Abbas Parsaie; saeid khosrobeghi; Seyed Ahmad Hosseini; Mahmodreza Tabatabaei
Abstract
Extended AbstractIntroduction Estimating the sediment load of rivers is one of the important and practical issues in the studies and design of water engineering projects, such as the design and development of irrigation and drainage networks, water extraction from rivers, etc. Sediment concentration ...
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Extended AbstractIntroduction Estimating the sediment load of rivers is one of the important and practical issues in the studies and design of water engineering projects, such as the design and development of irrigation and drainage networks, water extraction from rivers, etc. Sediment concentration can be calculated by direct or indirect methods, which are usually expensive and time-consuming direct methods. Various factors affect this phenomenon, which makes their analysis difficult. Statistical and regression models are the most common methods of analysis, which often provide erroneous results due to the linear solution of these phenomena. Therefore, they cannot model the sedimentation phenomenon with acceptable accuracy. Hydraulic models cannot always be trusted due to the need for a lot of data, the unavailability of the required data, and the inaccuracy of the data due to human error in simulating sediments. Due to their ability to solve complex and nonlinear phenomena, intelligent fuzzy and neural conductor systems have found many applications in various water engineering problems, including sedimentation. This research aims to evaluate and compare adaptive neural fuzzy models (ANFIS), machine Support vector (SVM), and GEP gene expression programming in estimating the sediment load of selected rivers in Central Province. For this purpose, the performance of three types of support vector machine (SVM), adaptive neural system (ANFIS), and GEP gene expression programming in the simulation of the sediment load of rivers was studied.MethodologyIn this research, first, the long-term daily statistics of temperature, rainfall, average flow rate, and sediment concentration of Bagharabad Abad hydrometric station and sediment measuring station located on the main branch of the of Qamroud River were collected. Then, the data sufficiency test for analysis, checking the correlation between parameters of river discharge, precipitation, temperature with sediment discharge, and determining the long-term average of suspended sediment in the studied stations were performed. In the next step, a suitable combination of input variables was selected. The design of input parameter pattern can be based on the relationship between flow and sediment flow parameters, rainfall, temperature, flow, and sediment flow. Determining the most appropriate time delay of input parameters in flow and sediment modeling. Estimation of sediment discharge using support vector machine (SVM), gene expression programming (GEP), and fuzzy-adaptive neural system (Anfis), comparing three data mining methods with each other as well as with gauge curve and observational data. The appropriate design of the structure of soft calculation models is used, in this research, the number of data required for training (usually more than 70 percent), research data as training, and also determining the required data (usually between 20 and 30 percent) is used for validation and testing.Results and Discussion In this research, the best performance of the GEP model has been obtained for pattern number 13. In this model, the R2 explanatory coefficient and the RMSE error obtained from the model are 0.97 and 0.033, respectively. The coefficient of explanation R2 and the RMSE error of the models in predicting suspended sediment values in the test phase were obtained as 0.53, 3.18 for the ANFIS model, and 0.70, 15.16 for the SVR model, respectively. Comparing the results of ANFIS and GEP models with the SVR model indicates the superiority of the GEP model, in predicting the amount of suspended sediment according to Verdi model number 13. According to the obtained results, it can be seen that the performance of GEP model was better compared to other models. SVR and ANFIS models are ranked second and third. According to the obtained results, it can be said that the GEP model as a powerful and high-speed model, can be used to model the suspended sediment in the Qomroud catchment area of Bagherabad station.ConclusionsThe results show the acceptable performance of the models compared to the gauge curve. Also, the results showed the superiority of the GEP model with the highest coefficient of determination R2 with a value of 0.99 and the lowest root mean square error RMSE in terms of tons per day with a value of 0.010. In this regard, the efficiency of the SVR model was somewhat better than the ANFIS model. The results showed that all three investigated data mining methods provide far better results than the sediment gauge curve.
Original Article
Pressurized Irrigation Systems
mahdi Younesi; afshin uossef gomrokchi
Abstract
Extended AbstractIntroductionAmong the applications of remote sensing in agriculture, we can mention the estimation of crop yield, the preparation of the cultivation map, the factors affecting the crop yield. The models presented to estimate the crop yield are generally based on the calculation of vegetation ...
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Extended AbstractIntroductionAmong the applications of remote sensing in agriculture, we can mention the estimation of crop yield, the preparation of the cultivation map, the factors affecting the crop yield. The models presented to estimate the crop yield are generally based on the calculation of vegetation indicators, which are used to estimate the amount of production using these indicators and with a specific algorithm. Researchers have used other methods (in addition to the direct use of vegetation indices) to estimate crop yield. In this regard, we can refer to Bastianssen and Ali's research (Bastianssen and Ali, 2003). This model (Bastiansen model) is a combination of the Monteith model to calculate the absorbed photosynthetic active radiation, the Stanford model to determine the absorbed energy efficiency, and the SEBAL model to describe the spatial-temporal changes of evapotranspiration.MethodologyThis research was carried out in rapeseed fields in the cultivated lands of Qazvin plain irrigation network. In this research, the fields were selected to cover soil texture, soil salinity, different crop management, irrigation water salinity and different irrigation methods. In order to be able to analyze the leaf area index in the process of crop performance modeling, rapeseed cultivars were the same in all the selected fields. In this research, a hybrid model was used to estimate crop yield, including the Monteith model to calculate the absorbed photosynthetically active radiation (APAR), the Stanford model to determine the light consumption efficiency (LUE), and the surface energy balance algorithm (SEBAL). In order to evaluate the crop yield prediction model, Pearson's correlation coefficient was used between the data to analyze the correlation of yield and leaf area index in different stages of growth. Results and DiscussionThe analysis of the leaf area index in the studied fields showed that the date of cultivation was one of the most important factors influencing the process of plant phenological growth and consequently the difference in crop yield in the fields. Considering that the potential yield of rapeseed in the Qazvin Plain irrigation network is estimated at 4000 kg/ha, none of the farms have reached the maximum leaf area index, and considering the direct effect of the leaf area index in the flowering stage on the crop yield, the maximum yield potential in the selected farms is not available. Therefore, the leaf area index in the flowering stage is considered a suitable criterion for estimating the yield reduction of rapeseed. The results of Pearson's correlation coefficient analysis showed that crop yield had a significant correlation with leaf area index in development and middle stages of rapeseed growth, and the highest correlation was related to the middle stage of crop growth. The results of Pearson's correlation coefficient analysis showed that there was a significant correlation at the 1% probability level between the field recorded data and yield estimation values. Also, the values of explanation coefficient (R2), root mean square error (RMSE), mean bias error (MBE), mean absolute error (MAE) were equal to 0.91, 444.06, 41.23, 433.03 kg/ha respectively. Is. Also, the results of the correlation coefficient analysis of yield values and calculated evapotranspiration based on the SEBAL method showed that there was no significant correlation.ConclusionsSeveral factors are effective in product performance, but modeling by simplifying the relationships related to a phenomenon, justifies the mutual relationships between independent and dependent variables by spending the least amount of time and money. The results of the research regarding yield estimation using vegetation indices, evapotranspiration algorithms and hybrid models show that it is possible to make an acceptable estimate of crop yield by using Remote Sensing techniques. For example, the results of present research showed that by preparing the selected image of Landsat 8 satellite (OLI and TIRS) related to the beginning of rapeseed flowering period in the following years and extracting the leaf area index in the middle period of growth, the yield of field can be predicted with reasonable accuracy. Also, the leaf area index in the rapeseed flowering stage is a suitable measure to estimate the yield gap of the rapeseed crop. The important point is that the accuracy of predicting crop performance by satellite images is still reported was average. The accuracy of field measurements, the low spatial resolution of satellite images, as well as the presence of clouds, fog, gas, and suspended particles, along with the complexities related to plant growth modeling, have an effect on reducing the accuracy of yield prediction and the validity of models. Although these researches are expected to improve and expand with the variety of satellite images and the entry of cloud computing into the field of complex computing.
