Irrigation and Drainage Structures Engineering Research

Original Article Irrigation network management

Evaluation the effectiveness of management strategies to reduce agricultural water use by using the AquaCrop model (case study: Hashtgerd plain)

Omid Raja; Sajjad Veysi; Ali Barzegar

Volume 25, Issue 96 , November 2024, Pages 26-1

https://doi.org/10.22092/idser.2024.367320.1595

Abstract

Extend AbstractIntouductionMany factors have contributed to the drop in the water table of groundwater, including the increase in cultivated area, decrease in rainfall, climate change, and the continuation of drought in recent years, and withdrawing excessive amounts of surface water sources and groundwater ... Read More Extend AbstractIntouductionMany factors have contributed to the drop in the water table of groundwater, including the increase in cultivated area, decrease in rainfall, climate change, and the continuation of drought in recent years, and withdrawing excessive amounts of surface water sources and groundwater from unauthorized wells, which has faced serious challenges in the water sector in Alborz province. The Hashtgerd plain is located in the Alborz province. The current situation of the Hashtgerd plain is the result of a series of human and natural factors over the past few decades, and the restoration and balance of the underground water of the plain is a priority. According to long-term statistics, the groundwater level has decreased by 19.8 m in 29 years (1990-2019) on average, there is a drop in the groundwater level of about 68 cm. per year. The total aquifer deficit is 487.85 million cubic meters, and the average annual amount of the aquifer deficit is 16.82 million cubic meters (6.2%). Given these conditions, it is essential to apply effective solutions for optimal and efficient water management.MethodologyThe purpose of this study was to provide practical and low-cost solutions to save water consumption in Hashtgerd Plain. There are different solutions with minimal cost, such as improving irrigation efficiency, changing the planting date, and different patterns of deficit irrigation. The approach of this study is to present and examine solutions that do not require changing the irrigation system or even changing the cultivation pattern and also not reducing the cultivated area in the region. It is the examination of the solutions that can be implemented at the lowest possible cost without adversely affecting the livelihood of farmers. The objective of the study was to reduce water consumption or prevent from excessive groundwater of Hashtgerd plain aquifer. The proposed solutions do not require new tools such as precision leveling machines and, so on. Each of the above strategies was evaluated based on the actual conditions in the region. The main objective was to evaluate and estimate the water requirements of the dominant crops in the Hashtgerd Plain, and to present different scenarios for improving irrigation efficiency according to the superior conditions in the region. The feasibility of saving water consumption through strategies to change the planting date and deficit irrigation was evaluated using the AquaCrop 6.0 model.Results and discussionIn this study, the AquaCrop model was used to simulate the yield of crops and the amount of water use in the region. The calibration of the AquaCrop model for regional conditions has demonstrated that the AquaCrop model is capable of predicting crop yield with the lowest relative error (RE) for wheat, barley, fodder corn, and alfalfa for the plains during the calibration phase of the simulation model. According to the levels of efficiency improvement in different regions and for different crops, it will lead to savings of 17.7 million cubic meters (5.9%) in the amount of allocated water consumption. This will can provide the possibility of supplying water to a larger area of land without reducing yield under water scarcity conditions. The outcomes of the scenario involving a change in planting date through AquaCrop model simulation demonstrated that this management pattern has the potential to reduce water consumption by 2.4 million cubic meters (0.8%) in the region. In addition, different levels of deficit irrigation can save 19.3 million cubic meters of water consumption.ConclusionThe obtained results show that in many cases, it is possible to provide without modern facilities and huge costs, applying different scenarios such as improving efficiency, changing planting dates and deficit irrigation has achieved significant savings in the required irrigation water consumption. Naturally, the share of each crop in the amount of savings is proportional to the average water consumption per hectare and the area of land under each crop. In general, the AcuCrop model can be used as a practical tool for simulating crop yield and evaluating management scenarios.

Original Article River engineering

Quantitative simulation of diverged flow using machine learning techniques and FLOW3D numerical modeling

Iman Karimi Sarmeydani; Mohammad Heidarnejad; Aslan Egdernezhad

Volume 25, Issue 96 , November 2024, Pages 46-27

https://doi.org/10.22092/idser.2024.366862.1591

Abstract

Extend Abstract Intouduction Groynes at water intake locations significantly increase the flow diverted from rivers by optimizing incoming water control. Vaghefi and Ghodsian (2017) experimentally studied flow patterns around a T-shaped Groyne within a 90-degree arc using a moving bed. Shaker and Kashfipour ... Read More Extend Abstract Intouduction Groynes at water intake locations significantly increase the flow diverted from rivers by optimizing incoming water control. Vaghefi and Ghodsian (2017) experimentally studied flow patterns around a T-shaped Groyne within a 90-degree arc using a moving bed. Shaker and Kashfipour (2013) compared flow velocity and shear stress distribution with and without Groynes. Behnam-Talab et al. (2018) simulated porous Groynes using FLOW-3D software. Shahinejad et al. (2022) applied a multi-objective algorithm to optimize T-shaped Groyne dimensions, achieving superior results, compared to previous designs. Zare and Honer (2016) investigated how simple Groynes reduce lateral erosion in river arches under laboratory conditions, emphasizing the influence of Groynes on erosion patterns. These studies collectively highlight the importance of Groyne design in enhancing water extraction and mitigating erosion. The review of literatures confirms that both laboratory and numerical studies have been conducted to examine the characteristics of various types of Groynes and the impact of flow patterns on them. However, there is a lack of studies addressing the simultaneous application and comparison of numerical and data-driven models in the investigation of geometric and hydraulic characteristics, particularly concerning the effect on the amount of diverted discharge from a canal into intake featuring T-shaped and L-shaped Groynes. Consequently, this research aims to evaluate the performance of two MLMs, specifically SVM and GEP in comparison with the Computational Fluid Dynamics (CFD)-based FLOW-3D model, on a laboratory scale. Materials and Methods Groynes play a crucial role in river engineering by regulating river flow. This study assesses the efficacy of two machine learning algorithms—support vector machine (SVM) and gene expression programming (GEP)—in comparison with FLOW-3D software for simulating diverted flow in a laboratory setting. The experimental model was tested in a laboratory flume with T-shaped and L-shaped Groynes positioned at 90 and 135-degree angles to channel the discharge into the intake system. The machine learning models incorporated three independent variables: the flow Froude number, the angle of water intake, and the relative length of the Groynes. Out of 96 laboratory data points, 70% were allocated for model training and 30% for model testing. Model performance was assessed using the root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R²) indices. Results and Discussion The results indicated that the GEP model surpassed the SVM model. For the L-shaped Groyne, the values for (R², MAE, RMSE) during both the training and testing phases were (0.9325, 0.9878, 1.2536) and (0.9836, 0.4102, 0.6325), respectively. For the T-shaped Groyne, the corresponding values were (0.9025, 1.2534, 1.8502) during training and (0.9873, 0.3337, 0.4972) during testing. In the FLOW-3D model, after calibration and validation, a Manning's roughness coefficient of 0.035 and the Prandtl's mixing length model were chosen for turbulence simulation. The performance indices during the testing phase for the L-shaped and T-shaped Groynes were (0.9607, 0.9363, 1.2070) and (0.9513, 1.1256, 1.3759), respectively. The GEP model showed a relative advantage over the FLOW-3D model. Concutions This study compares the performance of MLMs (SVM, GEP) with FLOW-3D in simulating diverted flow using T-shaped and L-shaped Groynes. Results from laboratory flume tests showed GEP outperformed SVM and FLOW-3D, particularly in simulating flow diversion, evaluated by RMSE, MAE, and R² performance indices.

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

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.

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

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.

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

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

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

Abstract

Extended AbstractThe 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 ... Read More Extended AbstractThe 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. 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%.IntroductionIn irrigation and drainage networks that are designed with a certain capacity, for various reasons, including improper operation by water collectors and in rivers and other natural channels, by imposing excessive capacity currently on them, excess current is created which can cause serious damage to them. And the economy of the project will be challenged and of course, it can lead to life-threatening risks. In the design of dams, according to the location of the dam and in order to use more of the volume of dams for flood control purposes or just more reservoir volume, sometimes the dam is located in such a way that the possibility of constructing a main weir perpendicular to the mainstream is technically and economically justified. Therefore, in such cases, the side weirs are introduced and designed as the main weirs of the dam. Also, in some dams that have been constructed with old hydrological information and meteorological statistics and information indicate that the weir will be potentially dangerous for future floods, the option of overflow correction or using side overflows as auxiliary overflows are suggested. Emin Emiroglu et al. (2010) performed about 2,900 experiments in the subcritical flow mode to analyze the water surface profile on the weir and the flow velocities along with the weir. Their results showed that the weir discharge coefficient in labyrinth weir mode is about 1.5 to 4 times higher than in rectangular weirs. Bagheri and Haidarpour (2012), by measuring the three-dimensional components of the flow velocity in the main channel near the rectangular side weir, concluded that the horizontal flow velocity component at the lower end of the stream decreases. Also, by examining the transverse and deep components of the flow, it was concluded that most of the flow is discharged from the lower end of the weir. Using physical models, Michelazzo (2015) proposed a new approach to solving the Dimarchi equation for zero-height side weirs in an open canal. To solve this model, the flow conditions were considered subcritical and the substrate constant. Solving them without using numerical methods makes it possible to estimate the weir outflow according to upstream and downstream hydraulic conditions. Aydin (2015), by placing the sill on the bed of the canal in three positions of the upstream end, the downstream end and in the middle of the weir, concluded that the presence of an obstacle at the lower end of the weir increases the lateral rectangular weir coefficient. Maranzoni et al. (Maranzoni, 2017) performed numerical and laboratory analyses on a side weir in a rectangular convergent channel. Their experiments, which were performed under subcritical and sustained flow conditions, show that the number of downstream landings and the dimensionless height of the weir has the greatest effect on the flow rate through the lateral weir in a converging channel. The approach of studies in recent years has tended to increase the efficiency and innovation in the use of new geometries of lateral weirs as well as new strategies and methods for estimating the discharge coefficient of these weirs. These findings include Ghaderi et al.'s (2020) studies to use numerical models to estimate the flow rate of trapezoidal zigzag weirs, Karimi et al. (2018) on the use of piano key weirs with a rectangular plan As side weirs, Saghari et al.'s (2019) studies and Seyed Javad et al. (2019) studies on the use of trapezoidal piano key weirs and Dibaco & Scorzini (2019) studies to estimate The lateral weir flow coefficient using neural network methods was pointed out. MethodologyConsidering several geometric parameters that affect the discharge coefficient of trapezoidal piano key side weirs, this study was designed to achieve the two main objectives of investigating the effect of trapezoidal piano key side weir height on its discharge coefficient and investigating the longitudinal profiles of flow depth in the main channel. In parallel with the main objectives, this study follows the study of the Dimarchi hypothesis in estimating the discharge coefficient of the piano key weir as well as its discharge capacity of it. In this regard, four trapezoidal piano key weir models differ only in height and therefore the inclination of the inlet and outlet keys, one trapezoidal labyrinth weir model, and a rectangular linear model as a control model will be tested in different Froude numbers.In line with the purpose of the present study, six models were designed and built. These models included a sharp rectangular linear model (control model), a trapezoidal labyrinth model, and four trapezoidal piano key weir models with heights of 10, 15, 20, and 25 (Figure 1). Figure 1 shows all the models in three perspective views, plan and cross-section.Results and Discussion Adjusting the water level in irrigation and drainage networks in order not to disrupt the operation of reservoirs b creating a water level profile at the upstream end of the reservoir and also the pressure on the body of piano s, especially the side crown and inlet and outlet gutters according to the thickness and materials used. They are important topics for design engineers in irrigation and drainage networks and spillway design. 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.Figure 3-a shows the Head-discharge curve of experimental models and 3-b shows the average flow rate of experimental models compared to the control model. As shown in this figure, for all dimensionless Y1/P ratios, the discharge through the TNRSW is higher than the control model (Lisw). Also, the flow rate through TPKSWP20 is higher than the TNRSW model. It is worth noting that in all dimensionless dimensions Y1/P, the flow through the piano key weir with a height of 10cm is less than all models. This rate is even 30% lower compared to the control model. The high velocity of the flow in the main channel and the impossibility of discharging the current even from the downstream cycle, which plays the greatest role in discharging the side weir, in the TPKSWp10 model reduces the effective length of the overflow crest in discharging the flow and is the main reason for this difference. Also, as shown in this figure, the flow rate of the TPKSWp25 model is higher than other models. A comparison of average flow rate overflows in Y1/P ratios and the Froude range of the present study shows that the average flow rates of TPKSWp25, TPKSWp20, TNRSW, and TPKSWp15 models are 2/60, 1/92, 1/59 and 1/38 times higher than the control model, respectively.

Estimation of rapeseed yield using Geo-data and remote sensing (Case study: Selected Lands cultivated in Qazvin plain irrigation network)

Volume 23, Issue 88 , February 2023, , Pages 126-148

https://doi.org/10.22092/idser.2023.360853.1530

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 ... Read More 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.

Determination of Applied Water and water productivity of lemon orchards in Iran

Volume 23, Issue 87 , October 2022, , Pages 1-20

https://doi.org/10.22092/idser.2022.358902.1512

Abstract

Extended Abstract IntroductionMost regions of Iran are considered as arid and semi-arid regions. Water management in the agricultural sector is very important as the largest consumer of water resources in the country. In order to better plan and manage water resources in the agricultural sector, ... Read More Extended Abstract IntroductionMost regions of Iran are considered as arid and semi-arid regions. Water management in the agricultural sector is very important as the largest consumer of water resources in the country. In order to better plan and manage water resources in the agricultural sector, it is necessary to have sufficient information about the amount of water used in different products. Given the importance of its lemon product in the country, and conducting little research on this issue, determining the applied water for lemon orchards in the country can be useful for planning and macro decisions in the country. A review of literature shows that a lot of information has been collected in the world about the required water and the effect of different irrigation methods on citrus fruit yield. However, little research has been done on irrigating lemon trees under the management of gardeners. In Iran, little research has been done on the management of lemon irrigation. Therefore, in this study, the volume of applied water and water productivity of lemon trees in the country have been measured and evaluated.Methodology In this field study, irrigation water volume and lemon yield in over 210 selected orchards in Fars, Hormozgan, Kohgiluyeh, Boyer-Ahmad and South Kerman provinces were measured directly. Fruit yield was obtained in three consecutive years and their mean was used in the analysis. Analysis of variance was used to investigate the possible differences in yield, irrigation water volume and water productivity in lemon production. After determining the inflow of water to the garden by carefully monitoring the garden irrigation program and measuring the area under cultivation, the volume of irrigation water applied by lemon trees in each garden was measured. Multiplying the flow rate during the total irrigation period during the season, the amount of irrigation water volume was obtained. In each of the gardens, items such as soil texture of the gardens, electrical conductivity of soil and irrigation water, etc. were also measured. The amount of evapotranspiration of the lemon tree in each region was calculated using meteorological data of the station closest to the project implementation area in the last 10 years and the year of the research using the Penman-Montieth method. The results were compared with the calculated net required irrigation water and the values presented in the National Water Document (NETWAT).Results and DiscussionThe results showed that the differences in yield, applied water volume, and indicators related to water productivity were significant in the mentioned provinces. The weighted average yield of lemon was 21.7 tons per hectare. The weighted average volume of irrigation water and total applied water were 11938 and 12993 cubic meters per hectare, respectively. The weighted average irrigation water productivity was estimated to be 1.94 kg/m3. Weighted average water+long-term effective rainfall productivity was 1.59, kg/m3. Weighted average of water and current year effective rainfall productivity were 1.75 kg/m3, respectively. The proportion of irrigation water volume of lemon orchards with gross water requirement in selected provinces was similar. In general, the average difference between the depth of irrigation water and annual and long-term gross water requirement in the country was -17 and -1 percent, respectively. In the orchards under drip irrigation system compared to surface irrigation, fruit yield and water productivity increased 43 and 89 percent, while irrigation water volume decreased about 20 percent. Salinity of water and soil, age of trees, literacy level of gardeners, climate, soil texture were some of the factors that affected yield, water productivity and volume of irrigation water.ConclusionsAccurate determination of plant required water and volumetric water delivery can be very effective in reducing irrigation water and increasing water productivity. In addition to these two factors, adhering to irrigation scheduling in lemon orchards can produce the maximum yield per allotted amount of water. In creating or renovating of lemon orchards, cultivars should be planted that are resistant to cold and salinity and have the ability to export, while increasing the area under cultivation in proportion to water resources.

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