جستجوی مقالات مرتبط با کلیدواژه « operation » در نشریات گروه « آب و خاک »

Limited water resources and low productivity of water consumption in agricultural sector, as the largest water consumer, necessitate performance improvement of irrigation networks. One of the necessary measures to do this is to use a systematic and comprehensive approach to evaluate and improve the performance of irrigation systems. The MASSCOTE approach is a comprehensive approach for modernizing medium to large-scale irrigation systems in terms of improving water delivery performance. MASSCOTE helps evaluate and prepare modernization programs in a step-by-step manner. In this research, the performance evaluation and improvement of Gotvand irrigation network was evaluated using the MASSCOTE approach. Based on the obtained results, the participation of users and the integration of their opinions and logical demands in the management of Gotvand Network, can be the solution to many problems. Establishment of water consumer association will reduce the problems related to water abstraction violations, and make it easier for users to access and regulate their contracts. Modifying the conventional method of water distribution, by volumetric distribution method creates a good capacity to reduce water losses and improve productivity in the network. According to the calculations, the annual supplied water, leakage and drainage of the network are 1209.5, 113.2 and 771 million cubic meters, respectively. Based on the network water balance, the evapotranspiration rate of crops was estimated at 325 million cubic meters, and the net irrigation requirement was calculated using meteorological information, was 389 million cubic meters, which is 64 million cubic meters less than the evapotranspiration rate. According to the results of MASSCOTE, in order to improve the network performance, the water balance should be improved to better maintain crop water requirement. It is recommended to change the cultivation pattern to a lower water consume pattern, and to reform the irrigation methods, and network management structure.

Water stored in the reservoir is one of the main sources of water supply in arid regions. Therefore, optimal operation of it is of utmost importance, especially in drought duration. In this study, optimal operation of Voshmgir dam using continues hedging policy optimized by linear programming (LP) and Partial swarm optimization Algorithm (PSO) that located in Golestan province north of Iran was investigated. The objective function is minimization of the Shortage index. In order to examine the effects of used hedging policy, 3 continuous drought years was considered. To evaluate the results of the models, evaluation criteria such as the percentage of water supply, reliability, vulnerability and stability indicators was used. The threshold volume changes per month was extracted and the base hedging rule curve for reservoir was presented. Evaluating the results of two models showed stability index in linear programming with 41.78 model was much higher than particle swarm algorithm with 6.416. Which indicates the higher performance of this model in the optimization of hedging policy in Voshmgir reservoir.

In this research, by considering the variable-speed pump, the effect of speed on pump performance, network hydraulics and energy consumption in a water distribution network in both single-objective and multi-objective models was investigated by using the new G-JPSO algorithm. The objective function in the single-objective problem is to minimize the amount of energy consumption throughout the day, and the decision variables are the amount of pump rounds in different hours of the day and night. In the multiobjective optimization problem, the first goal was to minimize the cost of consuming energy and the second goal was to maximize the hydraulic reliability. In order to determine optimal pump operation program, an optimization-simulation model based on G-JPSO optimization algorithm was developed. In this model, the algorithm was integrated into the MATLAB environment with the hydraulic part of the EPANET model as the reference of the commands and information. The proposed model was used in the Vanzyl distribution network and the optimal exploitation instructions were extracted and the results were compared with the JPSO algorithm and the ACO. The results of the paper showed that in the single-objective problem, the G-JPSO algorithm's results are 3.28 and 0.38 percent better than JPSO and ACO, respectively. In general, the energy consumption of variable-speed pumps was lowers the constant- speed pumps. In a multi-objective problem, in all optimization scenarios, the G-JPSO algorithm was able to achieve points in comparison with the ACO algorithm, which, in addition to cost reduction, has higher reliability.

Inefficient operational methods, in distribution of water within irrigation canals, call for applying more efficient ways such as using automation systems. This study assesses capabilities of the automatic operational systems, including centralized Model Predictive Control (MPC) and decentralized Proportional-Integral (PI) controller in enhancing the fairly water delivery throughout the Roodasht main irrigation canal. Existing canal’s operational condition was compared with operational status employing PI and MPC control systems. Comparison was conducted using water level error-based performance indicators of MAE and IAE, and equity indicator. Two operational scenarios including normal and severe inflow fluctuation were assigned. According to results of first scenario, upstream PI system resulting to better indicators of MAE and IAE values rather than other systems. MPC controller leading to better performance in comparison with upstream and downstream PI configurations. Application of MPC system resulted to 12% improvement in equity indicator. In the second scenario with sever inflow fluctuations at the headgate, the maximum IAE and MAE indices for MPC controller were 3.53% and 1.45%, respectively, while these indicators for decentralized systems exceeded 100%, demonstrating the inability of the decentralized systems to control the flow rate in severe water shortage conditions. Finally, calculated equity indicator in second scenario, for current operation, upstream and downstream PI and MPC, were 39.23%, 18.71%, 15.95%, and 4.33%, respectively. Results reveal that the application of centralized MPC controller has significantly improved the equity indicator by 35%.

Due to lack of available water resources and the continuous increase in the water demands, construction of new dams seems inevitable. Dams are such infrastructures for water storage and supply, especially in drought periods. If the operation of the reservoir is optimized, the purposes of dam construction is efficiently supplied. Since the optimum operation of large water resource systems are time consuming, complex and sometimes unattainable, the use of alternative methods of optimization models seems a good solution which are accurately acceptable and give near-optimum answer. Nohob Dam is one of these dams which are implementing at Khar-Rud River at the Qazvin province. The main aim of the operation of the dam is to store Khar-Rud river flows and adjust to meet water rights for agricultural lands downstream and artificial recharge of Qazvin plain. The aim of this study was to investigate the water allocation to agriculture and environmental uses and artificial recharge of aquifers in drought conditions using MODSIM model. The operation of the dam was simulated using the MODSIM model for a long period of 50-year and during the periods of 1965 to 2015, as well as a 17-year hydrological drought period during the periods of 1998 to 2015, which is determined on the basis of average changes in river discharge relative to the long-term average. Simulation was conducted monthly for four options of “before the sedimentation”, “20-year sedimentation”, “50-year sedimentation”, and “no-reservoir conditions”. Water allocation priorities are as follows: 1- environmental requirements, 2- agricultural water rights, and 3- artificial recharge. Reducing Khar-Rud water volume at the dam site from the years 1998 to 2015, has caused the loss of Nohob dam performance for various reasons, including drought and water withdraw from upstream, so that the needs of any sections is not supplied. By comparing the results of sedimentation options, it is identified that in 20-year sedimentation conditions, the reservoir has the best performance, which is due to the low dead volume compared to the useful volume of the reservoir in these conditions. By comparing reservoir performance with no-reservoir conditions with the other sedimentation options, it can be concluded that the dam construction will not have much effect on improving the water distribution conditions and the amount of supply in these conditions will not be significantly improved. In order to evaluate the simulation results of the operation of the reservoir, various parameters, such as, supply percentages, reliability, resilience and vulnerability were used. Also, the simulation results showed that in long-term simulation (50-year) and drought conditions, the dam construction would slightly change the increase in the volume and temporal water supply and demand in the region, so that the percentage of provision of the total demands of water in 20-year and 50-year sedimentation conditions are reduced from 77.4 to 37.6% and 73.7 to 35.8%, respectively, and for no-reservoir conditions, it is decreased from to 58.8 to 34.1%. By continuing the drought conditions and increasing water supply up to 1-2% as compared to the no-reservoir conditions, the dam construction and the continuation of its implementation is completely unjustified. In general, it can be concluded that in the drought conditions, the dam construction to improve the water distribution conditions is not justifiable, and perhaps its application is only to control the sudden flooding and prevent the damage caused by the flood at downstream of the dam.

Optimal operation of dam reservoirs is important due to their role in runoff control and water supply for different sectors. In this study, the Firefly Algorithm (FA) is investigated to solve the problem of optimal operation of Haraz dam reservoir to provide water for agriculture, drinking, industry and environmental of downstream for a period of 27 years (since 1984 to 2011). The objective function was defined as minimizing the sum of squared monthly relative deficiencies during operation. The efficiency of these algorithms was compared and evaluated by determination of reservoir performance indices, the value of objective function, annual deficit, monthly average deficit and release. FA method with reliability of 88.3 percent is supplied the downstream demands better than GA and SOP with reliability of 82.4 and 66.7 percent. The Vulnerability index of models is obtained 0.20, 0.23 and 0.99, respectively. The results showed the better performance of FA algorithm compared to the other two methods in solving the problem of the reservoir operation.

In this research, pressurized irrigation systems including 7 center pivot, 3 linear, and 8 solid-set with portable sprinklers systems in the provinces of Tehran, Qazvin, Alborz, and Qom were assessed using by uniformity coefficient, distribution uniformity, Potential Application Efficiency of Low Quarter, Application Efficiency of Low Quarter, and of Irrigation Adequacy indices. In order to compare the assessed systems, weighted averages of all used indexes were calculated. The results showed that the weighted average of mentioned indices are 78, 63, 69, 69 and 49 for center pivot, 75, 68, 64, 55 and 62 for Linear, and 77, 66, 60, 60 and 61% for solid-set with portable sprinkler respectively. By analyzing indices and comparison with field and pumping stations observations, it was found that the incorrect design, mismatch between design, performance and management, and incorrect operation are the main causes of low performance.

Geomembranes is a kind of geosynthetics that is used to control water losses in water storage ponds. and conveyance irrigation canals with a a fast growing rate. This lining material, in addition to the ease and speed of execution, can control water seepage losses completely. In this research, the role of execution and operation issues in control of water seepage losses in geomembrane linings was investigated. For this purpose, in 5 provinces of Alborz, Isfahan, Khouzestan, Semnan and Hamedan, 15 cases (ponds) were selected. All of these ponds were lined with HDPE geomembrane sheets with a thickness of 1.5 mm , made in Iran, with a lifetime of 8 years and ponds depth was 3 meters. Total water losses in these ponds were determined in three stages of one crop year. . Based on the results, the amount of water seepage losses from geomembrane lining is between 0.1 to 37.6 and on an average 13.9 liters/m2/day, which is about 125 times lower than the seepage losses in concrete lining. The lowest seepage losses were in Hamadan and Khuzestan provinces with 0.3 and 0.2 liters/m2/day ,respectively, and the highest value belonged to Alborz, Isfahan and Semnan provinces with 23.1, 16.2 And 29.6 liters/m2/day, respectively. Due to the uniformity of the geomembrane sheets and the geometric conditions of the ponds, the difference in the amount of seepage losses was found to be related to the quality of the execution and operation issues of geomembrane lining in the ponds. The most important issues in the ponds with high value of water seepage losses were the lack of attention to the slopes of the bed in design and execution, sediment accumulation and the need for dredging during operation, inadequate bed prepration and compaction, the presence of rocks and sharp objects under the lining, the formation of wave, the cuts due to the absence of under lining in the weld sides and the corners of the pond and human destruction during the lining.

In the present study, the state of pressurized irrigation systems in Qom province was investigated. Regarding the fact that by 2016, 81% of pressurized irrigation systems in this province are local and 19% are sprinkler, therefore, 11 local and 3 sprinkler irrigation systems (including solid-set with portable sprinklers, wheel move, and center pivot) were selected for investigation. First, the water and soil characteristics of the fields were studied then coefficient of uniformity (CU), distribution uniformity (DU), the yield of potential application efficiency of low quarter (PELQ), the yield of application efficiency of low quarter (AELQ) and adequacy of irrigation (ADirr) indexes were calculated. Obtained results showed that the mentioned indexes were 74.6, 60.8, 62.6, 62.6, 62% for solid-set with portable sprinkler, 57.6, 44.7, 76.1, 71.3, 86% for wheel move, and 81, 63, 85, 85, 71% for center pivot, respectively, and the weighted average of DU, PELQ and AELQ for local irrigation were 53.9, 45.3 and 53.9 %, respectively. Finally, the observed problems of system operation were analyzed and it was found that the main reasons of low performance were due to the management and some were due to the design and performance phases.

Considering the critical conditions that have occurred in recent decades for water resources of the country, agricultural managers are considering developing micro-irrigation systems in agricultural lands, so for their sustainable development and utilization, the evaluation of these systems is necessary. In this regard, the technical and hydraulic performance of 9 irrigation systems in Isfahan province was evaluated. In this experiment, some field measurements were taken to obtain the required parameters for system evaluation. Assessments were made based on the SCS guidelines. The results obtained from the calculation of the evaluation parameters show that amounts of coefficient of emitter discharge variation (qvar) was less than 10% for 33% of the projects, ranging from 10 to 20% for 44 percent of the projects, and over 20% for the rest of the projects, qualified as favorable, acceptable and unacceptable, respectively. The amounts of distribution uniformity (DU), in 22% of projects was more than 90%, 55% between 80 to 90% and the rest between 70 to 80%, qualified as excellent, good, and fairly good. The potential application efficiency of low quarter (PELQ) and application efficiency of low quarter (ALEQ) were between 42.4 to 78.1 % and between 47 to 81.5 percent, respectively, which is moderate. Inappropriate pressure in blocks, deficient skills of the operators, dripper clogging, and lack of proper maintenance for filters, reduce PELQ and AELQ in some projects.

Improving management of existing irrigation canals is indispensable in order to save more water. In this study, a set of four nonstructural solutions introduced in order to improve the operational performance of a main irrigation canals suffering from fluctuations of inflow water. To this end the existing operation of the Roodasht main irrigation canal was simulated applying a mathematical model and assessed by the operational performance evolution indices. Then the abovementioned solutions were investigated. The four solutions consist of operation with known disturbances; unknown disturbances; rotational water delivery out of the intakes alongside of the main canal and increasing discharge inflow. The results indicated that operational level were improved by the solutions, for example by employing the third and the forth operational solution, average value of the maximum error in water delivery was decreased by 25% and adequacy of water delivery activity was improved by18% respectively. Also, the results showed that under severe decrease of inflow to the canal, the mentioned solutions improved water delivery and distribution between upstream and downstream 17 percent.

Paddy fields development and renovation as the most important project to improve infrastructures of the rice sustainable production in North of Iran have had very slow Implementation pace due to various reasons and so that the project has been executed in less than 60000 hectares out of total paddy fields in Mazandaran province. Therefore, identification and prioritization of design, execution and operational problems is the basic requirements to change the existing situation. this research consider comparative comparison method between the design and as-built drawings, field monitoring of operating difficulties as well discussion and interview with experts. Then finalized list of problems, which used to develop a questionnaire with seven inquiries based on the Analytic Hierarchy Process (AHP). It contains four main indicators employers’ arrangements, design, execution and finally, operation and maintenance. So, 35 experts of paddy fields Development and Renovation were selected (from Jihad-e-Agriculture Organization, consulting engineers and the contractors) to fill out the questionnaire. The results indicate the fundamental limitations in order of priority are: failure to provide the timely required credits, the lack of integrated viewpoint on irrigation and drainage studies, the lack of f operational organizations same as agricultural NGOs, deficiencies in farmers training which needs for proper operation and maintenance of the projects and legal problems especially when private property is incompatible with the public profits. Therefore, serious offers of this research are change in the financing method of the projects, for example e use of combination of native and foreign countries finance, build of all layout components of project and use of other constructing project procedures such as EPC (Engineering Procurement Construction).

Improving agricultural water productivity is one of the important objectives in irrigation canal networks. Accordingly, localizing and implementation of the modern operational technologies is essential. In order to deal with operation of main irrigation canal under inflow fluctuations, in the present study, the application of decentralized automatic control system, as the first step towards the canal automation is investigated. The Inflow fluctuations happen due to water scarcity in those irrigation networks located in the southern part of the watersheds. To this end, a decentralized PI Controller is designed to be applied for operation of mathematical model of the of Roodasht main irrigation canal. The deigned controller was tested by two normal and harsh unpredictable inflow fluctuation scenarios. The results of the simulation are evaluated by the operational performance evolution indices. The results indicate that the canal operational condition under the normal inflow fluctuations is reasonably controlled by the designed PI system. But in the case of harsh inflow fluctuations, the PI controller is not capable to handle the condition and the middle and downstream canal reaches are suffering from inappropriate water taking. Therefore it can be concluded that, application of the modern centralized controller would be recommended as a reliable options for operation of the main canal.

A critical groundwater (GW) shortage in the Mahvalat Plain (MP) is alarming. As GW is the sole source of freshwater in the area, the objectives of this study are to survey and asses its current status, and to set a strategy for balancing the recharge and withdrawals to achieve the sustainable management of the most precious resource. The mean annual withdrawal and recharge of 48 production wells and 3 strings of aqueducts (Qanats) during the 1665-2008 period were 254 million m3 (Mm3) and 157 Mm3, respectively. This 97 Mm3 annual deficit resulted in the mean annual decline of the water table by 1.35 m during the same period. Chemical analyses of water samples from 48 wells and 3 strings of aqueducts indicate that the electrical conductivity (EC) increased from 0.17 s/m to more than1.5 s/m form the northeastern part of the MP towards its margins. Moreover, salinity, SAR and Sodium percentage of most samples made them unsuitable for irrigation. To achieve a sustainable management of the most precious resource, i.e., water, the solutions include: Restriction of the pumping hours according to the directives of the local water authorities to decrease the mean annual of 121Mm3, Reduction of the irrigated fields by 2/3 of the current practice, Installation of sprinkler and drip irrigation systems, Practicing advanced surface irrigation methods, Amortization of the wells with an EC of more than 0.75s/m of their water by the Government and closing them completely, and installation of smart water meters on the remaining productions wells and their continuous monitoring.

According to the low efficiency of irrigation and drainage networks and water distribution in Iran، simulating water flow and sensitivity structures and networks is considered as a new approach to evaluate the performance hydroelectric projects in the country. In this study، because of reduced water supply and distribution، especially in downstream irrigation and drainage networks Varamin to evaluate the sensitivity network in off takes structures. The sensitivity of the survey data by examining Water original data and compared them with the amount of water needed to grow the network. Network simulation and analysis using hydrodynamic model Sobek presented for sensitivity and relationships off take structures is done. Studies and sensitivity analysis for hydraulic structures Varamin irrigation system showed that baffle modules sensitivity are considerable. The study of equations، the sensitivity baffle modules occurred more than the depth upstream and valve patency rate in terminal structures. For optimal operation of the irrigation system in Varamin best way to provide for downstream water depth of each channel. In these conditions، the water supply and wastewater in all modules in the patency rate does not change.

Water resources systems as a set of structures and equipment، strongly need proper operational programming in order to optimally supply demands and perform suitable water conservation. Water reservoirs are the most commonly used water resources systems for supplying domestic demands whose incorrect management may lead to unsuitable water resources protection and huge financial losses. Approximately in all of the reservoir design، operation and management problems، real reservoir system case studies are studied and analyzed according to the existing conditions and their objectives. Under these conditions، it can be very useful to define and introduce a sample reservoir system which can be investigated for all conditions and objectives. In this research، a three-reservoir system is presented for the first time، considering all physical and hydrological parameters beside three general objectives of generating hydropower energy، supplying downstream demands (agricultural، municipal and industrial) and flood control. The obtained results are quite logical، with a natural trend based on the logically defined data for the sample reservoir system. Therefore، this sample case study is capable of showing the performance of reservoir systems in different states of single or multi reservoirs and single or multi objectives. As a result، the presented reservoir system can be used as a sample case study for introducing and developing different methods in solving water reservoir system problems.

Today, due to the decrease in water resources, the authorities intend to increase application of modern irrigation systems in farms and gardens. Therefore, evaluation and monitoring of drip irrigation systems are performed with the goal of improving systems performance. For this study, 20 samples of implemented drip irrigation systems in different cities of Golestan province have been studied in 2011-2012. The evaluation has been performed based on the guideline of Soil Conservation Service (SCS). Measurements in any field were included pressure and discharge of emitters, check the status of the central control, applied water, wetted area, water quality and talk to farmers about the state of the system strategy. The results showed that average amounts of emission uniformity (EU), statistical uniformity coefficient (UC), efficiency reduction factor (ERF), potential application efficiency of low quarter (PELQ) and application efficiency of low quarter (AELQ) were 79. 85, 90, 65 and 73%, respectively showing that the performance of drip irrigation systems is average. In general, the main problems of drip irrigation systems in the province can be classified in four main categories based on, design, implementation, management and operation of social and natural division, in each of which the most important are design and improper implementation, lack of cleaning filters, clogging and improper number of emitters, not-adjustment of inlet valve on manifold, inappropriate pressure and its nonuniform distribution, low wetted area and extreme weakness in operation management by the users.

One of the consequences of poor management and operation of irrigation systems, poor water delivery and distribution channels and divisions and consequently improper distribution of water level downstream. The study of simulation and performance evaluation software using hydrodynamic Sobek Varamin irrigation is done. In order to evaluate the network performance and compare the results of simulation, the parameters are used Molden and Gates. Simulation has been defined for the three channels degree in elementary, middle and end of irrigation network ranges, scenario for seven days and off nights. According to the results of the indicators of efficiency, adequacy, equity and reliability of the distribution network can be expressed in Varamin irrigation off night scenario is better. The result can be expressed that downstream network in the scenario of off night is better than seven days scenario and put enough water available to downstream farmers, and they can also fair to the farmers upstream, the water networks to harvesters.

The main purpose of this research was to study development strategies of implementation of agricultural water management technologies from the perspective of farmers This research was a sort of survey studies and a questionnaire was used for collection of data and information. Questionnaire''s reliability was confirmed through computing cornbanch''s Alpha coefficient which was more than 0.70. Face validity of questionnaire was confirmed by a panel of expert judgment. Statistical population of this study was consisted of 20156 farmers; out of which 205 people were selected as sample using multi-stage sampling technique. Accordingly¡ lining along the irrigation channels¡ promoting the pumps to electrical type¡ prevention of leakage from the gates¡ education of the farmers for operation and maintenance of the pumps¡ and observation of distance between the wells are priorities for development of the technology for agricultural water managements. Also factor analysis results of reception of farmers to alternative of development of agricultural water management technologies application revealed six factors totally they explained 65.28 percent of total variance.

Water user's participation in agricultural water projects is necessary for proper operation and maintenance of irrigation and drainage systems and it is one of the most important issues in development of growing communities. In Alborz Integrated Land and Water Management Project (AILWMP), due to the strategic policies and the support of the World Bank, a key goal of the project is the formation of Water Users’ Associations (WUAs). The sample population of this study was 103 board members of 19 WUAs within the AILWMP area in Mazandaran province. Field data collection instrument was a questionnaire which was validated using Cronbach– alpha, calculated at 0.73. To design the questionnaire, the Delphi method was used and, to evaluate the effective components, ten categories were determined and weighted. The first priority was sustainability, which was the main goal of the organization based on the project document. Necessity of organizing the WUA as well as education and information dissemination indexes were the second priority. Task definition and satisfaction indexes were considered as the third priority. To ensure the accuracy of answers, the questionnaire used active researchers approach. The research results showed that, up to this stage, WUA's progress have been fairly successful. The effective indexes of WUAs’ success were identified as information and training, the need to create association, roles definition, and sustainability, with respective weights of 0.326, 0.292, 0.266, and 0.239. Therefore, these components must be implemented carefully in future projects to achieve successful WUAs.