Atiyeh Bozorgi; Abbas Roozbahani; Seied Mehdy Hashemy shahdany
Abstract
Agriculture is one of the most important economic sectors of Iran and the largest consumer of surface and underground water resources. Since various risks threaten agricultural water supply systems, developing a risk analysis framework is inevitable in order to identify and assess the impact of the aforementioned ...
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Agriculture is one of the most important economic sectors of Iran and the largest consumer of surface and underground water resources. Since various risks threaten agricultural water supply systems, developing a risk analysis framework is inevitable in order to identify and assess the impact of the aforementioned systems on promoting sustainable agricultural development. Therefore, for the first time, the present study has attempted to develop a drought risk analysis model for agricultural water supply system with the Bayesian network. The structure of this model, which consists of nodes and their interactions, is designed by using river discharge, water released from the upstream water diversion system, groundwater and irrigation network demand to provide system risk. In order to investigate the capability of the developed model, the risk analysis of the modern Roodasht Irrigation System in Isfahan was investigated. The risk values of the Roodasht agricultural water supply system were estimated in the range of zero to 58.11% and an average of 39.82%. The results showed that this model has good accuracy and performance in both training and test sections, with the root mean squares error of 0.09 and 0.1, coefficient of determination of 0.85 and 0.75, and overall index of model performance of 0.82 and 0.74. The results of this research and the proposed model helps operators and decision makers to better plan the allocation of irrigation water based on the risks predicted in hydrological drought conditions.
Kazem Kamrani; Abass Rouzbahani; Seied Mehdy Hashemy shahdany
Abstract
This study investigated the impact of improving surface water delivery and distribution systems on reducing groundwater abstraction. For this purpose, the current operational management of the Rudasht irrigation network, located in Isfahan province, was modeled and evaluated. Then, impact of two ...
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This study investigated the impact of improving surface water delivery and distribution systems on reducing groundwater abstraction. For this purpose, the current operational management of the Rudasht irrigation network, located in Isfahan province, was modeled and evaluated. Then, impact of two methods as the modernization alternatives, including an improved manual operation and an automatic control system by using the Model Predictive Control (MPC), was investigated. Operation of the canal system was simulated under two operating scenarios, demonstrating the operational status under the normal and water shortages conditions. Improvement of water supply and distribution process in the canal was evaluated using adequacy and dependability indicators of water distribution. In the next step, the amount of surface water replaced by groundwater was calculated by improving the process of water distribution in the main canal based on spatial analysis of the adequacy index. The results obtained from the operational simulation in the normal condition scenario showed improvement of the adequacy index by 5% and 32% and the dependability index by 7% and 21%, respectively, for the improved manual method and MPC. Moreover, the improvement in this scenario resulted in 3% and 25% reduction in the aquifer extraction, respectively, for the modernization alternatives. Operational simulation results under the water shortage scenario revealed 2% and 13% higher adequacy index, and 11% and 25% improvement in the dependability index by employing the improved manual and MPC approaches, respectively. This improvement resulted in 1% effectiveness for the improved manual method and 9% effectiveness for the MPC method in reducing aquifer abstraction under water shortage scenario. According to the spatial maps of the adequacy index obtained for the MPC method, this method can achieve more uniform and fair water delivery to farmers, especially under water shortage conditions.
Morteza Babaei; abbas roozbahani; Seied Mehdy Hashemy shahdany
Abstract
Accurate identification of the potential hazards within the main Agricultural Water Conveyance and Delivery Systems (AWCDS) and their influences on the system failure could provide practical solutions for improving the operational performance of the systems. Therefore, risk analysis in AWCDS is inevitable ...
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Accurate identification of the potential hazards within the main Agricultural Water Conveyance and Delivery Systems (AWCDS) and their influences on the system failure could provide practical solutions for improving the operational performance of the systems. Therefore, risk analysis in AWCDS is inevitable to the system recognition and reliability endurance against the imminent hazards. Satisfactory operational of the AWCDS in irrigation networks is associated with delivery of adequate and equitable water to the entire off-takes located within the main irrigation canals. Accordingly, this study was conducted, for the first time, to present a unique framework to assess the adequacy, equity, and efficiency of water delivery risk analysis within AWCDS. To this end, the "fault tree" technique was employed for risk analysis of the disaster (hazardous event) which is called the "undesirability of supply and delivery". Consequently, factors leading to the occurrence of the failure, including natural hazards, human and operational threats as well, are recognized and formed the basic and middle events in the “fault tree" structure. The designed "fault three" was tested on the West Dez main irrigation canal, as the case study of the research. By interviewing the manager, local authorities, ditch-riders, and personnel of the Dez irrigation district, a set of questionnaires were filled up. According to the obtained information, failure probabilities of the basic events were gathered in the form of linguistic terms. Later, the assembled fault tree was analyzed and, as a result, the failure probability of the secondary events and the top event was determined. Failure likelihood of the top event was calculated at about 30%. Consequently, due to this high failure likelihood, basic events were ranked based on their share in the occurrence of the relevant secondary events as well as the top event. The five most important events were "failure to fund maintenance process", "lack of operation flexibility", "non-homogeneous operation system", "inactivity of cultural and training centers of the province" and "inaccurate operation of the intakes". The Birnbaum index of these events varied from 0.055 to 0.097. Ranking of the events affecting the adequacy, equity, and efficiency was performed, with similar results.
maryam yousefi; Mohammad Ebrahim Banihabib; jaber soltani; abbas rouzbahani
Abstract
To address farmers’ as well as water resources and environment managers’ opinions, it is necessary to develop the optimal cropping pattern models for maximizing farmers’ benefits, reducing nitrogen leaching, and improving the rate of aquifer recharge by applying quantitative-qualitative ...
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To address farmers’ as well as water resources and environment managers’ opinions, it is necessary to develop the optimal cropping pattern models for maximizing farmers’ benefits, reducing nitrogen leaching, and improving the rate of aquifer recharge by applying quantitative-qualitative conjunctive use of unconventional surface water (reclaimed wastewater) and groundwater. In this research, the developed models (nonlinear programming (NLP) and particle swarm optimization (PSO)) were run in Varamin Irrigation Network for water year 2012-2013. The results of solving 3-objective nonlinear programming (NLP) model showed that by improving the net benefit of cropping pattern optimization, water productivity and aquifer recharge by about 6%, 22% and 29% led to reduction of conjunctive withdrawals of wastewater and groundwater and fertilizer consumption by about 13% and 85%. Also, the results of solving 3-objective model by Particle Swarm Optimization (PSO) algorithm showed that by improving the net benefit of cropping pattern optimization, water productivity and aquifer recharge by about 7%, 49% and 30%, conjunctive withdrawals of wastewater and groundwater summation and fertilizer consumption decreased by about 35%, 88%, respectively. Comparison of the results of the values of objective functions in different scenarios by NLP and PSO methods showed a difference of about 0.002% to 0.01%. So, heuristic algorithm (PSO) has very little difference with NLP and has great ability in providing optimal results. The results of this research could be applied to the optimum use of water resources, increasing farmers’ benefits and decreasing nitrogen leaching in other irrigation network projects. However, it is to be emphasized that use of wastewater for irrigation of food crops for human and domestic animals is not recommended and full compliance with standards and regulations in applying reclaimed waste water in agriculture, is necessary and binding.
m y; j s; Mohammad Ebrahim Banihabib; a r; a r; e s
Abstract
Due to extensive agricultural activities on the plains and the use of chemical fertilizers containing nitrogen, significant amount of this element enter the aquifer. On the other hand, effluent of wastewater treatment plants is used in irrigation and drainage networks as an alternative or supplementary ...
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Due to extensive agricultural activities on the plains and the use of chemical fertilizers containing nitrogen, significant amount of this element enter the aquifer. On the other hand, effluent of wastewater treatment plants is used in irrigation and drainage networks as an alternative or supplementary source of surface water. Therefore, adoption of strategies for reducing and controlling the amount of nitrogen that enters the soil and aquifer is an important issue. The aim of this research was to develop a cropping pattern optimization model by quantitative-qualitative conjunctive use of unconventional surface water (wastewater) and groundwater. The three objectives of the model were maximizing profits from cropping pattern, reducing nitrogen leaching, and improving the rate of aquifer recharge. In order to integrate management of wastewater and irrigation water resources, the nonlinear three-objective optimization model was run for 7 scenarios (one-objective, two-objectives, and three-objectives) in water year 2012-2013, for Varamin irrigation network. The input data required for the model were collected in two ways: regional testing and obtaining information from various institutions.Solving one-objective model by first objective (first scenario: improving the network’s profit) showed the 49 percent improvement in the network’s net profit. The second objective (second scenario: reducing of fertilizer consumption) showed 95% reduction of fertilizer consumption, and the third objective (third scenario: improving the aquifer recharge) showed 120% improvement in the aquifer recharge, in comparison to the current situation. Solving the three-objective model (seventh scenario: combined objectives of improving network’s net profit, reducing fertilizer consumption, and improving the aquifer recharge) showed a reduction of 23% in cultivated area, 71% in nitrogen fertilizer consumption, and 13% in conjunctive withdrawals of wastewater and groundwater. Also, these reductions increase net benefit by 6%, aquifer recharge by 29%, and water productivity by 22%. Therefore, the seventh scenario was chosen as the best scenario. The results of this research could be adopted for optimum use of water resources, increasing farmers’ benefit, and decreasing nitrogen leaching in irrigation network projects. However, it is to be noted that, generally, use of wastewater for irrigation of food crops is not recommended.