Multi- Objective Optimal Design of on- Demand Pressurized Irrigation Networks

In the context of water as an economic good, from the use of water, one can derive a value, which can be affected by the reliability of supply. On-demand irrigation systems provide valuable water to skilled farmers who have the capacity to maximize economic value of water. In this study, simultaneous optimization of on-demand irrigation network layout and pipe sizes is considered taking into account both investment and annual energy costs. The optimization problem is formulated as a problem of searching for the upstream head value, which minimizes the total cost (investment and energy costs) of the system. The investment and annual energy costs are obtained in two separate phases. Max–Min ant system (MMAS) algorithm is used to obtain the minimum cost design considering layout and pipe diameters of the network simultaneously. Clement methodology is used to determine flow rates of pipelines at the peak period of irrigation requirements. The applicability of the proposed method is showed by re-designing a real world example from literature.     

用边际分析法推求喷灌工程设计风速

本文研究了设计风速与喷灌工程费用和设计风速与喷灌均匀度，作物产量之间的关系，应用自然风速的统计分析资料推求设计风速对工程效益和费用的影响，从而提出了用边际分析理论推求最优设计风速的方法，最后通过实例验证了这一方法是切实可行的。     

Design of Barrages with Genetic Algorithm Based Embedded Simulation Optimization Approach

Barrages are hydraulic structures constructed across rivers to divert flow into irrigation canals or power generation channels. The most of these structures are founded on permeable foundation. The optimum cost of these structures is nonlinear function of factors that cause the seepage forces under the structure. There is, however, no procedure to ascertain the basic barrage parameters such as depth of sheet piles or cutoffs and the length and thickness of floor in a cost–effective manner. In this paper, a nonlinear optimization formulation (NLOF), which consists of an objective function of minimizing total cost, is solved using genetic algorithm (GA). The mathematical model that represents the subsurface flow is embedded in the NLOF. The applicability of the approach has been illustrated with a typical example of barrage profile. The results obtained in this study shows drastic cost savings when the proposed NLOF is solved using GA than that of using classical optimization technique and conventional method. A parametric analysis has also been performed to study the effect of varying soil and hydrological conditions on design parameters and on over all cost.     

Optimal Design of Pressurized Irrigation Networks to Minimize the Operational Cost under Different Management Scenarios

The adoption of measures leading to higher efficiencies in the use of both water and energy in water distribution networks is strongly demanded. The methodology proposed combines a multi-objective approach and a financial analysis to determine de optimal design of pressurized irrigation networks which entails the minimization of both the investment cost and operational cost under three operating scenarios that incorporate energy saving strategies: 1- all hydrants operate simultaneously; 2- hydrants are grouped into sectors and irrigation turns are established; 3- the on-demand operation of the network is assumed. This methodology has been applied in a real irrigation network located in Southern Spain showing that the lowest overall design cost (investment and operational costs) is achieved in scenario 2. The comparison of the selected solutions in the three proposed scenarios with the current network design considering the total fulfillment of irrigation requirements showed that operational cost savings between 65% and 76% could be achieved.     

Optimal Design for Pressurized Irrigation Subunits with a Minimum Cost and Maximum Area for Uniformly Sloping Fields

The optimal design for pressurized irrigation subunits is a complicated problem that not only requires a confirmation of the layout but also requires a pipe diameter combination. Using a subunit with single lateral and a subunit with paired laterals as research objects, four mathematical optimization models were established to identify the optimal microirrigation subunit design. The optimization criteria were minimizing the annual total cost (C_T) and maximizing the subunit size (A); it was assumed that all the emitters have equal discharge, and only rectangular subunits were considered in this study. No allowable pressure differences allocation between the lateral and the manifold were made in this study, considering that there are many factors that affect the distribution ratio and the overall optimization of the subunit. A genetic algorithm was used to obtain the optimal design when simultaneously considering the layout and pipe diameters of the subunit. The results indicated that the investment cost (C_a) is the most important factor, and it makes up 43–66% of the C_T, followed by the water cost (C_w), which accounts for 28–49% of the C_T. A subunit with paired laterals is superior to a subunit with single lateral in terms of both the total cost and the control area. On the whole, with the increase in the lateral diameter, both the total cost and the control area will increase. With an increase in the emitter discharge, the total cost increases, while the control area decreases. The change of slope in the lateral direction has little effect on the total cost and control area. The method proposed in this study is applicable to the simultaneous optimization of the subunit in which the layout and area are undetermined, and it may provide a new path towards subunit optimization.

     

轮灌渠道设计流量计算方法的一点思考

通过自上而下分配末级续灌渠道的田间净流量,再自下而上逐级推算各级轮灌渠道设计流量的计算方法,分别推定利用灌区设计灌水率和该渠道灌溉面积计算该轮灌渠道设计流量的计算公式,给相关规范中的相关计算公式予以复核明确,以利于设计工作快速有效地开展。     

Application of Artificial Neural Networks for Identifying Optimal Groundwater Pumping and Piping Network Layout

The simulation-optimization approach is often used to solve water resource management problem although repeated use of the simulation model enhances the computational load. In this study, Artificial Neural Network (ANN) and Bagged Decision Trees (BDT) models were developed as an approximator for Analytic Element Method (AEM) based groundwater flow model. Developed ANN and BDT models were coupled with Particle Swarm Optimization (PSO) model to solve the well-field management problem. The groundwater flow model was developed for the study area and used to generate the dataset for the training and testing of the ANN & BDT models. These coupled ANN-PSO & BDT-PSO models were employed to find the optimal design and cost of the new well-field system by optimizing discharge & co-ordinate of wells along with the cost effective layout of piping network. The Minimum Spanning Tree (MST) based model was used to find out the optimal piping network layout and checking the hydraulic constraints in the piping network. The results show that the ANN & BDT models are good approximators of AEM model and they can reduce the computational burden significantly although ANN model performs better than BDT model. The results show that the coupling of piping network model with simulation-optimization model is very significant for finding the cost effective and realistic design of the new well-field system.     

Suspended sediment transport in rigid boundary channels at limit deposition

Sedimentation or deposition of sediments is a crucial economical and technical problem for the design of conveyances carrying sediment laden flow such as sewers, irrigation canals and, in general, rigid boundary channels. In light of investigations on sediment transport at the limit of deposition carried out during the last two decades at the University of Newcastle upon Tyne, experimental data on suspended sediment transport collected by Pulliah (1978), Macke (1982) and Arora (1983) are analysed. The data cover a wide range of volumetric concentrations (3.7 to 48542 ppm) and sediment size (0.006 to 0.37 mm). A new model for the prediction of suspended sediment transport in rigid boundary channels at limit deposit is proposed. The model was fitted by multiple regression analysis to Macke's (1982) and Arora's (1983) experimental data. Pulliah's (1978) data validate the relation. Nalluri et al. (1994) bed load friction model is checked with available data and a good agreement is observed.     

基于全水动力学模型的波涌灌溉管理系统

基于全水动力学模型建立起波涌灌溉管理系统，用于模拟间歇供水状态下的地面水流运动，确定适宜的波涌灌水技术设计与管理参数及其组合条件，比较和选择波涌灌水技术的田间实施方案，管理有关波涌灌溉技术应用的各类信息资料。该系统是一个以实际应用为目标的波涌灌溉管理应用软件，具有计算稳定性好、估值精度高、收敛性和守恒性较强等明显特点。     

基于全水动力学模型的波通灌溉管理系统

基于全水动力学模型建立起波涌灌溉管理系统，用于模拟间歇供水状态下的地面水流运动，确定适宜的波涌灌水技术设计与管理参数及其组合条件，比较和选择波涌灌水技术的田间实施方案，管理有关波涌灌溉技术应用的各类信息资料，该系统是一个以实际应用为目标的波涌灌溉管理应用软件，具有计算稳定性好，估值精度高、收敛性和守恒性较强等明显特点。     

缺水型灌区水资源优化调度模型研究

长江针对缺水型灌区的供水特点,以云南曲靖灌区为例,应用大系统分解协调原理,将整个系统设计为两层递阶控制结构;以运行费用和系统缺水量最小作为目标函数,建立了灌区库群系统水资源优化调度模型;对模型权重系数进行了率定;根据系统目标重要性的优先次序,确定了灌区优化配水矩阵;并采用模拟技术与优化技术相结合的途径,进行优化模型的求解,给出了优化决策算法的程序框图,所建模型符合曲靖灌区的实际情况,研究成果可为同类灌区水资源调度运行提供依据.     

Pumping Optimization of Coastal Aquifers Assisted by Adaptive Metamodelling Methods and Radial Basis Functions

The application of metamodelling frameworks is a popular approach to handle the computational cost arising from complex computer simulations and global optimization algorithms in simulation-optimization routines. In this paper, Radial Basis Functions (RBF) are used as metamodels for the computationally expensive variable-density flow and salt transport numerical simulations, in a pumping optimization problem of coastal aquifers. While RBF metamodels have been fairly utilized in many engineering optimization problems, their use is very limited in coastal aquifer management. Two adaptive metamodelling frameworks are employed, that is, the adaptive-recursive approach and the metamodel-embedded evolution strategy. In both frameworks, cubic RBF models are used to approximate the constraint functions imposed on the coastal aquifer pumping optimization problem. The optimal pumping rates are first calculated based on the variable-density and salt transport numerical models of seawater intrusion. The resulting optimal solutions and the computational times are set as benchmark values in order to assess the performance of the metamodelling optimization strategies. Results indicate that the metamodel-embedded evolution framework outperformed in terms of computational efficiency the adaptive-recursive approach while it successfully located the region of the global optimum. Furthermore, with the metamodel-embedded evolution strategy the computational time of the variable-density-based optimization was reduced by 96 %.     

Hybrid Genetic Algorithm and Linear Programming Method for Least-Cost Design of Water Distribution Systems

The problems involved in the optimal design of water distribution networks belong to a class of large combinatorial optimization problems. Various heuristic and deterministic algorithms have been developed in the past two decades for solving optimization problems and applied to the design of water distribution systems. Nevertheless, there is still some uncertainty about finding a generally trustworthy method that can consistently find solutions which are really close to the global optimum of this problem. The paper proposes a combined genetic algorithm (GA) and linear programming (LP) method, named GALP for solving water distribution system design problems. It was investigated that the proposed method provides results that are more stable in terms of closeness to a global minimum. The main idea is that linear programming is more dependable than heuristic methods in finding the global optimum, but because it is suitable only for solving branched networks, the GA method is used in the proposed algorithm for decomposing a complex looped network into a group of branched networks. Linear programming is then applied for optimizing every branch network produced by GA from the original looped network. The proposed method was tested on three benchmark least-cost design problems and compared with other methods; the results suggest that the GALP consistently provides better solutions. The method is intended for use in the design and rehabilitation of drinking water systems and pressurized irrigation systems as well.     

快速测定渠道水利用系数方法研究

渠道水利用系数是衡量渠道输水效率和节水管理水平的重要指标,也是灌区改造与节水灌溉发展的标志性指标.本项目以赣抚平原灌区各级渠道为测试渠道,结合实际运用多种渠道流量流速测量仪器,进行渠道流量测验,并进行对比分析,利用动水法进行渠道水利用系数测量,对如何快速测定渠道水利用系数的测定方法进行了探讨.     

参与式灌溉管理模式科层化问题分析

从管理模式的权限结构和交易成本视角出发,分析参与式灌溉管理模式科层化的内涵、成因及类别,探讨解决科层化问题的途径与方法。结果表明,理论上参与式灌溉管理模式在权限结构、决策方式和管理机制等方面表现为混合关系、共同决定和多种管理机制相融合的特点,但实践中却往往体现出等级制、层级决策、单一行政管理机制的科层化特征。基于节约交易成本的组织行为激励,政府凭借其权限控制权进行的选择性干预和农民用水户协会等组织的适应性反应是导致科层化问题的主要成因。将政府职责限定在公共服务范围内、完善法律体系支持成立非政府灌溉管理经营组织以及提高农民用水户协会等相关组织的自我管理能力是参与式灌溉管理模式得以可持续发展的关键所在。     

Non-Uniform Flow Effect on Optimal Waste Load Allocation in Rivers

In this study, the effects of non-uniform flow due to: (i) inflow from tributaries and (ii) the presence of a downstream control structure (such as a weir or a barrage), on the optimal waste load allocation decision and the resulting cost-equity trade-off relationships, have been investigated. These effects are illustrated with in the framework of a typical cost-equity multi-objective optimization model for optimal waste load allocation in rivers. This framework consists of an embedded river water quality simulator with gradually varied flow and transport (BOD-DO) modules and a cost-equity multi-objective optimization model. A multi-objective evolutionary algorithm known as Non-dominated Sorting Genetic Algorithm-II is used for solving the optimization problem. The optimal fraction removal levels, the treatment cost and the system inequity measure are under predicted in certain reaches of the river, if the uniform flow assumption is made, while actually non-uniform flow conditions exist. This effect is quite pronounced when the flow non-uniformity results from a downstream control structure such as a weir.     

Layout and Component Size Optimization of Sewer Network Using Spanning Tree and Modified PSO Algorithm

In the paper, a new method is introduced for optimally solve the problem of the layout and component size determination of sewer network. Simultaneously Layout and component size optimization of sewer network problem consists of many hydraulic constraints which are generally nonlinear and discrete; which creates a challenge even to the modern heuristic search methods. An algorithm generation of a predefined number of spanning trees is introduced to generate a predefined number of sewer layouts of a base sewer network in order of increasing length. These generated layouts are sorted in ascending order of total cumulative flow and sorted layouts are individually optimized for sewer components sizing. It has been found that the optimal sewer layout for total system optimization is one where the total cumulative flow has the minimal value. The modified particle swarm optimization (MPSO) algorithm has been used to optimally determine the component sizes of the selected layouts. The proposed method is applied to the Sudarshanpura sewer network (situated in Jaipur, India) design problem. The results are presented for optimal cost vs cumulative flow of the layouts. Further results of MPSO has been compared with the original PSO algorithm.     

Comparative Assessment of New Design Criteria for Irrigation Improvement in Egypt

The Egyptian Ministry of Water Resources and Irrigation (MWRI) has expressed concern about the current high cost of the Irrigation Improvement Project (IIP) implemented in the “old lands” of the lower reaches of the Nile River. Because the IIP is financed through fees paid by the direct beneficiaries of the project, i.e., irrigation water users, these same Egyptian agricultural producers are especially sensitive to the higher than expected costs that the project has incurred to date. The objective of the current study is to evaluate whether this cost reduction is associated with any deficiency in irrigation performance. This Monitoring and Evaluation (M&;E) study aims to answer questions such as: Does reducing pump capacity and increased pump operation affect the farmers negatively? And, does the use of electricity instead of diesel fuel affect the farmers positively? Six indicators were used to compare new design criteria in the W10 and the IIP1 irrigation system designs, water savings, irrigation cost, irrigation time, night irrigation, and land savings. The W10 project design achieved the minimum actual operating cost per unit of area and per unit of water compared to the IIP1 project design on both Meet Yazied and El-Mesk Canals. The total cost per unit of area in the W10 project design is lower than IIP1 by 19.33% and 24.92% on the Meet Yazied and El-Mesk Canals, respectively. The total cost per unit of water in the W10 design is also lower than IIP1 on the Meet Yazied and El-Mesk Canals. Average irrigation time for rice and cotton crops cultivated in the W10 area are higher than average irrigation time for these crops cultivated in the IIP1 area for all locations on the Mesqa (head, middle and tail), because of increased pump operation in the W10 area (16 to 20 h d^???1). The number of irrigation events at the head of the Sefsafa Canal in the W10 area is higher than on the Meet Yazied and El-Mesk Canals in the IIP1 areas because of the increased pump operation in the W10 area.     

不同灌溉工作制度下的灌溉管网优化设计研究

采用基于人工神经网络的两级优化设计模型 ,对自压式灌溉管网进行优化设计 ,并分析了不同灌溉工作制度对管网投资的影响。研究表明 ,通过灌溉管网优化设计 ,可以得到不同灌溉工作制度下的管网投资最小的优化设计结果。与原始设计方案相比能够节约大量的投资 ,并可用于选择合理的灌溉工作制度。     

Optimization of Irrigation Scheduling Using Soil Water Balance and Genetic Algorithms

In arid and semi-arid countries, the use of irrigation is essential to ensure agricultural production. Irrigation water use is expected to increase in the near future due to several factors such as the growing demand of food and biofuel under a probable climate change scenario. For this reason, the improvement of irrigation water use efficiency has been one of the main drivers of the upgrading process of irrigation systems in countries like Spain, where irrigation water use is around 70 % of its total water use. Pressurized networks have replaced the obsolete open-channel distribution systems and on farm irrigation systems have been also upgraded incorporating more efficient water emitters like drippers or sprinklers. Although pressurized networks have significant energy requirements, increasing operational costs. In these circumstances farmers may be unable to afford such expense if their production is devoted to low-value crops. Thus, in this work, a new approach of sustainable management of pressurized irrigation networks has been developed using multiobjective genetic algorithms. The model establishes the optimal sectoring operation during the irrigation season that maximize farmer’s profit and minimize energy cost at the pumping station whilst satisfying water demand of crops at hydrant level taking into account the soil water balance at farm scale. This methodology has been applied to a real irrigation network in Southern Spain. The results show that it is possible to reduce energy cost and improve water use efficiency simultaneously by a comprehensive irrigation management leading, in the studied case, to energy cost savings close to 15 % without significant reduction of crop yield.