A synchronous optimization method for self-pressure drip irrigation pipe network system is proposed. We have generalized the optimization design problem of the system and have established the mathematical models for the simultaneous optimization design of pipeline layout and pipe diameters. A genetic algorithm based on the infeasibility degree of the solution was used to solve the model. A typical example is used to validate the presented method. The method exhibits effective performance in the case studied. Designers can use the results of this study to efficiently design self-pressurized drip irrigation network systems.

A multilevel drip irrigation system generally uses a first-level pivot as the water source. The water is delivered to each head pivot in the field drip irrigation subsystems through the main water distribution pipe network system (MWDPNS). Subsequently, it is irrigated to farmland through field drip irrigation pipe network subsystems (FDIPNS). This paper focused on the lowest total investment of the pipe network to establish a model for simultaneous optimization of the pipe network layout and pipe diameter selection in a multilevel gravity drip irrigation system, and the method and steps based on atom search optimization are proposed. First, all the FDIPNS are optimized; then, the MWDPNS is optimized with the optimization results of each subsystem as the basic design parameters. For the MWDPNS, the available water diversion nodes other than the water demand nodes can be added and selected. By comprehensively considering the topological and hydraulic constraints, the topology design and pipe diameter selection are optimized simultaneously when the selection of the water distribution nodes is uncertain. For the FDIPNS, the field width is regarded as a linear piecewise function of the field length, and the constraints such as the pipeline layout, flow velocity, discharge, pressure, and rotational irrigation scheme are considered. This model can be applied to most irregular fields. Taking a two-level gravity drip irrigation project in Xinjiang, China as an example, the effectiveness of the proposed model and algorithm was assessed. The results demonstrate that the proposed optimization method has a good application value for the pipe network design of multilevel gravity drip irrigation systems.

Due to the influence of topographic drops, a large elevation difference often occurs in the middle and lower sections of the main pipe of a gravity-driven irrigation pipe network (GDIPN) system. This elevation difference must be reduced appropriately through pressure reduction facilities (pressure-regulating ponds (PRPs) or pressure-reducing valves (PRVs)). The number and locations of PRPs are crucial factors in regulating and balancing the pressure head of the main pipe of a GDIPN system as well as in reducing the project cost. However, there are few studies on the optimization of this kind of pipe network system. In this paper, first, we generalize such type of GDIPN system, and a simplified mathematical model for such system optimization was established. A genetic algorithm based on a fixed proportion and direct comparison (GA-FPDC) was introduced to solve the model. Two existing projects were tested by the proposed method. The results show that the presented method not only improved the design efficiency and rationality but also greatly decreased the project cost. The presented method is effective and efficient to address optimization design of such GDIPN system problems.

Based on the structural force analysis of a lap-assembled parabolic concrete channel, it is thought that the longitudinal tensile stress is the main factor that influences channel damage. The locations where the channel is most likely to be damaged were determined, and an optimization model was established with the tensile-stress value of the structure most prone to damage area as the objective function. The calculation method of the optimization model parameters is proposed, and the calculation formula of the lap assembled parabolic concrete channel structure is derived. The multi-objective optimization model is transformed into a single-objective model by using the weighted sum method, and the resulting model was solved with the Fmincon function in MATLAB R2010a. The example analysis shows that the channel with the optimum structure section obtained by optimization is better than the channel of the practical economic section in hydraulic performance and structural force performance, and the breadth–depth ratio is reduced by 48.51%, which greatly reduces the occupied land area. In a comparison with the optimum hydraulic cross section, the hydraulic performance of the optimum structure section was slightly worse, but the breadth–depth ratio decreased by 22.98%. Regarding the structural force performance, the transverse maximum tensile stress of the channel with the optimum structure section increased by 6.02%, the longitudinal tensile stress decreased by 5.63%, while the longitudinal tensile stress was the primary influencing factor of channel damage. Therefore, the optimum structure section is better than the optimum hydraulic cross section, which indicates that the optimization method is feasible and can provide significant guidance for the structural optimization of an assembled channel and similar structures.

Hydraulic performance and frost-heaving resistance should be considered simultaneously in the channel design of seasonally frozen soil areas. Quadratic parabolic channels have good water and sand transport capacities and high frost-heaving resistances. The width–depth ratio of a parabola determines its section structural form, which in turn determines the hydraulic performance and frost-heaving resistance. In this research, based on the current lack of a comprehensive optimization method that accounts for the hydraulic performance and frost-heaving resistance of the cross-section structures of parabolic channels, a multi-objective optimization model was established with the goal of achieving a minimum cross-sectional flow area and a uniform channel section force. Taking the flow velocity, the width–depth ratio and the crack resistance of concrete lining plate as constraints, the α method of the linear weighted sum method was used to optimize the calculation, and the comprehensive optimal quadratic parabolic channel section was obtained. The comprehensive optimal section of an actual parabolic channel in the Shijin Irrigation District was determined using this method, and the comprehensive optimal section was analyzed and compared to the original design section and two typical parabolic channel sections. The comprehensive optimal section was compared with the original design section in the Shijin Irrigation District. The force uniformity of the optimal section was 23.2% better, the hydraulic performance was 1.96% better, and the land use was 12.35% less. Compared with the values for the hydraulic optimal section, the maximum positive and negative bending moments of the comprehensive optimal section decreased by 5.6% and 11.89%, respectively, and the force uniformity increased by 7.62%. Additionally, compared with the values for the practical economic section, the force uniformity and the hydraulic performance of the comprehensive optimal section increased by 1.79% and 0.2%, respectively, and the land use decreased by 4.49%. Thus, the comprehensive optimal section met the engineering requirements and it could provide a reference for the design and selection of parabolic channels in seasonally frozen soil areas.