Long-distance Water Transfer Research Articles

Failure probability analysis of high fill levee considering multiple uncertainties and correlated failure modes

Such complex causative factors in current failure probability models are represented by simply random uncertainty and completely independent or correlation of failure modes, which can often limit the model utility. In this study, we developed a methodology to construct failure probability models for high fill levees, incorporating the identification of uncertainties and an analysis of failure modes. Based on quantification of stochastic-grey-fuzzy uncertainties, probability analysis involved with overtopping, instability and seepage failure modes was implemented combined with probability and non-probability methods. Given that the interaction among failure modes typically exhibits nonlinear behavior, rather than linear correlation or complete independence, a simple methodology for the binary Copula function was established and implemented in MATLAB. This methodology was applied to the high fill segments of a long-distance water transfer project characterized by high population density. It shows that the failure probability of a single failure mode is overestimated when uncertainties are not considered, because of the randomness and fuzziness of some parameters and the greyness of information. Meanwhile, it is found that the magnitude of failure probability related to levee breach is overestimated without respect to failure modes correlation, especially when the probabilities of seepage and instability are both significant and closely aligned.

Internal Flow Characteristics of Centrifugal Pumps under Different Startup Combination Schemes

Pump station engineering is a water conservancy project used for long-distance water transfer, irrigation and drainage, and urban living and industrial water supply. Centrifugal pumps are one of the main pump types commonly used in pumping stations, and their operation is of considerable importance for the safety, stability, and efficient operation of pumping stations. This paper takes a large pumping station with seven centrifugal pump units as the research object and combines experimental research and numerical simulation. The axial flow velocity uniformity, average cross-sectional deviation angle, and hydraulic loss of the pump inlet section are evaluated, and the internal flow characteristics of the pump under different startup combination conditions are analyzed based on entropy generation and vorticity. This study also explores the operational performance of the pump station under different startup combination conditions, revealing the mutual influence mechanism between different startup combinations of pump stations and the internal and external characteristics of centrifugal pumps and introducing the optimal startup combination scheme for the pump station system. Research results indicate that the difference in energy loss of centrifugal pumps under different startup combinations is mainly manifested in the impeller and guide vane flow channels. For the two existing inlet flow channel structures in the pump station, the unit effectively operates when the inlet flow channel is tilted to the left. The optimal startup combination method of the pump station under different startup combinations is determined.

Infrastructural lock-ins in the temporal and spatial development of a long-distance water transfer in Germany

Germany plans to expand water transfers over long distances in the light of numerous and pressing challenges for drinking water supply. Research on inter- and intrabasin water transfers warns, however, that major investments in large-scale infrastructure systems accompanied by institutional logics and political interests often lead to a so-called lock-in. As a consequence, long-distance water transfers can limit the potential for adaptive water governance in the involved supply areas over decades with negative impacts for people and the environment. By using a case study in Germany as an example, we researched when, where and how such lock-ins around long-distance water transfers emerge. In the infrastructural development of the Elbaue-Ostharz transfer system we found various lock-ins that overlap in space and time. Some are located at the centre others at the margins of the infrastructure and commercialization of the water sector as well as hydraulic and hygienic concerns interlocked with local protests in a way that the expansion of the long-distance water transfer infrastructure was continuously presented as imperative. Our findings contribute to a relational understanding of lock-ins of long-distance water transfers as contingent and diverse processes. Given the widespread occurrence of lock-ins, we argue for a context-specific assessment of potentials and risks of long-distance water transfers in times of multiple crises.

Experimental and numerical simulations of river-crossing pipelines for different water fill patterns

In the process of water filling in long-distance water transfer projects, the transient flow of water and air, along with the fluctuation in pressure, indicates the complexity of the hydraulic transition process, particularly when there are curved pressurized pipes, and the movement of air inside the pipes is not easily determined. This study focuses on pipeline systems with significant changes in elevation, such as those crossing rivers or roads. It employs a combined approach of generalized model experiments and numerical simulations to investigate the formation and transformation of flow patterns in the pipeline system during the filling process. It also analyses the fluctuation of pressure on both sides of the curved pipe under different filling modes and reveals the coupling mechanism between the movement of large-scale air bubbles and turbulent vortex structures within the curved pipe. When the water filling velocity at the pipeline inlet is v = 0.8 m s–1, the size of the bubbles formed by the air is larger, the variety of flow patterns is greater, and the evolution of flow patterns is more complex. When impounded water occurs in the river crossing pipeline due to maintenance, the pipeline system forms slug flow at a filling flow velocity of v = 0.8 m s–1. This leads to an abrupt change in the overall pressure of the pipeline system, with the maximum pressure being 1.36 times that of the filling flow velocity of v = 0.4 m s–1. At a filling flow velocity of v = 0.8 m s–1, bends in the pipe readily foster the formation of large-scale bubbles. The interaction between the buoyancy and drag forces acting on these bubbles and the centrifugal forces provided by the bends results in continuous changes in the hydraulic conditions within the pipe. The research findings not only enrich the study of the hydraulic transition process in pipeline systems but also hold significant importance for expediting the construction pace of long-distance water transfer projects.

Simulation of the Entire Process of an Interbasin Water Transfer Project for Flow Routing

The flow routing process plays a crucial role in underpinning the execution of real-time operations within interbasin water transfer projects (IWTPs). However, the water transfer process within the supplying area is significantly affected by the time lag of water flow over extended distances, which results in a misalignment with the water demand process in the receiving area. Hence, there is an imperative need to investigate the flow routing patterns in long-distance water transfer processes. While MIKE11(2014 version) software and the Muskingum method are proficient in simulating flow routing within a water transfer network, they fall short in addressing issues arising from mixed free-surface-pressure flows in water transfer pipelines. This study enhanced the capabilities of the MIKE11(2014 version) software and the Muskingum method by introducing the Preissmann virtual narrow gap method to tackle the challenge of simulating mixed free-surface-pressure flows, a task unattainable by the model independently. This approach provides a clear elucidation of hydraulic characteristics within the water transfer network, encompassing flow rates and routing times. Furthermore, this is integrated with the Muskingum inverse method to compute the actual water demand process within the supplying area. This methodology is implemented in the context of the Han River to Wei River Diversion Project (HTWDP). The research findings reveal that the routing time for the Qinling water conveyance tunnel, under maximum design flow rate conditions, is 12.78 h, while for the south and north main lines, it stands at 15.85 and 20.15 h, respectively. These results underscore the significance of the time lag effect in long-distance water conveyance. It is noteworthy that the average errors between simulated and calculated values for the south and north main lines in the flow routing process are 0.45 m3/s and 0.51 m3/s, respectively. Compared to not using the Preissmann virtual narrow gap method, these errors are reduced by 59.82% and 70.35%, indicating a significant decrease in the discrepancy between simulated and calculated values through the adoption of the Preissmann virtual narrow gap method. This substantially improves the model’s fitting accuracy. Furthermore, the KGE indices for the flow routing model are all above 0.5, and the overall trend of the reverse flow routing process closely aligns with the simulated process. The relative errors for most time periods are constrained within a 5% range, demonstrating the reasonability and precision of the model.

Measuring Dam Deformation of Long-Distance Water Transfer Using Multi-Temporal Synthetic Aperture Radar Interferometry: A Case Study in South-to-North Water Diversion Project, China

Long-distance water transfer is a critical engineering measure to rectify disparities in water resource distribution across regions. The effective operation and safety of such projects are paramount to their success, as localized issues can have cascading consequences, potentially disrupting the entire network. Conventional ground-based monitoring methods have limitations in measuring the deformation of large-scale structures. In this paper, InSAR is employed to monitor the deformation of the Shuangwangcheng (SWC) Reservoir, which features a long embankment dam as part of the South-to-North Water Diversion Project in China. We utilize data from both Sentinel-1 and TerraSAR-X satellites to derive 7-year deformation. Results reveal that the entire dam experiences continuous subsidence, with the maximum deformation in the line-of-sight direction measuring ~160 mm. While minor differential settlements are noted in different sections of the dam, the gradient is not significant due to the dam’s substantial length. The InSAR deformation results from multiple geometries demonstrate good consistency, with the highest correlation observed between the Sentinel-1 ascending and descending datasets, exceeding 0.9. Validation against the GNSS observations of the three sites on the SWC Dam shows the accuracy of InSAR displacements is ~8 mm. Water level changes do impact deformation, but consolidation settlement appears to be the primary controlling factor during the monitoring period. This study underscores the potential of InSAR in long-distance water transfer projects and highlights that spatially continuous deformation is the most significant advantage.

Finite Volume Method for Transient Pipe Flow with an Air Cushion Surge Chamber Considering Unsteady Friction and Experimental Validation

In various water transmission systems such as long-distance water transfer projects and hydropower stations, accurate simulation of water hammer is extremely important for safe and stable operation and the realization of intelligent operations. Previous water hammer calculations usually consider only steady-state friction, underestimating the decay of transient pressure. A second-order Finite Volume Method (FVM) considering the effect of unsteady friction factor is developed to simulate the water hammer and the dynamic behavior of air cushion surge chamber in a water pipeline system, while an experimental pipe system is conducted to validate the proposed numerical model. Two unsteady friction models, Brunone and TVB models, were incorporated into the water hammer equations, which are solved by the MUSCL–Hancock method. One virtual boundary method was proposed to realize the FVM simulation of Air Cushion Surge Chamber. Comparisons with water hammer experimental results show that, while the steady friction model only accurately predicts the first pressure peak, it seriously underestimates pressure attenuation in later stages. Incorporating an unsteady friction factor can better predict the entire pressure attenuation process; in particular, the TVB unsteady friction model more accurately reproduces the pressure peaks and the whole pressure oscillation periods. For water pipeline systems with an air cushion surge chamber, energy attenuation of the elastic pipe water hammer is primarily due to pipe friction and the air cushion. The experimental results with the air cushion surge chamber demonstrate that the proposed FVM model with the TVB unsteady friction model and the air chamber polytropic exponent near 1.0 can well reproduce the experimental pressure oscillations.

Investigation of partially expanded surge tank with self-adaptive auxiliary system controlling water hammer in pipelines

Intensive water hammer can cause pipe collapse in long-distance water transfer pipeline systems. Pressure control facilities like surge tank have been widely applied to help control the extensive pressure fluctuations. In our previous work, a kind of spring self-adaptive auxiliary control (SAC) system was proposed and demonstrated to have a significant improvement on pressure control capacity of a normal surge tank. In this study, an additional solution, a partially expanded structural treatment, was introduced to a conventional SAC surge tank to further improve its functional ability. The 1D numerical model was established in our in-house codes on FORTRAN. The dominant geometrical parameters were identified and quantitatively studied with various cases. According to the effects of the geometrical parameters, a designing protocol for searching the optimal solutions of partially expanded SAC surge tank was concluded. With the obtained optimal solutions, the proposed partially expanded SAC surge tank can perform a much better pressure control performance dealing with valve closure induced water hammer, compared with a conventional SAC surge tank as well as a normal surge tank.

Optimal operation toward energy efficiency of the long-distance water transfer project

Energy efficiency plays an important role in the sustainable operation of the world's largest water transfer project, i.e., China’s South-to-North Water Transfer Project, by reducing its energy-related operating costs. However, effective energy-saving measures are still under development for the project due to its huge scale and complexity. An optimized operational model was established in this study to reduce the energy use of the eastern route of the South-to-North Water Transfer Project by optimally scheduling the water-pumping process of the different pumps along the transfer route in the context of hydrological variability. The optimized operational rules and recommended operational parameters were obtained. The results show that the proposed operational rules in the form of piecewise functions can reduce the water pumping of the project, thus providing a basis for reducing energy consumption. The energy use of the project’s water pumping could also be reduced in the wet years by using the local water in midstream lakes along the transfer route rather than the pumped water from the Yangtze River at the southern terminus of the route. In addition, it was also found that the initial water storage of the lakes along the southern part of the route has a greater impact on the volume of the water pumping. Raising the water levels of these southern lakes using local runoff at the beginning of a year would help reduce the subsequent water pumping from the Yangtze River and the relative energy use of the project. In addition. the key areas for energy-saving along the eastern route of the South–North Water Transfer Project were identified, providing new insights for understanding the water-energy nexus behaviors of a long-distance water transfer project.

Impact of various multishaft combined ventilation modes on the removal of harmful gases released from mussel decay in a long-distance water conveyance tunnel

The harmful gases released from the decay of biologically invasive mussels are a major threat to the maintenance safety of long-distance water transfer projects in hot and humid climate areas. Setting up multiple working shafts along the long-distance underground water conveyance tunnel for maintenance ventilation can eliminate harmful gases and improve ventilation efficiency. The rational multishaft combined ventilation mode is an important guarantee for effective decontamination and maintenance safety in long-distance water conveyance tunnels. However, research on the release rule of harmful gases produced by rotten mussels and the multishaft combined ventilation modes of long-distance water conveyance tunnels has rarely been performed. In this study, a ventilation mathematical model considering the influence of harmful gases released by rotten mussels was implemented. The release rule of harmful gases was obtained by a mussel decay experiment, and the mathematical model was validated based on the data of a ventilation model test. Furthermore, the ventilation performance of multishaft combined ventilation modes was compared using a series of numerical simulations. The obtained results show that NH3 is the main component in harmful gases released by rotten mussels. The cumulative concentration of NH3 increases with the decay time of the mussel, reaching a peak value of 309.26 mg/m3. The maximum release rate of NH3 is 185.51 mg/(m3·d). In addition, the ventilation mode of alternately delivered and discharged airflow between adjacent working shafts is confirmed to be the best for long-distance tunnels with multiple working shafts according to the comparison of the airflow distribution and the removal effect of harmful gases under different modes of multishaft combined ventilation. This study provides useful guidance for the design and optimization of maintenance ventilation schemes in long-distance water transfer projects.

A new evaluation model of a water conveyance channel based on Bayesian theory by integrating monitoring and detection information

Channels are commonly used in long-distance water transfer projects, where landslides, collapses, or erosion may occur in its course of operation; thus, safety evaluation is conducted through monitoring and detection in its key and potentially hazardous areas. However, monitoring and detection information cannot comprehensively reflect the prominent problems of the safety state of the channel in terms of time and space. Therefore, studying how to realize the integration of monitoring and detection information is an important task for the safety evaluations of channels. In this paper, a method of integrating monitoring and detection information based on Bayesian theory is presented. The research shows that the fusion method of gathering monitoring and detection information based on Bayesian theory successfully captures the safety state of high-filling channels, and it can quantify and reduce uncertainty compared with fuzzy theory and the GA-BP neural network. By studying the influence of monitoring information on the safety of the channel, it is found that the horizontal displacement has a greater impact on the safety of the channel than the vertical displacement. A comparison of the results of fusing seven different monitoring points shows that the comprehensive utilization of horizontal and vertical displacement can improve the accuracy of the evaluation results. Compared to the safety coefficient calculated by the actual exploration, the error rate of the GA-BP neural network is 42.7%, and the fusion method based on Bayesian theory is 2.9%. The proposed method based on Bayesian theory can better use the detection information to recognize and understand the rock and soil in advance; hence, the evaluation results are more reliable and consistent with the actual engineering state.

A Gateway to Rapid Prediction of Water Quality: A Case Study in China’s South-to-North Water Diversion Project

Water quality assurance is the primary factor for the successful operation of water diversion projects across river basins. The rapid prediction of water pollution is the basis for timely and effective emergency control and disposal measures. In China, since the open channels intersect with numerous waterways and traffic arteries, water transfer projects are prone to sudden water pollution accidents. In this paper, the rapid prediction method was developed for sudden water pollution accidents that possibly occurred in the East Route of the South-to-North Water Diversion Project (ERP) in Shandong Province. With the empirical formula of the pollution transfer law, a rapid prediction model of water quality (WQRP) was established based on the simulation of the typical accidents in the main channel. Finally, four typical accidents were selected as application examples, and the prediction results were compared with the results from a computer numerical simulation to demonstrate the validity of the model. The results showed that the prediction results by the WQRP model meet the accuracy requirements. This method is of great significance for providing water transport security in the extreme conditions of long-distance water transfer projects.

Influencing Factors of biofilm nitrification in long-distance water pipeline

The long-distance water transfer project alleviates the situation of water supply tension in various parts of China. In the process of raw water transportation, the nitrification reaction will be carried out by microorganisms due to the existence of a pipe wall biofilm, which converts ammonia nitrogen in water into nitrite nitrogen and nitrate nitrogen. Nitrification of pipeline biofilm is affected by many factors, including temperature, dissolved oxygen concentration, nutrient content, type, and concentration of disinfectants. These factors can change the activity, quantity of nitrifying bacteria, and the conversion rate of ammonia nitrogen, which leads to the effect of nitrification.

Robust Placement of Water Quality Sensor for Long-Distance Water Transfer Projects Based on Multi-Objective Optimization and Uncertainty Analysis

It is important to place water quality sensors along open channels in long-distance water transfer projects optimally for rapid source identification and efficient management of sudden water contamination. A new framework which considers multiple objectives, including earliest detection time, lowest missing detection rate and lowest sensor cost, and combines the randomness of injected contaminant type and contaminant incident consisting of contaminant intrusion location, time and mass, was established to obtain optimal placement of water quality sensor with better robustness in this paper. The middle route of the South-to-North Water Diversion Project in China was chosen as a case study, and it was found that both missing detection rate and detection time decrease with sensor cost gradually; furthermore, given the higher detecting precision, the detection accuracy and efficiency would be improved, a smaller number of water quality sensors would be needed, and the ten key placement positions where sensor with different detecting precision placed could be identified. Under the constraints of the allowable maximum missing detection rate, 1.00%, and detection time, 120.00 min, the detecting precision of 0.20 mg/L and 38 sensors placed could be selected as the optimal sensor placement scheme. Finally, with the consideration of contaminant uncertainty, the sensor placement scheme with better robustness could be constructed. The proposed framework would be helpful in solving the problem of water quality sensor placement with high practicality and efficiency in long-distance water transfer projects.

Feasibility of coupling PV system with long-distance water transfer: A case study of China's “South-to-North water diversion”

To nationally optimize limited water resources, the Chinese government has had to build several nationwide long-distance water transfer channels. These channels have placed tremendous pressure on land resources, and some require large quantities of electrical energy to lift the water to a higher altitude. Within this context, this study attempts to make full use of local solar energy resource and upper space of water channel to construct an on-channel photovoltaic (PV) system. Based on-site data and PVsyst model, this study took the central line of the “South-to-North water diversion” project as an example to examine the technical and economic feasibility of the proposed on-channel PV system under two alternative scenarios. The major results indicated that the initial investment would be 3,733 million Yuan under the scenario 1, with an expected annual electricity output of 659 GWh; while under the scenario 2, the number of initial investments would increase to 18.665 billion Yuan with an expected electricity output of 3.295 billion kWh. Moreover, carbon balance analysis demonstrated that the rate of carbon emission reduction can reach as much as 98.45% comparing to the baseline case. Overall, the proposed on-channel PV system will bring good benefits both economically and environmentally and should be worthy of promoting in future.

Unraveling the Effects of Long-Distance Water Transfer for Ecological Recharge

Unraveling the Effects of Long-Distance Water Transfer for Ecological Recharge

An Optimal Model for Water Resources Risk Hedging Based on Water Option Trading

The uncertainty of forecasted runoffs brings risks of water shortages to water users in the intake area of long-distance water transfer projects, and the uncertainty of spot market prices may cause them to buy water at high prices. In order to hedge these risks, this paper proposes a risk hedging model for decision-making in water option trading from the viewpoint of water users. With the objective of maximizing the expected revenue of water users, the proposed model was solved by an analytical method and an optimal water option strategy was obtained for the users. The proposed model is applied to an intake area of an inter-basin water transfer project in China. The results show that the proposed water option trading model can provide water users with an optimal option strategy. The optimal options trading strategy can effectively reduce the risk caused by the uncertainties of forecasted runoffs and water prices. We also explored the influence of the uncertainty degree of the forecasted runoffs and water price on the option trading strategy. The results show that the expected revenue of water users increases as the variances of the errors of forecasted runoffs and water prices increase.

Study on the Motion Characteristics of Residual Air Mass in Pipelines in Water Transfer Project

For long-distance water transfer projects, the residual air mass in the pipeline will not only reduce the efficiency, but also be detrimental to the safety of the system. In order to study the influence of the water flow velocity of the pressurized water pipeline and the pipeline angle of the hump on the motion characteristics of the residual air mass, an experimental platform with Particle Image Velocimetry (PIV) measuring system was constructed to analyse the flow field. The RSM turbulence model was combined with the VOF multiphase flow model to construct a local high-point gas-liquid two-phase fluid dynamics model for numerical simulation. The results showed that with the increase of water flow velocity, the local hump residual air mass would go through three states, namely, no bubble generation, air bubble was generated and partial discharged, and air mass discharge at one time. If the gas was greater than a certain volume, the increase in the water flow rate required to carry the air mass out of the hump at one time would slow down; the larger the local hump angle was, the greater the water flow rate was required to carry the gas out of the local hump part.

A real-time, rapid emergency control model for sudden water pollution accidents in long-distance water transfer projects

A real-time, rapid emergency control (EC) model is proposed to cope with sudden water pollution accidents in long-distance water transfer projects. The EC model outputs the method of EC based on pollutant properties. A generalized form of EC model is proposed and tested with a demonstrative project. The rapid prediction formulas of emergency control parameters (ECPs) are proposed under different states of water diversion. The closing times of check gates and the pollution range are calculated by the rapid prediction formulas of ECPs. A case study is examined under the scenario of a sucrose spill in a demonstrative project conducted in the Fangshui to Puyang channel of the Beijing–Shijiazhuang Emergency Water Supply Project in the middle route of the South-to-North Water Transfer Project. The relative errors of peak concentration and arrival time of peak concentration are less than 20%. However, we could not use an actual toxic soluble pollutant to validate the EC model, so we performed the experiment with sucrose to test the EC model based on its concentration variation. The final result shows that the model is able to play a fundamental role in the decisions involved in the Emergency Environmental Decision Support System.

Non-conventional water resources research in semi-arid countries of the Middle East

Rapid population growth, climate impediments, poor implementation of regulatory frameworks, and challenging political relations have led to over-exploitation of conventional water resources in the Middle East. This situation may have impelled out-of-the-box thinking and advances in research on non-conventional water resources including desalination, wastewater reuse, rainwater harvesting, and long-distance water transfer. This paper aims to assess the extent of research on non-conventional water resources in the Middle East, and identify original and innovative research findings. Cyprus, Egypt, Israel, Lebanon, the Palestinian Territories, Sudan, Syria, and Turkey were selected for this purpose. A systematic online library search of the scientific literature was conducted, and relations between national indicators and the number of articles and citations were assessed. There was an increasing trend in the number of articles addressing non-conventional water resources. Desalination was the most popular research topic (44%; 5.4 citations, on average), followed by wastewater reuse (37%; 11.5 citations, on average). Publication of desalination articles has increased significantly since 2001, with a substantial number authored by private companies. Non-conventional approaches include commercial salt production at a desalination plant, the strengthening of wastewater reuse standards based on the adverse effects of long-term reuse, the application of a water-harvesting plough for large-scale rangeland rehabilitation, and the development of a 78-km long under-sea pipeline for water transfer. Research on off-site effects and environmental impacts was lacking. Investment in research capacity, as an element of social capital, can contribute to water resources diversification and sustainable solutions both for water-stressed and more humid countries.