Pumping Strategy Research Articles

Managing saltwater intrusion using conjugate sharp interface and density dependent models linked with pumping optimization

Coastal areas are densely populated due to associated socioeconomic benefits, and therefore have higher demand for freshwater. This ever-increasing demand for freshwater can be met by coastal aquifers, which act as giant reservoirs of freshwater. Excessive and unmanaged pumping from coastal aquifer allows saltwater to flow inward encroaching the voids created by pumping of freshwater. This phenomenon is called saltwater intrusion. To stop saltwater intrusion, an optimal pumping strategy needs to be adopted. Simulation models are generally linked with an optimization algorithm to develop optimal pumping strategy for management of saltwater intrusion. Sharp interface based simulation models are often used which are computationally inexpensive but lacks in prediction accuracy, as it does not incorporate the effects of dispersion and diffusion. Density dependent simulation models include the effect of dispersion and diffusion, but have very high computational budget in evaluating an optimal pumping strategy. To overcome above mentioned limitations a new methodology is developed, where a density-dependent model is used in conjunction with a sharp interface model to derive an optimal density ratio, such that interface obtained using this density ratio implicitly accommodates the effect of dispersion and diffusion in a sharp interface model. The performance of the developed methodology is evaluated for three hypothetical scenarios of saltwater intrusion, and in densely populated coastal city of Puri in India. The performance evaluation results show the applicability of the developed methodology for management of saltwater intrusion while maximizing freshwater pumping from coastal aquifers.

Strategies for mud-removal from washouts during cementing of vertical surface casing

In the context of both production and well abandonment, effective cementing of the surface casing is key in preventing leakage of formation fluids. Although there are general guidelines for the effective cementing of vertical casings, there is little known about the effects of wellbore irregularity, e.g. from formations that are badly eroded during drilling - washouts. Here we present a systematic study of the cementing of a vertical surface casing with a washout section. We study the effects of washout length, pump rate, positive density difference and viscosity ratio, all in the displacement flow of the drilling mud by a spacer. Of these parameters, flow rate increases can lead to both improved displacements and to mixing and potential contamination. A positive density difference improves the mud displacement and viscosity differences have minimal effect, at least over the ranges studied. We then propose a pumping strategy that may improve the displacement process in a targeted washout, potentially valuable as we move into the era of real-time (and while drilling) well calipers and are progressively able to include irregular borehole geometries into cementing designs.

Decade-long meteorological and water quality dynamics of northern Lake Dianchi and recommendations on algal bloom mitigation via key influencing factors identification

Worldwide extension of hazardous algal blooms (HABs) in lakes has threatened animal and human health, drinking water supply, and aquatic ecosystems. Although both climatic and water quality changes can give rise to HABs, specific contribution of each factor is often lake region dependent. In this study, data from intensive local sampling sites were introduced to identify the key influencing factors of HABs in northern Lake Dianchi, where the bloom is severer than the rest of the lake. Decade-long meteorological and water quality dynamics including HABs community changes at various sites were revealed. Both dry weight of the bloom biomass (DW) and Chlorophyll a concentration (Chl. a) were adopted as indicators to HABs. Spearman correlation analysis and multiple stepwise linear regression were respectively used to identify the individual and joint influencing factors of HABs. Efficiency of a condensed bloom biomass pumping strategy was evaluated on HABs mitigation, and the impact of changing nutrients measurement protocols was also analyzed. Results indicated that Chl. a rather than DW could better represent the extent of HABs among various sampling sites. Although both meteorological and water quality factors are responsible for HABs in northern Lake Dianchi when individually considered, it was water quality and particularly TN and TP that were the “game changer” in HABs mitigation when joint influencing factors were concerned. The “pumping strategy” can only be adopted as an emergency method, and recommendations on nutrients reduction should be based on the conventional measuring protocol that includes particulate nutrients as well.

Charge Pumping Strategy for Rotation and Sliding Type Triboelectric Nanogenerators

AbstractTriboelectric nanogenerator (TENG) is an emerging approach for harvesting energy from the living environment. But its performance is limited by the maximum density of surface charges created by contact electrification. Here, by rationally designing a synchronous rotation structure, a charge pumping strategy is realized for the first time in a rotary sliding TENGs, which is demonstrated to enhance the charge density by a factor of 9, setting up a record for rotary TENGs. The average power is boosted by more than 15 times compared with normal TENGs, achieving an ultrahigh average power density of 1.66 kW m−3, under a low drive frequency of 2 Hz. Moreover, the charge pumping mechanism enables decoupling of bound charge generation and the severity of interfacial friction in the main TENG, allowing surface lubricants to be applied for suppressing abrasion and lowering heat generation. The adaptability of the strategy to rotation and sliding type TENGs in low‐frequency agitations provides a breakthrough to the bottleneck of power output for mechanical energy harvesting, and should have a great impact on high‐power TENG design and practical applications in various fields.

Seeding High Brightness Fiber Amplifiers With Multi-Phase Coded Signal Modulation for SBS Effect Management

We propose a new modulation approach based on multi-phase coded signal (MPCS) to increase stimulated Brillouin scattering (SBS) threshold in high power narrow-linewidth fiber amplifiers. To investigate the SBS suppressing capacity of the proposed modulation technique, the dynamics of SBS process with different spectra are simulated in active fibers with different dopants, core diameters, lengths and pumping lights based on three typical types of pumping sources (976 nm laser diodes, 915 nm laser diodes and 1018 nm fiber lasers). Before simulation, a spectral-correlated combining efficiency criterion based on coherent beam combining (CBC) system is introduced and is set to be identical in different spectra. As a result, compared with the typical white-noise-signal (WNS) and pseudo random bit sequence (PRBS) modulation techniques, the MPCS modulation yields a higher SBS threshold in 915 nm and 1018 nm pumped fiber amplifiers with relatively longer active fiber. Besides, in fiber amplifier constructed by general 20/ $400~\mu \text{m}$ active fiber and with 976 nm pumping strategy, MPCS modulation performs better than WNS and PRBS modulation as well. We believe that this modulation signal is expected to be applied in narrow-linewidth, large-mode-area (LMA) high-brightness fiber laser systems to balance the SBS effect and thermal mode instability (TMI) phenomenon.

Artificial Neural Network and Grey Wolf Optimizer Based Surrogate Simulation-Optimization Model for Groundwater Remediation

We herein propose a simulation-optimization model for groundwater remediation, using PAT (pump and treat), by coupling artificial neural network (ANN) with the grey wolf optimizer (GWO). The input and output datasets to train and validate the ANN model are generated by repetitively simulating the groundwater flow and solute transport processes using the analytic element method (AEM) and random walk particle tracking (RWPT). The input dataset is the different realization of the pumping strategy and output dataset are hydraulic head and contaminant concentration at predefined locations. The ANN model is used to approximate the flow and transport processes of two unconfined aquifer case studies. The performance evaluation of the ANN model showed that the value of mean squared error (MSE) is close to zero and the value of the correlation coefficient (R) is close to 0.99. These results certainly depict high accuracy of the ANN model in approximating the AEM-RWPT model. Further, the ANN model is coupled with the GWO and it is used for remediation design using PAT. A comparison of the results of the ANN-GWO model with solutions of ANN-PSO (ANN-Particle Swarm Optimization) and ANN-DE (ANN-Differential Evolution) models illustrates the better stability and convergence behaviour of the proposed methodology for groundwater remediation.

Testing minimum cost strategies of pumping systems with scheduled electric tariffs in a lab scale plant

This paper describes the development and testing of a lab plant that emulates a water supply pumping system with the objective of testing optimal pumping strategies based on standard solvers. The emulated system consists of two tanks that supply the water to two districts in a town. There are two pumps, that can fill the tanks through a reconfigurable hydraulic system with several valves. The automatic controller determines the valves and pumps that are active at each instant of time in order to minimize the operation cost, taking into account the electric tariff periods. Some aspects on the development of the lab plant are first discussed, including hydraulic aspects and real time control implementation issues. Then, a mathematical model is proposed to be able to formulate, in matrix form, the cost index and the constraints, such that, standard solvers as Mosek or CBC can be used. The full optimization proposal is tested on several experiments, and compared to some simulations, to demonstrate the validity of the plant and the optimization approach.

Optimization and design of a novel small-scale integrated vacuum membrane distillation - solar flat-plate collector module with heat recovery strategy through heat pumps

This work aims to design a small-scale desalination unit for producing drinking water in remote places (~2 L/person). It considers an equipment where vacuum membrane distillation (VMD) and direct solar heating through solar flat-plate collector (FPC) are coupled within the same intensified module, with photovoltaic (PV) panels providing electricity. An adapted heat pumping strategy is conceived to bridge between the heat-demanding feed recirculation and the heat-releasing vapor condensation, aiming both to recover latent heat of evaporation and to condense vapor without using an additional intensive cooling system. Sensitivity analyses and multi-objective optimizations are provided, based on water production and electric consumption of both pumping and cooling, to orientate the design and to discuss the key issues for an optimal operation. Results reveal that for a tiny module (0.18 m2), a daily freshwater production of 3.7 L can be obtained with an average electric consumption of 17 W (~0.13 m2 PV). At a relatively bigger scale (3 m2), 96 L of freshwater is attained at a consumption of 449 W (~3.26 m2 PV). The need for PV power capacity per unit water production is almost constant, ranging in 4.2–5 W L−1.

Analysis of different operational control strategies for drinking water pump-tank systems: a case study

The management of drinking water pumping systems is a delicate task that most often requires the use of different pumping strategies ranging from the simplest to the most sophisticated control methods. In order to study the performance of these methods a numerical simulation of three pumping methods was carried out (two real-time control methods and one simple method). The first real-time control method is based on a model of multivolume regulation. It was developed as part of this study. This method is based on the volume of water in the tank and characterized by a cascade operation of the pumps depending on the control volumes. The second real-time control method is based on a progressive regulation model (PR). This model is characterized by a gradual start and stop of the pumps according to two control volumes: a volume of stop and a volume of starting of the pumps (Von and Voff). The third method is based on continuous 24-h pumping (H24).The study was validated on two pumping systems supplying the Hotel and Ighaouzene tanks in the city of Sidi Aiche. The results have shown the energy, hydraulic and operational efficiency of the two real-time control methods in the management of water supply systems.

Application of Monitoring Network Design and Feedback Information for Adaptive Management of Coastal Groundwater Resources.

Optimal strategies for the management of coastal groundwater resources can be derived using coupled simulation-optimization based management models. However, the management strategy actually implemented on the field sometimes deviates from the recommended optimal strategy, resulting in field-level deviations. Monitoring these field-level deviations during actual implementation of the recommended optimal management strategy and sequentially updating the management model using the feedback information is an important step towards efficient adaptive management of coastal groundwater resources. In this study, a three-phase adaptive management framework for a coastal aquifer subjected to saltwater intrusion is applied and evaluated for a regional-scale coastal aquifer study area. The methodology adopted includes three sequential components. First, an optimal management strategy (consisting of groundwater extraction from production and barrier wells) is derived and implemented for optimal management of the aquifer. The implemented management strategy is obtained by solving a homogenous ensemble-based coupled simulation-optimization model. Second, a regional-scale optimal monitoring network is designed for the aquifer system considering possible user noncompliance of a recommended management strategy, and uncertainties in estimating aquifer parameters. A new monitoring network design objective function is formulated to ensure that candidate monitoring wells are placed in high risk (highly contaminated) locations. In addition, a new methodology is utilized to select candidate monitoring wells in areas representative of the entire model domain. Finally, feedback information in the form of measured concentrations obtained from the designed optimal monitoring wells is used to sequentially modify pumping strategies for future time periods in the management horizon. The developed adaptive management framework is evaluated by applying it to the Bonriki aquifer system located in Kiribati, which is a small developing island country in the South Pacific region. Overall, the results from this study suggest that the implemented adaptive management strategy has the potential to address important practical implementation issues arising due to noncompliance of an optimal management strategy and uncertain aquifer parameters.

2D → 3D conversion of superwetting mesh: A simple but powerful strategy for effective and efficient oil/water separation

Previously unattainable success in using a single superwetting mesh to separate oil/water mixtures of various densities was achieved via 2D → 3D conversion of superwetting mesh. Unlike 2D superwetting mesh, 3D mesh container allows both oil and water to touch the container wall, ensuring the passage of wetting phase through the mesh. By properly pumping out the non-wetting phase accumulated in the container, continuous oil/water separation can be realized. Experimental results demonstrate that the use of a single metal mesh only coated with the conveniently available superoleophilic-superhydrophobic materials not only realizes continuous separation of large-volume oil/water mixtures of any density ratios with high efficiency and high purity, but also shows good capacity in consecutive collection of oil from the water with the promising potential in separation of oil/water emulsions. The idea of 2D → 3D conversion of the membrane together with external pumping strategy is a novel concept for oil/water separation, which will bring technologies based on special wettability a step closer to practical applications.

Spatiotemporally Controlled Multiplexed Photothermal Microfluidic Pumping under Monitoring of On-Chip Thermal Imaging.

Intelligent contactless microfluidic pumping strategies have been increasingly desirable for operation of lab-on-a-chip devices. Herein, we present a photothermal microfluidic pumping strategy for on-chip multiplexed cargo transport in a contactless and spatiotemporally controllable fashion based on the application of near-infrared laser-driven photothermal effect in microfluidic paper-based devices (μPDs). Graphene oxide (GO)-doped thermoresponsive poly(N-isopropylacrylamide)-acrylamide hydrogels served as the photothermally responsive cargo reservoirs on the μPDs. In response to remote contactless irradiation by an 808 nm laser, on-chip phase transition of the composite hydrogels was actuated in a switchlike manner as a result of the photothermal effect of GO, enabling robust on-chip pumping of cargoes from the hydrogels to predefined arrays of reaction zones. The thermal imaging technique was employed to monitor the on-chip photothermal pumping process. The microfluidic pumping performance can be spatiotemporally controlled in a quantitative way by remotely tuning the laser power, irradiation time, and GO concentration. The pumping strategy was exemplified by FeCl3 and horseradish peroxidase as the model cargoes to implement on-chip Prussian blue- and 3,3',5,5'-tetramethylbenzidine-based colorimetric reactions, respectively. Furthermore, multiplexed on-demand microfluidic pumping was achieved by flexibly adjusting the irradiation pathway and the microfluidic pattern. The new microfluidic pumping strategy shows great promise for diverse microfluidic applications due to its flexibility, high integratability into lab-on-a-chip devices, and contactless and spatiotemporal controllability.

A Generalized Additional Voltage Pumping Solution for High-Step-Up Converters

This study develops a generalized additional voltage pumping solution (GAVPS) for a series of high-step-up converters, whose topologies can be modeled by a generalized architecture. The newly designed converters can achieve additional voltage pumping by only applying an additional diode and capacitor to the conventional high step-up converter structure. Integrating the proposed solution into the existing high-step-up converters, five typical case studies with corresponding analyses and comparisons are conducted and presented, which verifies the proposed voltage pumping strategy. Additionally, five prototypes are built in this study, and the experimental results further validate the effectiveness of the proposed GAVPS solution. The proposed strategy in theory will work synergistically with all types of dc–dc converters, which demonstrates its unparalleled significance in expanding its applicability in contemporary power converter industries.

Sustainable three-well pumping strategy for efficient detection monitoring near waste impoundments

Sustainable three-well pumping strategy for efficient detection monitoring near waste impoundments

Optimal pumping strategies for the management of coastal groundwater resources: application of Gaussian Process Regression metamodel-based simulation-optimization methodology

ABSTRACT The present study utilizes a coupled simulation-optimization (S-O) methodology to develop a multi-objective management strategy for a coastal aquifer system. The aim of the multi-objective management model is to maximize pumping from freshwater wells (FWs) and minimize pumping from the barrier wells (BWs), while keeping salinity concentration in the aquifer within pre-specified limits (optimization constraint). To achieve computational feasibility of the management model, the numerical simulation model is substituted by the relatively new Gaussian Process Regression (GPR) metamodels. The GPR models are used to approximate coastal aquifer responses to variable transient pumping patterns from FWs and BWs. Prediction capabilities of the developed GPR metamodels are quantified using standard statistical parameters. Once trained and validated, the GPR metamodels are coupled to a multi-objective genetic algorithm optimization model and used to prescribe optimal groundwater pumping patterns. The outcomes of this study establishes the potential applicability of the GPR metamodel-based S-O model for developing sustainable coastal groundwater management strategies, which can utilize accurate and efficient prediction of management strategy impacts on the saltwater intrusion (SI) process when the optimal management policy development is based on the trained metamodel predictions. Once implemented, the developed strategy can help in controlling SI in coastal aquifer systems.

A New Approach to Mitigate Subsidence Problems: A New Approach to Mitigate Subsidence Problems

Mexico City has a decades-old problem with severe consequences: its lacustrine zone is subsiding due to pumping of potable water from the main aquifer. The geotechnical team assigned to work on the problem assessed the situation by using remote-sensing methods. This article describes the present situation as well as a new approach to mitigate the effects of subsidence. The new approach combines several actions, but consists mainly in progressively modifying the pumping strategy to avoid exceeding the soil preconsolidation pressure in the clayey compressible layers, including the superficial aquitards and in most of the main aquifer.

An integrated approach for choosing suitable pumping strategies for a semi-arid region in Jordan using a groundwater model coupled with analytical hierarchy techniques

The Azraq basin, Jordan, is characterized by high variability and a heterogeneous spatial distribution of groundwater recharge. Most of the recharge occurs in the north of the basin. The central part of the basin is covered by wetland (Azraq Oasis), characterized by a unique ecosystem and biodiversity. Groundwater abstraction for agricultural and domestic purposes occurs mainly near the oasis and results in a considerable decline of the water table. A groundwater model was developed for the Azraq basin to analyze and predict the groundwater level response to different pumping strategies. The model also enables determination of the safe yield. The extent to which the safe yield and specific pumping strategies are socially and economically acceptable was analyzed. Multi-criteria analysis using an analytic hierarchy process was applied to obtain the abstraction rate that achieves the most suitable trade-off between environmental and socio-economic criteria under two scenarios of future socio-economic development. Based on the calibrated groundwater model the response of the groundwater level until 2045 was simulated, resulting in a 15–25 m decline if current pumping strategies continue. At present, the safe yield of the groundwater resource equals 30% of the overall actual pumping rate, indicating that the aquifer is highly exploited. Results of the multi-criteria analysis show that the ‘safe yield alternative’ is the most suitable for the basin under a scenario of future economic prosperity. For circumstances of poor economy and low social awareness, keeping the current pumping rate was found to be the scenario with the highest priority.

Flood hazard mitigation in land subsidence prone coastal areas by optimal groundwater pumping

Continuing land subsidence can aggravate flood hazard and diminish the effectiveness of existing flood mitigation systems. This paper presents a study of groundwater‐ pumping management for mitigating flood hazard in a subsidence infested area in the southwest coast of Taiwan. An optimal groundwater‐pumping model is developed for preventing flood hazard from worsening and for satisfying the groundwater demand. In an area where the land is susceptible to pumping‐induced subsidence, the study shows that proper long‐term pumping strategy to manage spatial–temporal variation of future land subsidence should be an integral part of flood risk management as it can sustain the effectiveness of the flood mitigation measures.

Multi-objective groundwater management strategy under uncertainties for sustainable control of saltwater intrusion: Solution for an island country in the South Pacific

To date, simulation-optimization (S/O) based groundwater management models have delivered optimal saltwater intrusion management strategies for coastal aquifer systems. At times, however, uncertainties in the numerical simulation model due to uncertain aquifer parameters are not incorporated into the management model. The present study explicitly incorporated aquifer parameter uncertainty into a multi-objective management model for the optimal design of groundwater pumping strategies from the unconfined Bonriki aquifer situated in a small Pacific island country. The objective of the multi-objective management model was to maximise pumping from production wells and minimize pumping from the barrier wells (hydraulic barriers) to ensure that the water quality at different monitoring locations (MLs) were within pre-specified sustainable limits. To achieve the targeted management goal, a coupled flow and transport numerical simulation model of the Bonriki aquifer was developed using the FEMWATER numerical code. The developed three-dimensional numerical model was calibrated and validated using limited available hydrological data. To achieve computational efficiency and feasibility of the management model, the numerical simulation model in the S/O model was replaced with ensembles of Support Vector Machine Regression (SVMR) surrogate models. Each SVMR standalone surrogate model in the ensemble was constructed using datasets from different numerical simulation models with different hydraulic conductivity and porosity values. These ensemble SVMR models were coupled to the multi-objective genetic algorithm optimization model to solve the Bonriki aquifer management problem. The executed optimization model presented a Pareto-front with 600 non-dominated optimal trade-off pumping solutions. The reliability of the management model established after validation of the optimal solution results suggests that the implemented constraints of the optimization problem were satisfied, i.e., the salinity concentrations at respective MLs were within the pre-specified limits. Overall, the results from this study indicated that the developed management model has the potential to address groundwater salinity problems in small island countries.

Effects of the Rincon Bayou Pipeline on salinity in the upper Nueces Delta

A pipeline to pump water from the Nueces River to the upper delta at Rincon Bayou was constructed to mitigate the reduction of inflow from impoundments. Pumping has restored ecological function to the Nueces Estuary by increasing inflow and decreasing salinity, and transitioned the marsh into a positive estuary (lower salinities upstream increasing downstream towards the bay). Pumping has decreased the occurrences of salinities greater than 35 practical salinity units during drought conditions; however the current pumping regime causes a disturbed environment by creating extreme fluctuations in salinities in a very short time period. Immediately after pumping salinity fluctuations at the pumping outfall commence from hypersaline to fresh. When pumping ceases, salinity fluctuates from fresh to hypersaline until the next pumping event. Pumping often occurs during rainfall and flooding events when reservoir levels meet certain capacities that trigger pass-through requirements. This strategy provides inflow when it is not needed, and inhibits pumping during drought conditions when inflow is needed to maintain the quality of the estuarine ecosystem. While the current pumping regime has restored estuary conditions to Rincon Bayou by increasing inflow and decreasing salinity, it also causes extreme fluctuations in salinity that act as a disturbance. A lower magnitude, longer duration pumping strategy would create a more stable environment by providing freshwater continuously and would be an improved hydrological restoration strategy. Citation: Del Rosario EA, Montagna PA. 2018. Effects of the Rincon Bayou Pipeline on salinity in the upper Nueces Delta. Texas Water Journal. 9(1):30-49. Available from: https://doi.org/10.21423/twj.v9i1.7042.