山东龙口地下水开采-海水入侵水文地质模型设计若干问题——与薛禹群院士商榷

对山东龙口地下水开采-海水入侵水文地质模型设计提出6个问题:1建立剖面二维模型缺乏论证,也没有给出模拟方法;2海边界的设定没有建立在研究区水文地质条件的基础之上;3模型的范围取得过小,且所有边界均设为人为第一类边界条件而没有论证其合理性;4没有分析抽水井的井型,也没有阐明其模拟方法;5没有分析民井观测孔的水动力特征,更没有说明其模拟方法;6所设计的水文地质模型不能用于预测,不能给出海水入侵治理措施及地下水可持续开采量。前5点的模拟方法与地下水开采-海水入侵的对流-弥散方程的求解方法共同影响到"拟合"度;而第6点却大大降低了数值模拟解决山东龙口地下水开采-海水入侵问题研究应达到的目标,仅仅完成"拟合求参"。     

地表水源变化对含水层海水入侵的影响

运用一维突变界面有限元模型，对地表水位的线性变化引起海水入侵的瞬态特性进行了参数研究。通过与狭缝槽（赫尔－肖模拟）模拟结果的比较，验证了数值解的有效性，建立了在距海岸不同距离内，咸水楔趾运移与地表水位各种线性上升率之间的一般关系；对地表水位停止上升后界面的运动进行了监测。研究成果具有广泛的适用范围，并有助于沿海地区制订控制海水入侵的方案。     

基于变密度地下水流模型分析预测沿海地区海水入侵

辽宁大清河发生的海水入侵一方面是由于潮汐作用下的海水沿河道上溯,并向四周补给低水位地下水所产生的入侵;另一方面是由于地下水的大量开采形成降落漏斗,降落漏斗中心水位远低于海平面,海水沿水力坡降方向入侵。本文采用变密度地下水流动数学模型模拟该区域海水入侵过程,从监测井数据与模拟数据对比分析来看,该模型识别所得参数基本符合该区域的海水入侵的实际情况,效果较好。     

砂—粘土中海水入侵规律试验与数值模拟

近年来我国沿海城市海水入侵现象越来越严重,为了防治海水入侵,对其入侵规律的研究非常必要。本文通过室内试验与Geostudio数值模拟研究给出了砂—粘土介质中海水入侵的规律。结果表明,不同土体的海水入侵规律不尽相同;同种土体不同位置的入侵规律也不同;两种接触面上的入侵规律同时受两种介质影响,其入侵规律同时受土体颗粒大小、渗透系数、试验材料等因素影响。本研究对福建泉州地区海水入侵的研究有较大的参考价值。     

海水入侵地下水的研究

本文据盐、淡水之间过渡带的不同处理,将海水入侵地下水的数值解法分为两类,并分别进行了有限元数值计算。对防止海水入侵的方法进行了数值模拟和分析,还对计算中产生的一些问题进行了讨论。最后,用粘滞流物理模型做了盐、淡水之间突变界面的试验。     

龙口市滨海平原地下水警戒线划定

通过建立地下水数值模拟模型,确定了龙口市滨海平原区地下水警戒基本水位和黄色、橙色、红色警戒线。为该区域实施地下水预警管理、防治海水入侵提供了必要的技术依据。     

龙口市滨海平原地下水警戒线划定

通过建立地下水数值模拟模型,确定了龙口市滨海平原区地下水警戒基本水位和黄色、橙色、红色警戒线,为该区域实施地下水预警管理、防治海水入侵提供了必要的技术依据.     

海水经船闸入侵淡水运河的三维数值模拟

为研究船闸运行过程中盐分的输运规律及其对淡水水域的盐度影响,建立了三维k-ε两相混合流数值模型,模型控制方程组采用有限体积法进行离散,流速与压力耦合采用SIMPLEC算法,时间项采用一阶隐式格式,流项采用二阶迎风格式,计算区域采用六面体网格划分。采用某船闸的海水入侵原型试验成果对数值模型进行了验证,闸室内盐度的模拟值与实测值吻合较好。海水入侵淡水水域模拟结果表明:上游航道盐度分布可分为异重流段、过渡段和扩散段,各段盐分输运速度依次减小;各断面的盐度呈周期性变化,在船闸运行一段时间后逐步趋于动态平衡;一个循环内的盐分入侵量在船闸运行初期较大,随着运行时间的增加逐渐减小,并趋于恒定值。研究结果可为船闸的设计与运行调度提供科学依据。     

沿海缺水灌区水资源优化调配耦合模型

本文研究了一种基于含水层海水入侵模拟模型(子模型)和作物优化配水模型(子模型)的沿海缺水灌区水资源优化调配耦合模型，用数值方法求解了含水层海水入侵模拟子模型，并首次将基于分解协调的人工鱼群算法应用于作物优化配水的计算，通过地下水抽水量实现了子模型的耦合，利用Visual Basic6.0软件编制了耦合模型的计算程序。将模型应用于威海市节水灌溉示范区，得出其平水年(50％)、一般干旱年(75％)两种水文年型的水资源联合调配方案。结果表明基于分解协调的人工鱼群算法收敛性好，提高了计算速率，较好的解决了作物优化配水大系统中常见的变量维数高、约束方程多等问题；示范区平水年增加有效供水量997.05m3／hm2，一般干旱年增加有效供水量863.1m3／hm2，能高效利用水资源并能有效控制含水层海水入侵，经济效益和生态效益明显。     

王河流域地表水,地下水联合调度防治海水入侵的模拟分析

王河流域是莱州湾地区防治海水入侵的典型试验区。本文采用地表水、地下水联合调度动态模拟分析的方法，将水资源评价、拦蓄补源规划方案与防治海水入侵联系起来研究，为制定地下水资源优化开发利用规划和防治海水入侵工程规划提供了科学依据和应用软件。     

Coupled Sharp-interface and Density-dependent Model for Simultaneous Optimization of Production Well Locations and Pumping in Coastal Aquifer

The main management challenge in coastal aquifers is to prevent saltwater intrusion, ensuring ample freshwater supply. Saltwater intrusion happens due to unregulated pumping from production wells. Therefore, it is essential to have an effective management policy, which ensures the requisite amount of freshwater to be withdrawn from coastal aquifers without causing saltwater intrusion. A methodology for optimizing production well locations and maximizing pumping from production wells is presented to achieve these conflicting objectives. The location of production wells directly affects the amount of freshwater pumped out of the coastal aquifer. Simultaneous optimization of production well locations and pumping from the same is achieved by linking mathematical simulation models with the optimization algorithm. A new methodology using coupled sharp-interface and density-dependent simulation models is developed to find optimal well locations and optimize the amount of freshwater pumped from the coastal aquifer. The performance of the developed methodology is evaluated for saltwater intrusion in the coastal city of Puri, India. The performance evaluation results show the developed methodology's applicability for managing saltwater intrusion while maximizing freshwater pumping in coastal aquifers under constraints of well location.

     

Groundwater Circulation Well for Controlling Saltwater Intrusion in Coastal aquifers: Numerical study with Experimental Validation

Saltwater intrusion into coastal aquifers has become a prominent environmental concern worldwide. As such, there is a need to prepare and implement proper remediation techniques with careful planning of freshwater withdrawal systems for controlling saltwater intrusion in coastal marine and estuarine environments. This paper investigates the performance of groundwater circulation well (GCW) in controlling saltwater intrusion problems in unconfined coastal aquifers. The GCWs have been established as a promising in-situ remedial technique of contaminated groundwater. The GCW system creates vertical circulation flow by extracting groundwater from an aquifer through a screen in a single well and injecting back into the aquifer through another screen. The circulation flow induced by GCW force water in a circular pattern between abstraction and recharge screens and can be as a hydraulic barrier for controlling saltwater intrusion problem in coastal aquifers. In this study, an effort has been made to investigate the behavior of saltwater intrusion dynamics under a GCW. An experiment has been conducted in a laboratory-scale flow tank model under constant water head boundary conditions, and the variable-density flow and transport model FEMWATER is used to simulate the flow and transport processes for the experimental setup. The evaluation of the results indicates that there is no further movement of saltwater intrusion wedge towards the inland side upon implementation of GCW, and the GCW acts as a hydraulic barrier in controlling saltwater intrusion in coastal aquifers. The present study reveals the GCWs system can effectively mitigate the saltwater intrusion problem in coastal regions and could be considered as one of the most efficient management strategies for controlling the problem.

     

Optimal Management of Coastal Aquifers Using Linked Simulation Optimization Approach

Saltwater intrusion management models can be used to derive optimal and efficient management strategies for controlling saltwater intrusion in coastal aquifers. To obtain physically meaningful optimal management strategies, the physical processes involved need to be simulated while deriving the management strategies. The flow and transport processes involved in coastal aquifers are difficult to simulate especially when the density-dependent flow and transport processes need to be modeled. Incorporation of this simulation model within an optimization-based management model is very complex and difficult. However, as an alternative, it is possible to link a simulation model externally with an optimization-based management model. The GA-based optimization approach is especially suitable for externally linking the numerical simulation model within the optimization model. Further efficiency in computational procedure can be achieved for such a linked model, if the simulation process can be simplified by approximation, as very large number of iterations between the optimization and simulation model is generally necessary to evolve an optimal management strategy. A possible approach for approximating the simulation model is to use a trained Artificial Neural Network (ANN) as the approximate simulator. Therefore, an ANN model is trained as an approximator of the three dimensional density-dependent flow and transport processes in a coastal aquifer. A linked simulation – optimization model is then developed to link the trained ANN with the GA-based optimization model for solving saltwater management problems. The performance of the developed optimization model is evaluated using an illustrative study area. The evaluation results show the potential applicability of the developed methodology using a GA- and ANN-based linked optimization – simulation model for optimal management of coastal aquifer.     

Influences of coastal underground reservoir construction and utilization on saltwater and freshwater transport law in aquifersEI北大核心CSCD

In order to reveal the impact of underground reservoir construction and extraction methods on the saltwater and freshwater transport law in coastal aquifers, a 300m × 900m × 30m conceptual numerical model was established. The variable density current simulation method of unconfined aquifer was used to analyze the saltwater and freshwater transport law in coastal aquifer under different extraction scenarios before and after the construction of underground dam. The results show that the construction of underground dam can significantly reduce the scope and degree of seawater intrusion. Groundwater extraction can accelerate the intrusion and diffusion of residual saltwater in underground reservoirs within a certain time range. The coefficient of saltwater intrusion is exponentially related to extraction scale and the distance between extraction wells and underground dams. Reasonable layout of the location and scale of extraction wells can effectively reduce the negative impact of groundwater extraction on water salinity in the reservoir area. © 2023, Editorial Board of Water Resources Protection. All rights reserved.     

Elitist Continuous Ant Colony Optimization Algorithm for Optimal Management of Coastal Aquifers

This paper presents an evolutionary based approach to achieve optimal management of a coastal aquifer to control saltwater intrusion. An improved Elitist Continuous Ant Colony Optimization (ECACO) algorithm is employed for optimal control variables setting of coastal aquifer management problem. The objectives of the optimal management are; maximizing the total water-pumping rate, while controlling the drawdown limits and protecting the wells from saltwater intrusion. Since present work is one of the first efforts towards the application of an ECACO algorithm, sharp interface solution for steady state problem is first exploited. The performance of the developed optimization model is evaluated through application examples available in the literature. The comparisons indicate the applicability of the ECACO algorithm. In the second approach, the numerical simulation is combined with ECACO algorithm. In this model, through some simple schemes, such as continuity equations in the porous media cells and existing hydraulic systems in the study area, further details can be investigated. The evaluation results show the potential applicability of the proposed numerical based model for optimal management of coastal aquifers.     

陆源淡水流量对海岸水库海水入侵的影响

采用平板水槽系统开展了室内物理模型试验,探究了陆源地下水流量与入库地表水流量对海岸水库海水入侵的影响。结果表明:海岸水库的下盐水楔入侵长度与陆源淡水流量呈对数下降关系,随着陆源淡水流量的增大,下盐水楔入侵长度减小趋势减弱;与陆源地下水相比,入库地表水对海岸水库海水入侵的抑制作用更显著;随着陆源淡水流量增大,海岸水库库底盐分减少,上盐水楔比下盐水楔先减小、消失;通过减少地下水的开采和采取调水入库的手段可以抑制海岸水库海水入侵,缓解水库水体的咸化。     

基于FVCOM的磨刀门水道盐水入侵三维数值模拟

该文采用非结构化有限体积近岸海洋三维模型FVCOM(Finite-Volume Coastal Ocean Model),建立了磨刀门水道至伶仃洋盐水入侵数值模型,模拟2004年、2005年及2007年枯季的长序列流场过程,观察其水动力特性,研究盐度的时空变化规律,分析其垂向分层现象。结果表明仅对该文模拟范围的建模也能达到模拟珠江四口门或八口门时磨刀门水道的准确度,从而减少了建模工作量和模型计算量。对三个工况的模拟显示盐水入侵最远距离在2005年1月最大,越过了全禄水厂,2007年3月最小。垂向分层方面,由于盐水上溯的最远距离均处于内河道处,盐度垂向分层不明显,底表层盐水最远入侵距离的差距随入侵距离的增加而减小。海平面平均每升高1 cm,磨刀门水道咸潮入侵平均上移距离为0.85 km。     

Optimal Locations of Groundwater Extractions in Coastal Aquifers

A regional water supply management model for coastal aquifers was developed. One of its outcomes is the definition of the optimized locations for groundwater withdrawal. Such a tool permits the analysis of alternative plans for groundwater extraction and the sustainable use of water resources in a coastal aquifer subject to saltwater intrusion. The principal components are the evolutionary optimization and the analytical/numerical simulation models. The optimization technique looks for the best well locations taking into consideration the economic results and the satisfaction of the societal water demand. However these two concerns are conditioned by trying to control the saltwater intrusion, i.e., preserving the environmental equilibrium. The simulation model uses the governing mathematical equations for groundwater movement to find the interface between freshwater and saltwater. Because of the non-linearity in the system and the possibility of a jumping interface, a security distance was defined. This is a controlling variable which can be set by the decision makers. The model was applied to a typical case with interesting results. For example, diagrams showing the relationship between the location of the wells and the security distance(s) are of importance to the managers. It was also crucial to have an understanding of the tradeoffs between groundwater withdrawals, positions of the wells from the coast line, and the security distance. The model was also applied to a real case in order to relate the extractions, distances and artificial recharge (not presented in this paper).     

A Cost-Effective Method to Control Seawater Intrusion in Coastal Aquifers

Intrusion of seawater into coastal aquifers is considered one of the most important processes that degrade water-quality by raising the salinity to levels exceeding acceptable drinking standards. Therefore saltwater intrusion should be prevented or at least controlled to protect groundwater resources. This paper presents a cost-effective method to control seawater intrusion in coastal aquifers. This methodology ADR (Abstraction, Desalination and Recharge) includes; abstraction of saline water and recharge to the aquifer after desalination. A coupled transient density-dependent finite element model is developed for simulation of fluid flow and solute transport and used to simulate seawater intrusion. The simulation model has been integrated with an optimization model to examine three scenarios to control seawater intrusion including; abstraction, recharge and a combination system, ADR. The main objectives of the models are to determine the optimal depths, locations and abstraction/recharge rates for the wells to minimize the total costs for construction and operation as well as salt concentrations in the aquifer. A comparison between the combined system (ADR) and the individual abstraction or recharge system is made in terms of total cost and total salt concentration in the aquifer and the amount of repulsion of seawater achieved. The results show that the proposed ADR system performs significantly better than using abstraction or recharge wells alone as it gives the least cost and least salt concentration in the aquifer. ADR is considered an effective tool to control seawater intrusion and can be applied in areas where there is a risk of seawater intrusion.     

Simulation-Optimization Modeling for Sustainable Groundwater Development: A Moroccan Coastal Aquifer Case Study

A transient simulation model characterizing groundwater flow in the coastal aquifer of Rhis-Nekor was constructed and calibrated. The flow model was then used in conjunction with a genetic algorithm based optimization model to explore the optimal pumping schemes that meet current and future water demands while minimizing the risks for several adverse environmental impacts, such as saltwater intrusion prevention, avoiding excessive drawdown, as well as controlling waterlogging and salinity problems. Modeling results demonstrate the importance of this combined simulation-optimization methodology for solving groundwater management problems associated with the Rhis-Nekor plain.