Developing three-dimensional groundwater flow modeling for the Erbil Basin using Groundwater Modeling System (GMS)

This study presents the development of a comprehensive three-dimensional groundwater flow model for the Erbil Basin utilizing the Groundwater Modeling System(GMS).The Erbil Basin,situated in the Kurdistan Region of Iraq,is a vital water resource area facing increasing water demands and environ-mental challenges.The three-dimensional nature of the groundwater flow system is crucial for accurately understanding and managing water resources in the basin.The modeling process involved data collection,geological and hydrogeological characterization,conceptual model development,and numerical simulation using GMS software MODFLOW 2000 package.Various parameters such as hydraulic conductivity,recharge rates,and boundary conditions were integrated into the model to represent the complex hydrogeo-logical conditions of the basin.Model calibration was performed by comparing simulated groundwater levels with observed data from monitoring wells across the basin,using the automatic calibration method of automated Parameter Estimation(PEST).Pilot points were applied to adjust the hydraulic conductivity in the model area spatially.Sensitivity analysis was conducted to assess the influence of key parameters on model predictions and to identify areas of uncertainty.The developed three-dimensional groundwater flow model provides valuable insights into the dynamics of groundwater flow,recharge-discharge mechanisms,and potential impacts of future scenarios such as climate change and water resource management strategies.It serves as a useful tool for decision-makers,water resource managers,and researchers to evaluate differ-ent management scenarios and formulate sustainable groundwater management policies for the Erbil Basin.In conclusion,this study demonstrates the effectiveness of using GMS for developing three-dimensional groundwater flow models in complex hydrogeological settings like the Erbil Basin,contributing to improved understanding and management of groundwater resources in the region.

Impact of water table on hierarchically nested groundwater flow system

Water table configuration gives rise to hierarchically nested groundwater flow systems.However,there remains a lack of comprehensive understanding regarding the controlling factors of water table and its impact on flow systems.Moreover,it remains challenging to identify characteristics of water table space variation through limited groundwater observations at the regional scale.Based on two ideal two-dimensional cross-section analytical models,this study presents a simplified approach to preliminarily assess the nonlinear interactions between water table variation and three driving factors:Topography,geol-ogy and climate.Two criteria,C1 and C2,are utilized to address issues at different scales ranging from basin to local:(i)the influence of various factors on water table configuration;and(ii)the influence of water table on groundwater flow pattern.Then,the Ordos Plateau is taken as an example to explore the role of the water table in nested groundwater systems using the provided approach and criterion.The applica-tion of this approach in the Ordos Plateau demonstrates its appropriateness as a practical method for prelim-inarily determining the characteristics of water table configuration and its impact on flow systems.The study explores the mechanism influencing spatial variation in the water table and improves understanding of the interaction between topography,geology,and climate on groundwater flow patterns.

Effects of coal mining and tunnel excavation on groundwater flow system in karst areas by modeling:A case study in Zhongliang Mountain,Chongqing,Southwest China

A karst groundwater system ranks among the most sensitive and vulnerable types of groundwater systems.Coal mining and tunnel excavation can greatly change the natural hydrogeological flow system,groundwater-dependent vegetation,soil,as well as hydrology of surface water systems.Abandoned coal mine caves and proposed highway tunnels may have significant influences on groundwater systems.This study employs MODFLOW,a 3D finite-difference groundwater model software,to simulate the groundwater system's response to coal mining and tunnel excavation impact in Zhongliang Mountain,Chongqing,from 1948 to 2035.The results show a regional decline in groundwater levels within the study area following mining and tunnel construction.The groundwater flow system in the study area evolves from the Jialing River groundwater flow system to encompass the Jialing River,Moxinpo highway tunnel,Moxinpo,and the Liujiagou coal mine cave groundwater flow systems between 1948 and 2025.With the completion of tunnel construction,the groundwater level at the top of the tunnel is gradually restored to the water level in the natural state.The model also predicts groundwater level variations between 2025 and 2035.The groundwater level will rise further initially,however,it may take about 10 years for the system to stabilize and reach a new equilibrium.In light of these findings,it is advised that changes in groundwater flow systems caused by tunnel construction should be modeled prior to the practical construction.This approach is crucial for evaluating potential engineering and environmental implications.

The Design of a Three-Dimensional Physical Modeling System for Real-Time Groundwater Flows

In the past decades,physical modeling has been widely used in hydrogeology for teaching,studying and exhibition purposes.Most of these models are used to illustrate hydrogeological profiles,but few can depict three-dimensional groundwater flows,making it impossible to validate groundwater flows simulated by numerical methods with physical modeling.

Machine learning prediction of methane,ethane,and propane solubility in pure water and electrolyte solutions:Implications for stray gas migration modeling

Hydraulic fracturing is an effective technology for hydrocarbon extraction from unconventional shale and tight gas reservoirs.A potential risk of hydraulic fracturing is the upward migration of stray gas from the deep subsurface to shallow aquifers.The stray gas can dissolve in groundwater leading to chemical and biological reactions,which could negatively affect groundwater quality and contribute to atmospheric emissions.The knowledge oflight hydrocarbon solubility in the aqueous environment is essential for the numerical modelling offlow and transport in the subsurface.Herein,we compiled a database containing 2129experimental data of methane,ethane,and propane solubility in pure water and various electrolyte solutions over wide ranges of operating temperature and pressure.Two machine learning algorithms,namely regression tree(RT)and boosted regression tree(BRT)tuned with a Bayesian optimization algorithm(BO)were employed to determine the solubility of gases.The predictions were compared with the experimental data as well as four well-established thermodynamic models.Our analysis shows that the BRT-BO is sufficiently accurate,and the predicted values agree well with those obtained from the thermodynamic models.The coefficient of determination(R2)between experimental and predicted values is 0.99 and the mean squared error(MSE)is 9.97×10^(-8).The leverage statistical approach further confirmed the validity of the model developed.

基于GMS的地下水环境评价

地下水与人类生产生活密切相关,地下水环境评价是水电工程项目中十分重要的一环。以某抽水蓄能电站为例,通过GMS数值软件建立研究区水文地质模型,模拟该水电站天然情况下地下水渗流状态,并对该工程施工及运行期地下水系统进行预测。在此基础上,根据该工程施工及运营期特点,提出地下水环境保护措施与对策,从而对类似工程提供参考与建议。

基于GMS的某钢铁厂地下水污染运移研究

钢铁冶炼工序复杂,冶炼过程产生的污染物质如未经处理直接泄露,通过包气带入渗至含水层对地下水质量造成威胁。为探究污染物在地下水中的运移情况,以某钢铁厂为研究区域,使用GMS软件构建相应的地下水数学模型。选取研究区域内超标较为严重或普遍的1,2-二氯乙烷、石油烃类、苯和萘为典型污染物,预测研究区域内的典型污染物在地下水中运移的过程。结果表明:在研究区域内典型污染物随着地下水的流向向下游运移,并且随着时间的推移其浓度不断降低。在模拟期末(30 a)研究区内1,2-二氯乙烷、石油烃类和苯的最高浓度分别为1.52 mg/L、11.16 mg/L和3.55 mg/L,研究区内萘浓度已低于一类修复目标值。其污染羽前锋尚未影响到作为研究区南部边界的南淝河。

基于GMS的石化园区地下水数值模拟研究

石油化工类项目在运行过程中产生的泄漏,会对周边的地下水造成污染。以湖南省丘陵地貌的某石化园区建设项目为例,利用GMS软件对园区苯罐区和有机物料罐区非正常工况和风险事故工况下污染物在地下水的运移情况进行模拟预测。结果表明,两种工况下均有部分污染物会移出厂界,风险事故工况下的污染物浓度明显高于非正常工况,导致泄漏点附近的地下水受到不同程度的影响。因此,必须采取严格的防渗措施,生产运行期也需定期监测并做好应急措施,最大程度地保护地下水。

Pollution source identification methods and remediation technologies of groundwater: A review

Groundwater is an important source of drinking water.Groundwater pollution severely endangers drinking water safety and sustainable social development.In the case of groundwater pollution,the top priority is to identify pollution sources,and accurate information on pollution sources is the premise of efficient remediation.Then,an appropriate pollution remediation scheme should be developed according to information on pollution sources,site conditions,and economic costs.The methods for identifying pollution sources mainly include geophysical exploration,geochemistry,isotopic tracing,and numerical modeling.Among these identification methods,only the numerical modeling can recognize various information on pollution sources,while other methods can only identify a certain aspect of pollution sources.The remediation technologies of groundwater can be divided into in-situ and ex-situ remediation technologies according to the remediation location.The in-situ remediation technologies enjoy low costs and a wide remediation range,but their remediation performance is prone to be affected by environmental conditions and cause secondary pollution.The ex-situ remediation technologies boast high remediation efficiency,high processing capacity,and high treatment concentration but suffer high costs.Different methods for pollution source identification and remediation technologies are applicable to different conditions.To achieve the expected identification and remediation results,it is feasible to combine several methods and technologies according to the actual hydrogeological conditions of contaminated sites and the nature of pollutants.Additionally,detailed knowledge about the hydrogeological conditions and stratigraphic structure of the contaminated site is the basis of all work regardless of the adopted identification methods or remediation technologies.

Spatio-temporal variation of depth to groundwater level and its driving factors in arid and semi-arid regions of India

Climate change and increasing anthropogenic activities,such as over-exploitation of groundwater,are exerting unavoidable stress on groundwater resources.This study investigated the spatio-temporal variation of depth to groundwater level(DGWL)and the impacts of climatic(precipitation,maximum temperature,and minimum temperature)and anthropogenic(gross district product(GDP),population,and net irrigated area(NIA))variables on DGWL during 1994-2020.The study considered DGWL in 113 observation wells and piezometers located in arid western plains(Barmer and Jodhpur districts)and semi-arid eastern plains(Jaipur,Ajmer,Dausa,and Tonk districts)of Rajasthan State,India.Statistical methods were employed to examine the annual and seasonal patterns of DGWL,and the generalized additive model(GAM)was used to determine the impacts of climatic and anthropogenic variables on DGWL.During 1994-2020,except for Barmer District,where the mean annual DGWL was almost constant(around 26.50 m),all other districts exhibited increase in DGWL,with Ajmer District experiencing the most increase.The results also revealed that 36 observation wells and piezometers showed a statistically significant annual increasing trend in DGWL and 34 observation wells and piezometers exhibited a statistically significant decreasing trend in DGWL.Similarly,32 observation wells and piezometers showed an statistically significant increasing trend and 37 observation wells and piezometers showed a statistically significant decreasing trend in winter;33 observation wells and piezometers indicated a statistically significant increasing trend and 34 had a statistically significant decreasing trend in post-monsoon;35 observation wells and piezometers exhibited a statistically significant increasing trend and 32 observation wells and piezometers showed a statistically significant decreasing trend in pre-monsoon;and 36 observation wells and piezometers reflected a statistically significant increasing trend and 30 observation wells and piezometers reflected a statistically significant decreasing trend in monsoon.Interestingly,most of the observation wells and piezometers with increasing trends of DGWL were located in Dausa and Jaipur districts.Furthermore,the GAM analysis revealed that climatic variables,such as precipitation,significantly affected DGWL in Barmer District,and DGWL in all other districts was influenced by anthropogenic variables,including GDP,NIA,and population.As a result,stringent regulations should be implemented to curb excessive groundwater extraction,manage agricultural water demand,initiate proactive aquifer recharge programs,and strengthen sustainable management in these water-scarce regions.

基于GMS数值模拟的某矿床涌水量预测研究

某矿床在开采过程中遇到一定程度的涌水。为解决涌水问题,并为防治水方案提供依据,以该矿床为研究对象,通过分析矿床水文地质条件、含水层类型及特征、地下水补给径流和排泄条件、地质构造特征、水文地质试验资料和矿床开采设计资料等,对矿床水文地质条件进行了概化,对研究区水文地质单元进行了划定,采用GMS软件建立了地下水流数值模型,预测得到了-200 m以下中段的矿坑涌水量。

Harmful evaluation of heavy metals from soil layer to the groundwater: Take the Jilin Hunchun Basin as an example

The continuous enrichment of heavy metals in soils has caused potential harm to groundwater.Quantitative methods to evaluate the harm of heavy metals in soil to groundwater are lacked in previous studies.Based on the theory of groundwater circulation and solid-liquid equilibrium,a simple and easy-touse flux model of soil heavy metals migrating to groundwater is constructed.Based on groundwater environmental capacity,an innovative method for evaluating the harm of heavy metals in soil to groundwater is proposed,which has been applied in Hunchun Basin,Jilin Province,China.The results show that the fluxes of soil heavy metals into groundwater in the study area are Zn,Cu,As,Pb,Cd,Ni,and Hg in descending order.The content of heavy metals in groundwater(As,Hg,Cu,Pb,Zn,Ni,and Cd)in most areas has not risen to the threshold of environmental capacity within 10 years.The harm levels of soil heavy metals to groundwater in the most townships soils are at the moderate level or below.This evaluation method can quantify the flux of soil heavy metals into groundwater simply and quickly,determine the residual capacity of groundwater to heavy metals,evaluate the harm level of soil heavy metals to groundwater,provide support for relevant departments to carry out environmental protection of soil and groundwater,and provide a reference to carry out similar studies for related scholars.

基于GMS的某污染区地下水1,2-二氯乙烷的自然运移规律研究

以上海市普陀区某1,2-二氯乙烷地下水污染场地为研究对象开展地下水污染相关研究,通过数值模拟分析污染物在自然条件下及抽水条件下的污染扩散趋势。根据场地前期环境调查结果,收集分析污染点位、浓度、深度及场地水文地质信息,利用GMS地下水模型系统中的MODFLOW与MT3DMS模型分别模拟该区域的地下水流场及1,2-二氯乙烷在不同抽提条件下的运移情况,分析污染物的运移规律。研究表明,初始污染浓度为7.2 mg/L的1,2-二氯乙烷在自然流场作用下,污染扩散主要受地下水流方向影响,经10 a扩散,污染点位中心污染物的浓度仍能达到2.7 mg/L,污染物扩散范围不断增大。抽提井的抽水作用能显著影响污染物的自然扩散,随着抽提井数量的增多,经700 d的抽提,污染羽中心污染浓度可降低至0.03 mg/L以下,满足《地下水质量标准》的第Ⅳ类筛选值的要求。

基于GMS的地面沉降模型的研究和实践应用

以南沙地面沉降区域为研究对象,运用GMS软件模拟分析压缩土层、建筑荷载、地下水位等要素对地面沉降的影响程度,采用试错法,建立有效的地面沉降模型,并结合现状及历史数据进行预测和推演,模拟多种工况下南沙区地下水水位变化和地面沉降的变化量,结果表明:南沙区地面沉降较为严重的区域主要集中在龙穴岛北部,其建筑荷载造成的沉降量最大可达到149 mm。该模型的构建及运用为南沙区在地面沉降管理决策方面起到良好的辅助作用,具有应用性和实践意义。

基于GMS-MODFLOW的露天矿地下水流量预测数值模拟研究

某露天矿区地下水分布主要受岩体断层、裂隙等地质结构主导,开采过程中将对边坡稳定性和矿坑内排水产生影响。为预测矿区地下水量和矿坑排水条件,采用多段封隔器压水试验和变水头压水试验对岩质边坡岩体水力传导系数进行分析。在构建矿区水文地质概念模型的基础上,运用GMS软件MODFLOW模块建立了矿区岩体三维有限差分数值模型,研究了非饱和-饱和渗流模型中稳态和瞬态条件下地下水量动态变化,阐述了边坡降雨入渗导致地下水位上升和饱和区形成发展过程,分析了敏感条件下矿区地下水位分布变化,提出了按照开采深度进行不同的矿坑排水管理策略。

基于GMS的矿井涌水量预测

矿井涌水是矿山安全开采中难以解决又必须面对的问题。GMS(groundwater modeling system)具有强大的前、后处理功能,实现了地质模型、水文地质参数等的可视化,提供的自检功能为调试模型提供了极大方便。以宁夏某矿为例,应用GMS对其水文地质条件进行概化,建立水文地质结构模型和水文地质概化模型,通过MODFLOW模块对其涌水量进行预测。结果表明:三维地质模型具有很好地可视性,研究区地层能够更加直观的得以展示,模拟所得水位与实测水位拟合效果在置信区间内,模拟区首采面的涌水量的预测值为1450 m~3/h。为矿山开采、工程建设中涌水量预测的研究提供了更为直观、更为便捷的方法。

Groundwater quality assessment using multivariate analysis,geostatistical modeling, and water quality index(WQI): a case of study in the Boumerzoug-El Khroub valley of Northeast Algeria

In this study,the analytical data set of 26 groundwater samples from the alluvial aquifer of Boumerzoug-E1 khroub valley has been processed simultaneously with Multivariate analysis,geostatistical modeling,WQI,and geochemical modeling.Cluster analysis identified three main water types based on the major ion contents,where mineralization increased from group 1 to group 3.These groups were confirmed by FA/PCA,which demonstrated that groundwater quality is influenced by geochemical processes(water-rock interaction)and human practice(irrigation).The exponential semivariogram model WQI.Groundwater chemistry has a strong spatial structure for Mg,Na,Cl,and NO3,and a moderate spatial structure for EC,Ca,K,HCO3,and SO4.Water quality maps generated using ordinary Kriging are consistent with the HCA and PCA results.All water groups are supersaturated with respect to carbonate minerals,and dissolution of kaolinite and Ca-smectite is one of the processes responsible for hydrochemical evolution in the area.

Geochemical modeling of groundwater in southern plain area of Pengyang County,Ningxia,China

The purpose of this paper is to examine the evolution mechanisms of a hydrochemical field and to promote its benefits to the living standards of local people and to the local economy in the southern plain area of Pengyang County, in Ningxia, China. Based on understanding of the hydrogeological conditions in Pengyang County, the chemical evolution characteristics of groundwater in the plain area were analyzed. PHREEQC geochemical modeling software was used to perform hydrochemical modeling of water-rock interaction and to quantitatively analyze the evolution processes and the formation mechanisms of the local groundwater. Geochemical modeling was performed for two groundwater paths. The results showed that, along path 1, Na＋ adsorption played the leading role in the precipitation process and its amount was the largest, up to 6.08 mmol/L; cation exchange was significant along path 1, while along simulated path 2, albite accounted for the largest amount of dissolution, reaching 9.06 mmol/L, and the cation exchange was not significant. According to the modeling results, along the groundwater flow path, calcite and dolomite showed oversaturated status with a precipitation trend, while the fluorite and gypsum throughout the simulated path were not saturated and showed a dissolution trend. The total dissolved solids （TDS） increased and water quality worsened along the flow path. The dissolution reactions of albite, CO2, and halite, the exchange adsorption reaction of Na＋, and the precipitation of sodium montmorillonite and calcite were the primary hydrogeochemical reactions, resulting in changes of hydrochemical ingredients.

Solution for Distributed Model of Groundwater System with PCG2 for Naolihe Basin in Sanjiang Plain

PCG2 （Preconditioned Conjugate-Gradient Method 2）, the most popular mothod used in groundwater field, was used to solve the distributed model of large-scale groundwater system. Its principle and effect was analyzed mathematically, and verified by some specific examples. Numerical results acquired by PCG2 are accurate, it demonstrates that PCG2 is effective on methodology itself and man-ralated operation. So PCG2 is worthy of popularizing in the area of groundwater system for numerical analysis.