【研究】Groundwater | Volume 58, Issue 1
Letters to the Editor/编辑部来信
Comment on “A Particle Tracking Algorithm for Arbitrary Unstructured Grids”
评论“用于任意非结构化网格的粒子跟踪算法”
Comment by Stefano Bonduà
Reply to Comment on “A Particle Tracking Algorithm for Arbitrary Unstructured Grids”
对“任意非结构化网格的粒子跟踪算法”的评论答复
Comment by James R. Craig
Muhammad Ramadhan
Christopher Muffels
Book Review/书评
The Art of Water Wells
水井的艺术
reviewed by Erin Haacker
Review Paper/综述
Aquifer Storage and Recovery Using Saline Aquifers: Hydrogeological Controls and Opportunities
使用盐水层进行含水层的存储和回收：水文地质控制和机遇
by Robert G. Maliva
William S. Manahan
Thomas M. Missimer
Aquifer storage and recovery (ASR) is a valuable tool for managing variations in the supply and demand of freshwater, but system performance is highly dependent upon system‐specific hydrogeological conditions including the salinity of the storage‐zone native groundwater. ASR systems using storage zones containing saline (>10,000 mg/L of total dissolved solids) groundwater tend to have relatively low recovery efficiencies (REs). However, the drawbacks of low REs may be offset by lesser treatment requirements and may be of secondary importance where the stored water (e.g., excess reclaimed, surface, and storm waters) would otherwise go to waste and pose disposal costs. Density‐dependent, solute‐transport modeling results demonstrate that the RE of ASR systems using a saline storage zone is most strongly controlled by parameters controlling free convection (e.g., horizontal hydraulic conductivity) and mixing of recharged and native groundwater (e.g., dispersivity and aquifer heterogeneity). Preferred storage zone conditions are moderate hydraulic conductivities (5 to 20 m/d), low degrees of aquifer heterogeneity, and primary porosity‐dominated siliclastic and limestones lithologies with effective porosities greater than 5%. Where hydrogeological conditions are less favorable, operational options are available to improve RE, such as preferential recovery from the top of the storage zone. Injection of large volumes of excess water currently not needed into saline aquifers could create valuable water resources that could be tapped in the future during times of greater need.
Research Papers/研究文章
A Particle Tracking Algorithm for Arbitrary Unstructured Grids
任意非结构化网格的粒子跟踪算法
by J.R. Craig
M. Ramadhan
C. Muffels
A new semi‐analytical algorithm for generating the local groundwater velocity field within irregular three‐dimensional grid cells (such as a Voronoi cell) is presented. The method supports particle tracking in the MODFLOW‐USG software package for a variety of supported unstructured grid formats. It is shown to replicate the results from the fully analytical Pollock's method when used on a rectilinear grid, and is demonstrated for difficult test cases where there is high spatial variability in the flow field within individual cells. The method is now available as an option in the mod‐PATH3DU software package and may be used with most MODFLOW‐USG packages without additional intervention.
Pyrite Oxidation Halts Migration of a Phosphorus Plume
黄铁矿氧化阻止磷羽的迁移
by William D. Robertson
Dorothy L. Garda
We have established a monitoring record of phosphate (PO43−) migration in the Long Point, ON campground septic system plume that now spans 26 years. Previously, at year 16 (2006), a P plume 16 m in length was documented and provided a good fit with an analytical advection dispersion model when a P migration velocity of 0.8 m/yr was used (retardation factor of 37) and when P behaved in an otherwise conservative manner (sorption only). However, between years 16 and 26 (2016), the P plume length expanded by only 2 m (0.2 m/yr) and increased in depth by only 0.5 m. The zone of abrupt P depletion at depth occurs close to the zone where SO42− concentrations increase in response to NO3− oxidation of pyrite. Scanning electron microscope images of sand grains from the nose of the P plume reveal abundant authigenic mineral coatings of considerable thickness (∼5 to 20 μm), with Fe as the dominant cation and containing 1 to 3 wt % P. This evidence suggests that P is now being attenuated along a reaction front that coincides with the zone where pyrite oxidation is occurring. P migration may now be controlled by the rate of migration of the pyrite oxidation front and this is several times slower than the previously indicated rate in the shallower, sorption‐controlled portion of the plume. Monitoring at Long Point has demonstrated the danger of embracing an overly simplistic conceptual model when attempting to predict wastewater P migration in groundwater and also highlights the unique insight provided by a long‐term monitoring record.
Automatic Generation of Locally Refined Composite Grids for Efficient Solute Transport Modeling
自动生成局部优化的复合网格以进行有效的溶质运移建模
by M. Adil Sbai
N. Amraoui
Widely used numerical models of solute transport processes in subsurface aquifers are limited to nonlocally refined rectangular, or logically rectangular, structured grids. This presents an unsuitable option to efficient numerical simulations maintaining an acceptable level of accuracy. Optimal selection of locally refined cells for efficient solute transport models is challenging to the current generation of numerical models. We present a novel and relatively simple to implement algorithm addressing these shortcomings. This method operates in four steps involving travel times simulations, a grid coarsening stage followed by a selective local grid refinement based on a cell‐wise indicator, and a final postprocessing step. The refinement index is the sum of weighted logarithmic distributions of scaled forward and backward travel times. We calculate representative flow and transport properties at the two scales of the composite grid with a flow‐based upscaling technique. We present two test problems to demonstrate the performances of this new gridding algorithm. We obtain the most important speedups for composite grids generated with the highest indicator thresholds. When hydrodynamic dispersion effects increase, we obtain less important speedups. An important outcome of this work is that grid design depends on nature and strength of the underlying flow and solute transport processes. Therefore, we suggest developing solute transport workflows integrating this grid generation algorithm as an integral component to build comprehensive and efficient groundwater models.
Advective Transport Phenomena to Better Understand Dispersion in Field and Modeling Practice
对流传输现象，以更好地理解野外的分散性和建模实践
by Willem J. de Lange
The absence of recent research on dispersion in engineering applications indicates the need for a description that is more focused on field and modeling practice. Engineers may benefit from simple calculation tools allowing them to understand the processes encountered in the field. Based on a conceptual model for advective transport through an elongated conductivity zone, for example, in fluvial sediments, explicit expressions are presented for macro‐scale phenomena: (1) the different travel distances of water particles traveling in laminar flow through and adjacent to a single zone with conductivity higher or lower than that of the aquifer; (2) the affected thickness of the bundle of flowlines; (3) the distinction of inflow, outflow, and through‐flow sections; (4) the development of a plume front vs. that of a tail; (5) conservation of mass causing water particles to travel both slower and faster than the aquifer average velocity while passing a single zone. The spread derived from a spatial distribution in a field experiment relates to the geometric mean of the spreads of the plume front and tail. The results obtained for a single conductivity zone are expanded for a general aquifer that is characterized by stochastic parameters. A fundamental new expression describes the dispersive mass flux as the product of the advective volume shift and the related local concentration difference. Contrary to Fickian theory, the dispersive mass flux in both the front and tail of a plume in highly heterogeneous aquifers is limited. In modeling, the advective volume shift is proportional to the cell size.
Analytical and Numerical Modeling of Solute Intrusion, Recovery, and Rebound in Fractured Bedrock
裂隙基岩中溶质侵入，恢复和回弹的分析和数值模拟
by Ranjeet M. Nagare
Young‐Jin Park
Trevor Butterfield
Chad Belenky
Sheldon Scyrup
Contaminated groundwater in fractured bedrock can expose ecosystems to undesired levels of risk for extended periods due to prolonged back‐diffusion from rock matrix to permeable fractures. Therefore, it is key to characterize the diffusive mass loading (intrusion) of contaminants into the rock matrix for successful management of contaminated bedrock sites. Even the most detailed site characterization techniques often fail to delineate contamination in rock matrix. This study presents a set of analytical solutions to estimate diffusive mass intrusion into matrix blocks, it is recovered by pumping and concentration rebound when pumping ceases. The analytical models were validated by comparing the results with (1) numerical model results using the same model parameters and (2) observed chloride mass recovery, rebound concentration, and concentration in pumped groundwater at a highly fractured bedrock site in Alberta, Canada. It is also demonstrated that the analytical solutions can be used to estimate the total mass stored in the fractured bedrock prior to any remediation thereby providing insights into site contamination history. The predictive results of the analytical models clearly show that successful remediation by pumping depends largely on diffusive intrusion period. The results of initial mass from the analytical model was used to successfully calibrate a three‐dimensional discrete fracture network numerical model further highlighting the utility of the simple analytical solutions in supplementing the more detailed site numerical modeling. Overall, the study shows the utility of simple analytical methods to support long‐term management of a contaminated fractured bedrock site including site investigations and complex numerical modeling.
Differential Transport of Escherichia coli Isolates Compared to Abiotic Tracers in a Karst Aquifer
与岩溶含水层中的非生物示踪剂相比，大肠杆菌分离株的差异传输
by Ashley M. Bandy
Kimberly Cook
Alan E. Fryar
Junfeng Zhu
Lack of filtration and rapid transport of groundwater and particulate matter make karst aquifers susceptible to bacterial contamination. This study utilized quantitative polymerase chain reaction (qPCR) to examine the transport and attenuation of two nonvirulent isolates of Escherichia coli (E. coli) in relation to traditional groundwater tracers (rhodamine WT dye and 1‐µm diameter latex microspheres) in a karst‐conduit aquifer in central Kentucky. Bacterial isolates were labeled with stable isotopes (15N and 13C). All tracers were detected more than 6 km downstream from the injection site and demonstrated overlapping breakthrough curves, with differential transport observed between the two bacterial strains. The E. coli isolate containing the kps gene (low attachment) arrived at sampling sites 1.25 to 36 h prior to the bacterial isolate containing the iha gene (high attachment) and was detected in samples collected following storm events in which the iha isolate was not detected. The storage potential of contaminants within karst systems was demonstrated by the remobilization of all tracers during storm events more than 1 month after injection. Bacteria‐sized microspheres were more easily remobilized during periods of increased discharge compared to other tracers. The study demonstrated that molecular biology techniques such as qPCR can be utilized as a sensitive analysis of bacterial tracers in karst aquifers and may prove to be a more sensitive analytical technique than stable isotope analysis for field‐scale traces.
Redundant and Nonredundant Information for Model Calibration or Hydraulic Tomography
用于模型校准或水力层析成像的冗余和非冗余信息
by Jet‐Chau Wen
Jyun‐Lin Chen
Tian‐Chyi Jim Yeh
Yu‐Li Wang
Shao‐Yang Huang
Zhong Tian
Chia‐Yii Yu
Drawdown data from independent pumping tests have widely been used to validate the estimated hydraulic parameters from inverse modeling or hydraulic tomography (HT). Yet, the independent pumping test has not been clearly defined. Therefore, the goal of this paper is to define this independent pumping test concept, based on the redundant or nonredundant information about aquifer heterogeneity embedded in the observed heads during cross‐hole pumping tests. The definition of complete, moderate redundancy and high nonredundancy of information are stipulated using cross‐correlation analysis of the relationship between the head and heterogeneity. Afterward, data from numerical experiments and field sequential pumping test campaigns reinforce the concept and the definition.
Evaluating Subsurface Parameterization to Simulate Hyporheic Exchange: The Steinlach River Test Site
评估地下参数化以模拟氢交换：Steinlach河试验场
by Reynold Chow
Jeremy Bennett
Jürnjakob Dugge
Thomas Wöhling
Wolfgang Nowak
Hyporheic exchange is the interaction of river water and groundwater, and is difficult to predict. One of the largest contributions to predictive uncertainty for hyporheic exchange has been attributed to the representation of heterogeneous subsurface properties. Our study evaluates the trade‐offs between intrinsic (irreducible) and epistemic (reducible) model errors when choosing between homogeneous and highly complex subsurface parameter structures. We modeled the Steinlach River Test Site in Southwest Germany using a fully coupled surface water‐groundwater model to simulate hyporheic exchange and to assess the predictive errors and uncertainties of transit time distributions. A highly parameterized model was built, treated as a “virtual reality” and used as a reference. We found that if the parameter structure is too simple, it will be limited by intrinsic model errors. By increasing subsurface complexity through the addition of zones or heterogeneity, we can begin to exchange intrinsic for epistemic errors. Thus, the appropriate level of detail to represent the subsurface depends on the acceptable range of intrinsic structural errors for the given modeling objectives and the available site data. We found that a zonated model is capable of reproducing the transit time distributions of a more detailed model, but only if the geological structures are known. An interpolated heterogeneous parameter field (cf. pilot points) showed the best trade‐offs between the two errors, indicating fitness for practical applications. Parameter fields generated by multiple‐point geostatistics (MPS) produce transit time distributions with the largest uncertainties, however, these are reducible by additional hydrogeological data, particularly flux measurements.
Spatial Variability of Nitrate and Ammonium in Pleistocene Aquifer of Central Yangtze River Basin
长江中游更新世含水层中硝酸盐和铵盐的空间变异
by Yao Du
Yamin Deng
Teng Ma
Shuai Shen
Zongjie Lu
Yiqun Gan
It becomes increasingly important and challenging for nitrogen pollution prevention to identify key controls for spatial variability of nitrogen in groundwater that could be affected by multiple factors, including anthropogenic input, groundwater flow, and local geochemistry. This study characterized spatial variability of both nitrate and ammonium in the Pleistocene aquifer of central Yangtze River Basin and assessed the effect of various factors in controlling nitrate and ammonium levels based on multiple statistical approaches (correlation, geostatistics, multiple liner regression). The results indicate that nitrate is mostly influenced by Cl− that represents anthropogenic input, while Eh representing local redox state is a secondary variable influencing nitrate concentrations. The groundwater with elevated nitrate concentrations are estimated to occur mainly in areas with higher‐permeability near‐surface sediments which can facilitate more anthropogenic nitrate transport and less nitrate removal owing to more oxidized state. Ammonium is mostly correlated to Eh, followed by dissolved organic carbon (DOC), but only DOC improves significantly the accuracy of co‐kriging prediction model. The groundwater with elevated ammonium concentrations are estimated to occur mainly in areas with more organic‐rich sediments within or around the aquifer which can facilitate more ammonium release owing to natural organic matter consumption accompanying strong reducing conditions. The regional groundwater flow is not a factor significantly controlling nitrate or ammonium levels owing to flat topography and sluggish lateral flow.
Methods Notes/方法短文
Analysis of Transient Flow to an Extended Fully Penetrating Well at Constant‐Head Pumping
恒扬程泵送时延伸全穿透井的瞬态流动分析
by Wei‐Hao Jhuang
Chiu‐Shia Fen
Yu‐Te Shen
Hund‐Der Yeh
Vertical wells with radial extension at the well bottom can improve the rate of water production. No study has yet investigated the effects of the transient state and anisotropy in directional hydraulic conductivities on the wellbore flux rate for this type of well. This study derives a semianalytical transient drawdown solution for constant‐head pumping at a fully penetrating well radially extended at the bottom of a confined, anisotropic aquifer by applying Laplace transform and separation of variables as well as conducting a Fourier analysis. The results of this new solution indicate that transient and steady‐state wellbore flux rates can be increased by a factor of two for greater radial extension of the well. Compared with an isotropic aquifer (a ratio of vertical and horizontal hydraulic conductivities equal to one), an anisotropic aquifer with the ratio less than one may produce a higher transient wellbore flux rate and lower steady‐state wellbore flux rate. Moreover, the time required to achieve the steady‐state wellbore flux rate can be substantially affected by anisotropy of the aquifer.
Collected Rain Water as Cost‐Efficient Source for Aquifer Tracer Testing
收集雨水作为进行含水层示踪剂测试的经济高效来源
by Felix Tritschler
Martin Binder
Falk Händel
Diana Burghardt
Peter Dietrich
Rudolf Liedl
Locally collected precipitation water can be actively used as a groundwater tracer solution based on four inherent tracer signals: electrical conductivity, stable isotopic signatures of deuterium [δ2H], oxygen‐18 [δ18O], and heat, which all may strongly differ from the corresponding background values in the tested groundwater. In hydrogeological practice, a tracer test is one of the most important methods for determining subsurface connections or field parameters, such as porosity, dispersivity, diffusion coefficient, groundwater flow velocity, or flow direction. A common problem is the choice of tracer and the corresponding permission by the appropriate authorities. This problem intensifies where tracer tests are conducted in vulnerable conservation or water protection areas (e.g., around drinking water wells). The use of (if required treated) precipitation as an elemental groundwater tracer is a practical solution for this problem, as it does not introduce foreign matters into the aquifer system, which may contribute positively to the permission delivery. Before tracer application, the natural variations of the participating end members' tracer signals have to be evaluated locally. To obtain a sufficient volume of tracer solution, precipitation can be collected as rain using a detached, large‐scale rain collector, which will be independent from possibly existing surfaces like roofs or drained areas. The collected precipitation is then stored prior to a tracer experiment.
Case Studies/案例研究
Quantifying Threshold Water Tables for Ecological Restoration in Arid Northwestern China
西北干旱地区生态恢复阈值水量的量化
by Yong Wang
Minjian Chen
Long Yan
Guiyu Yang
Jing Ma
Wei Deng
In arid northwestern China, as many inland areas around the world with arid or semi‐arid climate, inland river flow recharges groundwater; vegetation pattern depends on the water table, which characterizes the landscapes of oasis, transition zone and desert, within different distances from an inland river. The water table conditions play an important role in water and land management—a high water table causes salinization within the oasis while a low water table causes desertification around the oasis. This study applies a theoretical‐empirical method to calculating critical groundwater depths including the depth of critical groundwater level causing salinization (DCGS) and the depth of critical groundwater level causing desertification (DCGD); the calculations are validated with field observations in the Luocheng Irrigation District located in the middle reach of the Heihe River, an inland river of the northwestern China. Specifically, the calculated DCGS is 1.29 m for the case study area and the range of water table depth at the locations with saline soil is 0.5‐1.2 m. The calculated DCGD for three vegetation communities, Nitraria tangutorum + Glycyrrhiza uralensis Fisch community, Tamarix chinensis + Phragmites australis community, and Alhagi sparsifolia + Phragmites communis, are 8.26, 11.26, and 13.26 m, respectively, basically within an observed range of 6.0‐13.0 m in the study area. The critical depths can be used to design an engineering approach to control water tables and mitigate salinization and desertification problem for ecosystem restoration in the study region.
Groundwater Monitoring Using GRACE and GLDAS Data after Downscaling Within Basaltic Aquifer System
玄武岩含水层系统缩小规模后使用GRACE和GLDAS数据进行地下水监测
by Kaushlendra Verma
Yashwant B. Katpatal
Gravity Recovery and Climate Experiment (GRACE) satellite mission is ground‐breaking information hotspot for the evaluation of groundwater storage. The present study aims at validating the sensitivity of GRACE data to groundwater storage variation within a basaltic aquifer system after its statistical downscaling on a regional scale. The basaltic aquifer system which covers 82.06% area of Maharashtra state in India, is selected as the study area. Five types of basaltic aquifer systems with varying groundwater storage capacities, based on hydrologic characteristics, have been identified within the study area. The spatial and seasonal trend analysis of observed in situ groundwater storage anomalies (ΔGWSano) computed from groundwater level data of 983 wells from the year 2002 to 2016, has been performed to analyze the variation in groundwater storages in the different basaltic aquifer system. The groundwater storage anomalies (ΔGWSDano) have been derived from GRACE Release 05 (RL05) after removing the soil moisture anomaly (ΔSMano) and canopy water storage anomaly (ΔCNOano) obtained from Global Land Data Assimilation System (GLDAS) land surface models (NOAH, MOSAIC, CLM and VIC). The artificial neural network technique has been used to downscale the GRACE and GLDAS data at a finer spatial resolution of 0.125°. The study shows that downscaled GRACE and GLDAS data at a finer spatial resolution is sensitive to seasonal groundwater storage variability in different basaltic aquifer systems and the regression coefficient R has been found satisfactory in the range of 0.696 to 0.818.
Historical Note/历史回顾
The Aqueducts and Water Supply of Ancient Rome
古罗马的渡槽和供水
by David Deming
END
点击图片，爆款原创，以飨共赏达西环境
邮箱：darcyenv@yeah.net
办公微信：Darcy_Env
做地下水环境的医生!