Fundamentals of Groundwater

Franklin W. Schwartz, PhD, is Professor and Ohio Eminent Scholar in Hydrogeology at The Ohio State University in Columbus. He is the co-author of Fundamentals of Groundwater and Physical and Chemical Hydrogeology. His research interests include groundwater sustainability, geo-environments and health, and water and societies. Hubao Zhang, PhD, is a software engineer at Rain Bird. He has extensive experience working in environmental consulting and groundwater modeling and is the co-author of Fundamentals of Groundwater.

• Preface xvAbout the Companion Website xvii1 Introduction to Groundwater 11.1 Why Study Groundwater? 11.2 Brief History of Groundwater 41.2.1 On Books 41.2.2 On the Early Evolution of Hydrogeological Knowledge 51.2.3 1960–2005 Computers and Contaminants 61.2.4 2005 and Onward: Research Diversified 8References 92 Hydrologic Processes at the Earth’s Surface 122.1 Basin-Scale Hydrologic Cycle 122.2 Precipitation 152.2.1 Snowpack Distributions 202.3 Evaporation, Evapotranspiration, and Potential Evapotranspiration 202.4 Infiltration, Overland Flow, and Interflow 232.5 Simple Approaches to Runoff Estimation 252.6 Stream Flow and the Basin Hydrologic Cycle 302.6.1 Measuring Stream Discharge 302.6.2 Hydrograph Shape 322.6.3 Estimation of Baseflow 352.7 Flood Predictions 37Exercises 38References 403 Basic Principles of Groundwater Flow 423.1 Porosity of a Soil or Rock 423.2 Occurrence and Flow of Groundwater 453.3 Darcy’s Experimental Law 463.3.1 Darcy Column Experiments 473.3.2 Linear Groundwater Velocity or Pore Velocity 483.3.3 Hydraulic Head 493.3.4 Components of Hydraulic Head 503.4 Hydraulic Conductivity and Intrinsic Permeability 513.4.1 Intrinsic Permeability 523.4.2 Hydraulic Conductivity Estimated from Association with Rock Type 533.4.3 Empirical Approaches for Estimation 533.4.4 Laboratory Measurement of Hydraulic Conductivity 553.5 Darcy’s Equation for Anisotropic Material 563.6 Hydraulic Conductivity in Heterogeneous Media 573.7 Investigating Groundwater Flow 613.7.1 Water Wells, Piezometers, and Water Table Observation Wells 613.7.2 Potentiometric Surface Maps 623.7.3 Water-Level Hydrograph 633.7.4 Hydrogeological Cross Sections 65References 674 Aquifers 694.1 Aquifers and Confining Beds 694.2 Transmissive and Storage Properties of Aquifers 704.2.1 Transmissivity 704.2.2 Storativity (or Coefficient of Storage) and Specific Storage 724.2.3 Storage in Confined Aquifers 734.2.4 Storage in Unconfined Aquifers 744.2.5 Specific Yield and Specific Retention 744.3 Principal Types of Aquifers 754.4 Aquifers in Unconsolidated Sediments 754.4.1 Alluvial Fans and Basin Fill Aquifers 754.4.2 Fluvial Aquifers 794.5 Examples Alluvial Aquifer Systems 804.5.1 Central Valley Alluvial Aquifer System 804.5.2 High Plains Aquifer System 814.5.3 Indo-Gangetic Basin Alluvial Aquifer System 824.5.4 Mississippi River Valley Alluvial Aquifer 834.5.5 Aquifers Associated with Glacial Meltwater 854.6 Aquifers in Semiconsolidated Sediments 874.7 Sandstone Aquifers 884.7.1 Dakota Sandstone 884.8 Carbonate-Rock Aquifers 894.8.1 Enhancement of Permeability and Porosity by Dissolution 904.8.2 Karst Landscapes 914.8.3 Floridan Aquifer System 934.8.4 Edwards-Trinity Aquifer System 944.8.5 Basin and Range Carbonate Aquifer 964.9 Basaltic and Other Volcanic-Rock Aquifers 974.10 Hydraulic Properties of Granular and Crystalline Media 994.10.1 Pore Structure and Permeability Development 994.11 Hydraulic Properties of Fractured Media 1004.11.1 Factors Controlling Fracture Development 101References 1025 Theory of Groundwater Flow 1065.1 Differential Equations of Groundwater Flow in Saturated Zones 1065.1.1 Useful Knowledge About Differential Equations 1075.1.2 More About Dimensionality 1095.1.3 Deriving Groundwater Flow Equations 1095.2 Boundary Conditions 1135.3 Initial Conditions for Groundwater Problems 1145.4 Flow-net Analysis 1155.4.1 Flow Nets in Isotropic and Homogeneous Media 1155.4.2 Flow Nets in Heterogeneous Media 1185.4.3 Flow Nets in Anisotropic Media 1195.5 Mathematical Analysis of Some Simple Flow Problems 1205.5.1 Groundwater Flow in a Confined Aquifer 1205.5.2 Groundwater Flow in an Unconfined Aquifer 1215.5.3 Groundwater Flow in an Unconfined Aquifer with Recharge 123References 1256 Theory of Groundwater Flow in Unsaturated Zones and Fractured Media 1266.1 Basic Concepts of Flow in Unsaturated Zones 1266.1.1 Changes in Moisture Content During Infiltration 1286.2 Characteristic Curves 1286.2.1 Water Retention or θ(ψ) Curves 1286.2.2 K(ψ) Curves 1306.2.3 Moisture Capacity or C(ψ) Curves 1326.3 Flow Equation in the Unsaturated Zone 1336.4 Infiltration and Evapotranspiration 1346.5 Examples of Unsaturated Flow 1366.5.1 Infiltration and Drainage in a Large Caisson 1366.5.2 Unsaturated Leakage from a Ditch 1376.6 Groundwater Flow in Fractured Media 1376.6.1 Cubic Law 1376.6.2 Flow in a Set of Parallel Fractures 1396.6.3 Equivalent-Continuum Approach 141References 1427 Geologic and Hydrogeologic Investigations 1447.1 Key Drilling and Push Technologies 1447.1.1 Auger Drilling 1447.1.2 Mud/Air Rotary Drilling 1457.1.3 Direct-Push Rigs 1467.2 Piezometers and Water-Table Observation Wells 1507.2.1 Basic Designs for Piezometers and Water-Table Observation Wells 1507.3 Installing Piezometers and Water-Table Wells 1527.3.1 Shallow Piezometer in Non-Caving Materials 1527.3.2 Shallow Piezometer in Caving Materials 1527.3.3 Deep Piezometers 1537.4 Making Water-Level Measurements 1547.5 Geophysics Applied to Site Investigations 1557.5.1 Electric Resistivity Method 1557.5.2 Capacitively Coupled Resistivity Profiling 1587.5.3 Electromagnetic Methods 1597.5.4 Large-Scale, Airborne Electromagnetic Surveys 1607.5.5 Borehole Geophysical and Flow Meter Logging 1627.5.6 Flowmeter Logging 1647.6 Groundwater Investigations 1667.6.1 Investigative Methods 167References 1688 Regional Groundwater Flow 1708.1 Groundwater Basins 1708.2 Mathematical Analysis of Regional Flow 1718.2.1 Water-Table Controls on Regional Groundwater Flow 1718.2.2 Effects of Basin Geology on Groundwater Flow 1758.3 Recharge 1798.3.1 Desert Environments 1798.3.2 Semi-Arid Climate and Hummocky Terrain 1808.3.3 Recharge in Structurally Controlled Settings 1818.3.4 Distributed Recharge in Moist Climates 1818.3.5 Approaches for Estimating Recharge 1818.4 Discharge 1838.4.1 Inflow to Wetlands, Lakes, and Rivers 1838.4.2 Springs and Seeps 1838.4.3 Evapotranspiration 1858.5 Groundwater Surface-Water Interactions 1868.6 Freshwater/Saltwater Interactions 1898.6.1 Locating the Interface 1908.6.2 Upconing of the Interface Caused by Pumping Wells 192References 1939 Response of Confined Aquifers to Pumping 1959.1 Aquifers and Aquifer Tests 1959.1.1 Units 1969.2 Thiem’s Method for Steady-State Flow in a Confined Aquifer 1979.2.1 Interpreting Aquifer Test Data 1989.3 Theis Solution for Transient Flow in a Fully Penetrating, Confined Aquifer 1999.4 Prediction of Drawdown and Pumping Rate Using the Theis Solution 2019.5 Theis Type-Curve Method 2019.6 Cooper–Jacob Straight-Line Method 2049.7 Distance-Drawdown Method 2069.8 Estimating T and S Using Recovery Data 208References 21410 Leaky Confined Aquifers and Partially-Penetrating Wells 21610.1 Transient Solution for Flow Without Storage in the Confining Bed 21610.1.1 Interpreting Aquifer-Test Data 21810.2 Steady-State Solution 22110.3 Transient Solutions for Flow with Storage in Confining Beds 22310.4 Effects of Partially Penetrating Wells 229References 23511 Response of an Unconfined Aquifer to Pumping 23611.1 Calculation of Drawdowns by Correcting Estimates for a Confined Aquifer 23611.2 Determination of Hydraulic Parameters Using Distance/Drawdown Data 23811.3 A General Solution for Drawdown 23911.4 Type-Curve Method 24111.5 Straight-Line Method 24511.6 Aquifer Testing with a Partially-Penetrating Well 247References 25012 Slug, Step, and Intermittent Tests 25112.1 Hvorslev Slug Test 25112.2 Cooper–Bredehoeft–Papadopulos Test 25512.3 Bower and Rice Slug Test 25712.4 Step and Intermittent Drawdown Tests 25912.4.1 Determination of Transmissivity and Storativity 26012.4.2 Estimating Well Efficiency 263References 26813 Calculations and Interpretation of Hydraulic Head in Complex Settings 26913.1 Multiple Wells and Superposition 26913.2 Drawdown Superimposed on a Uniform Flow Field 27113.3 Replacing a Geologic Boundary with an Image Well 27213.3.1 Impermeable Boundary 27213.3.2 Recharge Boundary 27713.4 Multiple Boundaries 27813.5 Calculation and Interpretation of Hydraulic Problems Using Computers 27913.5.1 Numerical Models for Groundwater Simulations 27913.5.2 Interpreting Aquifer Tests 281References 28214 Depletion of Groundwater Resources 28314.1 Water-Level Declines from Overpumping 28314.1.1 Challenges in the Investigation of Water-level Changes 28514.2 Land Subsidence 28514.2.1 Conceptual Model 28614.2.2 Terzaghi Principle of Effective Stress 28814.2.3 Subsidence in the San Joaquin Valley of California 28914.2.4 Challenges in the Investigation of Subsidence 29314.3 Connected Groundwaters and Surface Waters 29414.3.1 Declines in Streamflow 29414.3.2 Induced Infiltration of Streamflow 29514.3.3 Capture Zone for a Well 29814.3.4 Pumping of the High Plains Aquifer System and Streamflow Reduction 29814.3.5 Streamflow Declines in Beaver-North Canadian River Basin 30014.3.6 Challenges in the Investigation of Streamflow Loss 30114.4 Destruction of Riparian Zones 30114.5 Seawater Intrusion 30314.5.1 Salinas River Groundwater Basin 30414.6 Introduction to Groundwater Modeling 30614.6.1 Conceptual Model 30614.6.2 Model Design 30814.6.3 Model Calibration and Verification 30814.6.4 Predictions in Modeling 30914.7 Application of Groundwater Modeling 309References 31215 Groundwater Management 31515.1 The Case for Groundwater Sustainability 31515.2 Groundwater Sustainability Defined 31715.2.1 Sustainability Initiatives 31715.2.2 Sustainability Indicators for the Sierra Vista Subwatershed in Arizona 31815.2.3 Socioeconomic Policies and Instruments 32015.3 Overview of Approaches for Sustainable Management 32115.3.1 Indicator Tracking 32115.3.2 Water Balance Analyses 32215.3.3 Model-Based Analyses of Sustainability 32615.4 Strategies for Groundwater Sustainability 32715.4.1 Increasing Inflows 32715.4.1.1 Managed Aquifer Recharge (MAR) 32715.4.1.2 Traditional MAR Approaches 32915.4.1.3 “Sponge City” and Opportunities for Unmanaged Aquifer Recharge 33015.4.2 Reducing Outflows 33115.4.2.1 Replacing Groundwater with Surface Water 33115.4.2.2 Reduction in Water Used for Irrigation 33115.4.3 Scaling Issues with Sustainability 33115.5 Global Warming Vulnerabilities 33215.6 Chemical Impacts to Sustainability 33415.6.1 Salinization 33415.6.2 Geogenic and Aenthropogenic Contamination 33515.6.3 Salinity and Contamination—Indo-Gangetic Basin (IGB) Alluvial Aquifer 33615.6.4 Seawater Intrusion 339References 34216 Water Quality Assessment 34516.1 Dissolved Constituents in Groundwater 34616.1.1 Concentration Scales 34616.2 Constituents of Interest in Groundwater 34816.2.1 Gases and Particles 34816.2.2 Routine Water Analyses 35016.2.3 Contamination: Expanding the Scope of Chemical Characterization 35116.2.3.1 Contaminated Sites 35116.2.4 Comprehensive Surveys of Water Quality 35216.3 Water Quality Standards 35316.3.1 Health-Based Screening Levels—USGS 35316.3.2 Secondary Standards for Drinking Water 35416.3.3 Standards for Irrigation Water 35516.4 Working with Chemical Data 35616.4.1 Relative Concentration and Health-Based Screening 35616.4.2 Scatter Diagrams and Contour Maps 35816.4.3 Contour Maps 35916.4.4 Piper Diagrams 36016.5 Groundwater Sampling 36216.5.1 Selecting Water Supply Wells for Sampling 36216.6 Procedures for Water Sampling 36316.6.1 Well Inspection and Measurements 36316.6.2 Well Purging 36316.6.3 Sample Collection, Filtration, and Preservation 364References 36417 Key Chemical Processes 36617.1 Overview of Equilibrium and Kinetic Reactions 36617.1.1 Law of Mass Action and Chemical Equilibrium 36717.1.2 Complexities of Actual Groundwater 36817.1.3 Deviations from Equilibrium 36917.1.4 Kinetic Reactions 37117.2 Acid–Base Reactions 37217.3 Mineral Dissolution/Precipitation 37417.3.1 Organic Compounds in Water 37517.4 Surface Reactions 37517.4.1 Sorption Isotherms 37617.4.2 Sorption of Organic Compounds 37717.4.3 Ion Exchange 37917.4.4 Clay Minerals in Geologic Materials 38017.4.5 Sorption to Oxide and Oxyhydroxide Surfaces 38117.5 Oxidation–Reduction Reactions 38217.5.1 Kinetics and Dominant Couples 38417.5.2 Biotransformation of Organic Compounds 38517.5.3 pe-pH and E H -pH Diagrams 38517.5.4 Quantifying Redox Conditions in Field Settings 38617.5.5 Redox Zonation 38817.6 Microorganisms in Groundwater 38917.6.1 Quantifying Microbial Abundances 39017.6.2 Microbial Ecology of the Subsurface 390References 39218 Isotopes and Applications 39518.1 Stable and Radiogenic Isotopes 39518.2 18 O and Deuterium in the Hydrologic Cycle 39718.2.1 Behavior of D and 18 O in Rain 40018.3 Variability in 18 O and Deuterium in Groundwater 40118.3.1 Spatial and/or Temporal Variability of δ 18 O and δD Compositions in Aquifers 40118.3.2 Connate Water in Units with Low Hydraulic Conductivity 40218.4 Evaporation and the Meteoric Water Line 40318.4.1 Other Deviations from GMWL 40418.4.2 Illustrative Applications with Deuterium and Oxygen- 18 40418.4.2.1 Role of Wetland in Streamflow 40418.4.2.2 Integrated Study of Recharge Dynamics in a Desert Setting 40518.5 Radiogenic Age Dating of Groundwater 40618.5.1 Exploring Old and New Concepts of Age for Groundwater 40818.5.2 Carbon- 14 40918.5.3 Chlorine-36 and Helium-4: Very Old Groundwater 41118.5.4 Tritium 41218.5.5 Categorial Assessments Using Tritium Ages 41418.6 Indirect Approaches to Age Dating 41618.6.1 Isotopically Light Glacial Recharge 41718.6.2 Chlorofluorocarbons and Sulfur Hexafluoride 417References 42019 Mass Transport: Principles and Examples 42319.1 Subsurface Pathways 42319.2 Advection 42519.3 Dispersion 42719.3.1 Tracer Tests 42719.3.2 Dispersion at Small and Large Scales 42919.4 Processes Creating Dispersion 42919.5 Statistical Patterns of Mass Spreading 43119.6 Measuring, Estimating, and Using Dispersivity Values 43319.6.1 Sources with a Continuous Release 43319.6.2 Available Dispersivity Values 43419.7 Dispersion in Fractured Media 43519.8 Chemical Processes and Their Impact on Water Chemistry 43719.8.1 Gas Dissolution and Redistribution 43719.8.2 Mineral Dissolution/Precipitation 43819.8.3 Cation Exchange Reactions 43919.8.4 Dissolution/Utilization of Organic Compounds 43919.8.5 Redox Reactions 43919.9 Examples of Reactions Affecting Water Chemistry 44119.9.1 Chemical Evolution of Groundwater in Carbonate Terrains 44119.9.2 Shallow Brines in Western Oklahoma 44119.9.3 Chemistry of Groundwater in an Igneous Terrain 44219.9.4 Evolution of Shallow Groundwater in an Arid Prairie Setting 44319.10 A Case Study Highlighting Redox Processes 44419.10.1 Iron and Manganese 44419.10.2 Arsenic 44519.10.3 Nitrate 44619.10.4 Machine Learning for Mapping Redox Conditions 447References 45020 Introduction to Contaminant Hydrogeology 45220.1 Point and Nonpoint Contamination Problems 45220.2 Families of Contaminants 45520.2.1 Minor/Trace Elements 45520.2.2 Nutrients 45520.2.3 Other Inorganic Species 45620.2.4 Organic Contaminants 45620.2.4.1 Petroleum Hydrocarbons 45620.2.4.2 Halogenated Aliphatic Compounds 45720.2.4.3 Halogenated Aromatic Compounds 45720.2.4.4 Polychlorinated Biphenyls 45820.2.4.5 Health Effects 45820.2.5 Biological Contaminants 45820.2.6 Radionuclides 45820.3 Presence or Absence of Nonaqueous Phase Liquids (NAPLs) 45920.4 Roles of Source Loading and Dispersion in Shaping Plumes 46020.4.1 Source Loading 46020.5 How Chemical Reactions Influence Plumes 46120.5.1 Biodegradation of Organic Contaminants 46220.5.2 Degradation of Common Contaminants 46220.5.3 Reactions Influencing Plume Development 46320.6 Nonaqueous Phase Liquids in the Subsurface 46420.6.1 Features of NAPL Spreading 46420.6.2 Occurrence of DNAPLs in the Saturated Zone 46620.6.3 Secondary Contamination Due to NAPLs 46620.7 Approaches for the Investigation of Contaminated Sites 46620.7.1 Preliminary Studies 46720.7.2 Reconnaissance Geophysics 46720.7.3 Soil Gas Characterization 46720.7.4 Distribution of Dissolved Contaminants 46820.7.5 Plume Maps 47020.7.6 Mapping the Distribution of NAPLs 47120.8 Field Example of an LNAPL Problem 473References 478Index 481