Groundwater Hydrology

Mohammad Karamouz, Azadeh Ahmadi, Masih Akhbari

• ContentsPreface .....................................................................................................................xxiAcknowledgments ..................................................................................................xxvAuthors .................................................................................................................xxviiChapter 1 Introduction ..........................................................................................11.1 Introduction .................................................................................11.2 Water Availability ........................................................................21.2.1 Groundwater Availability ................................................41.3 Groundwater Systems .................................................................51.4 Science and Engineering of Groundwater ...................................61.5 Planning and Management of Groundwater ...............................81.5.1 Integrated Water Resources Management .....................101.5.2 Conflict Issues in Groundwater .....................................101.5.3 Economics of Water ......................................................111.5.4 Groundwater Sustainability ...........................................131.5.5 Supply and Demand Side Management ........................151.6 Tools and Techniques ................................................................171.7 People’s Perception: Public Awareness .....................................191.8 Groundwater Protection: Concerns and Acts ............................201.8.1 Clean Water Act.............................................................211.8.2 Groundwater Protection ................................................211.8.3 USEPA Groundwater Rule ............................................221.8.4 California’s Sustainable GroundwaterManagement Act ...........................................................231.9 Overall Organization of This Book ...........................................24Problems .............................................................................................25References ..........................................................................................25Chapter 2 Groundwater Properties ......................................................................292.1 Introduction ...............................................................................292.2 Vertical Distribution of Subsurface Water .................................312.3 Aquifers, Aquitards, and Aquicludes ........................................332.4 Types of Aquifers ......................................................................332.4.1 Unconfined Aquifer .......................................................332.4.2 Confined Aquifers .........................................................342.4.3 Aquitard (Leaky) Aquifer ..............................................342.5 Groundwater Balance ................................................................352.5.1 Water Balance in Confined Aquifers .............................362.5.2 Water Balance in Unconfined Aquifers .........................372.5.3 Water Balance in Unsaturated Zone ..............................372.6 Compressibility and Effective Stress .......................................382.6.1 Compressibility of Water ...........................................382.6.2 Effective Stress ..........................................................382.6.3 Compressibility of a Porous Medium ........................402.6.4 Effective Stress in the Unsaturated Zone ..................422.7 Aquifer Compressibility ..........................................................422.8 Aquifer Characteristics ............................................................432.8.1 Porosity and Void Ratio .............................................442.8.2 Specific Yield in Unconfined Aquifers ......................462.8.3 Specific Retention......................................................472.8.4 Storage Coefficient and Specific Storage ..................482.8.5 Safe Yield of Aquifers ...............................................522.9 Storage in the Unsaturated Zone .............................................522.10 Water-Level Fluctuations .........................................................552.11 Groundwater in Karst ..............................................................552.11.1 Karst Aquifer .............................................................552.11.2 Types of Karst............................................................562.11.3 Fluctuation of Karst Aquifer ......................................562.11.4 Recharge of Karst Aquifer .........................................572.11.5 Groundwater Tracing in Karst ...................................582.11.6 Water Resources Problems in Karst ..........................58Problems .............................................................................................59References ..........................................................................................61Chapter 3 Groundwater Hydrology .....................................................................633.1 Introduction .............................................................................633.2 Groundwater Movement ..........................................................633.2.1 Darcy’s Law ...............................................................633.2.1.1 Validity of Darcy’s Law..............................683.2.2 Hydraulic Head ..........................................................683.2.3 Hydraulic Conductivity .............................................693.2.3.1 Hydraulic Conductivity in SaturatedMedia ..........................................................693.2.3.2 Hydraulic Conductivity in UnsaturatedMedia ..........................................................703.2.3.3 Laboratory Measurement of HydraulicConductivity ...............................................723.2.3.4 Field Measurement of HydraulicConductivity ...............................................743.3 Homogeneous and Isotropic Systems ......................................753.3.1 Hydraulic Conductivity in Multilayer Structures ......763.4 Transmissivity .........................................................................803.5 Dupuit–Forchheimer Theory of Free-Surface Flow ................813.6 Groundwater Flow in Unsaturated Zone .................................833.7 Flownets .....................................................................................883.7.1 Isotropic and Homogeneous Media .............................883.7.2 Heterogeneous Media ..................................................923.7.3 Anisotropic Media .......................................................933.8 Statistical Methods in Groundwater Hydrology ........................953.8.1 Normal Distribution .....................................................953.8.2 Lognormal Distribution ...............................................973.8.3 t-Distribution ................................................................983.8.4 Chi-Square (χ2) Distribution ......................................1003.8.5 Errors .........................................................................1003.8.5.1 Sampling Error ..........................................1003.8.5.2 Standard Errors .........................................1003.8.6 Estimating Quantiles (Percentiles) ............................1013.8.7 Probability/Frequency/Recurrence Interval ...............1023.9 Time Series Analysis ...............................................................1033.9.1 Nonstationary Hydrologic Variables ..........................1033.9.2 Hydrologic Time Series Modeling .............................1043.9.3 Data Preparation ........................................................1053.9.4 Parameter Estimation .................................................1083.9.4.1 Method of Moments .................................1083.9.4.2 Method of L-Moments ..............................1093.9.4.3 Method of Least Squares ..........................1103.9.4.4 Method of Maximum Likelihood .............1113.9.5 Goodness of Fit Tests .................................................1133.9.5.1 Chi-Square Goodness of Fit Test ..............1133.9.5.2 Tests of Normality ....................................1153.9.6 Akaike’s Information Criterion ..................................1173.9.7 Autoregressive Modeling ...........................................1173.9.8 Moving Average Process ............................................1213.9.9 Autoregressive Moving Average Modeling ...............1223.9.9.1 Generation and Forecasting UsingARMA Models .........................................1223.9.10 Autoregressive Integrated Moving AverageModeling ....................................................................1233.9.10.1 Time Series Forecasting UsingARIMA Models ........................................124Problems ...........................................................................................130Appendix ..........................................................................................132References ........................................................................................135Chapter 4 Hydraulics of Groundwater ..............................................................1394.1 Introduction ............................................................................. 1394.2 Continuity Equation .................................................................1394.3 Equation of Motion in Groundwater .......................................1424.3.1 Groundwater Flow Equation ......................................1444.4 Wells ........................................................................................1534.4.1 Steady Flow into a Well ...............................................1554.4.1.1 Confined Flow ...............................................1554.4.1.2 Unconfined Flow ...........................................1584.4.2 Unsteady State in a Confined Aquifer .........................1614.4.2.1 Aquifer Test Application ...............................1654.4.2.2 Theis Method of Solution .............................1664.4.2.3 Cooper–Jacob Method of Solution ...............1684.4.2.4 Variable Pumping Test ..................................1724.4.3 Unsteady State for Unconfined Aquifer ......................1754.5 Multiple-well Systems .............................................................1814.6 Effective Conditions on Time-Drawdown Data ......................1824.6.1 Recharge Boundary .....................................................1824.6.2 Impermeable Boundary ...............................................1844.6.3 Partially Penetrating Wells...........................................1864.7 Design of Wells ........................................................................1884.8 Well Construction ....................................................................1914.8.1 Cable-Tool Drilling ......................................................1914.8.2 Rotary Drilling Method ...............................................1914.8.2.1 Well Development ........................................192Problems ...........................................................................................193References ........................................................................................197Chapter 5 Groundwater Quality ........................................................................1995.1 Introduction .............................................................................1995.2 Groundwater Constituents and Contaminants .........................1995.2.1 Inorganic Contaminants ...............................................1995.2.2 Organic Contaminants .................................................2005.2.3 Dissolved Gasses .........................................................2005.2.4 Particles .......................................................................2025.3 Water Quality Standards ..........................................................2035.4 Groundwater Solubility ...........................................................2095.5 Disequilibrium and Saturation Index .......................................2125.6 Sources of Groundwater Contamination .................................2145.6.1 Disposal of Solid Wastes .............................................2145.6.2 Underground Petroleum Tank Leakage .......................2145.6.3 Disposal of Liquid Wastes ...........................................2155.6.4 Sewage Disposal on Land ............................................2155.6.5 Agricultural Activities .................................................2165.6.6 Other Sources of Contamination .................................2165.7 Mass Transport of Dissolved Contaminants ............................2175.7.1 Diffusion ......................................................................2185.7.2 Advection.....................................................................2205.7.3 Mechanical Dispersion ................................................2215.7.4 Hydrodynamic Dispersion ...........................................2245.7.5 Derivation of the Advection–Dispersion Equation ......2255.7.6 Solute Transport Equation ...........................................2335.7.7 Capture-Zone Curves ...................................................2345.8 Modeling Contaminant Release ..............................................2405.8.1 Modeling Instantaneous Release of Contaminants ......2405.8.1.1 Fourier Analysis in Solute Transport ............2405.8.1.2 Point Spill Model ..........................................2415.8.1.3 Vertically Mixed Spill Model .......................2415.8.1.4 Vertical Mixing Region ................................2425.8.2 Modeling Continuous Release of Contaminants .........2445.8.2.1 Development of Contaminant PlumeModels ..........................................................2445.8.2.2 Simple Plume Model ....................................2445.8.2.3 Point-Source Plume Model ...........................2455.8.2.4 Gaussian-Source Plume Model .....................245Problems ...........................................................................................248References ........................................................................................250Chapter 6 Groundwater Modeling ....................................................................2516.1 Introduction .............................................................................2516.2 Process of Modeling ................................................................2516.3 Mathematical Modeling ...........................................................2526.3.1 Analytical Modeling ....................................................2536.3.2 Numerical Modeling ....................................................2546.4 Finite-Difference Method ........................................................2546.4.1 Forward Difference Equation ......................................2576.4.2 Backward Difference Equation....................................2616.4.3 Alternating Direction Implicit Method ........................2626.4.4 Crank–Nicolson Difference Equation .........................2816.5 Finite Element Method ............................................................2846.5.1 Discretize the Problem Domain ...................................2846.5.2 Derive the Approximating Equations ..........................2906.5.3 Transient Saturated Flow Equation .............................3036.5.4 Solute Transport Equation ...........................................3116.6 Finite Volume Method .............................................................3196.6.1 Steady-State One-Dimensional Flow Equation ...........3196.6.2 Unsteady-State, One-Dimensional Flow Equation ......3236.6.3 Two-Dimensional Flow Equation ................................3246.6.4 Orthogonals Coordinate System ..................................3336.7 Simulation of Groundwater Flow Using the DiscreteKernel Approach ......................................................................3366.8 Saturated-Unsaturated Transport (SUTRA) Code ...................3466.9 MODFLOW .............................................................................347Problems ...........................................................................................364References ........................................................................................366Chapter 7 Groundwater Planning and Management .........................................3697.1 Introduction .............................................................................3697.2 Data Collection ........................................................................3707.3 Simulation Techniques ............................................................3717.3.1 Model Calibration .......................................................3727.3.2 Model Verification .......................................................3727.3.3 Model Predictions .......................................................3737.3.3.1 Artificial Neural Networks ...........................3747.3.3.2 Fuzzy Sets and Parameter Imprecision ........3897.3.3.3 System Dynamics .........................................3957.3.3.4 Agent-Based Modeling .................................4057.4 Optimization Models for Groundwater Management .............4097.4.1 Optimization Model for Groundwater Operation ........4107.4.2 Optimization Model for Capacity Expansion ..............4137.4.3 Optimization Model for Water Allocation ...................4177.4.4 Optimization Model for Conjunctive Water Use .........4207.4.5 Optimal Groundwater Quality Management Model ...4217.4.6 Optimization Model for Parameters ofGroundwater Model ....................................................4227.5 Optimization Techniques .........................................................4237.5.1 Single-Criterion Optimization .....................................4247.5.2 Multi-criteria Optimization .........................................4267.5.2.1 Sequential Optimization ...............................4277.5.2.2 The ε-Constraint Method ..............................4277.5.2.3 The Weighting Method .................................4287.5.2.4 Interactive Fuzzy Approach ..........................4307.5.3 Special Methods for Groundwater Optimization ........4327.5.3.1 Dynamic Programming ................................4327.5.3.2 Genetic Algorithm ........................................4347.5.3.3 Simulation Annealing ...................................4387.6 Conflict Resolution ..................................................................4407.6.1 Stakeholder Involvement .............................................4467.6.1.1 Effective Meeting Facilitation ......................4477.6.1.2 Conflict Handling .........................................4477.6.1.3 Quantifying Meeting Outcomes ...................4487.6.2 Application of Game Theory in Multi-objectiveGroundwater Management ..........................................4497.6.2.1 Non-cooperative Stability Definitions ..........4527.7 Groundwater Systems Economics ...........................................4527.7.1 Economic Analysis of Multiple Alternatives ...............4577.7.2 Economic Evaluation of Projects UsingBenefit–Cost Ratio Method .........................................4597.8 Case Studies ............................................................................4607.8.1 Case 1: Development of a System DynamicsModel for Water Transfer ............................................4607.8.1.1 Area Characteristics .....................................4617.8.1.2 Conflict Resolution Model for LandResources Allocation in Each Zone..............4617.8.1.3 Results of the Conflict Resolution Model ....4637.8.1.4 Optimal Groundwater Withdrawal inEach Zone .....................................................4647.8.1.5 Sizing Channel Capacity ..............................4647.8.1.6 Conclusion—Making Technologies Work ...4657.8.2 Case 2: Conflict Resolution in Water PollutionControl for an Aquifer .................................................4667.8.2.1 Water Resources Characteristicsin the Study Area ..........................................4667.8.2.2 Conflict Resolution Model ...........................4687.8.2.3 Results and Discussion .................................4717.8.3 Case 3: An Agent-Based Modeling Applicationin Groundwater ............................................................4727.8.3.1 Case Study Characteristics ...........................4727.8.3.2 Model Characteristics ...................................4737.8.3.3 Model Calibration and Verification ..............4757.8.3.4 Results of Agent-Based Modeling ................4757.8.4 Case 4: Development of a Noncooperative Gamein Groundwater Management ......................................4767.8.4.1 Area Characteristics .....................................4767.8.4.2 Simulation-Multi-objective OptimizationModel ...........................................................477Problems ...........................................................................................482References ........................................................................................486Chapter 8 Surface Water and Groundwater Interaction ....................................4918.1 Introduction .............................................................................4918.2 Interaction between Surface and Groundwater .......................4918.2.1 Infiltration ....................................................................4928.2.2 Concepts of Interaction between Surface Water andGroundwater ................................................................4928.2.3 Bank Storage and Baseflow Recession .......................4958.2.3.1 Master-Depletion Curve Method ..................4968.2.3.2 Seasonal Recession Method (MeyboomMethod) ........................................................4978.2.3.3 Constant-Discharge Baseflow Separation ....4988.2.3.4 Constant-Slope Baseflow Separation ...........4988.2.3.5 Concave-Baseflow Separation ......................4998.2.4 Groundwater and Lakes ...............................................5008.3 Conjunctive Use of Surface and Groundwater ........................5028.3.1 Advantages of Conjunctive Use ..................................5038.3.2 Impediments of Conjunctive Use ................................5048.3.3 Case Study 1: Conjunctive Use of Surfaceand Groundwater in Lakhaoti Canal UttarPradesh, India ..............................................................5048.3.4 Surface and Groundwater Conjunctive UseModeling .....................................................................5078.3.5 Multi-objective Conjunctive Use Optimization ..........5158.3.5.1 Groundwater Resource SustainabilityLimits ...........................................................5168.3.6 Case Study 2: Application of Genetic Algorithmsand Artificial Neural Networks in Conjunctive Useof Surface and Groundwater Resources ......................5178.3.6.1 Simulation Model .........................................5178.3.6.2 Optimization Model Framework ..................5218.3.6.3 Results and Discussion .................................5238.3.7 Case Study 3: Water Allocation from theAquifer-River System Using a ConflictResolution Model ........................................................5248.3.7.1 Optimization Model Framework ..................5288.3.7.2 Results and Discussion .................................5308.3.8 Case Study 4: Conjunctive Use and Crop PatternManagement ................................................................5328.3.8.1 Optimization Model Structure ......................5348.3.8.2 Results and Discussion .................................5378.4 Operation of Groundwater Resources in Semiarid Region .....538Problems ...........................................................................................540References ........................................................................................541Chapter 9 Aquifer Restoration and Monitoring ................................................5439.1 Introduction .............................................................................5439.2 Partitioning Process .................................................................5449.3 Retardation ..............................................................................5469.4 Natural Losses of Contaminants..............................................5479.4.1 Volatilization ...............................................................5489.4.2 Biological Degradation ...............................................5489.4.3 Plant Uptake ................................................................5499.5 Groundwater Pollution Control ...............................................5509.5.1 Institutional Tools ........................................................5509.5.1.1 Regional Groundwater Management ...........5509.5.1.2 Land Zoning .................................................5509.5.1.3 Effluent Charges/Credits ..............................5509.5.1.4 Guidelines ....................................................5519.5.1.5 Aquifer Standards and Criteria .....................5519.5.2 Source Control Strategies ............................................5519.5.3 Stabilization/Solidification Strategies .........................5529.5.4 Well Systems ...............................................................5549.5.5 Interceptor Systems .....................................................5549.5.6 Surface Water Control, Capping, and Liners ...............5559.5.7 Sheet Piling .................................................................5569.5.8 Grouting ......................................................................5579.5.9 Slurry Walls .................................................................5579.6 Treatment of Groundwater ......................................................5599.6.1 Air Sparging ................................................................5599.6.2 Carbon Adsorption ......................................................5609.6.3 Adding Chemicals and In Situ Chemical Oxidation ...5619.6.4 Thermal Technologies .................................................5629.6.5 Bioremediation Techniques .........................................5639.6.6 Dissolved Phase (Plume) Remediation .......................5649.6.6.1 Pump and Treat ............................................5649.6.6.2 Permeable Reactive Barriers ........................5649.7 Aquifer Restoration—Overdraft Issues ...................................5669.7.1 Case Study: The National Restoration andRemediation of Groundwater Resources in Iran .........5679.7.1.1 General Purpose ...........................................5679.7.1.2 Projects .........................................................5679.7.1.3 Operational Program (Action Plans) ............5689.7.1.4 Time Table ....................................................5699.8 Monitoring Subsurface Water ..................................................5699.8.1 Vadose-Zone Monitoring.............................................5709.8.2 Groundwater Monitoring .............................................5719.8.3 Water Quality Variable Selection ................................5729.8.4 Geostatistical Tools for Water Quality-MonitoringNetworks .....................................................................5739.8.4.1 Kriging .........................................................5749.8.5 Location of Water Quality Monitoring Stations ..........5779.8.5.1 Definition and Discretization of theModel Domain .............................................5789.8.5.2 Calculation of Weights for CandidateMonitoring Sites ...........................................5799.8.5.3 Optimal Configuration of a MonitoringWell Network ...............................................5809.8.5.4 Kriging Method in Designing an OptimalMonitoring Well Network ............................5819.8.5.5 Genetic Algorithms in Designing anOptimal Monitoring Well Network ..............5829.8.6 Sampling Frequency ....................................................5849.8.6.1 Methods of Selecting Sampling Frequencies ....5849.8.6.2 Single Station and Single Water QualityVariable ........................................................5859.8.6.3 Single Station and Multiple WaterQuality Variables ....................................5869.8.6.4 Multiple Stations and a Single WaterQuality Variable ......................................5879.8.6.5 Multiple Stations and Multiple WaterQuality Variables ....................................5889.8.7 Entropy Theory in a Water Quality-MonitoringNetwork ...................................................................5889.8.7.1 Entropy Theory .......................................5899.9 Managed Aquifer Recharge ...................................................5919.9.1 Principal Consideration ...........................................5919.9.1.1 Sources of Recharge Water and ItsQuality Considerations ...........................5939.9.1.2 Hydrogeological Settings andControls on Recharge .............................5949.9.1.3 MAR Methods ........................................5959.9.2 MAR in Support of Groundwater Sustainability .....6009.9.2.1 MAR in Urban Settings ..........................6009.9.2.2 MAR in Agricultural Settings .................6029.9.2.3 MAR in Coastal Areas ............................6069.9.3 The United Nations MAR Portal .............................6079.10 Summary ...............................................................................607Problems ...........................................................................................607References ........................................................................................609Chapter 10 Groundwater Risk and Disaster Management ..................................61510.1 Introduction ...........................................................................61510.2 Groundwater Risk Assessment ..............................................61610.2.1 Elements of Risk Assessment ..................................61610.2.2 Assessment of Dose-Response ................................61810.2.3 Risk Assessment Methods and Tools .......................61910.2.3.1 Potency Factor for Cancer-CausingSubstances ..............................................62010.2.4 Environmental Risk Analysis ..................................62410.3 Groundwater Risk Management ............................................62510.3.1 Groundwater Risk Mitigation ..................................62610.4 Groundwater Disaster ............................................................62710.4.1 Requirements for Institutional and TechnicalCapacities ................................................................62710.4.2 Prevention and Mitigation of Natural andMan-Induced Disasters ............................................62810.4.3 Disaster Management Phases ..................................62910.5 Disaster Indices .....................................................................63010.5.1 Reliability ................................................................63010.5.2 Resiliency ................................................................63610.5.3 Vulnerability ............................................................63610.6 Groundwater Vulnerability ....................................................63710.6.1 Drought ....................................................................63810.6.1.1 Drought Indicators ..................................64110.6.1.2 Drought Triggers .....................................64110.6.1.3 Drought Management Strategy Plan .......64310.6.1.4 Drought Vulnerability Maps ...................64310.6.1.5 Drought Early Warning Systems ............64410.6.1.6 Case Study ..............................................64410.6.1.7 Qanats .....................................................64510.6.2 Flood ........................................................................64710.6.2.1 Maps of Groundwater Flood Hazard ......64810.6.3 Land Subsidence ......................................................65010.6.3.1 Subsidence Calculation ...........................65110.6.3.2 Monitoring Land Subsidence ..................65210.6.3.3 Reducing Future Subsidence ..................65210.6.3.4 Examples of Subsidence .........................65310.6.4 Widespread Contamination .....................................65310.6.4.1 Vulnerability Assessment inGroundwater Pollution ............................65710.6.4.2 DRASTIC Method ..................................65910.6.5 Case Study: Development of Vulnerability Mapsfor a Drought ...........................................................66410.6.5.1 Summary .................................................668Problems ...........................................................................................669References ........................................................................................671Chapter 11 Climate Change Impacts on Groundwater .......................................67511.1 Introduction ...........................................................................67511.2 Climate Change .....................................................................67611.3 Climate Change Impacts on Hydrological Cycle ..................67711.3.1 Floods and Droughts ................................................67811.3.2 Agricultural Droughts ..............................................67911.3.3 Water Use ................................................................67911.3.4 Water Quality ...........................................................68011.3.5 Habitat .....................................................................68011.3.6 Hydroelectric Power ................................................68011.3.7 Snowpack .................................................................68111.3.8 River Flow ...............................................................68111.4 General Climate Change Impacts on Groundwater ...............68111.4.1 Hydrological Components Affecting theGroundwater ............................................................68311.4.1.1 Temperature and Evaporation .................68311.4.1.2 Precipitation ............................................68311.4.1.3 Soil Moisture ..........................................68511.4.2 Direct Impacts of Climate Change onGroundwater ............................................................68611.4.2.1 Groundwater Recharge ...........................68711.4.2.2 Recharge Estimation Methods ................68811.4.2.3 Aquifers Recharging ...............................68911.4.2.4 Hydraulic Conductivity ...........................68911.4.3 Indirect Impacts of Climate Change onGroundwater ............................................................69011.4.3.1 Sea-Level Rise ........................................69011.4.3.2 Saltwater Intrusion in CoastalAquifers ..................................................69111.4.3.3 Storm Surge and Saltwater Intrusion ......69311.4.3.4 Ghyben–Herzberg Relation betweenFreshwater and Saline Waters .................69411.4.3.5 Island Freshwater Lens ...........................69511.4.3.6 Land Use and Land Cover ......................69811.5 Groundwater Quantity and Quality Concerns .......................69811.5.1 Depletion of Groundwater Table .............................69811.5.2 Deterioration of Groundwater Quality ....................69911.5.2.1 Increasing Groundwater Contamination ....69911.5.2.2 Salinization of Groundwater bySea-Level Rise ........................................69911.6 Adaptation to Climate Change ..............................................70011.6.1 Artificial Recharge ...................................................70111.6.2 Modification of Groundwater Extraction Pattern ....70111.6.3 Injection Barrier .......................................................70211.6.4 Subsurface Barrier ...................................................70211.6.5 Tidal Regulators .......................................................70211.7 IPCC Assessment Report .......................................................70211.8 Climate Change Simulation ...................................................70411.8.1 Spatial Variability ....................................................70511.8.1.1 Recent Communities’ ScenariosDevelopment ...........................................70511.8.1.2 Downscaling ...........................................70711.8.1.3 Regional Models .....................................70811.8.2 Statistical Downscaling ...........................................70911.9 Downscaling Models .............................................................71211.9.1 Statistical Downscaling Model ................................71211.9.2 LARS-WG Model ...................................................71511.10 New Insights—Risks and Vulnerabilities ............................72411.11 Climate Change Impacts on Water Availability in anAquifer .................................................................................72511.12 Conclusion ...........................................................................732Problems ...........................................................................................732References ........................................................................................734Index ...................................................................................................................... 739