Field Hydrogeology

Rick Brassington worked in the UK public water industry for some 24 years before moving into consultancy. He was employed at director level in three major companies before setting up his own consultancy in 1998. He has also been the Visiting Professor of Hydrogeology in the School of Civil Engineering and Geosciences at Newcastle University since 2007.

Preface to the Fifth Edition viii

Preface to the Fourth Edition ix

Acknowledgements x

1 Introduction 1

1.1 Groundwater Systems 1

1.2 Conceptual Model 4

1.3 Groundwater Computer Modelling 8

1.4 Hydrogeological Report Writing 9

1.5 Expert Witness 9

2 Desk Study 13

2.1 Defining the Area 13

2.2 Identifying the Aquifers 14

2.3 Groundwater Levels 15

2.4 Surface Water 17

2.5 Recharge 17

2.6 Groundwater Use 18

2.7 Groundwater Chemistry 18

2.8 Aerial Photographs and Satellite Imagery 19

2.9 Planning a Fieldwork Programme 20

3 Field Evaluation of Aquifers 23

3.1 Grain Size Analysis 23

3.2 Hydraulic Properties of Aquifers 25

3.3 Hydraulic Properties and Rock Types 27

3.4 Assessing Hydraulic Properties 33

3.5 Using Hydraulic Property Information 34

3.6 Recharge through the Vadose Zone 38

4 Groundwater Levels 45

4.1 Water Level Dippers 45

4.2 Continuous Water Level Recorders 48

4.3 Measuring Ground Levels and Locations 53

4.4 Tool-Box 56

4.5 Well Catalogue 57

4.6 Field Surveys for Wells, Boreholes and Springs 57

4.7 Interpretation of Abstraction Borehole Water Levels 62

Case History 1 – Interpretation of Groundwater Strikes 66

4.8 Groundwater-Level Monitoring Networks 70

Case History 2 – Groundwater-Level Interpretation 70

4.9 Groundwater-Level Fluctuations 71

4.10 Managing Groundwater-Level Data 78

4.11 Constructing Groundwater Contour Maps and Flow Nets 79

4.12 Interpretation of Contour Maps and Flow Nets 82

4.13 Using Other Groundwater Information 83

5 Rainfall, Springs and Streams 85

5.1 Precipitation 85

5.2 Evaporation 89

5.3 Springs 91

Case History 3 – Measuring Flows with Low Heads 92

5.4 Stream-Flow Measurement 98

5.5 Stage–Discharge Relationships 107

5.6 Choosing the Best Method 109

5.7 Processing Flow Data 109

6 Pumping Tests 111

6.1 What Is a Pumping Test? 111

6.2 Planning a Pumping Test 112

6.3 Pumps and Pumping 113

6.4 On-Site Measurements 116

6.5 Pre-Test Monitoring 121

6.6 Test Set-up 121

6.7 Step Tests 123

6.8 Constant Rate Tests 123

6.9 Recovery Tests 125

6.10 Pumping Test Analysis 125

6.11 Tests on Single Boreholes 134

6.12 Packer Tests 137

7 Groundwater Chemistry 141

7.1 Analytical Suites and Determinands 141

7.2 Sampling Equipment 142

7.3 Sampling Protocols 153

7.4 Monitoring Networks 160

7.5 Using Chemical Data 161

8 Recharge Estimation 165

8.1 Water Balance 165

8.2 Rainfall Recharge 167

8.3 Induced Recharge 168

8.4 Other Sources of Recharge 170

9 Specialist Techniques 171

9.1 Borehole and Piezometer Installation 171

9.2 Down-Hole Geophysics 177

Case History 4 – The Use of Borehole Geophysics 178

9.3 Using Artificial Tracers 181

Case History 5 – The Use of Groundwater Tracers 182

10 Practical Applications 189

10.1 Borehole Prognoses 189

10.2 Groundwater Supplies 190

10.3 Wells in Shallow Aquifers 195

10.4 Contaminated Land Investigations 197

10.5 Landfills and Leachate 198

10.6 Geothermal Energy 201

10.7 Groundwater Lowering by Excavation 202

10.8 Rising Water Tables 206

10.9 Soakaways 208

10.10 Investigating Wetland Hydrology 208

Appendix A Good Working Practice 211

A. 1 Safety Codes 211

A1. 2 Safety Clothing and Equipment 211

A1. 3 Distress Signals 212

A1. 4 Exposure or Hypothermia 212

A1. 5 Heat Exhaustion 213

A1. 6 Working near Wells, Boreholes and Monitoring Piezometers 213

A1. 7 Hygiene Precautions for Water Supplies 213

A1. 8 Trial Pits 214

A1. 9 Electrical Equipment 214

A1.10 Filling Fuel Tanks 214

A1.11 Waste Disposal Sites 214

A1.12 Stream Flow Measurement 214

Appendix B Conversion Factors 217

References 219

Index 225