Geochemical Processes, Weathering and Groundwater Recharge in Catchments Edited by

OLA M. SAETHER & PATRICE D E CARITAT Geological Survey of Norway

Geochemical processes, weathering and groundwater recharge in catchments O. M. SaetherSP. de Caritat (eds) ©1997 Balkema

Contents

PREFACE H V XIII

PARTI : CATCHMENT PROCESSES

1 WEATHERING PROCESSES James LDrever !: V: 1.1 Definitions of weathering i - ^ (..-iJ: Ji' 1.2 Types of weathering reaction 4

1.2.1 Congruent dissolution 4 1.2.2 Incongruent dissolution l,-..«

1.3 Cation exchange 7 1.4 Mineral dissolution kinetics 8

1.4.1 Relative rates 8 1.4.2 Effects of solution composition on dissolution rates of silicate minerals 9

1.5 Comparisons between field and laboratory dissolution rates 14 1.6 Modeling approaches 16 1.7 Future research directions 16 References - • 17

2 COMPOSITION, PROPERTIES A N D DEVELOPMENT OF NORDIC SOILS Ole K Borggaard 2.1 Introduction Si^uuin vyr: : : . j ; i ; j-o^. 21 2.2 Soil composition muv: 23

2.2.1 Soil air 25 2.2.2 Soil water 26 2.2.3 Soil organic matter (SOM) 30 2.2.4 Soil minerals 34

2.3 Soil properties u:; . ; . ! 41 2.3.1 Physical properties , J J : » ; y , \ 41 2.3.2 Chemical properties ' 47

V I Contents

2.4 Soil development processes 53 2.4.1 Decalcification 53 2.4.2 Gleization 54 2.4.3 Lessivage (clay migration) : 57 2.4.4 Podzolization 59

2.5 Summary with conclusions , 61 2.6 Future research directions 53 Appendix A: Definition, terminology, horizons and description of soil 64 Appendix B: Classification Acknowledgement 72 References 72

3 CATCHMENT HYDROLOGY Allan Rodhe tfe Anund Killingtveit 3.1 Introduction "jj 3.2 The catchment 77 3.3 Water balance < : i< r , ' * 73 3.4 Runoff processes in the catchment 79 3.5 Soil water storage and flow processes " ' T A O r i " J | j | f 3.6 Mathematical modelling of soil water movement 83

3.6.1 Soil water potential g3 3.6.2 Water flow-Darcy'slaw g4

f 3.6.3 Drainage equilibrium g4 3.7 Groundwater storage and flow g5

3.7.1 Aquifers and aquitards g5 3.7.2 Storage coefficient g5 3.7.3 Groundwater flow gg 3.7.4 Flow velocity ? :. ) •),: g7 3.7.5 Preferential flowpaths - macropore flow gg

3.8 Streamflow generation gq 3.8.1 Hortonian overland flow 90 3.8.2 Variable source area 9O 3.8.3 Recharge and discharge areas 92 3.8.4 Groundwater contribution in discharge areas 94

3.9 The role of topography 97 3.10 The HBV-model: A precipitation/runoff-model 99

3.10.1 The snow routine 99 3.10.2 The soil moisture routine 101 3.10.3 The runoff response routine 101

3.11 Model calibration and use 102 3.12 Componentsof the water budget in the Nordic countries 107 References IO7

4 GROUNDWATER RECHARGE David N. Lemer 4.1 What is recharge? s.-., IO9

4.1.1 Recharge and related concepts 109

V

Contents V I I

4.1.2 Recharge in the hydrological cycle 111 4.1.3 Objectives of chapter 114

4.2 Hydrogeological environments 115 4.2.1 Introduction 115 4.2.2 Permo-Triassic sandstone of the U K 115 4.2.3 Scandinavian conditions > 117

4.3 Precipitation recharge 119 4.3.1 Introduction 119 4.3.2 Lysimeters: Direct measurement 119 4.3.3 Empirical methods 121 4.3.4 Soil moisture budgeting method 122 4.3.5 Darcian approaches 125 4.3.6 Tracer techniques 127 4.3.7 Variability of recharge across catchments 133 4.3.8 Localised recharge 134

4.4 Recharge from rivers 136 4.4.1 River types 136 4.4.2 Rivers in contact with the water table 137 4.4.3 River recharge estimation methods 137 4.4.4 Groundwater response under ephemeral rivers 137 4.4.5 Water balances 139 4.4.6 Darcian approaches 140 4.4.7 Tracer techniques for groundwater recharge from river 141

4.5 Interaquifer flows 141 4.6 Net recharge over a region -• ^ i ; yiViiy, t S A 142

4.6.1 Introduction 142 4.6.2 Water table rise 142 4.6.3 Hydrograph analysis for groundwater discharge 143 4.6.4 Inverse techniques 145 4.6.5 Aquifer-wide tracers 145

4.7 Concluding remarks 146 References 148

PART 2: TECHNIQUES FOR CATCHMENT STUDIES

5 CHEMICAL ANALYSIS OF ROCKS A N D SOILS Magne 0degdrd 5.1 Introduction 153 5.2 Historical development 153 5.3 Total analysis versus partial analysis 154 5.4 Analytical methods 156

5.4.1 X-ray fluorescence (XRF) 156 5.4.2 Inductively coupled plasma atomic emission spectrometry (ICP-AES) 160 5.4.3 Atomic absorption spectrometry (AAS) 162

5.5 Quality control 165 References 166

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6 COLLECTION A N D ANALYSIS OF GROUNDWATER SAMPLES John Mather 6.1 Introduction 167 6.2 Data quality 167 6.3 Sample collection and analysis 169

6.3.1 Field parameters «<! 169 6.3.2 Laboratory measurements 173 6.3.3 Pore water analysis 178

6.4 Representation of data J 179 6.5 Water quality standards 181 Appendix A: Prescribed concentrations or values specified in the UK Water Supply (Water Quality) regulations 1989 183 References 184

7 ENVIRONMENTAL ISOTOPES AS TRACERS I N CATCHMENTS Sylvi Haldorsen, Gunnhild Riise, Berit Swensen & Ronald S. Sletten 7.1 Introduction 185

7.1.1 Environmental isotopes 185 7.1.2 The use of environmental isotopes in small catchments 187

7.2 Oxygen and hydrogen isotopes 188 7.2.1 Stable isotopes: 180 and 2 H ( D ) 188 7.2.2 Application of 5 I 8 0 and 8D in catchment studies 189 7.2.3 Tritium I95

7.3 Carbon isotopes 196 7.3.1 The 14c isotope 196 7.3.2 The 13c isotope 199

7.4 Nitrogen isotopes 200 7.4.1 Nitrogen isotope variations in precipitation 201 7.4.2 8l5NofN03 in the pedosphere and groundwater 202 7.4.3 Pollution studies in catchments and groundwater aquifers 202

7.5 Sulphur isotopes 203 7.5.1 Some examples of sulphur isotopes studies 204

7.6 Conclusions 205 Acknowledgements 206 References 206

8 H E L D INSTRUMENTATION ^ ' t O ^ i K Y J A K

Anund Killingtveit, Knut Sand & Nils Roar Scelthun 8.1 Streamflow measurements - 211

8.1.1 Introduction 211 8.1.2 Measurement of stage 211 8.1.3 Discharge measurement methods 214 8.1.4 Stage-discharge relation 219 8.1.5 Practical considerations 223

8.2 Automatic data acquisition systems in hydrology 226 8.2.1 Introduction 226 8.2.2 Main structure and system components 226

Contents I X

8.2.3 Hydrological data for hydropower design and operation 228 8.2.4 Data transmission 229 8.2.5 Hydrometric data for hydropower systems operation: Two examples 232 8.2.6 Recommendations 235

References 237

PART 3: INTEGRATED CATCHMENT STUDIES

9 CATCHMENT MASS BALANCE James I. Drever 9.1 Introduction 241 9.2 Terms in the mass balance equation 241

9.2.1 Solutes in outflow 242 9.2.2 Solutes from the atmosphere 242 9.2.3 Changes in the exchange pool 244 9.2.4 Changes in the biomass 244 9.2.5 Chemical weathering 246

9.3 Mass balance and mineral weathering 247 9.3.1 The Sierra Nevada, Califomia, USA 247 9.3.2 Absaroka mountains, Wyoming, USA 251 9.3.3 Adirondack mountains. New York, USA 253 9.3.4 Sogndal, Norway 254

9.4 The problem of excess calcium 255 9.4.1 South Cascade Glacier, Washington, USA 255 9.4.2 Loch Vale, Colorado, USA 257 9.4.3 Discussion 258

9.5 Conclusions 259 9.6 Future directions in research ^ 259 References 260

10 NATURAL ORGANIC MATTER I N CATCHMENTS James F. Ranville & Donald L . Macalady 10.1 Introduction 263 10.2 The nature and origin of natural organic matter ;•. 264

10.2.1 Nature of natural organic matter 265 10.2.2 Origin of natural organic matter 269

10.3 Geochemical reactions of natural organic matter 275 10.3.1 Weathering and natural organic matter in catchments 275 10.3.2 Development of natural organic matter profiles in catchments 276 10.3.3 Hydrological controls on the transport of natural organic matter 280 10.3.4 Redox chemistry of metal-organic complexes 282 10.3.5 Natural organic matter and metal ion transport 284

10.4 Interactions between natural organic matter and anthropogenic chemicals 286 10.4.1 Transport of pollutant metals as dissolved natural organic matter

complexes 286 10.4.2 Effects of soiption/partitioning to natural organic matter on the

transport of organic chemicals 287

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10.4.3 Effects of natural organic matter on hydrolytic reactions 290 10.4.4 Oxidation/reduction reactions facilitated by natural organic matter 290 10.4.5 Colloidal natural organic matter and facilitated transport 293 10.4.6 Natural organic matter... sink for pollutants or facilitator of transport?

Mysteries and research questions 295 10.5 Conclusions 2 % 10.6 Future research directions 297 References 297

11 RELATIONSHIP BETWEEN ROCK, SOIL A N D GROUNDWATER COMPOSITIONS

John Mather 11.1 Introduction tsorfij 305 11.2 The source term " 305 11.3 Factors affecting groundwater chemistry 307 11.4 Reactions in the unsaturated zone 309

11.4.1 Gas dissolution and redistribution 309 11.4.2 Carbonate and silicate dissolution 310 11.4.3 Sulphide oxidation 311 11.4.4 Gypsum precipitation and dissolution 311 11.4.5 Cation exchange 312 11.4.6 Organic reactions 312

11.5 Reactions in the saturated zone 312 11.5.1 Carbonate and silicate dissolution i 312 11.5.2 Dissolution of soluble salts 313 11.5.3 Redox reactions 314 11.5.4 Cation exchange * 314

11.6 Saline groundwaters 315 11.7 Groundwater compositions 316 11.8 Anthropogenic influences 321

11.8.1 Agricultural pollution 321 11.8.2 Industrial pollution 322 11.8.3 Acid rain 324

11.9 Conclusions 325 11.10 Future research 326 References 327

12 TOWARDS COUPLING HYDROLOGICAL, SOIL A N D WEATHERING PROCESSES WITHIN A MODELLING PERSPECTIVE

Colin Neal, Alice J.Robson & Nils Christophersen MA Introduction 329

12.1.1 General 329 12.2 A case study from Wales 331

12.2.1 Description of the study area 332 12.2.2 Hydrochemistry 333

12.3 Sources contributing to stream flow 338 12.3.1 Rationale 338

Contents X I

12.3.2 Hydrograph separation 339 12.3.3 Hydrograph separation using continuous data 342 12.3.4 Conclusions concerning water mixing relationships 343

12.4 Chemical mixing, speciation and solubility controls for aluminium 343 12.4.1 Rationale 343 12.4.2 Modelling chemical speciation 343 12.4.3 Mixing model results 344

12.5 Modelling studies 347 12.5.1 Modelling background 347 12.5.2 Short term modelling studies 347 12.5.3 Long term modelling studies 352

12.6 Towards integrated models 362 12.6.1 Developing a cation exchange model accounting for soil heterogeneity 363 12.6.2 Summary of findings 369

12.7 Discussions 369 12.8 Recommendations 373 12.9 Conclusions - i ^ r . y-j:: ; Tav '; M < 374 12.10 Future research directions > i i r r : ^ , . 374 References 375

13 CHEMICAL CHANGES ATTENDING WATER CYCLING THROUGH > , , v ' A CATCHMENT - A N OVERVIEW

Patrice de Caritat & Ola M. Saether 13A Introduction 381 13.2 The geochemical cycle 381 13.3 The water cycle 383 13.4 Every drop of rain 385 13.5 Soil searching 386 13.6 The water table 387 13.7 Discharge! r,^y. j i - y - c t . y ...A. v t : , . ^ . 388 13.8 A l l the rivers run -.>.•.,..•.,-• y-yyiv/rA >'K'..; . v i ^^/cr' 389 Acknowledgements 390 A non-comprehensive list of useful references , , i i y .•,•.,[ r J V . sisi 7 390

LIST OF AUTHORS 393

INDEX