Soil Water Measurement in the Field – A Practical Handbook

David Cooper graduated in Physics from Imperial College, London. He spent 23 years as a soil physicist with the UK Institute of Hydrology, later the Centre for Ecology & Hydrology (CEH), followed by 12 years as Head of the Hydrological Instruments Group at CEH. His work has focussed mainly on field measurement of soil water and solute fluxes and of soil hydraulic properties in a wide variety of lithologies and areas of the world, including at several sites in southern England, northern France, Kenya, Niger, Mauritius, India and China. He has contributed to advances in measurement of soil water content by neutron, capacitance and time domain reflectometry techniques, hydraulic properties measurement methods in situ in the field and soil water potential measurement using mercury manometer and pressure transducer tensiometers over extended periods at both shallow and deep depths, down to at least 60 metres. He has six children and, at the time of writing, nine grandchildren.

Preface vi Part I: INTRODUCTION 1 1 Soil Water in Context 3 2 How Does Water in Soil Interact with the Soil Matrix, Air, Roots, Gravity and Other Substances Present? 6 3 What Do We Need to Measure? 14 4 Spatial Variability 16 PART II: WATER CONTENT 21 5 Definitions 23 6 Gravimetric Method 26 7 Neutron Scattering 43 8 Dielectric METHODS 101 9 Dual-Probe Heat-Pulse Sensors 150 10 Electrical Resistivity Imaging 152 PART III: WATER POTENTIAL 159 11 Water Potential Measurement 161 12 Tensiometers 164 13 Indirect Methods of Water Potential Measurement 203 14 Beyond 10 Metres Water Head 214 PART IV: WATER CONTENT POTENTIAL RELATIONS 223 15 Soil Water Characteristic Measurement 225 PART V: HYDRAULIC CONDUCTIVITY 237 16 Hydraulic Conductivity Measurement and Prediction 239 17 Hydraulic Conductivity Measurement of Confined Soil Samples 241 18 Unconfined Measurements in the Field 257 PART VI: SOLUTE MEASUREMENT 277 19 Principles and Pitfalls 279 20 Solution Sampling 283 21 Solute Concentration Estimation by Electrical Conductivity 292 PART VII: WATER AND SOLUTE MOVEMENT 301 22 Water and Solute Transport Applications 303 23 Water and Solute Flux Measurement 306 24 Soil Water and Solute Balance Measurement and Estimation 312 PART VIII: CONCLUSION 333 25 Concluding Remarks 335 References 336 Index 353