chapter  6
42 Pages

Soil Properties and Moisture Movement in the Unsaturated Zone

WithRandel  Haverkamp, Samuel Debionne, Rafael Angulo-Jaramillo, and Devaraj de Condappa

An introduction to water in the unsaturated zone is given in Section 2.5. Chapter 6 is concerned with the movement of moisture in the unsaturated zone. It covers the conceptual aspects of unsaturated soil water ow related to soil physical properties and soil water characteristics. In Section 6.2 we deal with the soil physical properties, the soil hydraulic properties, and the choice of the functional relationships used to describe the soil hydraulic characteristics. Additionally, we also present some of the measurement and prediction techniques used for the estimation of

6.1 Introduction ............................................................................................................................. 149 6.2 Physical and Hydraulic Soil Properties ................................................................................ 150

6.5 Scaling Principles ..................................................................................................................... 177 Scaling Inltration • Scaling Evaporation

6.6 Conclusions and Perspectives on Future Research ............................................................ 182 Glossary and Parameter Notation ..................................................................................................... 182 Acknowledgments ............................................................................................................................... 184 References ............................................................................................................................................. 184 Further Reading ................................................................................................................................... 189

the soil hydraulic characteristics parameters. We then address the conceptual aspects of the dierent unsaturated soil water transfer equations used in subsurface hydrology (Section 6.3). An overview of the most signicant analytical solutions is presented in Section 6.4; the empirical inltration laws are discussed in detail in Chapter 7. Section 6.5 sets out the details of a new scaling approach of the water transfer equation (Richards, 1931) and its implications for the soil characteristic scale parameters. Concluding remarks are given in Section 6.6, followed by the references, and a glossary and parameter notation.