Infiltration Theory for Hydrologic Applications

Preface  vii

1. Introduction  1

Brief History  1

Runoff Mechanisms  3

Engineering and Scientific Approaches to Hydrology  4

Objective and Scope of this Work  5

2. Basic Porous Media Hydraulics  7

Capillary Properties of Soil Water  7

Porous Media  9

Darcy's Law  12

Hydraulic Characteristics of Porous Media  13

Steady Flow Soil Water Relations  14

Functional Representation of Hydraulic Characteristics 18

3. Some Essentials of One-Dimensional Porous Media Dynamics  25

Introduction  25

Absorption: Gravity-Free Intake  27

Infiltration: Vertical Flow  31

Mathematical Approximations for Soil Water Flow  34

Approximations for Soil Hydraulic Characteristics 36

4. A Realistic Integrable Nonlinear Model for Transient Unsaturated Flow 41

Introduction  41

Integrable Forms of Richards' Equation' 43

Solution of Nonlinear Diffusion Equation  46

Required Forms for Soil Characteristics 49

Solution of the Integrable Form  55

Discussion and Summary 60

5. Absorption and Infiltration Relations and the Infiltrability-Depth

Approximation 63

Introduction  63

Absorption 65

Infiltration  73

Stability of Flux-ConcentrationR elation  85

6. Infiltrability Models: Comparisons and Application  97

Introduction  97

Timing of Pending 98

Time Explicit Approximations 108

Applying the Infiltrability Models to Variable Rainfall Patterns 114

7. Applying Infiltration Models in Layered Soils and Redistribution Cases 119

Introduction  119

Redistribution and Reinfiltration  119

Layered Soils  122

8. Field Measurements of Infiltration Parameters  135

Introduction  135

Drip Infiltrometers 136

Ring Infiltrometers  138

Permeameters  141

9. Infiltration and Runoff on a Hillslope  159

Introduction  159

General Surface Flow and Infiltration Interaction  160

Effect of Surface Relief on Surface Water Losses  162

Infiltration Heterogeneity and Runoff  164

Appendices 185

I. Derivation of the Infiltration Integral from Richards' Equation  185

II. Attenuation of Characteristic Kinematic Shock in Soil Water Flow 187

III. Finite Difference Solution Method for Richards' Equation  190

List of Symbols and Abbreviations 199

References  203

Index  211