Physical Aspects of Soil Water and Salts in Ecosystems


Book Description

The papers collected in this book were given and discussed at the symposium on "Soil water physics and technology", which was held in Rehovot, Israel, from August 19th-September 4th, 1971. It was sponsored by the International Society of Soil Science (1.S.S.S.) through its Commissions I (soil physics) and VI (soil technology), and organized by the Israeli Soil Science Society. Thanks are due to the Editors for having assembled contributions and discussion remarks into a well-rounded, coherent book. The subjects covered in this book are the theoretical and practical aspects of the following topics: water movement in soils, soil-water interactions, evaporation from soil and plants, water requirements of crops, ion activity and migration in soils, soilwater management and salinity. In as much as these contributions were not solicited, they represent ideas and subjects considered important by the authors and debators. In science, one often finds a gap between basic research and practical application. If reading this book creates a feeling of an apparent lack of balance between theory and practice, this represents the state of our science today, and the thoughtful reader can and will recognize that much remains to be done. W. R. GARDNER T.]. MAR5HAL President, Commission I President, Commission VI 1.5.5.5.










Freezing of Soil with an Unfrozen Water Content and Variable Thermal Properties


Book Description

While many materials undergo phase change at a fixed temperature, soil systems exhibit a definite zone of phase change. The variation of unfrozen water with temperature causes a soil system to freeze of thaw over a finite temperature range. Exact and approximate solutions are given for conduction phase change of plane layers of soil with unfrozen water contents that vary linearly and quadratically with temperature. The temperature and phase change depths were found to vary significantly from those predicted for the constant-temperature or Neumann problem. The thermal conductivity and specific heat of the soil within the mushy zone varied as a function of unfrozen water content. It was found that the effect of specific heat is negligible, while the effect of variable thermal conductivity can be accounted for by a proper choice of thermal properties used in the constant-thermal-property solution. Keywords: Frozen soils; Phase change; Soils.







Soil Behavior on Freezing, with and Without Additives


Book Description

Paper 1: Results obtained from freezing experiments on soil systems at various porosities are described. Paper 2: Studies in permafrost areas show that a particle-size sorting occurs in saturated granular soils due to freeze-thaw cycling. This phenomenon is evidenced by a gradual change in size of soil grains, with the fines at the bottom of the active layer and the coarse at the surface.




Unsaturated Soil Mechanics in Engineering Practice


Book Description

The definitive guide to unsaturated soil— from the world's experts on the subject This book builds upon and substantially updates Fredlund and Rahardjo's publication, Soil Mechanics for Unsaturated Soils, the current standard in the field of unsaturated soils. It provides readers with more thorough coverage of the state of the art of unsaturated soil behavior and better reflects the manner in which practical unsaturated soil engineering problems are solved. Retaining the fundamental physics of unsaturated soil behavior presented in the earlier book, this new publication places greater emphasis on the importance of the "soil-water characteristic curve" in solving practical engineering problems, as well as the quantification of thermal and moisture boundary conditions based on the use of weather data. Topics covered include: Theory to Practice of Unsaturated Soil Mechanics Nature and Phase Properties of Unsaturated Soil State Variables for Unsaturated Soils Measurement and Estimation of State Variables Soil-Water Characteristic Curves for Unsaturated Soils Ground Surface Moisture Flux Boundary Conditions Theory of Water Flow through Unsaturated Soils Solving Saturated/Unsaturated Water Flow Problems Air Flow through Unsaturated Soils Heat Flow Analysis for Unsaturated Soils Shear Strength of Unsaturated Soils Shear Strength Applications in Plastic and Limit Equilibrium Stress-Deformation Analysis for Unsaturated Soils Solving Stress-Deformation Problems with Unsaturated Soils Compressibility and Pore Pressure Parameters Consolidation and Swelling Processes in Unsaturated Soils Unsaturated Soil Mechanics in Engineering Practice is essential reading for geotechnical engineers, civil engineers, and undergraduate- and graduate-level civil engineering students with a focus on soil mechanics.




Applications of Soil Physics


Book Description

Applications of Soil Physics deals with the applications of soil physics and covers topics ranging from infiltration and surface runoff to groundwater drainage, evaporation from bare-surface soils, and uptake of soil moisture by plants. Water balance and energy balance in the field are also discussed, along with tillage and soil structure management. The development and extension of Penman's evaporation formula is also described. This book is comprised of 14 chapters and begins with a systematic description of the field-water cycle and its management, with emphasis on infiltration and runoff; redistribution and drainage; evaporation and transpiration; and irrigation and tillage. Subsequent chapters focus on transpiration from plant canopies; freezing phenomena in soils; scaling and similitude of soil-water phenomena; spatial variability of soil physical properties; and movement of solutes during infiltration into homogeneous soil. Concepts of soil-water availability to plants are considered, together with principles of irrigation management and the advantages and limitations of drip irrigation. This monograph is intended for upper-level undergraduate and graduate students of the environmental, engineering, and agronomic sciences.