Soil Hydrology

The authors have intended to present an introduction to the physical interpretation of phenomena which govern hydrological events related to soil or the upper most mantle of the earth's crust. The text is based upon our teaching and research experience. The book can serve either as the first reading for future specialists in soil physics or soil hydrology. Or, it can be a source of basic information on soil hydrology for specialists in other branches, e. g. in agronomy, ecology, environmental protection, forestry, geomorphology, hydrologic science, meteorology and water management. They assume that those specialists do not intend to conduct research in soil hydrology but may wish to successfully use its tools in their own academic domains. The first requirement of such a book is its simplicity without neglecting all of the complexity of soils and their porous systems as they react with the atmosphere, biosphere and hydrosphere. With mathematical derivations in the majority of cases being reduced to the level of calculus, the authors were obliged in some instances to deviate from the usually rigorous derivations. However, if the reader has an aversion to mathematics, basic information on any particular problem can be gained even without going into the details of its mathematical development. According to our experience, the level of information presented in this book is adequate for a qualified use of programs and models in soil hydrology. If the reader does not intend to passively accept ready-made software, and has intentions of being more academically creative, we recommend more detailed study of information readily available in related journals and other publications. Physical interpretation and mathematical formulation of such complex events as rain infiltration or evapotranspiration cannot be done without a certain degree of simplification. The authors emphasize here that this simplification leads only to an approximation to reality. Similar simplifying approaches can be applied in neighboring branches of investigation. By removing some simplifying assumptions, a more exact but usually a more complicated but still approximate solution of the soil hydrological problem is formulated. Inasmuch as the text of this book is purposely not a monograph, the references cited are the subjective selections from the voluminous literature. Indeed, many titles to which there is no reference may be of the same importance as the selected references for a given problem . The same consideration applies to the theories presented in the text - not all are explained nor quoted in this book. Even if the authors had tried to subordinate their subjective choice to criteria based upon further development and broad applicability, they are aware of the fact that they would have neglected some which will eventually be extended to fundamental contributions in the future. Those contributions are the "surprises” that make research and scientific investigation so attractive to many creative brains.