Transport through unsaturated media is of importance in a quickly growing set of disciplines in both academic and engineering practice. Traditional areas of interest, including crop science, chemical engineering, agricultural engineering, and hydrology continue to be strong, while significant new interest has grown out of the environmental engineering fields, including contaminant transport, pollution remediation, and waste disposal. The objective of this book is to provide students and engineers working in these fields with a unified and up-to-date treatment of the subject. The basic equations governing flow and fate in unsaturated media will be developed with rigor, but with emphasis on maintaining an intuitive understanding of how the results are derived and how they are appropriately applied. The text will emphasize clarity rather than brevity, particularly in connection with mathematical derivations.