A new discipline of hydrogeophysics has evolved, aimed at improved simultaneous use of geophysical and hydrogeological measurements for hydrogeological investigations. By combining measurements made from hydrologic instruments with geophysical methods, accurate subsurface characterization and monitoring can be achieved, with high temporal and spatial resolution over a range of spatial scales. This helps to estimate parameters and monitor processes that are important to hydrological studies, such as those associated with water resources, contaminant transport, ecological and climate investigations.This book covers the fundamentals of the discipline from both the hydrogeological and geophysical perspectives, provides guidelines for application of different approaches and methods, and includes extensive examples of hydrogeophysical applications through case studies. Thirty five authors from nine countries, who are leaders in their respective areas, contributed to Hydrogeophysics. The book is intended to provide an introduction to new researchers to the field, to be used as a resource for researchers already active in the field, and to serve as a springboard for advances in the field that are needed to improve our understanding and management of the earths shallow subsurface.