Background and Hydrogeology -- to Hydrogeophysics -- Hydrogeological Methods for Estimation of Spatial Variations in Hydraulic Conductivity -- Geostatistics -- Fundamentals of Environmental Geophysics -- Relationships between the Electrical and Hydrogeological Properties of Rocks and Soils -- DC Resistivity and Induced Polarization Methods -- Near-Surface Controlled-Source Electromagnetic Induction -- GPR Methods for Hydrogeological Studies -- Shallow Seismic Methods -- Relationships between Seismic and Hydrological Properties -- Geophysical Well Logging -- Airborne Hydrogeophysics -- Hydrogeophysical Case Studies -- Hydrogeophysical Case Studies at the Regional Scale -- Hydrogeophysical Case Studies at the Local Scale: The Saturated Zone -- Hydrogeophysical Case Studies in the Vadose Zone -- Hydrogeophysical Methods at the Laboratory Scale -- Hydrogeophysical Frontiers -- Emerging Technologies in Hydrogeophysics -- Stochastic Forward and Inverse Modeling: The “Hydrogeophysical” Challenge.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 earth’s shallow subsurface.