The Lassen hydrothermal system is in the southern Cascade Range, approximately 70 kilometers east-southeast of Redding, California. The conceptual model of the Lassen system is termed a liquid-dominated hydrothermal system with a parasitic vapor-dominated zone. The essential feature of this model is that steam and steam-heated discharge at relatively high elevations in Lassen Volcanic National Park (LVNP) and liquid discharge with high chloride concentrations at relatively low elevations outside LVNP in the Lassen Known Geothermal Resource Area (KGRA) are both fed by an upflow of high-enthalpy, two-phase fluid within the Park. Liquid flows laterally away from the upflow area towards the areas of high-chloride discharge, and steam rises through a vapor-dominated zone to feed the steam and steam-heated features. The geometric model corresponds to an areally restricted flow regime that connects the Bumpass Hell area in LVNP with regions of chloride hot springs in the Mill Creek canyon in the KGRA south of LVNP. Simulations of thermal fluid withdrawal in the Mill Creek Canyon were carried out in order to determine the effects of such withdrawal on portions of the hydrothermal system within the Park. 19 refs., 17 figs., 4 tabs.

The 2006 second edition of this well received and widely adopted textbook has been extensively revised to provide a more comprehensive treatment of hydromechanics (the coupling of groundwater flow and deformation), to incorporate findings from the substantial body of research published since the first edition, and to include three new chapters on compaction and diagenesis, metamorphism, and subsea hydrogeology. The opening section develops basic theory of groundwater motion, fluid-solid mechanical interaction, solute transport, and heat transport. The second section applies flow, hydromechanics, and transport theory in a generalized geologic context, and focuses on particular geologic processes and environments. A systematic presentation of theory and application coupled with problem sets to conclude each chapter make this text ideal for use by advanced undergraduate and graduate-level hydrogeologists and geologists. It also serves as an invaluable reference for professionals in the field.

Groundwater in Geologic Processes first develops the basic theory of groundwater motion, solute transport, and heat transport. The second section applies flow and transport theory in a generalized geologic context and focuses on particular geologic processes and environments. The systematic presentation of theory and application makes this book ideal for graduate-level hydrogeologists and geologists with backgrounds in calculus and introductory chemistry. It will also be an invaluable reference for professionals in the field.