Wilfried Brutsaert (2022 Stockholm Water Prize Laureate) has revised and updated his classic textbook to take into account recent developments, while retaining the rigor and structure of the previous edition to introduce the fundamental principles of hydrology. New topics include the response of the global water cycle to climate change, the land surface energy budget closure, snow melt, groundwater trends and statistical surface variability with disturbed atmospheric boundary layers. Hydrologic phenomena are dealt with at the spatial and temporal scales at which they occur in nature. The physics and mathematics necessary to describe these phenomena are introduced and developed: readers will require a working knowledge of calculus and basic fluid mechanics. This classroom-tested textbook based on the author's long-running course at Cornell - is invaluable for entry-level courses in hydrology directed at advanced undergraduate and graduate students in physical science and engineering. In addition, it is also a great reference text for practising scientists and engineers.