Megaflooding is the sudden discharge of exceptional volumes of water. Megafloods have significantly altered the terrain of Earth and Mars, and may have acted as triggers for climate change on these planets. Recently, research into megaflooding has made important advances: on Earth, real-time measurements of contemporary floods in Iceland complement research into older and larger terrestrial floods, while on Mars terabytes of data from several spacecraft orbiting that planet are dramatically revising our view of flooding there. Beginning with a historical overview of flood science, the book presents sections on morphology and mechanisms, flood sedimentology, and modelling, each illustrated with examples from Earth and Mars. By juxtaposing terrestrial and Martian research, this volume creates a unique synthesis to further our understanding of these enormous paleoflood events. It is an invaluable reference for researchers and students of hydrology, geomorphology, sedimentology and planetary science, as well as environmental and hydraulic engineers.