This Special Issue on Dispersive Hydrodynamics is dedicated to the memory and work of G. B. Whitham who was one of
the pioneers in this field of physical applied mathematics. Some of the papers appearing here are related to work reported
on at the workshop \Dispersive Hydrodynamics: The Mathematics of Dispersive Shock Waves and Applications" held in
May 2015 at the Banff International Research Station. This Preface provides a broad overview of the field and summaries
of the various contributions to the Special Issue, placing them in a unified context
