This concise, contemporary book, which has contributions from several authors who have the experience and expertise in subjects dealt within the text, successfully integrates geographical information systems (GIS) and environmental models (EM). It is designed as a text for advanced courses in GIS/EM and for short-term courses in these subjects.The book begins with a disciplinary perspective of GIS/EM, explores modeling frameworks, paradigms and approaches, and highlights the impact of the computer models, termed geocomputation. It then delineates in detail the consequences of integrating GIS and environ-mental models for decision making, time dimension in modeling, and gives methodological and practical examples of the importance of process modeling for physical systems. An entire chapter is devoted to Case Studies in GIS. Finally, the book demonstrates the capabilities of the Environmental System software to explore the methods, capabilities and problems specific to visualization of environmental data.