We began this book primarily to collate into a single database relevant environmental data for rivers that discharge directly into the global ocean. As the book evolved, however, it began to take on a life of its own, and now contains, following a brief introductory chapter, three rather long chapters that attempt to give an overview to the environmental controls on fluvial discharge, short-term and longer-term temporal variations, and the impact of human activities on global rivers and their watersheds.

As geological oceanographers, we tend to view rivers differently than most hydrologists, geochemists or geomorphologists. While our data, analyses and interpretations of these data touch upon fundamental processes that govern fluvial runoff, physical, and chemical weathering, transport, dispersal and sedimentation, we do not explain in detail how fluvial systems work. We do, however, include a rather extensive bibliography that can help direct the interested reader to relevant literature.

In presenting such a large database – more than 1500 rivers – some of the data almost invariably will prove to be erroneous. We may have transposed numbers, and almost surely we have missed some key data sources. Where errors or omissions occur, we request the reader notify us – kindly, if possible – so that we can correct our mistakes and set the record straight.