Estuaries, bays and contiguous coastal seas are the world's most valuable, and yet most vulnerable marine ecosystems. Fundamental to the protection and management of these important resources is an understand- ing of the physical processes involved which affect the circulation, mixing, and transport of salt, nutrients and sediment. Residual Currents and Long-Term Transport processes appear to have direct control over freshwater inflows, contaminant loadings, dispersion and transport of sediments and nutrients, and causes of declining living resources. This volume provides a comprehensive and up-to-date summary of the research results on these processes in estuaries and bays. Contributions from ten countries include results based on theoretical formulations, analyses of field data, numerical models and case studies.