The book "Man and River Systems" offers a comprehensive analysis of the ecological functioning of river systems, an area that has received less attention compared to lakes and reservoirs. The selected contributions cover a wide range of topics, including aquatic communities, eutrophication, nutrient dynamics, organic pollution, erosion and sediment transport, as well as the effects of micropollutants at the watershed level. Integrated approaches are presented that have been developed to investigate the ecological functions of river systems affected by human activities. The analysis is conducted from both a fundamental research perspective and with a focus on the management of these systems. This book is aimed at researchers in the field of aquatic ecology, students, institutions involved in water resource management, and the drinking water and wastewater treatment industries.