River systems are complex systems, through which are focused irregular fluxes of water and mobile terrestrial materials derived from the lithosphere, atmosphere and biosphere. The dynamics of the transport, storage, and interactions of these materials creates channel and valley-floor environments with which the river continually interacts, creating certain functions and environmental conditions. The resulting functions and environments change both gradually and episodically due to both external forcings and internal dynamics. The continual creation results in spatial and temporal complexity rather than a single continuum of environments linked by transport. Differences among river systems in the relative strengths of gradual and episodic change result in differences of complexity and function.
River systems comprise features that have enormous social and ecological significance.
Throughout Earth history, these alluvial storages have sequestered sediment, carbon, and other biogeochemical materials, and they have generated intricate and dynamic habitats for plants and animals. Thus, large river valleys present some enduring, refractory problems of environmental management, which societies must control or adjust to. If you have questions or comments about this course, please emal Professor Dunne .