What is a natural river

Form and process in rivers around the world reflect a long history of human influences, but the effects of these influences are often not readily apparent to the casual observer. Progressive alteration of rivers over a period of decades to centuries as a result of land-use patterns influences expectations for the appearance of natural rivers. These expectations in turn help to govern strategies of river restoration, which is being increasingly practiced in industrialized countries. This article uses examples from three regions in the United States – headwater streams in the Rocky Mountains, streams in the mid-Atlantic piedmont region of the eastern United States, and coastal rivers of the Puget Lowland in the western United States – to explore how historical land-use patterns continue to influence contemporary river form and process, and the implications of these historical effects for understanding and managing rivers. If restoration is designed to facilitate natural river form and process, then it becomes critical to understand how human activities have altered rivers. Such an understanding defines the limits within which restoration can be undertaken and provides a conceptual framework for adaptive management of river restoration