Fluvial geomorphology is devoted to understanding rivers, both in their natural setting as well as how they respond to human-induced changes in a watershed. One goal is to predict what changes will occur to a stream channel in response to alterations in watershed conditions; and, in turn, how these changes will impact human infrastructure and fish habitat. A river's adjustment to watershed perturbations may take thousands of years, as is the case throughout much of United States as the result of deglaciation. In other instances, channel modifications may occur in less than a decade, as is frequently the case with direct human activity in a stream channel. Understanding how these perturbations, operating at different time scales, alter the width, depth, and planform of a channel is critical for identifying potential problem areas in a river system.

Changes in channel morphology over human time scales - one page science briefing paper