For the InstructorThese student materials complement the Water Science and Society Instructor Materials. If you would like your students to have access to the student materials, we suggest you either point them at the Student Version which omits the framing pages with information designed for faculty (and this box). Or you can download these pages in several formats that you can include in your course website or local Learning Managment System. Learn more about using, modifying, and sharing InTeGrate teaching materials.
River flow changes over time
The amount of water moving down a river at a given time and place is referred to as its discharge, or flow, and is measured as a volume of water per unit time, typically cubic feet per second or cubic meters per second. The discharge at any given point in a river can be calculated as the product of the width (in ft or m) times the average depth (in ft or m) times average velocity (in ft/s or m/s).
The vast majority of rivers are known to exhibit considerable variability in flow over time because inputs from the watershed, in the form of rain events, snowmelt, groundwater seepage, etc., vary over time. Some rivers respond quickly to rainfall runoff or snow melt, while others respond more slowly depending on the size of the watershed, steepness of the hillslopes, ability of the soils to (at least temporarily) absorb and retain water, and the amount of storage in lakes and wetlands.