The PEAKFLOW application is used to analyze the unit values for gage height and discharge to determine the annual peak and other peaks above a base discharge. The whole collection of peaks is sometimes called the "Peaks Over Threshold (POT)" or "peaks greater than a base discharge" (Novak, 1985) data series. The collection of annual and secondary peaks is also known as the "partial-duration [data] series" (because, on an average basis, each member of the series is associated with a duration of time that is a partial year rather than the full year associated with the "full-duration" or annual-peak data series). The preferred terminology for the individual peaks is "annual" and "secondary".

Users will have access to various portions of the application based on their specific needs. The use cases describe in detail the functionality available to specific groups of users.