ABSTRACT
Open-channel flow measurements require specialized training and equipment, and they are expensive to obtain. The majority of continuous streamflow records are not based on direct measurement of river discharge-they are derived from continuous measurements of river elevations or stage.[1] These stage data are converted into discharge by the use of a stage/ discharge relation (rating) that is unique for each streamgaging location. Much of the effort and cost associated with streamgaging lies in establishing and updating this relation. Hydrologists visit streamgaging stations 6-10 times a year to make direct measurements of river depth, width, and velocity. From these data, they compute the open-channel flow rate. The range of measured flow rates and concurrent river stages are then used to build the rating curve for each site and to track changes to the rating curve.
