Shift-Adjusted Ratings

Science Center Objects

Stage-discharge relations (ratings) are usually developed from a graphical analysis of numerous discharge and stage measurements. Discharge measurements are made on various schedules, at a variety of stages, and sometimes for different purposes. All discharge measurements are compiled and maintained in a data base. Each measurement is carefully made, and undergoes quality assurance review. 

Some measurements indicate a temporary change in the rating, often due to a change in the streambed (for example, erosion or deposition) or growth of riparian vegetation. Such changes are called shifts; they may indicate a short- or long-term change in the rating for the gage. In normal usage, the measured shifts (or corrections) are applied mathematically to a defined rating.

The files linked to from real-time streamflow websites for Wyoming and Montana are shift corrected, incorporating the mathematical adjustments for ease of use by the user. The shift adjustments are applied to the individual ratings as measured data becomes available, resulting in an adjusted rating. Some ratings may change as often as weekly, others may not change for months or years.

The stage-discharge rating provided in online files should be considered provisional and subject to change. It is the responsibility of the user to retrieve updated ratings. Users are cautioned to consider carefully the applicability of any rating before using it for decisions that concern personal or public safety or operational consequences.

Inquiries about stage-discharge ratings for the WY-MT WSC can be emailed to the Data Management Unit at: gs-w-wy-mt_data_support_unit@usgs.gov.