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River rating complexity

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Abstract

Accuracy of streamflow data depends on the veracity of the rating model used to derive a continuous time series of discharge from the surrogate variables that can readily be collected autonomously at a streamgage. Ratings are typically represented as a simple monotonic increasing function (simple rating), meaning the discharge is a function of stage alone, however this is never truly the case unless the flow is completely uniform at all stages and in transitions from one stage to the next. For example, at some streamflow-monitoring sites the discharge on the rising limb of the hydrograph is discernably larger than the discharge at the same stage on the falling limb of the hydrograph. This is the so-called “loop rating curve” (loop rating). In many cases, these loops are quite small and variation between rising- and falling-limb discharge measurements made at the same stage are well within the accuracy of the measurements. However, certain hydraulic conditions can produce a loop that is large enough to preclude use of a monotonic rating. A detailed data campaign for the Mississippi River at St. Louis, Missouri during a multi-peaked flood over a 56-day period in 2015 demonstrates the rating complexity at this location. The shifting-control method used to deal with complexity at this site matched all measurements within 8%.

Publication type Conference Paper
Publication Subtype Conference Paper
Title River rating complexity
Year Published 2016
Language English
Publisher CRC Press
Contributing office(s) Office of Surface Water
Description 8 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title River flow 2016
First page 679
Last page 686
Conference Title Proceedings of the International Conference on Fluvial Hydraulics (River flow 2016)
Conference Location St. Louis, MO
Conference Date July 11-14, 2016
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