Using remotely sensed data to estimate river characteristics including water-surface velocity and discharge

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Abstract

This paper describes a project combining field studies and analyses directed at providing an assessment of the accuracy of remotely sensed methods for determining river characteristics such as velocity and discharge. In particular, we describe a remote sensing method for surface velocities using mid-wave thermal camera videography combined with image analysis. One of the critical problems in this work is determining a method for relating remotely measured water-surface velocities to vertically averaged velocities through a velocity index. We explore three similarity profiles that allow a relationship between surface and vertically averaged velocity to be found either using empirical results or simple roughness-to-depth ratios. To test the approaches we compare them in a situation where vertical structure is known over most of the flow depth through ADCP measurements. By determining best-fit profiles through the ADCP profiles, average values of the velocity index are found for the cross-sections where measurement were made. By comparing these to the predicted velocity indices from the three similarity profiles, we find that, although the differences between the various similarity profiles are substantial, they are smaller than differences associated with local nonuniformity and nonhydrostatic flow. Nevertheless, the velocity indices are accurate to about +/-5%, meaning that remotely sensed vertically averaged velocities can be computed to well within the current accuracy standard for such values when used for river gaging.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Using remotely sensed data to estimate river characteristics including water-surface velocity and discharge
Year Published 2017
Language English
Publisher IAHR
Contributing office(s) National Research Program - Central Branch
Description 10 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title E-proceedings of the 37th IAHR World Congress
First page 1
Last page 10
Conference Title 37th IAHR World Congress
Conference Location Kuala Lumpur, Malaysia
Conference Date August 13-18, 2017