Remote sensing of tracer dye concentrations to support dispersion studies in river channels
November 20, 2019
In river channels the flow field influences the dispersion of biota, contaminants, and other suspended or dissolved materials. Insight on patterns and rates of dispersion can be gained by injecting a pulse of visible dye and observing spatial and temporal variations in dye concentration as the pulse moves downstream. We evaluated the potential of passive optical remote sensing to enhance such tracer experiments by providing spatially distributed concentration information. During tests performed in both an experimental flume facility and a large natural channel, we made field measurements of Rhodamine WT dye concentration and above-water spectral reflectance. At Korea's River Experiment Center, a small unmanned aircraft system (sUAS) was used to acquire hyperspectral images of a sinuous outdoor flume. On the Kootenai River in northern Idaho, USA, field spectra were collected from a boat and hyperspectral image data and high resolution aerial photographs were obtained from manned aircraft. We modified an Optimal Band Ratio Analysis (OBRA) algorithm to identify wavelength combinations that yielded strong correlations between a spectrally based quantity X and dye concentration C. For both the flume and field tests, we obtained very strong (R^2 from 0.94 to 0.99) relationships between X and C across a broad range of visible wavelengths. On the Kootenai, we found that X vs. C relations derived from field spectra could be applied to airborne hyperspectral images and that dye concentrations could be estimated nearly as reliably from relatively simple three-band images as from hyperspectral data. These results imply that remote sensing could become a powerful tool for mapping dye patterns. Such a capability would advance our understanding of dispersion processes by enabling more rigorous testing of numerical flow models.
Citation Information
Publication Year | 2019 |
---|---|
Title | Remote sensing of tracer dye concentrations to support dispersion studies in river channels |
DOI | 10.1080/24705357.2019.1662339 |
Authors | Carl J. Legleiter, Richard R. McDonald, Jonathan M. Nelson, Paul J. Kinzel, Ryan L. Perroy, Donghae Baek, Il Won Seo |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Journal of Ecohydraulics |
Index ID | 70207583 |
Record Source | USGS Publications Warehouse |
USGS Organization | Colorado Water Science Center; WMA - Integrated Modeling and Prediction Division |
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Hyperspectral image data and Rhodamine WT dye concentrations from a tracer study at the River Experiment Center, Korea, in May 2017
Hyperspectral image data and field measurements of Rhodamine WT dye concentration were obtained during a tracer study conducted at the Korea Institute of Civil Engineering and Building Technology's River Experiment Center May 17-20, 2017, to support research on dispersion in river channels. The image data included in this data release were acquired using a Nano-Hyperspec (Headwall...
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