We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Novel dimensionless index for physically based assessment of thermal refugia characterizes off‐channel habitat on gravel bed river.
- Authors
Gombert, Carolyn E.; Lancaster, Stephen T.; Grant, Gordon E.; Flitcroft, Rebecca L.
- Abstract
In the Willamette River, OR, main channel temperatures can be too warm for cold water fishes, causing fish to concentrate in secondary channel features that provide thermal refugia. However, temperature regimes vary among and within features. Improved understanding of physical processes controlling thermal regimes is needed. This study developed a dimensionless index for assessment of thermal refugia on the upper Willamette River. The novel hyporheic insolation (HIN) index uses minimal field measurements to predict thermal refugia resulting from buffering. Continuous water temperature measurements at one side channel, eight alcoves, and six beaver ponds provided data to ground truth calculated ℍin predictions. Water temperature records were first used to characterize stratification at sites. Calculation of the Richardson number, an index of stability, showed two well‐mixed sites and 13 stratified sites. At stratified sites, calculated ℍin values characterized the ratio of cooling flux from hyporheic discharge to heat flux from incoming solar radiation. As ℍin increased, measured temperatures at sites decreased. Despite overall scatter, a logarithmic fit to bin‐averaged ℍin values showed R2 = 0.91. Calculations suggest that secondary channel features characterized by stratification and cool hyporheic discharge can provide thermal refugia. Accordingly, the HIN index may serve as a practical tool grounded in physical processes governing temperature across a floodplain.
- Subjects
RIVER channels; WATER temperature; RICHARDSON number; GRAVEL; SOLAR radiation; HEAT flux
- Publication
Journal of the American Water Resources Association, 2023, Vol 59, Issue 4, p615
- ISSN
1093-474X
- Publication type
Article
- DOI
10.1111/1752-1688.13096