Braided rivers exhibit high spatial thermal heterogeneity that is difficult to understand using only in situ measurements. In this summer study, we used a drone and a powered paraglider to acquire very high spatial resolution (14–27 cm) thermal infrared (TIR) images
of nine braided reaches located in the French Alps. We applied atmospheric corrections to TIR images and calibrated them based on in situ data. To characterize spatial and temporal thermal patterns, three temporal approaches were applied. A single survey of each site was performed to
comparatively explore the nine braided reaches. Three reaches were imaged twice, in 2010 and 2011, to explore inter-annual variability. Finally, two reaches were selected for an intra-day survey for which four and three flights, respectively, were realized within one day. We reported two types
of thermal patterns in braided reaches, the first showing very low thermal variability throughout the day. This low variability was linked to the low diversity found in the aquatic habitat, notably due to proglacial regimes with high summer flows which homogenize water temperatures. The second
type exhibited a higher thermal variability with changes during the day. The temperature of flowing channels changed during the daytime according to air temperature. In contrast, the temperature of channels downstream connected to the main network exhibited smaller changes, which created thermal
variability over space and time associated with hyporheic or phreatic flows. Non-proglacial and proglacial reaches behaved differently according to air temperature. Proglacial reaches were colder and less sensitive to air temperature in comparison with non-proglacial reaches. These findings
allow for a prediction of habitat diversity from temperature heterogeneity based on time and the proportion of ponds, alluvial, and groundwater channels.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
Document Type: Research Article
Affiliations:1: Université de Lyon, CNRS-UMR 5600, ENS de Lyon, Plateforme ISIG, 15 parvis René Descartes, BP 7000, 69342 Lyon Cedex 07, France 2: Université de Lyon, CNRS-UMR 5276, Université Lyon 1, ENS de Lyon, 2 rue Raphaël Dubois, 69622 Villeurbanne Cedex, France