69th Annual Meeting of the APS Division of Fluid Dynamics (November 20, 2016 — November 22, 2016)

V0083: HYporheic Flow Through a Triangular Dune

Authors

• Willaim Jeffery Reeder, University of Idaho, Department of Civil Engineering
• Annika M. Quick, Boise State University, Department of Geosciences
• Tiffany B. Farrell, Boise State University, Department of Biological Sciences
• Christina Beeson, Boise State University, Department of Geosciences
• Shawn G. Benner, Boise State University, Department of Geosciences
• Kevin P. Feris, Boise State University, Department of Biological Sciences
• Daniele Tonina, University of Idaho, Department of Civil Engineering

DOI: https://doi.org/10.1103/APS.DFD.2016.GFM.V0083

The hyporheic zone is the volume of porous sediments adjacent to and below the stream water where surface water exchanges with subsurface flows.  These saturated sediments include the stream bed, stream banks, particularly in outcroppings and meander bends, and abandoned channels (paleo channels) that maintain hydraulic connectivity with the stream waters.  Hyporheic exchange, the flow of water into and out of the HZ, is driven by pressure gradients that exist at the interface between the surface waters and the stream bed.  At local, bedform scales these pressure gradients are primarily caused by flow obstructions from bedform features (e.g. dunes, riffles and woody debris) protruding into the stream flow. While the mechanics of hyporheic flow have been well described in the scientific literature, visulization of those flows can be difficult even for those well versed in the art and science of river mechanics.  This video, through the use of a fluorescent dye, traces the paths of several packets of water through the hyporheic region of a traingular sand dune. The images in the video provide a clear visualization of the scale and dynamics of the subsurface flow while also providing a direct measure of residence time of the subsurface water and the hydraulic conductivity of the bed material.