Water Resources Research Act Program

Details for Project ID 2018ID222B

Seeing through a sediment bed: A novel transparent sediment simulant for unveiling the bed topography and interstitial processes

Institute: Idaho
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $14,714 Total Non-Federal Funds: $29,458

Principal Investigators: Daniele Tonina, Ralph Budwig

Abstract: Inland waters interact with bed sediments creating a water exchange known as hyporheic flow. This exchange is the key mechanism for transporting solutes and particles between surface and subsurface waters with important consequences for surface and subsurface water quality. The ability to measure the flow paths and monitor biological activities within sediments is paramount to better constrain, model and predict these processes. However, current techniques do not allow the measurement of intra-gravel flows that have been predicted by numerical modeling. Thus, the scope of this research is to provide a new economical, efficient and non-invasive method to measure interstitial flows hydraulics. This research is fundamental to developing a new methodology that will help to address key issues concerning water quality: (1) nutrient fate along streams (2) heavy metal fate and storage in water body sediments (3) near-surface sediment biogeochemical processes (4) water and solute exchange at the water sediment interface (5) aquatic vegetation growth and development (6) studying redd internal flow structure to investigate sustenance of embryos (7) studying the movement of organisms in a sediment bed This research proposes to test a new “transparent” sediment that has the same refraction index as water mixed with ~20% glycerin. For the first time, this will allow using Refractive Index Matching (RIM) with a sediment simulant and with a safe, biologically friendly and non-toxic fluid that can mimic both fresh and salt waters. The material proposed is fluoroplastic THV 221GZ granules that can be annealed at 125 C, melted at low temperature (165 C) and molded in the needed shape such that we can produce particles that resemble sediment grains. THV has a specific gravity (SG=2) near that of natural sediment (SG=2.6). RIM coupled with Particle Image Velocimetry (PIV) and analytical modeling will allow measuring the flow field and pressure distribution both in the surface water and in the pores interstices at a high resolution and in a non-intrusive way. The complete internal topography of the sediment bed can also be mapped. RIM coupled with Planar Laser-Induced Fluorescence will be used to quantify solute diffusion and dispersion within sediments. The benefit of this seed funding will be to place the University of Idaho research team at the front edge of the optical exploration of transparent simulated sediment beds. It will allow us to develop new research proposals that would be highly competitive respect to other research teams because of the ability to measure flow field accurately in both surface and subsurface flows. The objectives of this research are: (1) Test PIV with melted particles into different and irregular shapes (2) Develop methods to apply PIV to a packed bed of irregular shaped grains to determine sediment bed topography as well as velocity field through interstitial passage (3) Test if we can 3D printing the particles. (4) Test PIV with 3D printed particles (5) Test PIV and PLIF with and without biofilm