HR: 14:25h
AN: H23J-04 INVITED    [Abstracts]
TI: Understanding processes in streambeds with reductive models and high-resolution data
AU: * Cardenas, M B
EM: cardenas@mail.utexas.edu
AF: Department of Geological Sciences, The University of Texas at Austin, 1 University Station C1100, Austin, TX 78712, United States
AB: Streambeds host coupled physical, chemical, and biological processes that can impact watershed scale processes. Fluid flow through streambeds provides the template for most of the processes since it controls transport. Unfortunately, fluid flow within streambeds may be complicated, even at the grain scale, owing to current-topography driven exchange, heterogeneity, and turbulent-porous media flow coupling. We analyze several interacting processes within streambeds using reductive numerical modeling of hydrodynamic, biogeochemical and thermal processes, while placing equal emphasis on river hydraulics. This leads to predictive models that can potentially be useful in field settings. Results from our models can be used to constrain interfacial fluid fluxes, chemical reaction rates and solute fluxes, and observed thermal patterns. However, streambeds are heterogeneous and seldom uniform. Detailed observations of permeability fields input into models indicate that in certain cases, internal control by permeability may be more important than external fluid flow forcing. Lastly, we present observations of the thermal regime of rivers and show how geomorphologic and ecologic factors could complicate streambed temperature distribution. Despite the complex physics and spatial variability of many parameters, recent developments in observational and modeling technology allows us to inspect streambeds more closely. Although the goal of the community should be to unravel the myriad roles of the streambed in a broader space and time, as well as disciplinary, context, we need to be simultaneously and firmly grounded in process-level understanding.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 1814 Energy budgets
DE: 1828 Groundwater hydraulics
DE: 1860 Streamflow
SC: Hydrology [H]
MN: 2007 Fall Meeting