Quantifying Streambed Hydrological Exchange Flows Using Structure-From-Motion Photogrammetry and Computational Fluid Dynamics Modeling
Abstract
Streambed hydrological exchange flows (HEFs) are the exchange fluxes of water and concentration at the water-sediment interface. These fluxes are the primary control of nutrient dynamics, carbon cycles, and ecosystem health in dynamic riverine ecosystems. Despite their importance, quantifying HEFs at streambeds in a fast and accurate manner is still a challenge. To explore new directions, this work aims to establish a framework that enables HEFs prediction by combining structure-from-motion (SfM) photogrammetry and computational fluid dynamics (CFD) modeling. Specifically, the SfM photogrammetry was used to obtain millimeter to centimeter-scale resolution riverbed topography such that the sizes and shapes of fine-scale sediments can be measured and parameterized. With such a high-resolution riverbed, hyporheicFoam, a fully coupled groundwater-surface water CFD code in OpenFOAM, was then used to calculate the fluxes of water and concentration of oxygen, nitrate, carbon dioxide, and dissolved organic matter at the riverbed. Quantitative relationships between HEFs and important factors, including parameterized riverbed topography, flow velocity, and water depth, were then identified. Finally, interFoam, a three-dimensional two-phase flow CFD solver in OpenFOAM, was used to obtain flow velocity and water depth over a 30 km long river section in the Columbia River, and these data were subsequently used in the previously identified quantitative relationships to predict HEFs over the 30 km long river section. HEFs predicted in this way will also be compared to those measured from field surveys. The mechanisms of microtopography control of streambed hydrodynamics, chemical reactions, and HEFs, and the integration of future SfM photogrammetry surveys for large-scale rivers with our CFD modeling will also be discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH086.0005C
- Keywords:
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- 1804 Catchment;
- HYDROLOGY;
- 1805 Computational hydrology;
- HYDROLOGY;
- 1830 Groundwater/surface water interaction;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY