On the Transferability of Residence Time Distributions in Two 10-km Long River Sections with Similar Hydromorphic Units
Abstract
Quantifying hydrologic exchange fluxes (HEFs) at the stream-groundwater interface and their residence time distributions (RTDs) in the subsurface are important for managing the water quality and ecosystem health in dynamic river corridors. Direct computation of the detailed HEFs and RTDs, however, is time-consuming, especially for watershed-scale modeling. Efficient surrogate models that link the RTDs to hydromorphic units (HUs) are ideal alternatives to simulate RTDs in large-scale models. However, a persistent problem of the surrogate models is the transferability issue, i.e., whether the relationship between the RTDs and HUs identified for one river corridor remains valid for another one. To answer this question, this work will compare the HEFs and resulting RTD-HU relationships for two 10-km long river corridors along the Columbia River leveraging a framework we previously developed. In this framework, we first simulated the streamflow hydrodynamics, including water stage, flow velocity, and dynamic pressure, by numerically solving the two-phase Reynolds averaged Navier-Stokes equations within OpenFOAM, an open-source computational fluid dynamics platform. Using the OpenFOAM-derived dynamic or static pressure as a streambed pressure boundary condition, PFLOTRAN, a subsurface flow, and reactive transport model, was then used to compute the flow velocities in the subsurface, which were subsequently fed to a particle-based residence time model to derive the RTDs. By applying such a framework at the two selected 10-km long river corridors with similar hydromorphic units, HEFs and RTDs will be compared to provide some insights on the transferability question of the surrogate models.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H42D1287B