Investigating stream longitudinal geomorphic variability and hyporheic exchange residence time distribution using a groundwater flow model
Abstract
Reach scale solute transport modeling has been widely used to characterize hyporheic transient storage processes and coupled biogeochemical reactions. Recently, groundwater flow and particle tracking models have also been used to simulate hyporheic flow paths and hyporheic residence time distributions (RTDs). In this study, we investigate hyporheic exchange comparing groundwater/particle tracking simulations using MODFLOW/MODPATH to observed stream tracer Rhodamine WT RTD in 2nd and 4th-order stream reaches of Lookout Creek basin, in central Oregon, USA. Surveyed longitudinal water surface and bed elevation profiles were used to define MODFLOW/MODPATH model domains. Our results indicate that longitudinal changes in the stream energy profile caused by stream geomorphic variability account for a substantial portion of the volume and RTD of hyporheic exchange in these reaches. Hyporheic flow paths defined here suggest that hyporheic biogeochemical functioning may be spatially selective. The degree to which other factors, such as alluvial thickness, bedrock geometry, and heterogeneity in hydraulic conductivity determine volume and RTD is under investigation.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.H52D0901G
- Keywords:
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- 1824 Geomorphology (1625);
- 1829 Groundwater hydrology;
- 1860 Runoff and streamflow;
- 1871 Surface water quality