Spatiotemporal Variability of Hyporheic Flow in a Losing River Section
Characterizing the spatiotemporal variability of water fluxes at the stream‐groundwater interface is extremely challenging due to the lack of methods for estimating hyporheic flows at different scales. To address this, we demonstrate the potential of Active‐Distributed Temperature Sensing (DTS) meth...
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| Published in: | Water resources research Vol. 60; no. 6 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Washington
John Wiley & Sons, Inc
01-06-2024
American Geophysical Union |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Characterizing the spatiotemporal variability of water fluxes at the stream‐groundwater interface is extremely challenging due to the lack of methods for estimating hyporheic flows at different scales. To address this, we demonstrate the potential of Active‐Distributed Temperature Sensing (DTS) methods for measuring and mapping hyporheic flow in a lowland stream. Experiments were conducted by burying a few hundred meters of heatable Fiber‐Optic cables within streambed sediments in a large meander, where permanent stream‐losing conditions are observed along the stream reach. We propose a new methodology to filter ambient temperature variations along the heated section of the DTS cable and to extend the application of Active‐DTS to losing streams. After data processing, the results show that, along lateral and longitudinal stream profiles, both thermal conductivity and water flux values follow normal distributions with relatively small standard deviations. Hyporheic fluxes vary by one order of magnitude. The absence of correlation between water fluxes within the hyporheic zone and streambed topography variations suggests that the variability is mainly controlled by local streambed heterogeneities. This means that the spatiotemporal variability of fluxes may be used as a marker of the variability of streambed hydraulic conductivities. The relatively low spatial variability (one order of magnitude) in hyporheic flow suggests a small variability of streambed properties. This is an important result for calibrating models assessing hyporheic processes, in which the hydraulic conductivity distribution is generally assumed. Additionally, measurements made over three years yield similar estimates showing the remarkable stability of hyporheic flows through time.
Plain Language Summary
Characterizing the interactions between groundwater and surface water is extremely challenging although such interactions control water quality and ecosystems resilience to climate changes. Here, we used an innovative approach based on heated fiber optic cables, called Active‐Distributed Temperature Sensing, to image the spatial variability of hyporheic fluxes in a lowland stream. Our results show that the instrumental developments as well as the data processing methodology are very robust to accurately measure in‐situ the thermal conductivity of stream sediments and hyporheic fluxes within the streambed. Interestingly, groundwater flux variability was found relatively limited and not correlated to the morphology of the riverbed. In addition, measurements made over three years yield similar estimates showing the excellent reproducibility of the measurements and the remarkable stability of hyporheic flows through time. These results shed new light about the spatial and temporal variability of hyporheic fluxes in a lowland river.
Key Points
Active‐Distributed Temperature Sensing was used in a lowland stream to assess and map the spatiotemporal variability of stream infiltration
An innovative field setup and a new methodology was developed to remove ambient temperature variations from the raw temperature signal
Results suggest relatively homogeneous streambed properties and show remarkable stability of hyporheic flow during few years |
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| ISSN: | 0043-1397 1944-7973 |
| DOI: | 10.1029/2023WR035475 |