Spatiotemporal Variability in Transport and Reactive Processes Across a 1st- 5th Order Fluvial Network
Abstract
Fluvial networks integrate and transport constituents from terrestrial and aquatic ecosystems. To date, most research on water quality dynamics has focused on process understanding at individual streams and, as a result, there is a lack of studies analyzing how small-scale, physical and biogeochemical drivers scale across fluvial networks. We performed tracer tests in five stream orders of the Jemez River continuum to quantify reach-scale hyporheic exchange during two different seasonal periods to address: how do hyporheic zone contributions to riverine processing change with space and time? And does the spatiotemporal variability of hyporheic exchange scale across fluvial networks? Combining conservative (i.e., bromide) and reactive (i.e., resazurin) tracer analyses with solute transport modeling, we found a dominance of reaction-limited transport conditions in space (for all stream orders) and time (two contrasting flow regimes). Moreover, we found a trend toward more reaction-limited conditions with increasing discharge across all stream orders. We found that our studied fluvial network did not consistently follow the expectations of decreasing hyporheic exchange contributions with increasing stream order previously suggested by modeling, but we found that reaction rate coefficients, volume-averaged processing rates, and effective processing rate significantly varied with increasing discharge. Our findings suggest that knowledge transferability of hyporheic zone processing along fluvial networks follows scaling expectations for reactivity and materials processing. Improving catchment scaling relationships requires further study of network-wide spatiotemporal variability.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H12I..18G
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 1830 Groundwater/surface water interaction;
- HYDROLOGY;
- 1871 Surface water quality;
- HYDROLOGY